Threats To U.S. Aquaculture Overview of … RAS/Overview...Overview of Recirculating Aquaculture...

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FRESHWATER INSTITUTE

Overview of RecirculatingAquaculture Systems in the

United States

Steven Summerfelt

Conservation Fund Freshwater Institute

Shepherdstown, West Virginia

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Threats To U.S. Aquaculture

� “The biggest threat is importation…”(Jim Carlberg, Kent Seatech, IntraFish, May 10, 2006)

…. & the resulting decline in farm gate price

Kent Seatech is no longer producing fish;

they had produced ~1400 mt/yr hyb. striped bass

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OUTLINE

�Introduction to large commercial RAS

�Examples of existing industry

�Rumored growth in large commercial RAS

�Some defunct facilities

�Gross similarities & differences

�Basics of design for 1000 MT/yr

�Economies of Scale

�Reducing capital & operating costs

�Large & deep circular tanks

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Introduction

�We must overcome scale-up issues to develop systems that improve production per unit investment.�large-scale culture tanks

�fish handling techniques

�low cost but appropriate buildings

�improved energy efficiency

�system integration & biosecurity

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Large Operations Dominate Commercial Trout & Salmon Culture

� Both culture technologies face tough environmental

challenges.

� There are few large water resources available for aquaculture

development.

1,000-20,000 m3 per cage

6 m3/s flows to some farms

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Large Production Systems are More Cost Effective

�Economies of Scale�Reduce fixed costs per MTON produced

�Reduce variable costs per MTON produced

�Economies of scale are also valid for controlled, intensive RASs.

Wade et al. (1996). In: Successes and Failures in Commercial Recirculating Aquaculture.

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Holy Grail for Aquaculture in RAS

�Ideal – successful domestic commercial industries will develop in following areas:

�Land-based salmon growout farm

�Tilapia farm competing with imported filets

�Large zero-exchange shrimp production

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Large RAS Facilities Producing 400-1800 MT Annually are the

Exception

Not the Standard

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Examples of Existing RAS Industry

�Tilapia (domestic)

�Most large producers use some type of RAS

• Production total exceeds 9000 MT (20 million lb)/yr

~ $40 million annual US sales

• Bigger producers are 400-1800 MT/yr (1-4 million lb)

• Live fish market

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�Tilapia

�Blue Ridge Aquaculture

Courtesy Jim Michaels(photos courtesy of http://www.blueridgeaquaculture.com/tilapia.cfm)

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�Sturgeon

�Stolt/Sierra Aquafarm (CA)

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�Barramundi

�Australis Aquaculture, Turners Falls, MA

Courtesy Josh Goldman

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�Large RAS for Salmon Smolt

�E.g., Target Marine Hatcheries, Sechelt, BC

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Rumored Growth in Large Domestic Commercial RAS

� Tilapia (Intrafish)

� Barramundi (Intrafish)

� Sea Bream & Sea Bass (Intrafish)

� Perch (Bell Aquaculture)

�Cobia (VA Cobia Farm)

�Moi (Troutlodge Marine Farms Kona)

�Atlantic salmon (American Salmon Company)

�Arctic char (Coldwater Fisheries)

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Large Commercial RAS now Defunct

�Hybrid Striped Bass

�Kent SeaTech (CA)

Courtesy Mike Massingill16



� Simplot, Caldwell, ID

� Intended to feed tilapia @ 4.5 MT/day (10,000 lb)

�95 circular tanks, each 13.7 m (45 ft) diameter

�Swirl settlers & hyacinth bed biofilters

�Shut down in 1990

Ismond (1996). Successes & Failures in Commercial RAS.

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�Solar Aquafarms (1986-1994)

�Produced up to 2300 MT/yr (5E6 lb) tilapia

Serfling (2000; 2006). Global Aquaculture Advocate.

Circular tanks

96 ft Φ x 4 ft deep (820 m3)

D-ended raceways

60 ft x 480 ft (2080 m3)

(Courtesy Steve Serfling)

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�Solar Aquafarms (1986-1994)

� ODAS Systems

• 70-130 mg/L TSS optimum

• paddle wheel aerators

• Solids settling

• Now used for shrimp farming

Serfling (2000; 2006). Global Aquaculture Advocate.

(Courtesy Steve Serfling)

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Large Commercial RAS Now Re-Invented

�AquaFuture � Fins Technologies

� Australis Aquaculture

�Blue Ridge Fisheries � ?

