Laamu Atoll Mariculture Project: Seaweed Mariculture

Norman Reichenbach and Steve Holloway

March, 1997

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Executive Summary

Kappaphycus alvarezii (commercially known as Eucheuma cottonii) and

Eucheuma denticulatum (commercially known as E. spinosum) were imported from the

Philippines in order to establish a pilot scale seaweed farm in Laamu atoll, Republic of

Maldives. Several attempts in using the traditional monoline culture method were

unsuccessful due to excessive fish herbivory. The bag culture method was then introduced

and proved to be effective in farming the seaweeds.

Site selection was then conducted in 9 areas around the islands between Fonadhoo

and Gan, Laamu atoll in order to select the best sites for pilot scale farm operations.

During the site screening, K. alvarezii was selected as the best species to work with since

this species grew at a much faster rate than E. denticulatum. The average growth rate for

E. denticulatum was -0.58%/day at all the sites while K. alvarezii had a growth rate

ranging from 0.45 to 5.27%/day depending upon the site. One site just south of the

Thundi village, Gan island (G site) and another site on the west side of Bodufinolhu (BF

site) were selected as the two best areas to start pilot scale farm operations.

At each site, a 25 m anchor line was placed. Growth rates were monitored starting

in July, 1996 for both the brown and green strains of K. alvarezii. Seaweeds at the G site

maintained a very high growth rate averaging 6.4%/day (11 day doubling time) for the SW

monsoon season and 5.7%/day (12 day doubling time) for the NE monsoon season. In

contrast, at the BF site, growth rates fluctuated from a high of about 7%/day to negative

growth during one month when excessive fish herbivory was noted. At the BF site growth

rates were generally between 2 to 4%/day. Other bag styles and culture methods were

examined at this site but it was not expanded beyond the one, 25 m anchor line.

The G site, with its consistently high growth rates, was expanded to six, 100 m

anchor lines with each line holding approximately 1000 bags. With the growth rates

recorded from the seaweeds at the G site, the six, 100 m lines could produce about 12,000

kg or more of fresh seaweed per month. Various farm design options at the G site were

evaluated for strength and cost of construction using various combinations of concrete

blocks, coconut tree logs, rerod and coral blocks.

Economics of farming seaweeds in the Maldives was also evaluated. Dried

seaweed sent to the Philippines for analysis indicated that our seaweed met the standards

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needed for international marketing. Costs were considered in three different ways

including 1) profit to a company that would pay salaries to the workers, 2) profit to the

farmer(s) if they owned the farm and sold the seaweed, and 3) cost to produce a ton of dry

seaweed under various labor rates, growth rates, and harvest intervals. Assuming direct

marketing to the buyer, fresh seaweed might sell for 1 rf per kg. This would be equivalent

to $683/MT of dry seaweed assuming 1 MT of dry seaweed can be produced from 8000

kg of raw seaweed (this price is reasonable when selling directly to a company using the

seaweed. If the farmers sell to a middle person they will likely get 50 laari per kg of raw

seaweed).

For a company owned farm the profits per ha per month would range between

$1,610 to $1,661 depending upon the farm design used. For a farmer owned farm the

return to the farmers per ha per month would range between $2,954 to $3,005 depending

upon the farm design used. This amount would be divided between the number of farmers

needed to service the one ha area which might be around 10 people. The costs to produce

a ton of dry seaweed were typically between $200 to $300 depending upon the growth

rate, harvest interval and labor rate.

In the recommendations, the exponential growth potential of seaweeds was

examined as to how it relates increasing production volume by increasing the starting

weight of seaweeds used and having a harvest interval of one month. The merits of a

larger bag were discussed in relation to increasing the starting weight of seaweeds and to

ensuring that the harvest interval would be one month. A farm was then designed which

would use larger bags.

Introduction

Eucheuma seaweed culture was started and developed in the Philippines in the late

1960's by Dr. Doty's group. Since this time, the Eucheuma seaweed industry has become

one of the Philippines top foreign exchange earners (Llana 1991). Due to the success of

farming seaweeds in the Philippines other countries such as the Pacific island countries,

Indonesia, Tanzania, and Malaysia have also started Eucheuma seaweed farming with

varying degrees of success.

Eucheuma seaweeds contain carrageenan which is commercially important due to

its excellent properties as a thickener, emulsifier, stabilizer, and gelling agent for a number

of products. Some of the products where carrageenan is used include ice cream, tooth

paste and desserts/sweets (Llana 1991).

