Autumn 2011

PRINT POST APPROVED NO 768108–00002 ISSN 0818–5522

The world’s best salmon?

Biofloc boost for prawn farms

Barra Gold wins medals and fans

Flat oysters’ expanding markets

Native fish’s thinking pioneer

Tropical rock lobsters’ 2nd generation

Sand filtration by marine worms

Microalgae biotechnology push

Volume 25 No 1 – Autumn 2011

1Autumn 2011 | Austasia Aquaculture

RESEARCH

Microalgae biotech provides ‘green’ diversification 32

Second generation tropical rock lobster produced in Australia 37

Marine worms to assist sand filtration of mariculture effluents 39

Quantification of alkaline phosphatase in phosphate limited barramundi ponds 42

TECHNOLOGY

Aquasonic is focused on energy efficient technology 44

Contents

Editor-in-chiefDr Tim Walker

Regular contributorsDavid O'SullivanJohn Mosig

Subscription/editorialAustasia AquaculturePO Box 658, Rosny, Tas. 7018Ph: 03 6245 0064Fax: 03 6245 0068Email: [email protected]

AdvertisingMegan Farrer

Design/typesettingCoalface Production Pty Ltd

Prepress & PrintingGeon Group

Copyright © by Austasia Aquaculture. Contents cannot be reproduced without permission. Statements made or opinions expressed are not necessarily those of Turtle Press Pty Ltd (ABN 98 506 165 857).

Austasia Aquaculture magazine (ISSN: 0818 552) is published by Turtle Press Pty Ltd (ABN 98 506 165 857) for the promotion of aquaculture in the Australasian and Asian regions – inclusive of farming in marine, freshwater, brackish and hypersaline waters. Reader's contributions are encouraged on the clear understanding they will be subject to editorial control and, if accepted, will appear in both printed and online versions.

Cover photoA montage of photos taken from stories contained in this issue. Captions and photo credits as per the details inside.

FARM PROFILES

The World’s Best Salmon? 3

Environmental certification and biofloc technology boost prawn farm profitability 8

Quality and service wins for Barramundi Gold 12

Flat oysters finding expanding markets 16

FEATURE

Thinking out of the square with native fish 22

Seafood High Schools prepare students for a fishy career 26

Trout fishers work to support endangered native fish 28

www.AustasiaAquaculture.com.auwww.AustasiaAquaculture.com.au

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2 Austasia Aquaculture | Autumn 2011

Aireng 33

Ajay & Duraplas Tanks 11

AquaFauna Biomarine 33

Aquahort 36

Aquasonic Inside Front Cover

Aquatic Diagnostic Services International 35

AQUI-S 20

Austasia Auqaculture Subscription 32

BGB Marine 30

BST Oyster Supplies 19

Fresh By Design Group Outside Back Cover

HR Browne & Sons 43

Murray Darling Fisheries 15

Quinntech P/L 40

Ray White – Fish Farm For Sale 35

Seafarm Systems 38

Seapa 43

Sydney Fish Market 21

Technolab Marketing 25

TTP Plastics by Design 41

Uarah Fisheries 20

The Market Place Inside Back Cover

Abalone Farm for Sale, Aquabuild,

Aquaculture Services Australia, AQUIS NZ,

Baseline, Midland Insurance Company

www.AustasiaAquaculture.com.auwww.AustasiaAquaculture.com.au Advertisers Index


FA R M P R O F I L E

The World’s Best Salmon?

Owned and managed by Peter and Frances Bender, Huon Aquaculture

(HA) is a great success story for aquacul-ture in Australia. Established in 1985, HA now produces each year more than 10,000 tonnes of Atlantic Salmon (Salmo salar) and around 1,000 tonnes of Ocean Trout (Oncorhynchus mykiss). Over the past five years the business has grown at an average rate of 25 per cent per annum and now employs more than 350 people across Australia.

Like most other salmon farmers, they mostly ‘just kept their heads above water’ during the period 1998-2002 when all of the industry suffered from poor salmon growth. Selective breeding and an R&D

Through this period of rapid business growth, Huon has maintained its repu-tation for growing the biggest (5+kg head-on-gutted, HOG) and best Atlantic salmon.

State-of-the-art technology & facilitiesOne of the hallmarks of the company has been its reinvestment of profits back into the business.

HA has seventy-one 100/120m and fifty-six 160/168m circum-ference Plastic Fabrications pens in over 600ha of leases located in the Huon River and D’Entrecasteaux Channel (south-east Tasmania) and in

program focussed on improving health and nutrition has seen salmon growth and survival rates increase significantly at HA.

The farm originally focussed on contract growing for other salmon companies in Tasmania specialising in ‘early fish’, pro-viding large fish earlier than the other companies could achieve. The market demand for HA fish grew strongly and in 2004 the Benders introduced their own Huon Aquaculture Company label. In 2006 they bought the existing Springs Smoked Seafood business and started supplying branded salmon products through to the end consumer. In 2008 all company products were relaunched under the Huon brand.

Huon Aquaculture is Australia’s second-largest producer of salmon, supplying both national and international markets with over 10,000 tonnes of consistently high-quality product. The company’s operations have many examples of world’s best practice and the premium prices show the respect the market has for the Huon Aquaculture Company labelled products.

Beautiful fresh, premium Huon salmon. These fish are around 3-4kg.

Peter and Frances Bender, owners and operators of Huon Aquaculture, producing some of the best Atlantic Salmon in the world.

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Macquarie Harbour (western Tasmania). Since 1992 AQ1 automated feeding sys-tems have been used exclusively on all production pens.

Gill amoeba is one of the continuing challenges to farming salmon in the south of Tasmania. This single celled animal clogs up the gills preventing the fish from efficiently obtaining oxygen. If left untreated Amoebic Gill Disease (AGD) can result in stock losses of 80-90% in summer.

The remedy is to bathe the fish in fresh-water every 30-100 days depending on the time of year, a total of 6-8 times over the production cycle. This is an expensive process – of 100 people employed on HA farms, 60 are involved in bathing and support infrastructure. It is also stressful for the fish and will reduce their feeding activity and increase the risk of mortality.

HA have developed a novel fish lift system for use during freshwater bathing. Their Fish Race allows up to 1.2 tonnes of fish to be lifted 2m so they can be ‘gravity fed’ into a new pen lined with tarpaulins holding freshwater. The fish are gently lifted out of water; they are in the air for less then 12 seconds, before sliding into the freshwater bath where they remain for up to four hours.

Built with the aid of 50% AusIndustry grant funding, HA believe it is the largest

naturally convincing the fish that it is the wrong time to breed. The fish then continue to grow and do not produce secondary sexual characteristics that can downgrade flesh quality.

HA always has two year classes in the growout phase. This allows continuous year round supply. The year classes are kept geographically separate to best utilise lease space and maximise biosecurity.

Environmental and risk managementHA don’t have a formal EMS in place; however, they use a range of measures to manage environment related issues associated with its operations. This includes best practice in:

• fish health and feeding management;• fallowing of sites between growing

cycles, usually for at least six months so any build up of fish wastes are broken down, and

• careful control of the use of antibiotics – usage rates are provided to the DPI.

HA also participate in the Tasmanian Broad-Scale Environment Monitoring Program, which provides for independent assessment of water and sediment quality in reference sites close to their marine finfish farms.

The smolts are either stocked in upriver (brackish water) sites or directly into the marine sites in cohorts of 50,000 fish . As the fish grow and their feed demands increase, they are transferred into larger pens and moved down river to open water leases (the fish can be moved up to 90km during the production cycle).

The large growout pens can hold over 200 tonnes of fish. This innovative strategy ensures appropriate nutrient input in the lower energy upriver environments that are not scoured so regularly with tidal movement. The highest nutrient inputs are in the largest fish classes located in the deeper waters near the river mouth where ocean swells provide substantial scouring on the river bottom.

HA have developed strong in-house fish health monitoring and management protocols overseen by fish vet Dr Steve

fish elevator in the world. With the special HA raceway, up to 100t/hr of fish can be moved versus only 60t/hr with a fish pump. For 25,000 fish moved, the Fish Race will only lose 1 or 2 fish, with other systems 30-40 fish can be lost and even more damaged.

HA has a 18% share holding in the SALTAS salmon hatchery located at Wayatinah in central Tasmania. But it has its own state-of-the-art freshwater hatchery too a short trip away from the sea pen farm; this includes an ultra-modern recirculation unit designed by Billund Aquaculture. Bore water is used and the small amount of waste water is sent to irrigate adjacent plantation land. The facility can produce more than 1.8 million smolts (100g, range 80-130g) per year; usually availa-ble from around April to November.

In 2009 HA bought the Springfield hatch-ery group (northern Tasmania) adding a further capacity of 1.6 million smolts.

At 11-18°C the Tasmanian growing waters are the warmest in the world for salmonid culture, so a fast growout time is achieved. HA aim for an average market size fish of 4kg (3-5kg) which can be grown from smolt-stage in 12-14 months. There have been some problems with early maturity of stock, so the farmers prefer to harvest fish before their second summer in the sea. R&D has shown that photoperiod manipulation can delay maturation by

Management MetricsKey Management Decisions for Huon Aquaculture include:

• Certification: BRC (international) Food Safety certification, GlobalGAP (under application), AQIS (Export)

• Fully integrated from hatchery, smolt, growout, primary processing and value adding

• Reinvestment of profits to achieve goals through innovative technology.

Key Performance Indicators (KPIs) include:• Culture or Holding System utilised: Plastic Fabrications sea pens• Growth rate (from stocking to market): 12-14 months (100g to 4.5kg)• Survival rate: 90% from first stocking to sale size• Av. stocking density: 8kg/m3 in summer, 12kg/m3 in winter• Annual harvest: 10,000 tonnes • Production rate: 30 tonnes/ha (growout system area) per year • FCR: 1.4 (number of kg of food to produce 1kg stock) • Productivity: 30 tonnes per Effective Fulltime Unit (240 days, 48wk x 40hr).



Percival, which means that they can undertake their own screening for AGD and other pathogens. Fish samples can be also sent to DPI’s Mt Pleasant Labs (Launceston) or other analytical labs for specialist screening for virus or other potential pathogens.

A series of eighteen trial pens (5m x 5m) are in continual use to undertake exper-iments on diet formulation, vaccines, other fish species (eg. Striped Trumpeter Latris lineata), light and dark regimes for combating maturation, and so on. Whilst operating these units increases costs, the benefit is having the facilities that allow research in an identical environment to HA production fish. The small numbers of fish in each pen means that work that would be too risky or complex to attempt in full scale production can be confidently undertaken.

Selective breeding has been a late devel-opment for the Tasmanian Atlantic Salmon industry. The delay in implementing this approach to improving production effi-ciency was primarily due to concerns over in-breeding as a result of the relatively small number of stock introduced into Tasmania during the 1980s to start the industry. HA started their mass-selection breeding program in 2002 and the industry (SALTAS/CSIRO) program started in 2004. The initial generations from these programs are showing improved resistance to AGD and better growth performance.

Seal predation has been a major problem for stock in sea pens. One seal can kill 300-500 fish in a single day by simply sucking out the livers of fish caught through loose netting; the most vulnerable time is when fish are in the swim-through tunnel from their ongrow pen to harvest raceways. Seals are protected so the farmers can’t harm them; in the past they have been trapped and relocated to Bass Strait, however, this was not successful as the seals quickly returned to the pens.

A number of non lethal measures have been tested to minimise fish losses. Exclusion methods are continually being improved as seals find their way around

six weeks. The nets can be cleaned in situ by a specialised Tasmanian-designed net cleaning boat. Alternatively the fouled net is taken ashore and soaked in freshwater pits to reclaim the copper and wash off the fouling. This work is now undertaken by a local contractor which has reduced the cost of antifouling the nets by 30%.

Trials are underway to reduce and elimi-nate the use of antifouling paint whilst maintain the benefits of improved water

the defences. Underwater HA deploys very tight, very thick, dual net layers with a thick (40mm) anti-predator ‘China’ net to prevent the seals from pushing in the netting and catching fish. Above water 2.4 metre tall outward leaning fences prevent seals from climb-ing into the pens.

To reduce the need for regular net changing, copper-based antifouling is used on all predator netting which can mean an additional usage time of four to

Aerial shot of part of Huon Aquaculture’s salmon farming operation.

The beautiful waters of southern Tasmania – where Huon salmon is grown.



flow and low structural weight.

Optimal feeding is vital for good fish growth; large fish need one feed/day whilst the smolts require up to six per day – this means that HA can be feeding more than 700t/week at peak biomass. Using pellet sensors, backed up with underwater cameras and solar powered smart feeders, HA feed to satiation to get the best growth; they don’t focus on FCR, although they regularly have FCRs between 1.3–1.45 using a 20MJ diet with varying protein content to match fish requirements. The farm uses Ridley and Biomar feeds.

HA have found the best strategy is to have good water flow through larger mesh nets, regularly cleaned and a lower fish density. As water temperature increases and dissolved oxygen falls below 5.5mg/L in the centre of the pens, the feeders can add bottled oxygen through perforated grid inside the pens to support metabolic requirements of the fish and allow feeding.

The AQ1 Smart feeding technology is used to optimise fish feed consumption and reduces the wastage of aquaculture feeds. These units consist of a floating silo which can hold up to 6 tonnes of feed with spinner and underwater sensor. The pens are all bird netted to prevent birds taking pellets.

A 168m pen full of fish can use up to 3 tonnes of feed a day. In mid 2007 a new 100 tonne feed boat, Zeus, was introduced. Zeus can resupply 10-16 pens each trip. Feed is stored at Port Huon pier which is also the location of HA’s workshop where Zeus was built.