� Blue Ridge Aquaculture

In these examples, continuity benefits RAS productions.20


Experience

�Continuity in both research & industry has benefited design & management of RAS

�analogous to that required for broodstockdevelopment programs.

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Gross Similarities in RAS Technologies

�Most existing large commercial RAS use:

�Microscreen drum filters

�Pure oxygen addition

• LHO

• Cone

• U-tube

• Other

�CO2 stripping

�Ozonation

�Circular tanks (except tilapia)

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CO2 Stripping & Oxygenation

�Large-scale units are widely applied.

LHO

stripper

(Nutreco’s Big Tree Creek Hatchery for salmon smolt)

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CO2 Stripping & Oxygenation


oxygenators

Extended aeration

(Mote Marine RAS for sturgeon growout,

Courtesy Jim Michaels)24


CO2 Stripping & Oxygenation�Sidewall box airlift pumps.

�Decouples CO2 stripping from recycle flow to biofilter and solids removal process

�Simple system – reduces fixed & variable costs

Courtesy of HE Products

foam

skim

mer

inlet

outlet

airlift

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Sidewall Box Airlift Pumps

Courtesy Troutlodge Marine Farms Kona26


Dynamic O2 Control System

�O2 added to cone on a side-stream flow

returning to culture tank

�Improve O2 transfer

�Reduce O2 use

�Increase feeding capacity

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Ozonation of Recirculated Water

�Ozonation of RAS at relatively low, non-disinfecting dosages

�improves water quality

�improves rainbow trout growth

�reduces bacterial gill disease mortalities

�Ozone called ‘Vitamin O’ & the ‘Silver Bullet’

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* RAS with ozone similar to high exchange

* RAS with ozone better than high exchange

1.9 x 101.9 x 10229.1 9.1 x x 101055Heterotrophic Heterotrophic

BacteriaBacteria (counts/mL)(counts/mL)

4.8 x 104.8 x 10332.0 x 102.0 x 1044Total Particle Total Particle

CountsCounts (0(0--200 200 µµm)m)

81 81 ±± 0060 60 ±± 22UV TransmittanceUV Transmittance(%)(%)

2 2 ±± 1152 52 ±± 33ColorColor (Pt(Pt--Co units)Co units)

2 2 ±± 005 5 ±± 11cBODcBOD55 (mg/L)(mg/L)

9.8 9.8 ±± 0.00.09.9 9.9 ±± 0.00.0Oxygen (mg/L)Oxygen (mg/L)

12 12 ±± 0012 12 ±± 00COCO22 (mg/L)(mg/L)

ParameterParameter No Ozone No Ozone OzoneOzone

TSSTSS (mg/L)(mg/L) 10 10 ±± 11 5 5 ±± 11*

*

*

*

*

*

*

*

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Removal Efficiencies (%)Removal Efficiencies (%)

ParameterParameterUnit Unit

ProcessProcess No OzoneNo Ozone OzoneOzone

TAN TAN BiofilterBiofilter 51 51 ±± 22 66 66 ±± 3 3

COCO22

Stripping Stripping

ColumnColumn 40 40 ±± 11 49 49 ±± 55

TSSTSSRadial Radial

SettlerSettler50 50 ±± 1010 72 72 ±± 22

TSSTSSDrum Drum

FilterFilter 7 7 ±± 33 25 25 ±± 11

* RAS with ozone similar to high exchange

* RAS with ozone better than high exchange

*

*

*

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Gross Differences in RAS Technologies

�Large-scale commercial facilities rely on

many types of biofilters:

�Trickling filters

�RBC’s

�Polystyrene bead filters

�Moving bed biofilters

�Fluidized-sand biofilters

�Many biofilter types have been used successfully when properly applied

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Trickling Filters

� Fish Farm Yerseke � Speekenbrink eel farm

Most common in Netherlands where 100’s are in operation!

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Rotating Biological Contactors

�Most notable in large tilapia RAS’s at Blue Ridge Fisheries (courtesy Brian Brazil).

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Polystyrene Micro-Bead Biofilter

Southern Farm Tilapia

flow distribution via orifice plates

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Moving Bed Biofilter


(Mote Marine RAS for sturgeon growout,

Courtesy Jim Michaels)

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Fluidized-Sand Biofilters

�Example FSB in salmon smolt RASs at Marine Harvests Big Tree Creek Hatchery (BC)

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Biofilter Selection

�Biofilter selection does not appear to ultimately determine success of the

facility,

�unless TAN & NO2-N limits are strict.