Though Eucheuma is not an indigenous species to the Maldives, studies have

shown that introduction of Eucheuma to new areas has had minimal effect on the local

tropical reef environment (Neushul et al. 1989; Russell 1983). In addition, Eucheuma had

been imported to the Maldives before. In 1987-1988, private interests in the Maldives

brought in strains of Eucheuma for use in a pilot project on the island of Goiyadhoo in Baa

Atoll. The pilot project used typical monoline culture techniques which have been

successful in the Philippines. The Goiyadhoo project demonstrated that Eucheuma could

be grown in the Maldives (Holloway 1992).

The goal of this project was to establish a pilot scale Eucheuma seaweed farm in

Laamu atoll, Republic of Maldives. Details on establishing this pilot scale farm are

provided in this report which includes sections on: 1) seaweed importation and selection

of the best culture methodology, 2) selection of the best species, 3) selection of the best

site, 4) seaweed farm: growth rates, 5) seaweed farm: design considerations, 6) seaweed

farm: maintenance and harvesting/drying, 7) product quality, 8) economic analysis, 9)

environmental impact, 10) recommendations, 11) literature cited.

Section 1: Seaweed Importation and Selection of the best culture

methodology

Three trials were required to determine the most appropriate culture methodology

for areas in Laamu atoll. As is usually the case in introducing new technologies,

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established culture techniques from other parts of the world must be refined and adapted

to the new environment (Adams and Foscarini 1990).

The details of these trials are given in the following three subsections.

Subsection 1a: Bodufinolhu - monoline trials

Bodufinolhu is an uninhabited island just north of island of Gan, in Laamu Atoll.

Initially, several test sites were identified in the lagoons around this island. Materials for

the monoline culture technique were prepared for these sites. This culture technique

consists of monofilament lines of 10 meters each, stretched between reinforcement rod

stakes, with one stake in the center. These stakes were driven into the sandy substrate of

the lagoon floor. Thirty to forty Eucheuma plants, each about 100 g, are then tied by

`plastic straw' to the monofilament line.

In late December 1994, 10 kg of Kappaphycus alvarezii (commercially known as

Eucheuma cottonii) and 10 kg Eucheuma denticulatum (commercially known as E.

spinosum), were imported from GENU Corporation in the Philippines. The monolines

were distributed around the Bodufinolhu area, to find favorable conditions. All of the E.

denticulatum were lost in the first month. The plants wasted away on the lines showing

symptoms of the stress-related condition called ice-ice. A significant portion of our K.

alvarezii seed stock was also lost because the monolines were too close to a reef where

there were a significant number of herbivores.

A site for the remaining K. alvarezii was found in late March 1995, between

Bodufinolhu and the next island north, Gasgandufinolhu, where the plants stabilized. This

site between the two islands is the exchange point between the extensive shallow lagoon

area between the atoll island chain and the barrier reef to the east, and the interior of the

atoll to the west. Current flow is primarily from the daily tidal surge going in and out of

the opening between the islands. A pen was built out of plastic netting (1/2" mesh size) to

protect the initial crop from herbivores. The pen was designed to contain 4 monolines.

Lines were then placed both inside and outside the pen. At this point measurements on

growth and environmental parameters were started. The data on growth indicated that the

seaweeds on the lines inside the pen demonstrated better specific growth rates (SGR) than

those outside (Table 1).

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Table 1. Bodufinolhu monoline trials with Kappaphycus alvarezii (10 April - 3 May 1996)

Location Inside the Pen Outside the pen

Current (m/min) (24 hour averages)

Average 2.29 7.76

Range 0.91 - 4.52 5.43 - 11.16

Temperature (C)

High 33 32

Low 28 28

SGRa (%/day), average 2.46 (Line A)b

2.48 (Line B)

2.86 (Line F) 1.76 (Line G)

a: SGR = (ln(wt)-ln(wi))/t*100 where wt is final weight, wi is initial weight, t is time in days

b: Lines A and B are the original 'parent' plants from which cuttings were taken for lines F

(inside the pen) and G (outside the pen). Each monoline contained 25 plants.