Harvest and processingFor harvest, the growout pens are towed in at one knot into the more sheltered Hideaway Bay; some pens might take 60hrs to reach their destination. The tow boat is set several 100ms away from the pen to avoid the wash from the pro-pellers stressing the fish.

The fish are transferred into either of two 480m3 raceways; together these can hold 200 tonnes of fish which are purged for 2-4 days. These harvest raceways have thick knotless nets to keep out the seals

Marine scientists are trialling the first near-shore water temperature forecasts to assist Australia’s aquaculture farm managers contending with rising ocean temperatures.

While land farmers have used seasonal forecasting for nearly a decade, marine farmers in south-east Australia have sought the technology for a region identified as a climate change hotspot, with rates of ocean warming up to four times the global average.

CSIRO Climate Adaptation Flagship scientist, Dr Alistair Hobday, said the project, funded through the Fisheries Research and Development Corporation, is a response to requests by Tasmania’s four major salmon companies for short-term ocean forecasts for their farm sites.

“Marine farms in this region, particularly south-east Tasmania, want to use all available resources to ensure proper planning and response measures are in place to combat against the warmer summer months which can have adverse effects on fish performance,” Dr Hobday said.

“While adaptation to long-term change is seen as important by the sector, dealing with climate variability exacerbated by ongoing climate change is a more immediate need.

“Our objective is to provide marine farmers with forecasts at their salmon farming

sites up to four months ahead. This will enable management to consider a number of responses that will help main-tain industry profitability in an uncertain environment. It should also help this valuable industry to come to terms with long-term climate change and begin formulating adaptation strategies.”

The trials began in September last year, with forecasts provided to Tasmania’s four major salmon farmers each month. Historical data back to 1990 and a seasonal ocean-atmosphere model developed by the Bureau of Meteorology are being used in the predictions.

An associated cost-benefit analysis of the predictions applied to each site also will be generated. The project involves trialling advanced statistical techniques to determine how well scientists can resolve the variations at the different time scales.

Dr Hobday said warm summers can significantly impact farm production through an increase in operational expenses and direct impacts on salmon, while cool winters slow growth in salmon.

He said validation of the forecasts using historical data is improving their accuracy and illustrating the likely benefits to the industry.

For further Information contact Dr Alistair Hobday, CSIRO Marine & Atmospheric Research. Ph: 03 6232 5310 Email: [email protected]

The first near-shore water temperature forecasts are being developed to assist Australia’s aquaculture farm managers contend with rising ocean temperatures.

Trialling ocean temperature forecasts for fish farms


and also prevent damage to the fish. They are also supplied with aeration to main-tain dissolved oxygen levels.

The actual harvest takes place at night. The salmon are sucked through a 40cm wide intake pipe of the Transvac triple chamber vacuum fish pump (this model is the largest in world). Over the night there is a continuous flow of up to 100 tonnes of fish into a battery of automatic stunner machines (made by Seafood Innovation, Qld) which humanely kill the harvested fish and then automatically bleed them to maximise quality. This system means that the fish are killed with little stress and it takes about eight hours before rigor sets in.

The fish are transported in ice slurry-filled, 1-tonne plastic insulated bins on trucks for the five hour trip to their pri-mary processing factory at Parramatta Creek near Devonport; this facility has a daily capacity of 150 tonnes of HOG, 25 tonnes of fillets.

Fish are gutted using a Baader vacuum type system, a manual ‘hand’ line is also used when caviar is being collected during late summer. A Marel weighing system that links a computer with the daily orders to a scale and label printing machine allows for easy packing and tracking of order fulfilment. The HOG fish packed in plastic bags and ice are sent to market in Huon labelled boxes. Harvesting at night coupled with same day processing and sea freight means fish are available for sale in Melbourne or Sydney the next day, the freshest salmon in the world.

Second quality fish are graded for filleting. A Carnitec automatic filleting machine and Marel trimming machine enables four tonnes of fillets to be produced per hour of operation. The fillets are either individually vacuum packed or sold loose in 18kg cartons; most go to HA’s value-adding smoked salmon operation but an increasing amount go to domestic and export customers.

The internationally recognised BRC’s (British Retail Corporation) food safety certification is difficult to achieve, and few companies are certified at their first

strong commitment to ongoing Research & Development as an essential tool for peak performance,” he said. “We con-stantly strive to turn our research into practical on-farm innovations, to keep us ahead of our competitors.”

A major focus of the company was to become vertically integrated. “We are no longer reliant on others for seed stock, and our purchase of Springs Smoked Seafoods in 2005, has seen the company enter new market segments that previously weren’t open to us.”

“With the catch of all wild fish declining around the world, while the demand for fish and seafood continues to rise, Huon Aquaculture’s future looks bright,” Peter said.

The Huon product is particularly sought in Japan where it is sold branded in many large Japanese department store food halls and supermarkets. It is recognised in Australia as the premium fresh product by wholesalers, retailers and chefs through-out the country and appears on many significant restaurant menus by name.

There is no doubt that HA will continue to be a successful, growing and dynamic business.

By Dos O’Sullivan

For more information contact Frances & Peter Bender, Huon Aquaculture Company, PO Box 1, Dover 7117. Tel: 03 6295 8111, Fax: 03 6295-8161email: [email protected]

audit. However in August 2010 a BRC auditor checked the systems and processes at the processing facility at Parramatta Creek and found they complied with every one of the 332 items in this most rigorous standard. HA are the only ‘A’ rated seafood processor in Australia. To receive this world class A rating with no non-con-formances within four months of opening a new facility is something HA and its staff are justifiably proud of.

HA are lining up further accreditation with GlobalGAP – this certification will cover the farming operations from egg through to harvest fish embodying Huon’s commitment to continuous improvement and quality.

Awards, awards, more awardsThroughout the years HA has been con-tinually successful with its range of fresh and value added products.

In 2010 HA was selected as a finalist in the prestigious ‘President’s Medal’ section of the Sydney Royal Show. The field of 5,000 food and beverage products was narrowed down to just six products. HA’s unique Banquet Slice (a fillet length slice of premium cold smoked salmon) was judged against such Australian food giants as The Yalumba Winery, Bulla Diary, Peter Lehmann Wines, T& R Pastoral and Holy Goats Cheese. This same product went on later to win the Perpetual ‘Richard Langdon’ Trophy at the Hobart Royal Fine Food show with a perfect score of 100 points.

In 2007 Peter was one of the Australian winners of the Ernst & Young Entrepreneur of the Year Award. Peter received the award in the Retail, Consumer & Industrial Products category. The Entrepreneur of The Year celebrates entrepreneurs who are building and leading, recognising them through regional, national and global award programs in over 100 cities and more than 40 countries.

Peter dedicated the award to his wife Frances and all Huon Aquaculture staff, and said the company’s success had been built on attention to detail and innovation. “Since inception, we have maintained a

Huon Hot Smoked Salmon Italian Frittata.



A north Queensland prawn farming company has been leading the charge for Aussie prawn farms to be more sustainable. In 2006 it attained ISO 14001 certification for environmental management; one of the first prawn farms in the world to achieve such recognition. Applied research into the use of biofloc in their ponds has also contributed to considerable increases in profitability.

Environmental certification and biofloc technology boost prawn farm profitability

A three-year research project funded by the FRDC and the Seafood Cooper-

ative Research Centre through the Australian Prawn Farmers Association (APFA) examined the use of bioflocs to allow low water exchange culture of prawns.

Biofloc technology combines the control of water quality – by removing waste nutrients from the ponds – with the production of a microbial community which can be used by the culture spe-cies as an additional food source.

undertaken at Australian Prawn Farms (APF), an hour south of Mackay in north Queensland. In November 2006 APF became the first Australian prawn farm to achieve ISO 14001 (environ-mental) certification, one of the first to do so in the world.

According to Farm Manager Matt West, APF was one of the five farms involved in an eco-efficiency program funded by the Federal Department of Environment & Heritage and coordinated by the APFA. “We believed this was an

The main focus of this research was to

determine if these innovative methods

increased on-farm profitability.

Did it ever! The results are extraordinary:

• an 80% decrease in pumping costs• FCR reduced by 25% from 1.8 to 1.2• Saving with a good floc can be 3

tonnes of feed/ha• Nutrient discharge down 65%• Productivity increase from 8t/ha/crop

to 12t/ha/crop.

This remarkable research was

The proud ‘boys’ at Australian Prawn Farms show off their award winning prawns. Photo courtesy of Aust Prawn Farms.



important initiative to help us improve our environmental management prac-tices. It shows how committed APF are to environmental sustainability. And even though there are no current finan-cial benefits of having ISO 14001 accreditation, it does open up potential future markets,” he says.

The farm grows Black Tiger Prawns (Penaeus monodon) in 33 one-hectare ponds; the facility also includes a large modern hatchery, a HACCP-certified onsite processing plant and a 20ha set-tlement system built to reduce the release of suspended solids, total nitro-gen, and total phosphorous. As part of the EMS, fortnightly tests on effluent are carried out to ensure the efficiency of the settlement ponds and compliance with Government regulations. APF has built up a good rapport with the regula-tory agencies and prides itself on con-stantly improving its system to better the environment.

“Our company’s approach to reduce environmental pressures is very proac-tive, which is why implementing an EMS (environmental management sys-tem) to achieve and maintain our ISO 14001 accreditation was very important,” Matt explains. “The system gives us an important tool to undertake a compre-hensive review of our efficiency throughout the entire workplace, through identifying certain environmen-tal risks and having a documented approach to deal with them.”

Biofloc productionThis management system put the com-pany in an excellent position to critically examine options for innovative produc-tion practices and the environmental risks associated with these. “I was forced into alternative methods of culture at a site with good water quality but limited availability at times. This led to limited water exchanges with an ever increasing pressure of higher production.”

Dr Dave Smith, as part of the CSIRO Food Futures Flagship, oversaw the research at APF which used five of APF’s commercial ponds operating under an

Key Management Decisions for Australian Prawn Farms include:• Certification: Environment ISO 14001, HACCP• Use of EMS systems to improve environmental performance as well as assess

other innovative process• Commercial scale research into biofloc production• Time spent in providing extension of the research to industry.

Key Performance Indicators (KPIs) for biofloc ponds include:• Culture or Holding System utilised: 1ha earthen ponds with biofloc• Growth rate (from stocking to 20g): 1.4g/week• Survival rate: 80% from first stocking to sale size• Av. stocking density: 50-60 PL/m2 (first stocking)• Production rate for test ponds: 12t/ha/crop, average farm production: 11t/ha• Water use: significant recycling, nutrient discharge down 65%• Power use: 80% decrease in pumping costs• FCR: 1.2 (number of kg of food to produce 1kg stock), savings up to 3 tonne

of feed/ha

Management Metrics

Aerial view of the growout and settlement ponds at Australian Prawn Farms. Photo courtesy of Aust Prawn Farms.

Mixing up the biofloc in the prawns ponds. Photo by David Smith, CSIRO



Silica was added at rates to maintain lev-els greater than 1mg/L after week 2 when the PLs are introduced. Given the importance of the phosphorus for pri-mary production, the levels of this nutri-ents were kept at >0.1 mg/L. With sun-light this process resulted in very high blooms of large diatoms, a favourite feed of the prawns and an excellent seed for floc development.

Both inorganic and organic sources of carbon are important for the bioflocs. Crushed limestone, or sodium bicarbo-nate, provides an inorganic carbon for microalgae (such as the diatoms) and autotrophic (self-feeding) bacteria. Measured as Total Alkalinity, the best range is between 80-120 mg/L. The project found that neither hydrated lime nor sodium carbonate is directly suita-ble for the maintenance of bioflocs, but hydrated lime is used to keep pH in the range suited for good autotrophic bacte-rial growth.

Matt said that a good floc would cause Total Alkalinity to drop so the farmer needs to keep adding sodium bicarbo-nate to maintain the optimum levels.

Heterotrophic bacteria don’t use sun-light; rather they use ammonia for their energy production. Thus organic carbon sources such as molasses, bagasse (cellu-lose-based by-product of sugar cane production) or even dead algae can be used to increase their production; how-ever, the best results were achieved with molasses. “Care needs to be undertaken with the addition of molasses as it is expensive and it can result in hetero-trophic bacterial blooms which in turn can lower dissolved oxygen.”

If a stable environment is maintained then there can be great nutritional bene-fits for the prawns as they exhibit less stress and use less energy. Matt found that FCRs around 1.2 to 1.3 were recorded; a poor floc or normal feeding usually results in FCRs in excess of 1.6. “This can mean that with a well main-tained floc the savings in a one hectare pond can be over three tonnes of feed during a 136 day production cycle. The

intensive monitoring program. The project had six aims:

1. Confirm nutrients needed to establish and maintain the floc.

2. Establish the effects of different sources of carbon for the floc.

3. Determine the nutritional benefits to the prawns using FCR.

4. Assess changes in the levels of nutrients in farm discharge.

5. Calculate the influences on farm profitability.

6. Extension to industry.

The results were presented at the 2010 annual APFA conference and exhibition to an engrossed audience.

A range of phosphorus and silicate ferti-lisers were tested to determine which was the most efficient at establishing early diatom blooms, the key to floc production. A process was developed which started with the addition of 20kg Urea and 7kg MAP per hectare in a recently filled pond. This resulted in an increase in pH to 9 within two weeks.

Annual ReviewAPF conducts annual reviews which include assessment of the following practices and procedures:

• Maintenance records (eg vehicles, equipment, bins, down time, accidents, fuel usage and electricity)

• Feed use and feed use monitoring systems

• Water usage and water monitoring

• Communications (e.g. on the farm and between farms)

• Disease management and monitoring

• Disease response• Emergency Action and

Response Planning• Daily task lists• Induction and training

verification systems• Administration efficiencies• Recycling and re-use.