• then use fluidized biofilters with fine sand

�Biofilter chosen for its familiarity and local design experience….

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Devil in Detail of Design�Successful RAS requires getting all

details right.

�Avoid failure in every aspect:�business management

�marketing

�fish husbandry

�biosecurity, and

�culture system design

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Devil in Detail of Design

�Beware short-cuts & design errors!

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�Design assumptions that contributed to RAS failure:

�I can’t afford to pump that much water• Mistake – insufficient flow will limit carrying capacity

�I can’t afford to use large pipes• Mistake – designed with high pipe velocities (5-10 ft/s),

this produced high �P & increased operating cost.

�I can’t afford microscreen filters• Mistake – settlers were used that resulted in biofloc

system with high DO demand & high CO2 levels.

�I can’t afford to use a more conservative arial TAN removal rate (or I can’t afford excess biofilter cap)• Mistake – biofilter produced high TAN & NO2 conc.

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�Design assumptions that contributed to RAS failure:

�I can’t afford to vent CO2 from the room• Mistake – CO2 accumulation limits stripping efficiency

& CO2 levels in room exceed OSHA.

�I can’t afford sidewall boxes & LHO sumps• Mistake – pumps and LHO sumps in the fish tanks

(DISASTER).

�I need to hold more groups of fish in separation than I have fish tanks• Mistake – hang a net pen in the circular culture tank &

destroy rotation hydraulics, causing formation of biofloc & high TSS, higher DO demand, and higher CO2

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�I can’t afford to put up a building �Biosecurity is missing and disease runs

rampant

�I can’t obtain certified pathogen free eggs or fingerling�Biosecurity is missing & disease can create

huge losses

�Use seedstock that have been tested and certified free from specific listed salmonidpathogens.

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�MOTE MARINE – Nursery & Growout Systems

�Outstanding attention to detail in channels & sumps!

�Other systems….

(Courtesy Jim Michaels)

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�USDA National Cold Water Marine Aquaculture System – Atlantic salmon breeding facility

�Outstanding attention to detail in pipes & sumps!

�Other systems….

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BEWARE AQUA-SHYSTER’s

They may be better at sales than engineering.

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Economics of RAS’s

�Increased fixed & variable costs.

�So far….

�Mostly higher value fish are produced:

• tilapia, hybrid striped bass, sturgeon, Arctic char, barramundi, halibut; turbot, eel, African catfish, marine nursery fish (salmon smolt, etc.), ornamental fish;

• No food-size channel catfish produced;

• Relatively small biomass of food-size trout & salmon.

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Variable Costs for Growout RAS

�After feed, variable cost breakdown:�Amortization 11-22%

�Energy 8-15%

�Labor 8-11% (3% for eel)

�Fingerlings 9-12% (41% for eel)

For commercial eel, sea bass, & African catfish farms.

(Schneider et al., 2006, Aquaculture 2006)

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Economies of Scale

�Increased RAS scale will reduce:

�capital (amortization) for buildings, systems, & infrastructure

�labor per MT produced.

�Capital for the building ≥ capital for systems.

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Economies of Scale

�Large & deep circular tanks can reduce:

�building capital by approximately 40%

�overall facility capital costs by approximately

20-30%

(defunct Hagonsborg salmon

farm, BC)

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Square Tanks w/ Rounded Corners�Approximate circular tank hydrodynamics.

�Option used to maximize floor utilization.

Fish Farm Fish Farm Fish Farm Fish Farm YersekeYersekeYersekeYerseke B.V.B.V.B.V.B.V.The Netherlands


Use of Fewer but Larger & Deeper Culture Tanks

�Reduces floor space requirements

�Reduces cumulative cost of equipment:

� flow control valves

� effluent stand-pipe structures

� fish feeders

� probes: oxygen, pH, temperature, ORP

� flow, level switches


Use of Fewer, but Larger & Deeper Culture Tanks

�Reduces labor:

� time required to analyze water quality

� distribute feed

� perform cleaning chores

� harvest fish

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Large-Scale Circular Tanks

�Design & management requirements:

�self-cleaning tank

�fractionate & rapidly flush solids (< 1-5 min)

�provide optimum swimming speeds for fish

�provide homogeneous water mixing

�remove mortalities w/o entering tank

�harvest/transfer fish w/o entering tank

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Large-Scale Culture Tanks

�Water rotational velocity �Bottom drain flow

> 6 L/min per m2 tank area

�Solids fractionation is controlled by:

Davidson and Summerfelt. 2004. Aquacultural Engineering 32, 245-271. 54


Large-Scale Culture Tanks� Adjustable inlet nozzles systems can be used to

optimize water rotational velocities & mixing.