In mid-May 1995, about 95% of the seaweeds were lost during the transition

period between the northeast (NE) and southwest (SW) monsoon seasons. There is a time

during this shift where winds and waves virtually cease. The sea becomes like a mirror and

the horizon can actually disappear. When the lines were checked just after this transition

period, there were only a few stumps of seaweed left attached to the lines, and a few

pieces scattered on the bottom of the pen, all with signs of severe ice-ice.

Evaluating the die-off during the first set of trials on both E. denticulatum and K.

alvarezii, it was apparent that several factors in the local lagoon area combined to over-

stress the plants. Grazing pressure was a major factor. A significant portion of our K.

alvarezii seed stock was lost because the monolines were initially too close to a reef

where there were a significant number of herbivores. The monolines with K. alvarezii

which were within the plastic pen had some protection from large herbivores, but not from

the juvenile siganids which lived in the lagoon area and could easily pass through the

mesh. Some lines were initially placed in waters too stagnant for the seaweeds, and were

moved to sites with better currents when the plants were observed to be stressed. There

was a difference between the current speeds inside the pen and outside the pen, and

though the plants inside had better growth rates, this was probably due to the protection

from grazing pressure. Temperatures in the lagoon were also at the high end of the

tolerance range for K. alvarezii and E. denticulatum. This would be particularly so during

the monsoon shift when it is very calm.

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Subsection 1b: Kadhdhoo - monoline trials

The few remaining pieces of K. alvarezii left over from the initial Bodufinolhu die-

off were collected and moved to another site two islands to the south of Gan, near

Kadhdhoo, the atoll's airport island. Kadhdhoo, and several other islands near Gan, are

connected by a series of causeways across the lagoons. The longest causeway is between

Kadhdhoo and Fonadhoo to the south and it is a little less than 1/2 mile long. Here the

seaweed stubs began to recover but since they were not protected by a pen, they were

consumed by herbivores within a week of being out planted.

Kadhdhoo had been considered as an alternate site for monoline growth trials.

During a survey of this area conducted in 1992 a significant standing crop of seaweed and

marine plants was noted in the lagoon on the eastern side of the causeway between the

islands of Kadhdhoo and Fonadhoo. This seaweed population was characterized by

relatively large patches of Spiridia and Halymeda, with clumps of Hydroclathrus drifting

around on the lagoon floor, and a few areas of the marine angiosperm, Thalassia. This

was different from most of the reef flats of Laamu, which are characterized by extensive

Thalassia `meadows' and large areas of bare sand (Lewis et al. 1992).

In mid-September, 1995, a new site was prepared for seaweed growth trials near

Kadhdhoo. A new pen was constructed in the lagoon between the causeway and the atoll's

barrier reef to the east. This pen was larger than the one at Bodufinolhu, and could contain

11 monolines. New seaweeds were imported and trials at Kadhdhoo began.

K. alvarezii, at times, grew quite rapidly, with individual plants demonstrating

growth rates as high as 7.4% per day. The average growth rate was 5.5%/day (3.2 to

7.4%/day, minimum to maximum growth rates). The temperatures ranged from 26-31 C.

The overall good growth rates were surprising since the recorded current speeds were

extremely slow (24 hour average, 0.64 cm/sec, range during trials: 0.04 - 1.35 cm/sec)

compared to what is considered optimal for K. alvarezii (10-20 cm/sec).

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E. denticulatum, in contrast, was especially stressed at this site.The average

growth rate was 0.6%/day (-3.1 to 3.0%/day; minimum to maximum growth rates). The

negative growth rate reflects, primarily, plant breakage due to ice-ice, with the plant

pieces falling and drifting to the floor of the pen. The pieces of E. denticulatum were

collected from the bottom of the pen and retied to the monolines, or if they were too

small, placed in net bags. In all probability, the slow current speeds contributed

significantly to their deterioration. In addition the light intensities may have been too high

for E. denticulatum (Ray Lewis, pers. communication).

In the Kadhdhoo trials, plants were divided when they grew beyond 300 g. The

cuttings were used to seed empty areas of the monolines in the pen in an effort to increase

biomass. All the plants in the pen were weighed because of the various genetic strains

present. Individual strains were tracked to look for ones that grew especially well in the

new environment. The trial started on 5 October with 19 kg, and on November 5, the

seaweed biomass had increased to 58 kg. By the next cutting, if the K. alvarezii growth

rates had continued, all available lines in the pen (eleven,10 m monolines, 30 plants on

each line) would have been occupied by seaweeds. The next step was to prepare

monolines outside the pen.