Above: Some of the settled biofloc sampled from a growout pond.

Left: A drained biofloc pond showing the clean substrate left following harvest. Photos by David Smith, CSIRO.



normal feed amount is around 16 tonnes/ ha/crop, so the farmer can reduce his feed bill by over $6,000/ha/crop.”

Significant decreases in nutrients dis-charged were also recorded. For example Total Nitrogen discharge in 2003/04 was 41kg for every tonne of prawns harvested; the floc reduced this to 9.4kg/tonne in 2008/09.

Matt says that the floc also increases the management options for the farmer. “During heavy rain the prawn farmer can’t exchange water even though this can lead to increased ammonia levels which in turn reduce production in a normal pond. In a floc pond the ammo-nia is used by the bacteria which in turn become food for the prawns.”

Significant increase in profitabilityThe five test ponds performed signifi-cantly better than the other ponds that were operated using conventional prawn farming techniques. Average harvest increased from 8t/ha/crop to 12t/ha/crop. At a farm gate price of $10/kg, this results in an increase in market sales of $40,000/ha; at $15/kg the extra profits could be greater than $60,000/ha/crop.

Matt found that slightly more labour was required to initiate and maintain the flocs as well as analysing water quality; the extra cost was around $1-2,000/ha. “On a large farm (say 40-60ha) this job could not be handled by one person.”

Stocking densities of PLs have also been increased from 30-35/m2 to 50-60/m2, which Matt says also boosted pond pro-ductivity. “In Belize, where this technol-ogy was developed in the early 2000s, they stock white shrimp (Litopenaeus vannamei) at 180PL/m2; however, they produce 25g prawns, whereas our Black Tigers average closer to 30g.”

Matt is well aware that different species exhibit different behavioural characteristics which is important when considering adopting different techniques. “Vannamei inhabit more of a 3-dimensional space, whereas Monodon are more 2-dimen-sional bottom dwellers. This difference

identify the challenges to implementing

the strategies needed to undertake

Biofloc technology.”

At least three major farmers are now

using bioflocs on their farms.

Research is now underway to fine-tune

the process as there are a number of

things which still need to be worked

out. The first is the uncertainty about

how best to establish the diatom bloom

at the start of the crop. The application

of molasses is another area as well as the

continual maintenance of the appropri-

ate levels of silicates and phosphates.

As with the previous results, this highly

successful research will be communi-

cated quickly to industry.

By Dos O’Sullivan.

For more information contact Matt West, Australian Prawn Farms Pty Ltd 12, Lot 12, Notch Point Rd, Ilbilbie, QLD, 4738, T: (07) 4950-3111, 0428 457-787, E: [email protected]

Dr David Smith, CSIRO, 07 3826-7239, E: [email protected]

leads to reduced stocking densities and thus lower nutrient loads (for Monodon ponds) which require a slightly different way of ‘low water exchanges’.”

Industry workshopsMatt and APFA have been extremely active in ‘spreading the word’ through phone calls to answer questions to farm visits to demonstrate the process or trouble shoot. Presentations have been made at the annual APFA conferences from 2008 to 2010.

In conjunction with the Sunshine Coast Institute of TAFE (SCT), a two day industry workshop on Biofloc was run in Townsville in May, 2010. Attended by many farm and pond managers and technicians, the workshop aimed to develop changed management strategies for the implementation of Biofloc tech-niques on prawn farms.

Organiser Stuart Whitney said the work-shop demonstrated the management practices implemented and lessons learned during APF’s Biofloc grow out cycles. “The delegates were able to assess the capacity of their farms and

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Barramundi Gardens, winner of a gold medal for large Barramundi at the Spring 2010 Sydney Royal Show Fine Foods competition, is reaping the benefits of a focus on quality products and customer service that’s ‘second to none’. The farm has just launched the Barramundi Gold brand name and is gaining more customers for its delicious Barramundi spring roll.

Quality and service wins for Barramundi Gold

Tim and Gail Thiele, along with their

extended family and three young boys,

have been running Barramundi Gardens

since 2002. Located in the Port Douglas

hinterland, only 25 minutes drive from

the vibrant tourist town, the six hectare

property offers a diverse range of products

and activities. The farm was featured in

AA in March ’09 (Vol 23.1).

“Of course we’re also locally famous for our ‘Barramundi Spring Rolls’ which are distributed nationally.

“Our hydroponic lettuce, Asian greens and herbs are grown for local wholesalers, retailers and restaurants. Growing our own produce to include in our spring rolls is the added bonus which not only cuts costs but gives us total confidence in our ingredients.”

The barramundi growing process begins with 25mm fingerlings purchased from hatcheries around north Queensland. The fingerlings are grown to around 100-130mm (10-25g) over 8-10 weeks in the nursery – consisting of 48 x 400 litre tanks, four1,000 litre tanks and six 5,000 litre tanks. These small fish are fed GroBest barramundi pellets three times a day.

“Our fingerling nursery is a fully closed recirculation system that pumps 50,000L/hr. We have a drum filter to remove solid waste, a 5,000L capacity biofilter to remove ammonia and nitrites, a polygey-ser, ozone and oxygen generators which inject ozone into the system and UV lights for sterilisation. We purchased this system from Aquasonic.”

The pond water comes in through 6 inch PVC pipe from a header dam which is topped up for evaporation losses by a spring fed creek flowing from neigh-bouring rainforests.

There are12 growout ponds, each 0.1ha in size and up to 2m deep. Each pond has a 2.5HP double paddlewheel to maintain water circulation. Water quality is main-tained by a weekly 20% water exchange into a settling ponds. “The settling pond acts as a natural wetland ecosystem which purifies the water before being held in the header dam.”

After the nursery stage the fish are first stocked in 6 x 3m floating PVC pontoons with a 1-1.5m deep hanging net. Once

“We’re constantly working to improve the quality of our products, expand our range and ensure a friendly customer service,” explains Tim. “We have a commercial 2ha aquaculture farm, a 50m2 fingerling nursery and a 150m2 hydroponic produce complex. Each year we can produce up to 45 tonnes of Barramundi from pan size to large whole (and fillets) and sell over 200,000 fingerlings to local farms.

Looks good enough to eat a dozen! The famous Barramundi Spring Roll.



the fish reach 100-150g (200mm+), they are released to free range in the ponds. To prevent predation from shags and night herons, the ponds are netted with bird netting held up with poles located in the centre of the pond and attached to the ground with star pickets.

Tim says that the pond fish are fed Ridley’s floating barramundi pellets in the mornings. “We do this in the mornings to maximise the optimum dissolved oxygen level throughout the day.”

Once the fish exceed 300g Tim removes the netting as the fish are now too big for most predators. However there is a local sea eagle that will take the occasional bigger fish.

Fish are harvested depending on orders with a 30 metre fish net. They are mustered to one end of the pond and then moved quickly to a bin with an ice slurry. These are transported to the packing facility.

The Thieles once ran a sports fishing tourist facility in one of their ponds. “We started the Barramundi Sports Fishing Park back in 2004,” Gail says. “This proved to be extremely popular with people from all ages and parts of the world enjoying the opportunity to get up close and personal with the world renowned barra. Both professional fishermen and recreational fishers came here to enjoy the prospect of bringing home the big one (we stocked fish between 4-5kg) and making sure they don’t have a story to tell about ‘the one that got away.’”

But they closed the fishing park two years ago to concentrate on growth of other aspects of the business. “The sports fish-ing/ tourism potential is an avenue that we intend to go back into in the future.”

Processing plantBarramundi Gardens has a HACCP accredited processing plant. “We have been third party certified since 2002,” Gail says.

“We also are audited annually by Safe Food

Queensland and have a food manufac-

turer’s licence with the Tableland Regional

Council. So we can show that we are

committed to all aspects of food safety.”

The Thieles sell barramundi year round.

Most of the fish are sold as whole chilled

(0.2°C) fish to wholesalers in Sydney and

Brisbane. “We also offer a 5kg shatter

pack (fresh or frozen) of fillets between

800g and 1.2kg and pan size gut’n’gilled

barramundi. Fish are packed in 20kg

polystyrene foam boxes with ice packs

Asian Greens and Lettuce are grown at the hydroponic facility.

Healthy fingerlings grown in the nursery shed.

Chris, Sandra and Tim in their popular

Barramundi Gold stand at Master Chef

Live Event held last December in Sydney.

All

phot

os c

ourte

sy B

arra

Gar

dens

.



or bulk half-tonne bins for transporting

by road to customers.”

Barramundi Gardens also manufactures

a wide range of spring rolls and dump-

ling products for the Crazy Dragon

Gourmet Food Company which

and the best’ Barramundi Spring Roll. “By combining locally grown produce and our own finest barramundi fillets we have created a unique Spring Roll that surpasses all taste expectations. The individually handmade, rolled and created spring roll cannot be matched with its superior quality ingredients, finest taste and uni-form presentation. Our product is a must for every restaurant wanting to offer an Australian product of such high quality.

“In 2004 our spring rolls were awarded the endorsement as one of Queensland’s Fine Foods through the Les Toques Blanches Queensland Chapter. Since then our spring rolls continue to offer the highest quality product in taste and presentation that Executive Chefs from many establishments are proud to offer on their menus throughout Australia.

“Repeat customers and new restaurants show we have a great product.”

Gail is quick to point to the synergies of these two parts of their business. “The processing is a part of the business which is continually developing and expanding and we are enjoying the ride that it is taking us on, diverging from the traditional primary producer and value adding our products at the same time. Both are successful due to our attention to quality and customer service. Our aim, as for is most small business, is to be able to get a better price at the farm gate for our aquaculture and its products.”

Barramundi Gold & Master Chef LiveThe Thieles entered an 18month old barramundi in the Sydney Fine Foods Spring ’10 competition – the section was for 2-4kg whole fish. Fish from several farms were all steamed and judged on external appearance and eating quality – texture, sweetness, flavour and aftertaste. Their ‘entrant’ won gold; one other pro-ducer also received a gold medal in this category. “The judges described both gold medal-winning fish as being of ‘outstanding presentation with the high-est quality’ and ‘very well fleshed’.

“We were very happy with this,” Gail says.

wholesales frozen Asian food around

Australia. “In partnership with Crazy

Dragon, we have built a state of the art

processing facility,” Gail explains.

“Using high grade machinery we are able

to manufacture spring rolls and dump-

lings very efficiently. Part of the facility

involves high speed blast tunnels for

freezing of the products. Our facility allows

us to produce approx 2,000 spring rolls

per hour, with them being frozen and

packed within 50 minutes of manufacture.”

No surprise then that she reckons

Barramundi Gardens makes the ‘original

Management MetricsKey Management Decisions for Barramundi Gardens / Gold include:

• Certification: HACCP and consistent quality and customer service• Diversification into other high quality, high turnover products such as

spring rolls, dumplings, etc.• Use of discharge water for hydroponics operations. – research more into

aquaponics, to continue and enhance the links between aquaculture and the horticulture side of the business

Key Performance Indicators (KPIs) include:• Culture or Holding System utilised: 0.1 ha earthen ponds, nursery tanks• Growth rate (from stocking to market): <18 months (2g to 3kg+)• Survival rate: 80% from first stocking to sale size• Annual harvest: 45 tonnes• FCR: 1.2 (number of kg of food to produce 1kg stock)

Untitled-1 1Untitled-1 1 17/11/10 10:44:41 AM17/11/10 10:44:41 AM

A delicious award winning Barramundi.

Barramundi Gold Logo – award winning artwork for the brand.



“The judges also remarked that there’d been significant improvement in the quality of fish supplied for judging over previous years.”

The Gold Medal award underpins the Thieles’ new ‘Barramundi Gold’ brand.

“Our aim is to get our fish well known as high quality in the market,” Gail continues. “Customers can have confidence in our fish as they are grown in rainforest-sourced water. We want to lift the profile of farmed barramundi not only with chefs and caterers but also with the average consumer. We want it to become the fish of choice for everyday Australians wanting to eat quality, great-tasting, Australian-grown fish on a regular basis.

Tim has also exhibited their fish at Sydney’s three-day Master Chef Live show in Sydney last December. Tagged as the ‘Foodies Ultimate Day-out’, the event attracted more than 25,000 hungry and discerning food enthusiasts.

“We were lucky enough to engage the services of Martin, 4th year chef from the Ochre Restaurant in Cairns to help us present our fish,” Gail says. “We sent down around a total of 300kg of fish (average size 2kg) of which some were baked with white wine and other special flavourings.

“We also served Barramundi in a gougon style – deep fried Barramundi fillets in a tempura batter served with lime aioli – and offered a Barramundi ceviche – thin slices of Barramundi ‘cooked’ in a lime, vinegar, chilli, ginger and coriander sauce.

“The Barramundi Spring Roll as usual was a resounding success with a lot of what we call ‘repeat offenders’, people returning for another bite.

“Overall it was definitely worth doing and really raised the overall awareness of our products.”


For more information contact Tim & Gail Thiele, Barramundi Gardens, P.O. Box 159, Mt Molloy Qld 4871, T: 07 4094-1293, F: 07 4094-1434, Email: [email protected]

Location, location, location – paradise at Julatten, north Queensland.

Tim Thiele sending off a fine specimen of ‘Barramundi Gold’ to market.

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Our native Flat oyster (Ostrea angasi) is also sometimes called the Mud oyster or Angasi oyster. Native oysters very closely resemble the Belon oyster (O. edulis), which was previously common in Europe and is now reported to be the most expensive oyster in the world. Our Flat oyster is popular for its fine textured meat, full-bodied taste and distinctive salty flavour. Thanks to hatchery production of spat, some NSW farmers have been growing Flat oysters commercially for about fifteen years and over the past few seasons a grower in SA has been growing award-winning Flats.