150 m3,

9.1 m φ

growout

tank

10 m3,

3.7 m φ

nursery

tank

Davidson and Summerfelt. 2004. Aquacultural Engineering 32, 245-271.

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Controlling Tank Rotation

�Velocity near tank perimeter controlled by:

�Nozzle orientation (β)

�Nozzle velocity (UO)

�Tank Flow (V/HRT)

�Velocity near the tank center controlled by:

�Surface loading rate on bottom-center drain

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Controlling Tank Rotation

� Example #1: 13.7 m Φ

V = 600 m3

HRT = 60 min

UO = 100 cm/s

UR,perimeter ≈ 31 cm/s

� Example #2: 13.7 m Φ

V = 600 m3

HRT = 45 min

UO = 100 cm/s

UR,perimeter ≈ 36 cm/s

Larger circular tank can be designed to provide

safe swimming speeds for many fish.

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Large-Scale Culture Tanks

�Question: How to manage fish in large and deep circular tanks?

�Incorporate technologies to

�Rapidly flush daily mortalities

�Grade and selectively harvest

…. from large circular culture tanks without ever entering the culture tank!


Circular Tanks: Removing Morts

�Mechanisms to remove dead fish must be considered!

�decrease labor costs

�reduce spread of fish disease

�maintain water level

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NO SCUBA DIVING!



(out of business: Hagonsborg salmon farm, BC)

�Hinged exclusion screen on bottom drain

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�Center drain uses four 110 cm (4”) diapipes to pull morts up to surface drain

�Live fish swim out over top of inlet weir

Courtesy of Ragnar Joensen, Marine Harvest Faroes

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� Flushing dead fish:�Block flow over sidebox outlet weir

�Pull 30 cm diameter sidebox stand-pipe

�Raise bottom-drain cover using pneumatics

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Advanced Mort Flushing System

dam board

� Flushing dead fish�Replace standpipe

�Remove dead fish

�Remove dam board

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�Purse seine is not selective, but brings fish to pump or brail.

Fish Harvest from Deep Tanks

Summerfelt et al. 2003. Aquaculture America 2003 Abstract Book. Pg 282.

150 m3 tank @ Freshwater Institute

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�Pescalator & purse seine @ Australis

(courtesy Josh Goldman)66


Tank

Lip

Airlift

Pump

Dewaterin

g Grate

Hand

Sorting

Area

Harvested

Fish

Undersized

Fish

Larger Fish

Crowded Between

Clamshell Grader

Gates


�Clam-shell

grader

�Airlift Fish Pump & Grading Box

�Sidewall

Harvest Box

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Clam-Shell Grader & Crowder

150 m3 growout tank 10 m3 nursery tank

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Airlift Pump & Sorting/Dewatering Table

�Passive clam-shell grader with airlift pump and hand sorting/dewatering table.

Hand sorting & dewatering table rests on lip of tank.

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Sidewall Harvest Box�Crowd fish to sidewall box

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Sidewall Harvest Box

�Open gate, allowing crowded fish to slide into dewatering area with water flow

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CO2 Avoidance for Fish Transfer

�Fish can sense elevated concentrations of CO2

�fish will seek to avoid areas with high CO2

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CO2 Avoidance for Fish Transfer

�Fish gather in front of the ‘fish transfer’pipe after CO2 exceeds ~ 60 mg/L

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Results: CO2 Avoidance Study� Last 20% of fish gather in front of the

‘fish transfer’ pipe.

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Results: CO2 Avoidance Study

�Each trial ended by terminating flow

carrying the low CO2 water into the tank:

�99% of fish moved out of growout tank during 2-3 hrs in each of 3 replicated trials.

�Cost of CO2 used for a fish transfer was only ~$4/event.

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OVERALL CONCLUSIONS

�Future looks positive for large

increases in fish production within industrial-scale RAS’s.

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Acknowledgements

� Freshwater Institute research was supported by the Agriculture Research Service of the United States Department of Agriculture, under Agreement No. 59-1930-1-130

�Opinions, conclusions, and recommendations are of the authors and do not necessarily reflect the view of the USDA.

�All experimental protocols involving live animals were in compliance with Animal Welfare Act (9CFR) and have been approved by the Freshwater Institute Animal Care and Use Committee.

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THANK YOU FOR YOUR ATTENTION!

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