On 13 November 1995, project staff arrived at the pen to find all monolines

stripped, without even drift seaweed in the pen (usually there were drift pieces if the

seaweed had broken off from the lines). The monolines had only the empty plastic ties and

the individual plant identification tags attached. The only seaweed remaining, about 2 to 3

kg, was that in a net bag made up of pieces too small to tie to the monolines. The evidence

strongly pointed to the pen being stripped by herbivores. Vandalism, another option, was

ruled out because of the undisturbed empty ties on the monolines, lack of even small drift

seaweed pieces on the pen floor, and the untouched seaweeds in the net bags. The top of

the pen was about 22 cm under water at the highest tide. There were nocturnal tides (45

cm above the mean) during the full moon on the 7th and 8th of November which likely

allowed herbivores to enter the pen and consume the seaweeds.

Subsection 1c: Bodufinolhu - bag trials

In January 1996, Mr. Ruben Barraca Sr., an FAO seaweed consultant, visited our

project and demonstrated a new technique for seaweed farming. The culture technique

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uses net bags which are anchored to lines staked out on the lagoon floor (Barraca, 1996).

This technique has several advantages over the traditional monoline method. The bag

netting gives the seaweed some protection from herbivores. This system is much less labor

intensive and it is easier to maintain, manage, and harvest the crop. The bags allow the

plants a much greater range of movement in the water, assisting them in nutrient uptake,

as well as giving increased resistance to algal blooms and diseases while protecting the

plants from photo-oxidation. The design of the bag culture system allows it to be more

resistant to adverse weather conditions.

This first trial (Table 2) was conducted near the site used for the first Bodufinolhu

monoline trials described above. The objectives of this initial trial were to evaluate the bag

culture technique in general, compare the growth rates at the western and eastern

extremities of the 125 m anchor line and compare the growth rates of the plants in the

bags relative to those on the monolines in our first trial. The seaweed remnants from the

Kadhdhoo monoline trials were initially used. Though there was some herbivorous grazing

on the seaweed tips that extended beyond the confines of the net bag, the seed stock

remained healthy throughout the trial, and displayed no symptoms of ice-ice. Growth rates

at both extremes of the anchor line were essentially the same for the two species, and so

they were combined. In addition the growth rates for plants in the bag were comparable to

those on the monolines in the first trial.

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Table 2. Bodufinolhu bag culture trials with Kappaphycus alvarezii and Eucheuma

denticulatum.

current temperature SGRa

mean min-max min max old K. ab. new K. a.b E. d.b

date m/min m/min (C) (C) (%/day) (%/day) (%/day)

17/3-9/4/96 10.0 4.5-20.4 28 32 2.6 (1.5-3.6) -- 2.4 (1.8-3.9)

14/4-4/5/96 8.0 6.6-10.1 28 31 2.7 (1.4-3.7) 4.2 (3.0-5.1) 1.7 (0.9-2.7)

8/5-28/5/96 12.4 9.5-16.5 28 32 2.6 (1.1-3.7) 2.3 (0.5-3.5) 1.5 (0.4-2.7)

a: SGR = (ln(wt)-ln(wi))/t*100 where wt is final weight, wi is initial weight, t is time in days

b old K.a. is the K. alvarezii stock left over from Kadhdhoo, new K. a. is stock from a new

shipment of K. alvarezii and E.d. is E. denticulatum

Another shipment of both K. alvarezii and E. denticulatum was received from

GENU in late March 1996. The second trial (14/4 to 4/5/96; Table 2) was conducted to

quantify the observation that the newly acquired K. alvarezii from the Philippines was

growing more rapidly than the K. alvarezii seed stock left over from the Kadhdhoo pen.

The growth rate difference is much less pronounced in the third trial (8/5 to 28/5/96;

Table 2) which seems to confirm the idea that the high growth rates of the new seaweed

stock were a temporary phenomena.

This second trial spanned the period of monsoon change, which seemed to have

little effect on growth rates. This supports the hypothesis that seaweeds, protected from

the stress of herbivorous grazing, can survive and even thrive during this period.

In conclusion, both trials at two locations using the monoline culture method

demonstrated that the K. alvarezii can grow at a good rate. The trials also demonstrated

that the monoline method did not provide enough protection from grazers so that a stable

crop could be produced. The bag culture method seemed to provide an adequate

environment for the seaweeds protecting them from excessive herbivory and allowing the

seaweeds to transition through a monsoon season shift. The bag culture method was

therefore selected as the best culture method to pursue for our pilot scale farm.