Flat oysters finding expanding markets

Sydney Rock Oysters (Saccostrea glomer-ata) on the south coast of NSW and with Pacific oysters (Crassostrea gigas) in South Australia. These oysters reach market size in about 18 months or half the time of Sydney rock oysters. They are also receiving a high farm-gate price of about $9-10 per dozen and are the preferred traditional oyster of people from Western Europe, Asia and New Zealand. Farmers are reporting increas-ing interest in the Flats by chefs at the top end restaurants in Melbourne and Sydney along with increasing prices.

According to Steve Feletti of Moonlight Flat Oysters®, the Flat oyster is the oyster lover’s oyster. On his fantastic website (www.moonlightflatoysters.com.au/) he

writes that the flesh is usually a dull

mushroom pinky brown with a chalky

white in winter. In comparison to Sydney

Rocks, he claims the Flats taste a little

smoky, earthy, like duck compared with

chicken and notes that, whilst some

consumers may have previously found

them challenging due to their texture and

stronger taste, superb handling by some

restaurants is increasing their popularity.

The Batemans Bay oyster marketing

supremo is also quick to point to its

similarities to Europe’s famed Belon oyster,

using recent DNA findings as research

collateral. Surprisingly the Flat Oyster is

closer to the Belon than to the New

Zealand Bluff Oyster (Tiostrea chilensis).

The Flat oyster is endemic to southern

Australia, ranging from Western

Australia (Albany) to southeast New

South Wales (Newcastle) and around

Tasmania. Also known as Angasi, Bluff,

Mud and Belon oysters, Flat oysters are

found in sheltered silty or sand bottomed

estuaries at depths of between 1 and

30m. They actually attach themselves to

hard substrates before later breaking free

to settle on sand or soft mud.

Like all other oysters they are filter feed-

ers, feeding on, and taking in anything

small enough to be filtered in their gills.

This may include plankton, microalgae

or inorganic material.

Flat oysters, are being farmed alongside

An aerial view of part of the intertidal leases at Pristine Oysters. Courtesy of Pristine Oysters



Hatchery basisDue to low numbers and an unreliable wild catch, the NSW Flat Oyster industry has been reliant on hatchery-produced spat (3-5m seed/yr) for the past six years. Most hatchery production comes from the Port Stephens Fisheries Institute (NSW Industry & Development) although a couple of farmers on the NSW south coast have also established small scale hatcheries to meet their own needs.

According to PSFI scientist Stephen O’Connor, Flat oysters brood larvae in their gill cavity for 7-10 days, depending on food availability and water temperature. The larvae are then released for a plank-tonic stage of 7-10 days after which the larvae settle on a suitable surface, adhere and metamorphose into oyster spat.

In the past hatchery production of O. angasi spat has relied on ground scallop shell as a settlement substrate. However this has proven problematic. Given PSFI research (published in Aquaculture Research Vol 40 Issue 14, 2009) showing that epinephrine successfully produces cultchless Flat Oyster spat, such chemical induction is now used for routine com-mercial production.

Stephen has also been researching the effects of larval diets on the energy reserves of the Flat oyster larvae at set-tlement. “During this transitional stage of larval development (from free swimming to benthic) larvae loose the ability to feed and rely on energy reserves accumulated during larval growth,” he says.

“Epinephrine treatment of larvae to induce larval metamorphosis has been used to examine the effects of different alga diets on the development rate of hatchery produced flat oyster larvae.”

Stephen points to the importance of die-tary assessment for hatchery culture of different bivalve species. “As an example many Pacific Oyster hatcheries have used an algal mix of up to 80% of the diatom Chaetoceros calcitrans, whereas the Flat oysters would not grow well on such a diet. We do know they grow well Pavlova lutheri and Tahitian Isochrysis galbana. However a mix of several algal species

have been identified that will maximise the diet’s nutritional value for the larvae.”

He’s also developed a technique to remove larvae from adult oysters on the leases without damaging the larvae or the broodstock. “A 500mg/L solution of magnesium chloride is used to narcotise individual adult oysters; the process can take up to 2 hours to take effect. Once narcotised, the adult oyster gape open and the larvae can be easily rinsed from the oyster. The adult oysters are returned to fresh seawater and recover within an hour. The larvae are rinsed in fresh seawater and held in an aerated bucket of 1µm filtered seawater for transport back to the hatchery where they are on-reared in one tonne tanks.”

The seed are ongrown until they are about 1mm shell length when they are sold to oyster farmers. Genetic research has found that the New South Wales estuaries represent a geographically homogeneous population (Hurwood et al. 2005, Marine & Freshwater Research, Vol. 56, no. 8, pp. 1099-1106). This essentially removes any potential genetic constraints on broodstock sourcing and spat translocation within this region. So hatcheries can produce seed which can be stocked in waterways up and down the NSW coast in accordance with NSW I&I translocation protocols.

From top: Flat Oysters in tray washed and ready for retail sale. Sales are either opened or

unopened as requested by the customer..

Flat Oysters in 20mm mesh tray, in the finishing stages to gain depth and mature for sale.

Flat oyster presented for retail sale. Hessian bags are used as they keep the oyster cool and

extend the shelf life. Courtesy of Pearl Oyster Bar.

Ostrea angasi larvae at the crawling stage (note foot extended along shell grit particle) just prior to metamorphosis. Courtesy of S. O’Connor NSW Dep. Industry and Investment – Port Stephens Research Institute



Farmer advice and assistanceAs part of the NSW Government’s con-

tinued commitment to aquaculture

development, over the past decade NSW

Fisheries has been providing farmers

with advice on design, assembly and

operation of Flat oyster nursery equip-

ment as well as advice on care and han-

dling of stock (three workshops were

held between 2000 and 2002).

Oyster farmers have established pump

ashore field nurseries at sites in Pambula

Lake, Merimbula, Bermagui, Narooma,

Batemans Bay, Port Stephens and

Camden Haven. They use upwellers

product in other parts of Australia have been caused by the disease Bonamia, for which there is no known cure. Preliminary surveys by NSW DPI of five south coast estuaries have confirmed the presence of Bonamia. However, to date no mass mortalities of Flat oysters caused by Bonamia have been reported in NSW. R&D is underway to find a molecular test for diagnosing Bonamia.

Low salinity and mud deposition can also cause troubles. Last year, at least one farmer lost his entire Flat oyster crop due to freshwater flooding along the river where his farm was located.

Stefan Paschailidis has been farming oysters on the Clyde and Tomago Rivers for over 35 years and currently operates 25ha of leases. His family business has been selling Sydney Rocks through their retail store The Pearly Oyster Bar at Batemans Bay; it remains in the same location where it was established by family patriarch Christos in 1972.

Stefan was the first farmer in the Clyde River to try growing Flat oysters and he has been doing this for more than 15 years. He purchases an average of 50,000 1mm-2mm seed from the NSW PSFI and grows them up in a pump ashore nursery upweller system for 2-3 weeks. They are then transferred into 2mm mesh trays that are floated in the surface waters under capped 100mm polypipes.

“Every three weeks we lift the trays out, wash and grade the seed through sieves,” Stefan continues. “And then we thin them out into new larger mesh trays. When the oysters reach 30-50mm they are moved into 20mm mesh trays and are suspended in a pontoon system in 10 tray modules. All of the seed received should have reached this point by 17 weeks. At this point the oysters are still very thin; it can take several years to fin-ish the oysters and provide them with the depth they require to be mature enough for sale. Fish predation – espe-cially stingrays on the juvenile Flats – can be a problem so 20mm plastic mesh covers the trays to exclude the predators.”

which are compatible for a number of

shellfish species. In most cases, results

achieved by the farmers have exceeded

expectations. Growth rate and survival

of spat on a diet of wild phytoplankton

have been far superior to that achieved

in previous years with hatchery spat fed

cultured microalgae.

In NSW an average market size is

achieved in 18-24 months when the Flat

oysters are grown on existing intertidal

rack and tray leases developed for Sydney

Rocks and even faster if grown in sus-

pended culture on deeper sub-tidal leases.

Mass mortalities of wild and cultured

Top: The oyster processing room at Pristine Oysters, South Australia.

Above: Flat and Pacific Oysters growing in the beautiful waters of Coffin bay, South Australia. Images courtesy of Pristine Oysters



Fouling is an ongoing headache during growout, especially cunjevoi (sponges) and barnacles. “You can dry out the Sydney Rocks and kill the fouling, but you can’t do that with Flats. So we try to avoid the fouling settlements by moving the Flats up or down in the water col-umn. We wash and grade the larger oys-ters every 6-8 weeks.”

Stefan finishes his Flats in intertidal racks for around 3 months. “We gradu-ally hold them higher and higher in the racks to harden them as they don’t like being out of water for more than three days, even when it is cool.”

He says his Flats are quite different to the Sydney Rocks. “They are an unusual product. Some people love them and at our store we get a bit of interest from people wanting something out of the ordinary. We have tried selling them to restaurants but lack of knowledge about them can limit sales; the Flats have a much stronger taste.

Whilst the Flats are only a small part of his business they do retail at $14/dozen for 75-100mm oysters for 2-3 year-old

longlines for the Flats, in much the

same way as Pacifics are grown in the

region. The brothers have used a range

of baskets and are experimenting with

stocking density and height in the water.

The shell of a Flat is not as hard as that

of the Pacific oyster so farmers need to

take care with how the they are handled,

especially during mechanical grading.

“We can’t put them through the auto-

matic SED oyster grader so we use the

rotary (PVC tube) graders for them,”

Brendan says.

“It is important to get the small seed into

the drink quickly. However, they are

fairly robust. We don’t have a Bonamia

problem here in SA perhaps due to our

higher salinity or water temperatures.

“The angasi has a much stronger lingering

flavour than the Pacifics, so they don’t

need to be overly large,” he continues.

“We are finding chefs place more emphasis

on a clean nicely shaped oyster shell

rather than going for a large size.”

Many of Australia’s leading judges believe

the Flat oyster has a great future. Pristine’s

product. And well worth it too he reck-ons. In 2008, Stefan won the Gold Medal for Flat oysters at the Sydney show (Fine Foods awards) as well as the Champion Oyster award.

Culture in SASome seed has also been sent interstate under strict biosecurity protocols. Such income is considered vital to securing a commercial hatchery for NSW as sales for local producers are currently too low to underwrite such an operation. One customer is Pristine Oysters, located in Coffin Bay at the remote southern end of the Eyre Peninsula, run by brothers Tony, Brendan and Nick Guidera.

In September 2008 they purchased 6,000 Flat Oyster seed from Shellfish Culture in Tasmania to trial. “We were happy with the results selling the majority of them at 75 to 80mm in 4-18 months,” says Brendan. “The only problem we had was sourcing more spat. It wasn’t until March 2010 that we managed to get 200,000 angasi spat from NSW.”

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But a premium product requires very high standards and Steve Feletti of Moonlight Flay Oysters suggests – through his website – that oysters in Australia are generally “under-marketed, poorly handled and badly delivered”. He believes that Australians should lift the standard of oyster growing from the ground up and ensure product integrity and consistency in all aspects of cultiva-tion and delivery right way through to the consumer.

He follows up this assessment with compelling data on why the way in which we enjoy oysters in Australia doesn’t do them justice. “France pro-duces 129,000 tonnes of table oysters per year,” he says. “Australia produces about 10,000 tonnes. In France not a single oyster is sold pre-shucked and tap rinsed – in Australia the bulk of product is pushed through opened and rinsed.

“This is the challenge. If we are to cre-ate real demand for quality product then the grassroots of the industry have to change. I’m astonished that Australians will pay good money to eat pre-frozen imported oysters laid out on those groaning hotel buffet tables, or buy chilled, shucked oysters when it’s easier and cheaper to buy live oysters in their shell and open them at home.”

By Dos O’Sullivan

For more information contact:

Stefan Paschailidis, Pearly Oyster Bar, 02 4472-7322 / 4472-4233, E: [email protected]

Stephen O’Connor, Port Stephens Fisheries Institute, E: [email protected]

Brendan Guidera, Pristine Oysters, 0427 292-430, E: [email protected]

Steve Feletti, Pelican Beach Oysterage 02 4472-9000, 02 4472-7186, Moonlight Flat Oysters, Batemans Bay, www.moonlightflatoysters.com.au/

Flat oysters won the Champion Oyster award at the 2010 Sydney Royal Fine Food Show plus that year’s Delicious magazine ‘Producer of the Year’ award as judged by Philip Johnson, Matt Moran, Neil Perry, Alla Wolf-Tasker, Maggie Bier and Cheong Liew.

“The judges singled out our angasis for special mention at the awards,” Brendan adds.

Changing how oysters are sold Through broodstock selection in the hatcheries and innovative culture tech-niques on the leases, farmers hope to further develop Flats as a premium product line suitable for both local con-sumption and for export, especially into Asia and Europe.

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Some of Pristine Oysters’ award winning Flat oysters. Courtesy of Pristine Oysters




The really big changes in technology often come when people work independently, think ‘out of the square’ and move away from the conventional thought processes. A NSW native fish hatchery operator has used his science background and practical experience to critically assess the biology of his fish. The results are some very interesting ideas which he has detailed in a 410 page book to be launched this year.

F E AT U R E

Thinking out of the square with native fish

Since 1996 Greg Semple has owned and operated the Murray Cod Hatcheries

(MCH) which was first developed by David ‘Pat’ McLaren in 1969. The 38.6ha facility is located within the sub-urbs of Wagga Wagga just 7km from the CBD and 270 km southwest of Sydney. The hatchery/farm and its production methods have been featured in Austasia Aquaculture in 2001 and 2006.

Greg has earned a living from the produc-tion of Murray Cod (Maccullochella peelii), Silver Perch (Bidyanus bidyanus), Golden Perch (Macquaria ambigua), Freshwater Catfish (Tandanus tandanus) and Yabbies (Cherax destructor) but clearly his moti-vation has been more than only fiscal.

“For 15 seasons, most of the World’s endangered Tandanus tandanus production has been from MCH,” he explains. “I have dedicated a great deal of time, pond space and other resources to the preservation of six endangered Catfish strains. Many of the parental populations are now believed to be extinct in the wild. This has been undertaken with no formal Government stocking program and a limited private market, around 22,000 fingerlings a year.”

The fish were being donated for stockings by the Wagga Wagga City Council, by children during Water Week and by local recreational fishing clubs. However, such programs were largely suspended because of a failure of the stocking groups to notify the Fisheries Authority, so the presence of young fish gave the false

veterinary, biology or aquaculture groups.

“During 50 years of independent fish keeping (Greg started keeping fish when he was 5 years old) and 35 years of study as a biologist and water quality analyst, I have long thought through my ideas on fish biology,” Greg continues. “I am publishing this information in my book ‘Fish Biology with emphasis on the Cod, Bass and Perches Maccullochella and Macquaria (Pisces: Percichthyidae)’.

“My somewhat altruistic philosophy is that the roles of science should be to expand and nurture our knowledge and understanding, and to critically review and question the validity of earlier work. In my book I challenge our earlier understanding of native fish biology by re-examining fish biology and genetics, reinterpreting baseline data and reas-sessing scientific techniques.”

In a wide ranging interview Greg gave Austasia Aquaculture some interesting insights to his views with some key mes-sages on Australian native fish.

Fisheries management strategiesGreg believes that the scientists and fish-eries managers will always have problems on reaching consensus. “Disagreement always existed in how to best manage and improve each fishery. This is not surprising when one considers the numerous different fractional self-interest groups and strong personalities involved.”

He considers that at least some of the

impression that the species was breed-ing and recruiting naturally.

“Most fish have quite short effective pro-ductive lives. During my work I have culled in excess of 1.5 million fish to maintain the genetic diversity of my six catfish strains. These excess fish were fed to other game fish species such as broodfish cod and perch.”

Scientific backgroundGreg was university trained as a scientist, initially specialising in zoology and genetics. Later formal postgraduate stud-ies in the USA were in Aquaculture and Aquatic Environmental Sciences. He has worked with, and consulted for, a wide range of government and private projects.

One job was the supervising and upgrading of monitoring equipment (fish biosensors and electronic water quality monitors) used to safeguard the potable water supplies of the Sydney Basin. For a year and a half he helped study the catchment impoundment and even managed to spawn the Macquarie Perch (Macquaria aust ralasica) in moni-tored glass races.

From 1983 to 1990 – prior to becoming a full-time farmer – he was an author of over 80 scientific publications (Government reports and peer-reviewed papers). Greg has presented scientific papers to international conferences in Canada, USA and Australia and is often requested to give interviews to the media or to present lectures to

veterinary, biology or aquaculture groups.

“During 50 ears of independent fish


F E AT U R E

information represented as fact has sim-ply managed to ignore basic fish biology, genetics, historic native fish distributions and changes in the natural carrying capacity of the waterways, particularly the Murray-Darling Basin (MDB).

Growth rates and reproductive success

“Whilst the growth rates, size and age at which any fish will commence and cease to reproduce is largely genetically prede-termined, it is also conditional on its habitat. Precocious maturation and over-stocking can reduce growth, creating stunted populations. The periodicity, spawn size, total number of batches, and lifetime fecundity of each fish are all very much functions of the environment in which it has lived.”

Environmental change and habitat alteration

“Habitat changes over 150 years have clearly altered the landscape of the Murray-Darling Basin (MDB). Lieutenant John Oxley in 1817 and Charles Sturt 1828-1835 gave very bleak accounts of the Basin. These expeditions noted either little water or saline water in many inland rivers and native forests dying from drought. Ironically, these same ephemeral rivers and wetland areas which never supported any continuous permanent finfish populations or water, are now considered to be suffering from over-fishing and desiccation.”

According to Greg, people have over estimated the amount of fish that were in the MDB. “Many people believe that the Basin once had a huge commercial fishery. Figures for the Commercial Fisheries of Inland Australia show that the maximum annual catch of native fish before weirs were used to regulate water in the Basin was only 147 tonnes in 1883. The creation of permanent water due to the weirs actually increased the com-mercial harvest of native species – in FY1976-77 some 290.7 tonnes were harvested in NSW (Water Resources Commission, 1996) and a maximum 340 tonnes in 1993 was reported for the MDB (Australian Bureau of Agricultural

Resources Economics annual fisheries report 1993).

Recreational fishing is now being sup-ported by the stocking of hatchery raised fingerlings. Government estimates suggest between 6 and 10 million native fish fingerlings are stocked each year by government and private groups into the more permanent waterways and farm dams within the MDB.

The introduction of alien or exotic species has added pressure to the system. “Managed sports fisheries have been created for trout (mostly Rainbows [Oncorhynchus mykiss] and Browns [Salmo trutta]), and Carp (Cyprinus carpio) numbers have exploded in the Basin. For example, some 27,000 tonnes of Carp have been removed over 36 years by a single commercial fisherman.”

Fish circadian rhythms, migrations & translocations

“Australia’s hostile ephemeral aquatic habitat means that local extinction and recolonisation by immigrants is the norm rather than the exception.”

Fortunately aquatic species are readily transported to allow these recolinisations. “The notion that fish in different bodies of water are isolated simply ignores the ease by which genetic material is moved long distances by water, the wind, birds and man. For example, all my ponds are filled with bore water so no other fish species can be introduced in the water. Yet last year I caught a 10kg Carp in one of my isolated Murray Cod broodstock ponds (0.2ha). The pond only had water in it for two growth seasons. The fish must have been introduced as an egg on bird’s legs or by some other manner.

“In addition, wild freshwater species often move between river systems by means of diluted water in the coastal currents.

“The general daily and seasonal movements of fish will often show some cyclic pattern of consistency for a population. However, the movements of each fish, or the same species in a different case scenario, are very much the ultimate functional response to a biological need at that

From top: A small ATV is a versatile and cost effective

means of movement around the ponds.

Greg Semple sexing mature Tandanus Catfish by examining

their genital papillae.

Returning conditioned brood Tandanus Catfish to a recently refilled and fertilised pond for

spawning.


F E AT U R E

time. For example, these movements could involve environmental triggers and earlier experiences of a preferred feeding, resting or nest site.

“Species which migrate thousands of kil-ometres may have individuals or popu-lations which are quite sedentary. Inconsistency of movement is well dem-onstrated by most native fishes; a Murray Cod may live in a preferred deep hole for much of its life or it may make an exten-sive general movement either upstream or downstream.

“A key message on the translocations of Australian native fish is that the species will expand its range to the limits of its physicochemical and competitive endurance.”

Fish taxonomy & genetics“Many people don’t know that as few as 20 continuously variable genetic traits define the physical differences of an individual. The comparative ease by which a species can be selectively altered by nature or man must make one question the validity of short-term genetic studies in the management of wild fisheries. Even fish which have been selectively inbred

Fish reproductive biology“Some of the commonly presented life histories of Australian fish make no sense. For example, the Australian Bass and Estuary Perch share their reproduc-tive characteristics - physiology, timing and locality. These fish are clearly the same biological species – Macquaria colonorum. These fish are not catadromous,as they do not migrate to sea to reproduce and are known to recruit young within some freshwater environ-ments. The oestrogenic responses that trigger reproduction in all fish require a drop in blood sodium levels. The only fish which move to sea to breed are the Anguillid Eels which then later move upwards from the salty ocean depths to less saline surface water before spawning.

“A key message for fisheries managers is that much of the earlier research on Australian native fish has been undertaken by enthusiastic but inexperienced young scientists. The results and interpretation of the data are often based on a few case studies and are subject to reinterpretations and further later revisions.”

MCH’s future – Fish or land development?With almost 40ha of land protected from flood events by approved levee banks and its proximity to Wagga Wagga, Greg says that his property is quite valuable and he is examining the option of selling.

“Wagga Wagga is the largest city in Inland NSW and the local topography has created a shortage of space. Local land values have quite consistently outperformed other safe investments. The MCH busi-ness is quite resilient and has continued operation for 41 years, including through the longest drought (1997 to 2010) on record when many other farms failed. The proximity of the airport and road freight depots has meant that fish con-tinued to be shipped even at the height of the regional flooding (Dec ’10).”

“It would be nice, but naïve, to believe that the property could remain a farm. The location and approved local zoning as a Business Village makes the usage of the property highly flexible. With 360

for many generations produce throwback culls in each generation. Highly domes-ticated species will quickly revert to their native, green or wild type. Feral and wild strains of fish can sometimes breed together where wild stocks are depleted. However, the progeny of any spawns produced will be selected for the wild characteristics which are suited to the local habitat.”

Greg has proven that the jaw length and body colour in Australian native fish – like the Cod – are altered by age, growth, gender, maturation, nutrition, toxins and environmental stress. “These are invalid traits by which to identify Maccullochella sp. The head:body length ratio in Murray Cod decreases with growth and devel-opment and becomes noticeably smaller in biologically soft water populations. However, healthy aging, malnourished or sick fish can all shorten in length by >3%, making the head to body length ratio proportionally greater.”

The key message Greg is making is that the restriction of the stocking of certain biotypes or genotypes may actually have no positive benefits and may even have a gross negative impact.

Clockwise from top left: Once they are more than 70mm long Tandanus fingerlings become increasingly difficult to sell and ship. The aquarium trade prefers smaller fish.

A 16 year old Murray Cod broodfish.

Aquatic species are readily transported. This 10kg Carp grew a 0.2ha pond of mature Murray Cod in two growth season. As all his ponds are filled with bore water, Greg believe this fish was self sown, possibly through an egg being carried in on the legs or feet of a bird.


F E AT U R E

degrees of beautiful panoramic views, the MCH is a pretty amazing place to live and work. You feel as though you’re in the country alone, just surrounded by the incredible wildlife. It is only when you look at the town plans and go for a drive that you realise just how close the built-up areas and major city services really are. The property has full town services avail-able, and four bore licences. Normally only one of the bore pumps is ever needed for operation at any given time.

“I have no regrets about a lifetime working with fish. Fish keeping, commercial fish-ing and fisheries research haven’t just paid the bills. Fish have given me a pas-sion, the means to travel and study, not to mention the great privilege to repre-sent my country. I’ve met a lot of really nice people, had interesting experiences and visited terrific places. It is not over yet, with more adventures ahead.

“The MCH property is being under-utilised. Production was progressively cut back so that I could handle the work alone. The equipment is operational to again scale up production. However, I no longer have the stamina or competitive


For more information contact Greg Semple, Murray Cod Hatcheries, 3681 Sturt Hwy, Wagga Wagga, NSW 2650. Tel: 02 6922-7360, fax: 02 6922-7619.

need to produce up to two million fish a year as I once could largely on my own.”

Perhaps the release of his thought pro-voking book may inspire some people to take up the reins of MCH. Nevertheless Greg’s legacy will survive at least with his book.

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Yabbies can be polycultured with Tandanus but few other native fish species, especially Percichthyids such as Murray Cod and Golden perch as invertebrates for the major portion of their diet.


F E AT U R E

Seafood High Schools Prepare Students for a Fishy Career

As the seafood industry continues to

grow in specific regions of Australia,

it becomes evermore interwoven into

the fabric of these communities. These

communities generally are not large

state capitals but small tight knit centres

of population – such as Port Lincoln in

South Australia, Huonville in Tasmania

and Cardwell in Queensland. The youth

of these communities see fisheries and

aquaculture as an attainable career and

many grasp this opportunity.

However this has not happened by

chance. One of the more successful

mechanisms in promoting the plethora

of careers around fisheries and aquacul-

ture is its integration into high school

programs. Future staff, researchers and

managers of the seafood industry are

currently within the Australian educa-

tion system. Effectively communicating

all of the career possibilities that the sea-

food industry has to offer to students

while they are formulating decisions

• Stuart High, Whyalla;• Port Lincoln High School, Port Lin-

coln; and• Cowell Area School, Cowell.Each school delivers quality programs but were individual enough to offer unique learning and skills development opportunities.

Stuart High is based in the northern region of the Eyre Peninsula in Whyalla. The precursors to the current aquaculture program were developed in 1993 when the school was looking at techniques to better engage students in science-based learning. It now has now a purpose built indoor recirculation facility that grows Barramundi, Murray Cod and trout.

Other important points about Stuart High’s seafood program are use of the facility as a tourist attraction: students conduct the tours of the facility and it is now part of the South Australian Government’s Seafood and Aquaculture Tourist Trail. There is a commercial fish

about their future is vital for the longev-

ity of the industry.

To acknowledge the vital role high

schools play in the seafood industry, the

Australian Seafood Cooperative Research

Centre (Seafood CRC) has just com-

pleted a High School Engagement

Initiative. The cornerstone of the initia-

tive was to undertake three case studies

of high schools that have implemented

successful seafood programs.

It was a definite challenge to find exam-

ples of high school programs of this

nature in most states of Australia; how-

ever after scouring the country there

were three high schools that stood out

both in terms of program delivery and

vision. All three were based in arguably

the most famous seafood and aquacul-

ture region in Australia, the Eyre

Peninsula, South Australia. The three

high schools that took part in the case

study were:

Stuart High’s Seafood Facility


F E AT U R E

smoker onsite and the school sells its very tasty smoked kingfish; the fish is either its own home-grown product or bought off a nearby facility. Students can undertake a Certificate II in Aquaculture while at Stuart High.