Section 2: Selection of the best species

During all the initial trials to determine the best culture method, K. alvarezii grew

better than E. denticulatum (see Section 1). In the site screening study (Subsection 3a)

this was again confirmed at all of the sites evaluated. E. denticulatum lost weight and had

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an average growth rate of -0.58%/day at all the sites while K. alvarezii had a growth rate

ranging from 0.45 to 5.27%/day depending upon the site. K. alvarezii was selected as the

species for use in the pilot scale seaweed farm.

Section 3: Selection of the best site

Many guidelines of site selection have been made, only to be broken by successful

farmers in other areas (Barraca, 1990). Since farming K. alvarezii was new to Laamu

atoll, our farm site selection was based upon measured seaweed growth rates at the

various sites rather than evaluating the physical environment for what would seem to be an

optimal environment for the seaweeds. Site selection was a two step process. The first was

to do a broad screening of different areas near Gan and Fonadhoo in order to identify 3

good sites using seaweed growth rates and other seaweed culture related information. The

second step was to see how homogenous these 3 best areas were and in the process to

locate two potential pilot scale farm sites as close as possible to the villagers who would

be doing the seaweed farm work.

Subsection 3a: Site screening

The purpose of this experiment was to evaluate 9 different sites which

characterized various environments in Laamu atoll to determine 3 'best' sites for further

evaluation.

The bag culture method was used and the duration of the experiment was one tidal

cycle or approximately 28 days during June and July, 1996. Eight bags of K. alvarezii (6

of the green strain and 2 of the brown strain) and 2 of E. denticulatum were placed at each

site with each bag containing approximately 1/2 kg seaweed (for E. denticulatum about

1/4 kg per bag). The number of bags and biomass per bag was dependent upon the

biomass available for each species and strain at the time of experiment initiation.

Measurements included initial and final weights of seaweed plus qualitative measures of

bag cleanliness, ease of conducting culture activities at the site (water depth, current

velocity, waves), and area available for farm construction. From the initial and final

weights a SGR was calculated. Doubling times were calculated using the SGR.

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Site characteristics considered in site selection included water velocity, substrate,

exposure to air during extreme low tides, and general weather conditions of the area

during June and July, 1996 (Table 3 and Fig. 1).

Table 3: General characterization of sites selected for seaweed site screening experiment.

Site/description

Water velocity

(max)

Substrate

Exposure

(air)

Exposure

(weather)

1/island gap N of BF high rubble none rough

2/tip of BF high sand none rough

3/east of BF moderate sand yes calm

4/east of BF near Gan moderate Thalassia yes calm

5/east of Gan near reef moderate rubble/Thalassia yes moderate

6/west of BF near BF moderate sand none moderate

7/west of Gan moderate sand yes rough

8/Kadhdhoo west of causeway moderate sand/Thalassia yes moderate

9/Kadhdhoo east of causeway slow sand none calm

3

6

7

N

Bodufinolhu

Gan

1

2

4

5

8 9

Fonadhoo

Kadhdhoo

Figure 1. Site locations in Laamu atoll for seaweed site screening experiment.

The results for K. alvarezii are summarized in Table 4 and are discussed below on

a per site basis.

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Table 4. Growth data and scores for various factors used to assess each site for its

potential for seaweed production.

Growth Rate Bag Area Ease of

Site SGR (%/d)a doubling (days)b scorec cleanlinessd Availablee Culturef Totalg

1 1.45+0.44ch 48 1 1 1 1 4

2 1.36+1.07cd 51 1 1 2 1 5

3 2.44+0.46b 28 2 1 2 2 7

4 1.36+0.54cd 51 1 1 2 2 6

5 0.45+0.24d 155 0 3 2 1 6

6 3.24+0.39b 21 2 2 2 2 8

7 5.27+0.41a 13 3 2 2 1 8

8 3.24+0.56b 21 2 1 2 2 7

9 -- -- -- 2 2 2 --

a SGR = (ln(wt)-ln(wi))/t*100 where wt is final weight and wi is initial weight and t is time in

days, the SGR is followed by + one standard deviation

b doubling time is ln(2)/(SGR/100)

c score based upon significant differences from ANOVA test using a 0 to 3 scale with 3 being the

highest growth rate and 0 the lowest.