Port Lincoln High is fortunate enough to be situated in the epicentre of the region’s seafood industry and the school has had seafood-related programs for over ten years. It currently has a Seafood Industry Pathway Program allowing students to experience a diverse array of learning and practical experiences including deckhand skills, PADI diving, aquaculture, vessel operations in addition to having minimum of 20 days work experience with local commercial operators.

The qualifications they can achieve range from a Certificate I level through to the commencement of Certificate III. For some of the maritime components of the program the students attend the Australian Fisheries Academy. Port Lincoln High also has a purpose-built seafood facility that grows Barramundi, Murray Cod and trout. The teaching staff at Port Lincoln have had extensive commercial experience and do every-thing they can to assist students to enter the seafood industry.

Cowell Area School is situated in the central area of the Eyre Peninsula and caters for students from Reception to year 12. Set in a rural community, the principal industries in the area are aqua-culture (specifically oysters), agriculture and mining. The school is considered one of the centrepieces of the tight-knit community of Cowell and is revered as an excellent example of rural schooling success by many. Cowell Area Schools seafood program is extremely diverse for such a small school. Its indoor facility has a strong focus on sustainability with fish such as Barramundi grown in an aquaponics system along with leafy green vegetables.

Cowell Area School also has a commer-cial oyster farm which has its own full time manager. Students work on the

• It is crucial to gain support from the local commercial seafood industry;

• To allow the local commercial seafood industry to advise on relevant learning experiences and skills development;

• Having aquatic livestock on site requires at least 6 days a week monitoring;

• Having individuals with plumbing/construction skills is crucial; and

• Relevant staff should undertake professional development focused on gaining the skills needed to run a program of this nature.

If your school is interested in developing

a seafood related program please don’t

hesitate to Call Jan Potter of Cowell Area

School on 08 8629 2150. She is more

than happy to share wit h you how they

developed and now manage their program.

By Mark Oliver

The Seafood CRC would like to thank the staff and management of the three schools for allowing our researchers access and for their wonderful hospitality during the whole process.

farm as part of their seafood program

and the oysters they grow are recog-

nised by the commercial sector as a

quality product and have won a host of

awards. The school also partners with

the Australian Fisheries Academy to

deliver some of the maritime compo-

nents of their certificate level seafood

courses.

In conclusion, all three schools agreed

that industry involvement was the key

to ensuring the longevity of these pro-

grams and that was one factor they all

would like to enhance in the future.

The other common thread was that a

core group of extremely devoted indi-

viduals within these schools ensure

these programs run successfully and

continuously improve. As long as indi-

viduals like these are around, the future

of the seafood industry in the Eyre

Peninsula looks bright.

For any other schools wishing to

embark on programs of this nature,

some important points to consider are:

Above: Port Lincoln High School students working at

the school’s facility.

Right: Smoked kingfish ready for sale by the

students


Members of the Australian Trout Foundation, the leading organisation representing trout fishers, have worked with scientists from Vic DSE to support a population of the critically endangered Barred Galaxias.

F E AT U R E

Trout fishers work to support endangered native fish

The Barred Galaxias (Galaxias fuscus) is

one of Australia’s most endangered –

Victoria’s only endemic – freshwater fish.

This species has a restricted distribution

in eastern Victoria and is only known

from a small number of mountain

streams above 400m in elevation in the

upper Goulburn River catchment. At

least five populations are presumed to

have become extinct since its descrip-

tion in 1936. Most of the remaining

populations are effectively geographi-

cally isolated from each other by the

presence of predators such as trout, red-

fin and other species.

Many of these populations were

adversely affected during the February

2009 bushfires prompting a rescue (in

March) of several hundred of these fish

by scientists from Department of

Sustainability & Environment (DSE). In

April 2009 a major rain event occurred

in the fire-affected areas in which large

volumes of silt and ash flowed down

have no scales and when stressed they

are pretty susceptible to fungal infec-

tions, especially in the pits and pores of

their lateral lines. In addition we gave

them regular salt baths and treatments

with Pimafix (a common antifungal

treatment for aquarium fish).”

Fish vet Jim Griffiths also prescribed

some antibiotic treatments.

“These fish live in very clean waters. We

therefore needed to be very careful of

nitrogen or ammonia spikes so we were

kept busy cleaning tanks and undertak-

ing water exchanges.”

The fish ranged from around 50mm

(about 3 years of age) up to 100mm

(approx. 8-12yrs). “These fish grow very

slowly. We fed them blood worms (lar-

vae of the mosquito-like midge family

Chironomidae) as closer to release times

we fed them brine shrimp nauplii and

small earthworms to get them foraging

for feeds.”

Whilst some populations have been

returned to their natal streams in

December ’09 and June ’10, others have

been maintained in the aquaria for more

than 12 months awaiting appropriate

rehabilitation of their stream habitats.

Rehab working beeAccording to DSE Native Fish Strategy

Coordinator Fern Hames, it was an

eclectic mix of over thirty people who

gathered last June to reconstruct the

many of the Barred Galaxias streams. So

the DSE scientists should be to be con-

gratulated for their foresight and quick

action.

The ‘rescued’ fish were housed in secure

aquaria at the Arthur Rylah Institute

(ARI) research aquarium at Heidelberg.

Each population was held in a separate

tank, with a separate chilled recirculat-

ing water supply.

Salinity and temperature controlAccording to ARI’s Tarmo Raadik, 400

fish were held in water temperatures

that closely mimicked those in the wild.

“We held them at 5°C in winter and

below 12°C in summer,” he says. “Even

so they were pretty stressed so we kept

them in a higher (slightly isotonic) salin-

ity around 2-3,000 EC (~2.8ppt) than

their normal 40 EC. This is a common

method when holding or transporting

stressed natives. The Barred Galaxias

Members of the ATF, ARI DSE staff and young people from the district gather on the predator barrier in Leary’s Creek, Marysville, after revegetating the banks to support the resident Barred Galaxias population. Photo by DSE.


F E AT U R E

bushfire affected area around Leary’s

Creek, which runs through Marysville.

“Trout anglers were working side by side

with kids from the Marysville Youth

Incorporated and with scientists from

DSE and ARI. The work included planting

of native vegetation and debris removal

around the repaired man-made predator

barrier on Leary’s Creek which was

badly damaged by the 2009 bushfires.

“Revegetation around the creek will assist

in maintaining water quality by reduc-

ing the amount of silt and ash which

can be washed into the creek. It also

forms important habitat and food

sources for the rare fish,” Fern said.

“We believe there are still some Barred

Biology and HabitatThe Barred Galaxias is a rich orange-coloured fish growing up to 15 cm, but commonly reaches 7-9 cm long. It has 1-10 vertical ovoid black bars on its side and clear to reddish brown fins. Scales are absent.

The Barred Galaxias occurs in cool (<11°C), clear, upland streams with stony or sandy substrates. Little is known of its ecology due to its highly threatened status and small population size. The preferred habitat is thought to be slow-flowing (0-0.2 m/sec), deep pools adjacent to riffles and cascades.

Spawning is triggered by an increase in day-length and water temperature in August–September. Average fecundity is about 500 eggs, which are large (unshed eggs are ~ 2.2 mm diameter) and adhesive. The eggs are laid on or under in-stream rocks and boulders when water temperatures are around 2–3°C. Time to hatching and size of larvae at hatching are unknown, but 12 mm long larvae are present in streams by December.

Movement requirements are unknown, but the species is thought to be non-migratory and relatively sedentary, judging by recolonisation rates of streams where trout have been removed.

The diet consists of drifting and benthic aquatic invertebrates taken at the upstream end of pools.

The species is relatively long-lived for a small fish – individuals up to 13 years old have been recorded.

Arthur Rylah Institute (Vic DSE) staff releasing Barred Galaxias into a population site. Photo by Fern Hames (DSE).



first of many. We would also like to congratulate the members of DSE, MDBA, and Arthur Rylah Institute who have gone out of their way to work side by side with the ATF; it truly is a great sign for the future.”

Assistance for trout farmThe ATF have also been active assisting a local trout farm which was badly damaged during the 2009 Black Saturday bush-fires, lending a helping hand to rebuild the very popular Buxton Trout Farm.

Recently owner/operator Mitch MacRae offered the ATF a gift of 20,000 Rainbow Trout fingerlings (8-10cm). To keep everything above board, the ATF in turn has offered these trout to Fisheries Victoria to assist in getting those once dry Western district lakes back on line for recreational fishing of trout. Over 10,000 of these fingerlings were stocked into Lake Hepburn on 15th December and the balance is to go in sometime in early 2011.

“These fingerlings are only small,” said Mick, “However by spring next year they hopefully will be a lot bigger and the year after that, with the aquatic food chain already coming back on line, (see pictures) we can expect to see some of the best trout fishing this state has seen in many years. All we need to do is just keep on adding water.”

By Dos O’Sullivan

The Australian Trout Foundation is an independent, non-profit organisation, dedicated to ensure that all Australians can enjoy trout fishing now and for future generations to come. For more information contact Tom White (secretary) Australian Trout Foundation, P.O. Box 466, Mooroolbark, Vic 3138. T: 03 9726-7973, F: 03 9726-7961, Email: [email protected]

The ARI contact is Tarmo Raadik 03 9450-8600, [email protected]

Galaxias in Leary’s Creek but we need this type of revegetation work to occur to help the site recover sufficiently to support the return of the fish we removed more than a year ago.

“This recovery action has been vital for the survival of this already rare species because 90 per cent of its known habitat has been affected by either the 2006 or the 2009 bushfires.

“The fires also damaged the trout barrier in Leary’s Creek but this has since been repaired. The barrier stops predators from moving into the section of Leary’s Creek used by the Barred Galaxias and having an impact on this rare fish.”

ATF’s vice-president Mick Hall said their members were enthusiastic participants in the work at Marysville. “The Australian Trout Foundation is committed to assist wherever possible to maintain the viability of our native fish species and we hope that this small yet significant project is the

Above: Tank systems at Arthur Rylah Institute (Vic DSE) holding the Barred Galaxias populations rescued from fire affected areas. Photo by Tarmo Raadik.

Left: Stuart Rees from the Australian Trout Foundation releasing fingerlings donated by Buxton Trout at Hepburn Lagoon, near Ballarat. Photo by Lyndon Webb (ATF).


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The use of algae as biofuel is providing opportunity for savvy aquaculturists to ‘value add’ their production systems.

Microalgae biotech provides ‘green’ diversification

Research into biofuels is now pioneer-

ing new technology in algal selection,

culture, harvesting and processing (i.e.

extraction of proteins, lipids or pigments).

That’s of immediate interest to aquacul-

turists. Growing microalgae is a key

process in commercial and R&D hatcher-

ies, providing an essential nutrients for the

larvae/juveniles of prawns, mussels, oys-

ters, pipis and scallops as well as feeding

the zooplankton eaten by finfish larvae.

• maintain oxygen levels;

• reduce levels of ammonia and other

toxins;

• provide food for zooplankton eaten

by culture stock;

• provide benthic algal food for newly

stocked juveniles or larvae, and

• produce algal flocs in carbon added

ponds as a food source.

But culturing the wrong algae can be

bad. TasUni’s Dr Gustaaf Hallegraeff lists

some negatives:

• ‘bad taste’ or odour problems in fish

or mollusc flesh or in drinking water

(e.g. cyanobacteria Microcystis and

Anabaena);

• kills of fish and invertebrates due to

oxygen depletion or natural toxins;

As well, there are a number of higher value

algal-derived products such as biofuels,

omega-3 fatty acids and pharmaceuticals.

Algae can also have a vital contribution

in nutrient removal processes thereby

increasing water availability recycling.

And algae remove carbon dioxide too.

Murdoch University’s Professor Michael

Borowitzka estimates that 108 tonnes of

CO2 are fixed per hectare of algae ponds

each year.

Important role of algae in water qualityFish and prawn farmers stimulate algal

blooms in ponds to:

• shade and shelter their stock;

The NCRIS 3.5m3 Algelink Solutions

photobioreactor at SARDI. Photo courtesy of SARDI

Aquatic Sciences.



• damage or clogging of gills of culture

stock;

• potent toxins causing human gastro-

enteritis and neurological illnesses

(e.g. PSP, DSP or Ciguatera), and

• swimmer itch (sensitive skin).

“All farmers need to carry out long-term

routine monitoring of the many algal

species is their ponds to develop a feeling

for what are the good and what are the

bad species.”

Algal biotechnology opportunitiesSeveral projects spread around Australia

are likely to provide opportunities for

aquaculturists to diversify into algal

biotechnology.

As part of an Australian Research

Council Linkage Grant, the Schenk

Laboratory group at the University of

Queensland (UQ) is investigating the

use of microalgae lipids for biodiesel.

Associate Professor Peer Schenk’s team

(www.algaebiotech.org) aims to effec-

tively scale-up a low-cost technology to

a pilot-plant facility to facilitate further

commercial evaluation.

In addition to producing algal lipids for

conversion to biodiesel, PhD student

Steve Magarry told the recent APFA/

ABFA Conference that such technology

could provide significant biomass for

aquaculture nutrition.

“We have more than 50 SE Qld strains of

microalgae in the UQ collection,” Steve

explained. “We are evaluating their

omega-3 lipid content and production

for further targeted use within the aqua-

culture industry for broodstock matura-

tion and general nutrition enrichment.”

Also at the APFA/ABFA conference,

Ridley Aquafoods’ Richard Smullen

noted that with some microalgae species

containing 50-70% protein and 10-20%

lipids, there’s a huge market opportunity

to supply basic human nutritional needs.

The production of high value omega-3

oils for human consumption provides

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Culturing microalgae species in two of the outdoor 20m2 raceways at SARDI, Chaetoceros (left) and Nannochloropsis (right). Photo courtesy of SARDI Aquatic Sciences



“There is a sense of urgency within the

UQ team,” said Steve. “We believe it is

only a matter of time before we can

make the opportunity for an ‘Australian

first’ commercial production of the EPA

and DHA oils.

“The global industry is worth around

US$10 billion for these oils in health

products and enriched infant formula.

There are no algae-sourced omega-3 oils

available in Australia right now

although fish oil omega-3 sales exceed

AU$200 million a year. Wholesale fish

oil (with a ratio of EPA/DHA 18:12) sells

for between $5-10/L and retails between

$40-60/L. Refined and purified ALA/

EPA/ DHA wholesales for $80-120/L in

some pharmaceutical markets.”

A range of pharmaceutical quality chem-

icals as well as phytosterols (plant derived

cholesterol, stigmasterol, campesterol,

etc.) and antioxidants for human con-

sumption can be manufactured algal-

derived fatty acid ethyl esters. But, as

Steve quickly pointed out, not all these

product lines are complimentary. “Typical

commercial biodiesel manufacture uses

methanol which limits the opportunity

to produce for other market sectors.”

UQ’s preferred mass algal production

model incorporates a ‘split-system’

sequential approach. A photobioreactor

(PBR) maintains the algae in its expo-

nential growth phase with specific nutri-

ent media dosed at intervals based on

the weather and available solar energy.

Next the algal biomass is harvested for

transfer to open raceway ponds where

nutrient concentrations are manipulated

to boost lipid synthesis.

“We have a built a low-cost 2,500L split-

system consisting of a 1,500L airlift PBR

and two 1,200L raceway tanks,” Steve

continued. “There are plans for a

120,000L pilot-plant facility to be com-

missioned in 2011.”

Initial results are very promising. “We

have achieved biomass productivity

greater than 50 gm DW/m2/day which

equates to the industry benchmark of

Aquacultured larvae/juveniles and zooplanktons need different combinations of microalgal species to meet their specific nutritional requirements at different developmental stages. “Therefore, the reliable provision of the right species at the right time and at the required quantity and quality is challenging to all the hatchery operators,” says Dr Xiaoxu Li, Aquaculture Senior Scientist at SARDI.

These challenges can be overcome to a large degree by a move from the traditionally used continuous flow

500L ‘Bayes’ bag system to a ‘thinner bag’ system. Mark Gluis, SARDI’s Shellfish Hatchery Specialist has shown that the same physical space can grow a more diverse range of species as well as boosting cell densities within the bags used by two to fourfold.

Mark is receiving such a high level of interest in his ‘thinner bag’ system that he’s proposing SARDI host a national microalgal seminar including a system demonstration seminar and training course.

Thinner bags for growing algae

Synchronised lipid production in Tetraselmis cells.

Photo courtesy of Schenk Lab.



60 t/ha of DW/year. And we’ve had lipid

accumulation at 10% DW biomass

(equivalent to 7.5 t/ha DW/yr; the industry

benchmark is 15 t/ha/y.”

At least ten algal strains have been selected

by the UQ Algae Biotechnology Group

as having potential. These include the

commonly used aquaculture species such

as Chlorella, Nannochloropsis, Tetraselmis,

Pavlova, Isochrysis, Scenedesmus,

Chaetoceros and Skeletonema. Research is

also underway for growth optimisation

and using genetic selection (non-GM

approach) of these algae to further

increase production.

The primary constraints to commercial-

ising microalgae culture is the cost of

energy to drive the dewatering (separa-

tion of microalgae and water), biomass

drying and extraction of lipids. Steve

said the solution may lie with novel

methods of lipid extraction directly from

the microalgae culture.

Bolt-on Opportunities:UQ’s team reckons the new biotechnology

offers aquaculturists the means to leverage

facilities into further profit.

“We call them the ‘bolt-on’ opportunities,”

explained Steve. “Discharge ponds or

channels, hatchery, processing and purging

water discharge points, prawn or finfish

hatcheries and algae / live feed facilities

may not be not fully occupied for all of

the year.

“Many could be used off-season or for

polyculture using floating (pond or

drainage channels) or surface (bank or

levee) based PBR’s.

Another opportunity is to use the algal

technology for better nutrient removal.

“A PBR operating in full sunlight could

take every 6 hrs -some 80-100 mg/L of

nitrogen and 20-50 mg/L of phosphorus.”

S.A. Aquaculture ProgramDr Sasi Nayar heads the Algal Production

Group at the South Australian Research

& Development Institute (SARDI), West

Beach, Adelaide. SARDI has been

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Harvesting algae with flocculants used widely in the wastewater treatment industry. Photo courtesy of SARDI Aquatic Sciences.



between 80 and 95% of the algal biomass

with the remainder used for gasification.

Pilot Plant at Karratha Michael Borowitzka, Professor of

Phycology at Murdoch University has

worked for over 30 years on commercial

culture of microalgae. With Adelaide

Uni’s David Lewis and Peter Ashman, he

heads up a Commonwealth on the pro-

duction of biofuels from saline microalgae.

“Our long-term (> 18 months) trials have

proven reliable, high productivity culture

in outdoor raceway ponds in Perth as well

as Chennai, India, he said. “We have

integrated harvesting and dewatering

processes, and we have optimised lipid

extraction techniques.”

With modelling having confirmed the

design and constructability of 50 km2

production plant, a $1.5m pilot plant at

Karratha (Pilbara region) should be

completed before the end of the year.

The plant has two 20m2 intensive ponds

and three 200m2 raceways, plus large-

scale harvesting and dewatering system.

“People ask me, why the Pilbara,” he said.

“The region has all what we need –

appropriate sunshine and climate, inex-

pensive land, loads of saline water,

many sources of CO2 (e.g. Rio Tinto’s

Yurralyi Maya Power Station), plenty of

infrastructure and a high local demand

for diesel. We have achieved production

rates of about 60 tonnes of algal biomass

per hectare per year, over 40% of which

is converted to oil. These high produc-

tion rates are expected to increase at the

new pilot plant due to the even better

climatic conditions in Karratha.”


For more information contact:

Schenk Laboratory UQ, E: [email protected] W: www.algaebiotech.org

Dr Sasi Nayar, SARDI, M: 0428 542-101, E: [email protected]

Prof Mike Borowitzka, Murdoch Uni, E: [email protected]

bioprospecting and selecting native high lipid microalgal strains as a feedstock for biodiesel production and other applica-tions for over six years.

He said the cost of production of biofuels needs to be kept to around $1.00 per litre to be competitive with conventional petrochemical fuels. “Currently we are in the order of $5.00 to $300/L so we have to find systemic and economic improve-ments in production, harvesting, dewa-tering and extraction.

There are two approaches to produce biomass – the open ponds such as race-ways and the closed photobioreactors. Sasi estimates that it costs approximately $100/m2 for photobioreactors in contrast to about $30/m2 for raceways. When used in combination as a ‘hybrid system’ the benefits of both systems can be harnessed.

The Algal Fuels ConsortiumTM (SARDI’s Algal Production Group together with Flinders University and CSIRO) are to develop a pilot and pre-commercial scale production facility on Torrens Island, just north of Port Adelaide. The pilot scale facility of 0.4 ha should be operational in 2011.

It will use nutrient rich Port River seawater, carbon dioxide from adjacent power plants and Adelaide’s abundant sunshine. It has been designed to include a series of raceways between 3.5 m2 to 1000 m2 and PBRs all with control and monitoring systems for salinity, depth of water, dis-solved oxygen, chlorophyll a, pH, flow and nutrient inputs. Flocculation and dewatering will enable concentrated algal biomass to be bioprocessed for high and low value co-products such as pigments, poly unsaturated fatty acids, proteins, carbohydrates and feedstock for aquac-ulture and livestock.

The biorefinery is expected to use

Left: High performance Tetraselmis cells after selective breeding at UQ’s Schenk Laboratory.

Below left: Tow tubes of the low cost 1,500L photobioreactor in operation at Schenk Laboratory (UQ). Photos courtesy of Schenk Lab.

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Leading lobster aquaculture company Lobster Harvest (LH) has developed unique hatchery technology to propagate the high value lobster species such as Slipper Lobster (bugs) (Thenus australiensis and T. parindicus) and Tropical Rock Lobsters (Panulirus ornatus and P. versicolor). The WA-based company was featured in AA 24.1 (pp 49-52). In another ‘World First’ Lobster Harvest have produced F2 (second generation) P. ornatus.

Second generation tropical rock lobster produced in Australia

All spiny wild lobster fisheries are either fully exploited or over-

exploited, with many experiencing trends of catch declines over the past several years. Tropical Rock Lobsters are the most highly prized and most valua-ble of all tropical lobster, with wholesale live prices of Au$50-70/kg reaching as high as Au$100/kg at times. Increasing demand from China has outstripped supply. The solution to this imbalance clearly is lobster aquaculture. However, Tropical Rock Lobsters are widely recog-nised as one of the most difficult of all

these first generation females occurred in late December 2009, resulting in the first hatch of second generation (F2) lar-vae on the 24th January 2010.

Three cohorts of the second generation P. ornatus have been successfully cultured through the larval phase to pueruli and the juvenile stage in 2010 – another ‘World First’ for the team in remote Exmouth, WA. A survival rate from Stage I newly-hatched larvae to juve-niles of 9.6% was achieved using small-scale tanks, with concurrent production at survival rates near to rates deemed

aquaculture species and the most diffi-cult crustacean to propagate. This is due to the protracted and complex larval phase, and extremely delicate larvae, also known as phyllosoma.

First generation (F1) female P. ornatus from a cohort produced by MG Kailis technicians in Exmouth, WA, in 2006 were stocked in maturation raceways, together with first generation males from the 2007 cohorts (produced by LH technicians, also in Exmouth). In 2009 mating occurred, with ‘tar-spots’ observed on the females. Spawning of

Hatchery-reared tropical rock lobster broodstock (female and male)


R E S E A R C H

commercially viable achieved in produc-

tion-scale tanks.

The company’s Commercial Development

program is now focused on further

developing the larval nutrition and scaling-

up of larviculture tanks in the hatchery.

Commercial survival rates in the hatchery

of 5 - 10% have already been achieved,

albeit using small-scale tanks, in replicated

experiments. Mean survival in the best

feed formulation replicated experiment

was 8.1% to the juvenile stage in 2010,

with the highest tank survival in a small-

scale tank of 9.6%. Scale-up to commer-

cial scale began in 2010 with the unique

LH larviculture custom-designed and

built tanks. Production-scale tanks have

fast-growing and robust P. ornatus, which relies on using wild-caught post-larvae and juveniles, with an estimated annual export value of $US80m.

These results will be presented to the World Aquaculture Society Meeting in New Orleans at the end of February 2011.

By Roger M. Barnard, Aaron Turner, Travis Rumballe, Matthew Johnston and Bruce Phillips

For further information contact Lobster Harvest Ltd, 50 Mews Rd, Fremantle, WA 6160.

Technical Program Leader: Roger Barnard (LH Aquaculture Development Manager)E: [email protected]

Business: Terry Burnage (LH General Manager), E: [email protected]

Acknowledgements: Vaughan Hastie, Simon Harries, Bill Hamilton, Rhys Channing, Tim Quick, Clive Jone

repeatedly produced juvenile lobsters

(P. ornatus) in 2010, at survivals of 4.4%,

4.4% and 4.0% survival from Stage I to

juvenile.

Multiple hatchery production batches of

first generation P. ornatus and the recent

success in truly closing the life cycle with

the production of second generation

progeny are significant steps for the

commercialisation of tropical spiny

lobster aquaculture. The development of

LH’s unique propagation technology

places them in a strong unprecedented

position to benefit from this situation

and to expand the lucrative Rock Lobster

market. Vietnam has an established

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Above: The world’s first hatchery-reared Tropical Lobster puerulus larvae (clear) and juveniles (mottled yellow and brown).

Left: A F1 generation Tropical Lobster from the Exmouth hatchery.


R E S E A R C H

Marine worms to assist sand filtration of mariculture effluentsDemand is increasing for marine worms as feeds for aquacultured and aquarium animals, especially valuable broodstock. There are also markets for human foods and as bait. However, there are more uses for these intriguing worms – an innovative project in Queensland has found that these worms can also provide significant benefits in treating large volumes of low nutrient effluents typically discharged by brackish water aquaculture farms.

In addition to being popular as bait, marine worms are recognised interna-

tionally as one of the best diets for maturing prawns and fish. With a high fatty acid content – providing essential nutrition – and feeding attractants – which make them very palatable – a number of countries around the world use them as live, frozen or processed aquatic feeds. The worms are also used to flavour human foods and are considered a delicacy by many nations.

However, these worms may have even greater uses. Dr Paul Palmer – Senior Biologist (Aquaculture) at the Queensland Department of Employment, Economic Development and Innovation’s (DEEDI) Bribie Island Research Centre (BIRC) – has been experimenting since 2005 with two species of marine polychaetes (the sandworms Perinereis nuntia and P. helleri) commonly found in Moreton Bay, near Brisbane. Both live in intertidal natural habitats and grow to relatively large sizes (>1g) and at moderate to high densities

needed to be for commercial prawn farms and also evaluate their productivity (at the end of the prawn crop the worms can be harvested and sold for bait or for fish or prawn broodstock feeds).”

Water remediation trials“A two year pilot program conducted at BIRC won National Landcare Program innovation funding to test the concept at a commercial farm,” Paul continues. “In the 2006-07 culture season I conducted wastewater remediation trials using sandworms at the Bullock Creek Prawn Farm operated by Peter Spindler and Judy Butler (featured in AA 20.2 April-May ’06). The farm trial assessed the worms as a natural, low maintenance and environmentally friendly way to reduce the annual nutrients released from earthen prawn ponds.