d bag cleanliness scored on a 1-3 scale, 3 no cleaning needed, 2 some cleaning, 1 daily to every 2nd

day cleaning

e area available scored on a 1-2 scale, 2 several ha available, 1 one ha or less available

f ease of culture scored on a 1-2 scale, 2 easy access and currents/waves not to strong/large, 1

currents/waves strong/large at times

g total is simply a sum of the scores

h letters a, b, c, d reflect significant differences based on ANOVA test with Bonferroni multiple

comparison test (P<0.05)

Site 1 was the channel between Bodufinolhu and Gasgandufinolhu. The substrate

was coral rubble. The growth rate was low with a doubling time of 48 days (growth score

= 1). The bags needed frequent cleaning due to algae growing on the bags (bag cleanliness

score = 1). The current was also strong during tide changes and it was best to conduct

culture activities during low tide (ease of culture score = 1). The area available was about

1 ha (area score = 1). The total score was 4.

Site 2 was near the tip of Bodufinolhu on the east side. The substrate was coral

rubble. The growth rate was low with a doubling time of 51 days (growth score = 1). The

bags needed frequent cleaning due to algae growing on the bags (bag cleanliness score =

1). The current was also strong during tide changes and it was best to conduct culture

activities during low tide (ease of culture score = 1). The area available was several ha

(area score = 2). The total score was 5.

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Site 3 was east of Bodufinolhu near the middle of the island. The substrate was

white sand. The growth rate was moderate with a doubling time of 28 days (growth score

= 2). The bags needed frequent cleaning due to algae growing on the bags (bag cleanliness

score = 1). The site was simple to access since the current was moderate and the water

depth was 1 to 2 meters (ease of culture score = 2). The area available was several ha

(area score = 2). The total score was 7.

Site 4 was just north of Gan over a bed of seagrass, Thalassia. The growth rate

was low with a doubling time of 51 days (growth score = 1). Damage to the seaweed due

to herbivory was noted multiple times. The bags needed frequent cleaning due to algae

growing on the bags (bag cleanliness score = 1). The site was simple to access since the

current was moderate and the water depth was 1 to 2 meters (ease of culture score = 2).

The area available was several ha (area score = 2). The total score was 6.

Site 5 was east of Gan about 20 meters from the barrier reef. The substrate was

seagrass and coral rubble. The growth rate was very low with a doubling time of 151 days

(growth score = 0). The seaweed at the end of the experiment were pale and did not look

healthy. The bags did not require any cleaning (bag cleanliness score = 3). While the site

was simple to access since the current was moderate and the water depth was less than 1

meter, the frequent twisting of the bags at the base due to the perpendicular nature of the

waves and the current added to the maintenance of the site (ease of culture score = 1).

The area available was several ha (area score = 2). The total score was 6.

Site 6 was west of the tip of Bodufinolhu about 20 meters from the shore. The

substrate was white sand. The growth rate was good with a doubling time of 21 days

(growth score = 2). The bags required a minimal amount of cleaning which in most cases

was no more than shaking the bag a little in order to remove deposited sediments.(bag

cleanliness score = 2). The site was simple to access since the waves were small and the

water depth was 1 to 2 meters (ease of culture score = 2). The area available was several

ha (area score = 2). The total score was 8.

Site 7 was west side of Gan about 1/2 km south of Thundi. The substrate was

white sand. The growth rate was the highest with a doubling time of 13 days (growth

score = 3). The bags required a minimal amount of cleaning which in most cases was no

more than shaking the bag a little in order to remove deposited sediments.(bag cleanliness

score = 2). The site was often difficult to access because of the large waves (ease of

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culture score = 1). The area available was several ha (area score = 2). The total score was

8.

Site 8 was west of the causeway between Fonadhoo and Kadhdhoo. The substrate

was coral rubble and Thalassia. The growth rate was good with a doubling time of 21

days (growth score = 2). The bags needed frequent cleaning due to algae growing on the

bags (bag cleanliness score = 1). The site was simple to access since the waves were small

and the water depth was less than 1 meter (ease of culture score = 2). The area available

was several ha (area score = 2). The total score was 7.

Site 9 was east of the causeway between Fonadhoo and Kadhdhoo. The substrate

was sand. All the seaweed were gone within 4 days after placement. Presumably the

seaweed were eaten by fish. An additional bag placed at this site one week later was empty

several days after placement. The bags left in place were fairly clean throughout the

duration of the experiment. The area available was several ha but because of the herbivory,

this site was dropped as a potential farm site using the current version of the bag culture

methodology. No total score was assigned to this site.

The site total scores indicated that Sites 6 and 7 had the highest scores (total score

= 8). These sites are located on the west side of Bodufinolhu and Gan, respectively

(Figure 1). Sites 3 and 8 had the second highest scores (total score = 7). Site 3 was on the

east side of Bodufinolhu and Site 8 was on the west side of the causeway between

Fonadhoo and Kadhdhoo. Since the best sites, (Sites 6 and 7) were on the west side, Site

3 was selected as the third site since it was located on the east side. This provided a wide

range of environmental conditions especially with respect to the monsoon seasons.

Further trials were conducted in July/August, 1996 to determine how

homogeneous the growth rates are in areas around Sites 3, 6, and 7 (Fig. 2). Following

these trials, pilot scale seaweed farm operations were initiated.

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N

Bodufinolhu

Gan

6b 6a

3a

3b6a6a6d 6c

7a

7b

Figure 2. Sites used to test for homogeneity of the growth rates within the areas

associated with potential farm sites 3, 6 and 7.

Subsection 3b: Site Homogeneity Experiment

The purpose of this experiment was to measure how homogeneous the growth

rates for K. alvarezii were in the 3 sites (Sites 3, 6 and 7) identified as the 'best' sites in the

site screening experiment (Fig. 1). Two sites were then selected to initiate pilot scale farm

operations.

Site 3a was the original Site 3 of the site screening study and Site 3b was placed in

an area similar to Site 3a but closer to Gan. Sites 6a through 6d were placed either near

the tip of Bodufinolhu or close to Gan, both close and far from the beach of Bodufinolhu.

Site 6b was close to the original Site 6 of the site screening study. Sites 7a and b were on

the west side of Gan. Site 7a was the original Site 7 of the site screening study and Site 7b

was simply a site closer to Gan (Fig. 2).

The bag culture method was used and the duration of the experiment was from 21

to 25 days depending upon the site. The experiment was conducted in July and August

1996. Ten bags of K. alvarezii (5 of the green strain and 5 of the brown strain) were

placed at each site with each bag containing approximately 1/2 kg seaweed. Measurements

included initial and final weights of seaweed. From the initial and final weights a SGR was

calculated. Doubling times were calculated using the SGR.

The growth data are summarized in Table 5 and are discussed on a per site basis.

14

Table 5. Growth data for site homogeneity study.

Site SGR (%/d)a Significanceb doubling (days)c

3a 0.47+1.11 a 147

3b 2.89+0.25 b 24

6a -4.31+2.88 c --

6b 5.72+1.12 a 12

6c 1.92+1.30 b 36

6d 5.02+0.51 a 14

7a 6.39+0.64 NS 11

7b 6.81+0.42 10

a SGR = (ln(wt)-ln(wi))/t*100 where wt is final weight and wi is initial weight

and t is time in days, average SGR value followed by one standard deviation

b NS indicates no significant difference between Sites a and b within a

numbered site, letters indicate sites within a numbered site which are

significantly different (P<0.05).

c doubling time is ln(2)/(SGR/100)

Site 3 had significant differences between the growth rates for Sites a and b (Table

5). This difference may have been due to the origin of the stock used in the experiment.

The stock used at Site 3a was from Site 3 in the site screening experiment. Essentially the

seaweeds were at this site for a 2 month period and the growth dropped from 2.44 to 0.47

during the second month at the site. The seaweeds during the second month became pale

and ice-ice was noted on several plants. The stock from Site 3b was from a high growth

site during the site screening experiment.

Sites 6a through d growth rates indicated that the sites near Bodufinolhu had low

growth rates. This was primarily due to herbivory. The seaweeds in some bags were

totally consumed. The sites further from Bodufinolhu had significantly higher growth rates

relative to the sites closer to the beach (Table 5). Site 6b had a growth pattern for the

brown strain similar to that seen at Sites 7a and b (see below).

Sites 7a and b had similar growth rates, both of which were high (Table 5). In

addition to the growth rates being high the growth pattern of the seaweeds at these sites

were dense clumps. These clumps could easily be dumped out of the bags. In contrast the

growth pattern at the other sites except Site 6b was such that seaweed removal was more

difficult. The seaweeds had to be carefully removed from the bags by hand.