“The aim was to test a series of treatment tanks which combine the worm’s spe-cialisation as benthic feeders with the mechanical properties of a down flow

(>400g/m2) in constructed sand beds.

“I am particularly interested in their use for nutrient removal,” Paul says. “The worms’ appetites increase as they grow but they are happy to sit and wait for their next meal. This is great for aquaculture operations like prawn farms which pro-duce seasonal crops and have varying levels of wastes during the crop. Nutrients in the water are generally bound up in very small algae and plankton which the worms can use after they lodge in the sand.”

“The worms can also help to prevent sand filters blocking with organic debris.”

He has been trialling the sandworms for their benefits in sand filters used for waste-water treatment at mariculture facilities. That research has been published recently in the internationally acclaimed scientific journal Aquaculture.

“By working out how well the worms dealt with the range of conditions found in sand beds used to filter pond waters, I could determine how big the worm operations

Constructed beds at the Bullock Creek Prawn Farm.

Recently harvested Perinereis helleri.

All

imag

es b

y Pa

ul P

alm

er.


R E S E A R C H

trials which was the focus of the recent scientific publication (see Figures 1 and 2 taken from Aquaculture 306: 369-377).

Commercial applications testedIn July 2008 a Department of Agriculture, Fisheries and Forestry grant allowed continued developmental work on the integrated sandworm filter tech-nologies at a commercial scale. Two prawn farms and one fish farm in the SE Queensland and Burnett regions were selected for the studies. Different con-struction methods have been tested including low profile above-ground sand beds where the sides are supported by timber battens, as well as in-ground lined ponds similar to those currently used for aquaculture crops.

HDPE plastic liners have been used to form the water proof bed enclosures. Medium bedding sand that is commonly used in the construction industry is then spread to a depth of 200mm over gauze-covered drainage pipes. This simple method of construction allows large beds to be built very cheaply. Work so far has shown that each square metre of sand

bed can filter up to 1,500 L of wastewater per day, and this provides a guide to the scale that may be required at different establishments. In a prawn farm environ-ment, the worms grow during the prawn crop whilst the pond wastewater is being discharged and treated. After the prawns are harvested, the worms are harvested for their respective uses. The sand beds are then dried, re-levelled and prepared for the next season.

“The project was designed to investigate the efficacy of this new wastewater treatment system at a larger scale, in terms of con-struction methods, volumes of water able to be handled, and worm biomass pro-ductivity,” Paul explains. “The pilot trial demonstrated excellent solids and chlo-rophyll a removal (reductions >50% for both) (Figure 3) and maintenance-free operations. Nutrients are converted into bio-available dissolved forms and dis-solved oxygen, redox and pH levels are also lowered significantly by the process.”

Paul says that P. helleri appears to be better adapted to live in muddier environments than P. nuntia. “Although P. nuntia appeared

sand filter. Normally sand filters clog up over time with algae and debris. However, when worms are living in the sand they tend to eat the organic debris and create a network of burrows which allows the water to continue to pass through the layers.”

Broodstock worms captured from Moreton Bay were spawned and cultured in nursery systems.

“The worms were initially stocked at a range of sizes, ages and densities in a controlled process that could be applied in a farm environment. As they grew and migrated across the bed, the surface layers changed from green and fouled to a much cleaner appearance. The earlier trials clearly illustrated their feeding activities and the network of burrows they created substantially increased the sand bed’s filter-surface area and improved the condition of subsurface sediments.”

The sand worms lowered the amounts of organic matter in the upper layers of sand and increased the percolation rates of water through the filtration beds. This has now been demonstrated in replicated

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Filter beds with (left) and without (right) worms living in the sand. Note the darker colour of the wormless filter beds showing more blockages and sometimes anaerobic conditions.


R E S E A R C H

more suitable than P. helleri for stocking directly into sand filtration beds at a very young age, we found that the best growth rates were achieved by P. helleri so this species became the focus of our ongoing and future research.”

Paul’s conclusion is that worms can act as natural vacuums for prawn-farm waste. “They can be an important component in an integrated marine farming system that captures waste and converts it into useful products. We achieved production of about 400g of worms per square metre of sand bed during the term of a prawn crop (16 weeks).

“In Australia, settlement ponds are used to capture nutrients wasted in pond dis-charges prior to release. They often account for up to 30% of farm area yet they are generally non-productive parts of the operation. In the future we may see a portion of this area become worm production units that feed on organic waste from the farm. In this way they could assist in effluent treatment and also provide a secondary crop for on-farm use or off-farm sale.

“Industrial expansion of this process is

Figure 3: Mean (± se) levels of Chlorophyll a (Chl a) and total suspended solids (TSS) in inflow and filtered discharge waters during mid-tide sampling in the farm trial in 2007 (n = 6).

Figure 2: Mean (± se, n = 4) water depths above operating sand filtration beds 10 weeks after stocking with different densities of 1-mo-old P. helleri (low = 1000 m-2, medium = 2000 m-2, high = 4000 m-2).

Figure 1: Organic matter content (%) of surface and core sand samples from sand beds with various P. nuntia densities (n = 8). Data shown includes the linear fit for surface organic matter.

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high on the agenda for our future work

in this area, and there are several other

functional uses that we will be exploring

to further utilise these interesting and

unique animals.”


For more information contact Dr Paul J Palmer, Senior Biologist (Aquaculture), Bribie Island Research Centre. Phone: 07 3400-2050, Email: [email protected]


R E S E A R C H

Quantification of alkaline phosphatase in phosphate-limited barramundi ponds

Phosphate (PO4) is an essential

nutrient for life and is useful in

aquaculture ponds where it helps

promote algal blooms. As with many

things, too much of a good thing can

be hazardous and PO4 in ponds is no

exception to this. During 2010 and

into this year we have been learning

about the impact of limiting PO4 in

our saltwater barramundi ponds near

Darwin in the Northern Territory. We

initiated this work is response to

harmful algal blooms that had caused

us substantial losses in 2009. Some of

the work we have been doing was

reported in Austasia Aquaculture’s

2010 summer edition. This article

reports on further information we

have gathered over the past few

months on how the ponds respond to

PO4 limitation.

A substantial amount of work has

been done by researchers that shows

that when PO4 is limited in the envi-

ronment, algae respond by producing

alkaline phosphatase (APase) which

is an enzyme that works on (or

hydrolyses) complex P-containing

molecules to liberate PO4 . These

researchers found that when PO4 was

less than about 0.03 mg/L, algal cells

began to produce APase. On our farm

we were measuring PO4 levels at

close to 0.00 mg per L after applica-

tion of Phoslock and figured that

there was a strong possibility that

APase would be present. We figured

this because we found that although

the behaviour of the blooms and

bloom composition was altered, the

bloom densities (as measured by Chl

Fig 4. APase activity is higher in the unfiltered samples indicating that most of the APase is closely associated with algae.

Fig 1. This shows how PO4 responds to Phoslock application. On average over this period, 1 kg of Phoslock was applied for every 20 kg food added to the pond

Fig 2. Absorbance is a measure of the amount of enzyme present in the pond. For example an absorbance of 0.5 equals APase activity of about 70 uM PO4 liberated per hour

Fig 3. A strong relationship between enzyme activity and algal density suggests the algae is the source of the APase


a or by Secchi) stayed more or less the

same. There had to be a reason for this,

because with PO4 close to 0.00 the

bloom density should be reduced. So

we set about measuring whether or not

APase was present, and if so, how much

was present.

To measure PO4 we used a compound

called pNPP, which turns a yellow colour

when it is hydrolysed by APase. The

yellow colour can be measured with a

spectrophotometer and so we can work

out from this how much APase is in the

sample. The data we collected are shown

in Figure 1 and Figure 2. From these

data we conclude that the ponds produce

large amounts of APase when PO4 is

limited. Is the APase coming from algae?

Two sets of data indicate that it is. Figure

3 shows a strong relationship betweeen

Chlorophyll a and APase. Figure 4 shows

that most of the APase is associated with

particles more than 1 um in size. These

two sets of information suggests strongly

costs of Phoslock and molasses, our

experience suggests that the 1 kg of

Phoslock for every 20 kg of feed applied

and 10 kg molasses per ha per day are

adequate to keep PO4 levels under 0.03

mg per litre and pH under 7.7.

By Adam Body

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that the APase is closely associated with

algal cells.

What does this information mean for

fish and prawn farmers? As mentioned

earlier, limited PO4 impacts on the

behaviour and composition of the

blooms. In terms of the bloom behaviour,

limitation of PO4 leads to less bloom

volatility as measured by diurnal DO and

pH. In terms of composition the blooms

are dominated by very small (less than 7

um) algae of numerous genera with clear

absence of blue green algae (cyanobacte-

ria). It should be stated here that on our

farm we hold pH at less than 7.7 as

reported in the previous Austasia article,

as we have found that this along with

PO4 control is necessary to achieve the

results we are seeking: stable and low

risk blooms. Some water exchange is

still required as the blooms can still

exceed the densities we consider safe

(about 25 cm water transparency) due

to the action of the APase. In terms of

R E S E A R C H

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Aquasonic is focused on energy efficient technologyRecent times have seen an exponential

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Pumping costs traditionally burn the biggest hole in a fish farmer or breeders pocket. With this in mind we embarked on an exercise to find a premium quality, low cost, low energy pump that would be able to be used for both fresh and saltwater applications. We have found a pump that we believe ticks all those boxes and have been marketing these pumps for about six months now, with very pleasing results.

Our premium range of Performance Pro pumps made in the USA, have all those attributes and come with a diverse range of flow rates and head capabilities to suit most applications. They range in flow rates from 9,000lph @ 1.5m head (Cascade model) which uses 0.71amp (90watts), up to the 3HP Artesian (Pro High Flow model) pump which at 1.5m pump 70,860lph using just 7.9amps (1,480watts) of current. When comparing the wattage and amp draws to your exist-ing pumps and you will see that sub-stantial savings that can be made in run-ning costs with these new pumps. Performance curves on all these models can be viewed on our website or in our catalogue supplement available on request.

Aquasonic have also sourced a continu-ous use 12v pump which can move sur-prising amounts of water for applica-tions where 240V is not an option. The smallest of these pumps is just 43watts, pulls 3.6amps and will pump 7300lph @0.5m head. The largest of these

blower also results in a significant reduction in the amount of power required to achieve that transfer of oxy-gen in the water. Maintenance is also reduced considerably – no more chang-ing or repairing reduction boxes, as blowers are typically reliable and require little maintenance. Aquasonic can assist with sizing the airlift grids to meet bio-mass requirements in either your tank or pond application.

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Oxygenation of water bodies is another

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costs for farmers. Running traditional

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Fast starts can be routine. Pure fresh-cultured OzBugZz© microbes nitrify & denitrify wastein marine & fresh water recirc. & purge systems. Quality + O.Night Del + Tech Support.

Dr Steven Nearhos Baseline (07) 335 66 111.

AQUACULTURE SERVICES AUSTRALIA

Get the right information by purchasing copies of The Australian Yabby Farmer at $47.50 and

The Australian Fish Farmer at $97.50(inc GST & postage)

Tel: 03 9817 3043 or email: [email protected]

AQUABUILDUniversal Artificial Reef System

www.aquabuild.com.au - Tel: 0419 894 172

®

AUSTRALIAN DISTRIBUTION

CALL FOR EXPRESSIONS OF INTEREST

AQUI-S New Zealand Ltd. is seeking expressions of interest for the rights to distribute AQUIS® in the territory of Australia. AQUI-S® is a registered aquatic anaesthetic (APVMA NRA: #48157) widely used in the salmon, trout, crayfish, barramundi, silver perch,

kingfish and abalone industries.

Interested businesses should have strong ties in theAustralian aquaculture and wild catch sectors.

Please contact Nic Paton for an information pack: Nic Paton - Technical & Marketing ManagerPO Box 44-269, Lower Hutt, New Zealand

[email protected] Ph: +64 4 587 0389 Fax: +64 4 587 0388

Completed applications will be accepted up to the 30th April 2011

For more information please visit

www.aqui-s.com

FOR SALE Abalone Farm PackageThis Green Lip Abalone farm is located at Farm Beach near Coffin Bay in South Australia.

All the equipment to make it a going concern is included in this package. For Sale is 1x5ha at sea abalone lease, 1x13mt maintenance vessel with crane, 1x6mt pontoon hull aluminium feed/work vessel with Yamaha 115hp outboard. Approximately 30 Tool Tech abalone cages consisting of 20 trays in each cage, feed system to feed 1 cage in 5 minutes without lifting, 1 x very large steel floating cage, various long lines, ropes buoys, anchors etc. $120,000 for the lot.

Phone John: 0427 821 281 or Andrew: 0402 254 124 Email: [email protected]

w w w . f r e s h b y d e s i g n . c o m . a u

The Fresh By Design Group is an Australian company providing the Australasian aquaculture industry with high quality equipment, expertise, experience together with an extensive product range and reliable ongoing backup service. We cover commercial and hobby aquaculture, waste

needs of educational facilities.

Ben Pope and Peter Koller3 Old Oak Place, PO Box 1020 Moss Vale NSW 2577Ph: 02 4868 1762 Fax: 02 4868 2206 Mobile: 0419 288 [email protected]

The only equipment supplier to be allied with Future Fisheries Veterinary ServiceDr Matt LandosMobile: 0437 492 863 [email protected]

Veterinary Services

Aquaculture Heater - Chiller

Aquaculture Heater-Chiller

C O N T A C T U SYour Australian agent of Faivre products

Providing high quality equipment to the aquaculture industry

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Autumn 2011

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