15

The sites selected for pilot scale farm operations included Sites 7b and 6b. Site 7b

was selected because of the optimal growth rates (6.81%/day), the clumped growth

pattern and because of its proximity to Thundi. This site was frequently rough, with 1 m

high waves, which made the site difficult to maintain at times. Site 6b was selected

because of the high growth rates (5.72%/day), the clumped growth pattern seen in the

brown strain and because the waves were much smaller relative to Site 7b.

Section 4: Seaweed farm: growth rates

During June and July, 1996 pilot scale farms were initiated at sites 7b and 6b. Site

7b is called the Gan site (G site) and Site 6b is the Bodufinolhu site (BF site). At each site,

25 m anchor lines were initially constructed. Then 180 bags attached to the propagule

lines were placed at each site. Growth rates were monitored monthly at each site. The

usual measurement period was 2 weeks and generally 10 bags from each of the two strains

(brown and green) were weighed. If other bag types or culture methods were being tested

than weights were taken on a comparable number of units over a comparable period of

time. In all cases SGRs were calculated as well as doubling times.

For the BF site during the SW monsoon (Months 7 through 11), growth rates

declined over time due to fish herbivory (Fig. 3). The tips of the plants were frequently

missing due to herbivory. Plants were severely cropped by herbivores during December

(Month 12) at which time the lowest growth rates for the site were recorded. During the

NE monsoon period (Months 12 through 3) the growth rates were initially low and then

started to recover. Fish herbivory was not observed during the later months of this

monsoon period though the water temperatures would sometimes rise to 33 C. Due to the

low growth rates noted at this site, the number of lines was reduced and only the brown

strain was maintained at this site after Month 11. Other culture methods were tested at this

site including modifications to the original bags used, bags made of different netting

material, and propagule holder (PH) culture method (Ruben Baracca Sr., pers. comm.;

Fig. 4).

16

Figure 3. Growth rates (SGR, %/day) for seaweeds at the BF site.

float

propagule line

seaweed plant

rope loop

Figure 4. Illustration of the propagule holder (PH) where seaweeds are tied to the rope

loop.

Because of the fish herbivory noted in the SW monsoon period, the bags were

initially modified. First the bag normally used was simply doubled. That is one bag was

placed inside another bag. This style was tested over a 2 month period using only the

brown strain. In October, there was no significant difference in the growth rates for the

two styles of bag. In November the growth rates of seaweeds in the double bags was

better than those in the normal bags. For both months though the growth rates were low

with a best doubling time of 25 days (Table 6). An additional type of bag was then tested

17

which was larger and made with a heavier nylon material instead of the monofilament used

with the normal bags. In each of the large bags 2 kg of seaweed was placed initially as

opposed to the normal 0.5 kg which was placed in the normal bags. During December the

growth rates in the heavy bags were significantly better than for those in the normal bags

(Table 6). Seaweeds in the normal bags were heavily grazed during this month. During the

subsequent month (January) the normal bags resumed a more usual growth rate while

those in the heavy bags dropped to 0.5%/day (Table 6). This was most likely due to the

shift in the monsoon season where the water movement was much less at this site than

previously. The heavier and larger nature of the bag may have reduced water exchange

within the bag relative to the normal bag with the subsequent drop in growth rates in the

larger bags.

As noted above, fish herbivory declined during the NE monsoon period. Because

of this, the PH culture method was also tried at BF. Initially the growth rates were

somewhat slower than the seaweeds in the bags (Table 6) but during the second month the

growth rates were not significantly different from those in the bags (Table 6).

Table 6. Growth rates for the brown strain of seaweeds cultured in various modifications

to the net bags and PH method in relation the growth rates recorded for seaweeds in the

normal bags.

Time Period SGRa -normal bag SGRa-double bags t/df/Pb

Oct./1996 2.4+0.3 2.6+0.4 1.0/18/0.32

Nov./1996 2.2+0.5 2.8+0.5 2.8/18/0.01

SGRa-heavy bags

Dec./1996 -0.6+1.8 2.6+0.6 1.8/13/0.002

Jan./1997 2.0+0.5 0.5+0.4 5.8/13/<0.001

PH method

Feb./1997 3.4+0.8 2.7+0.3 2.4/18/0.03

March/1997 4.1+0.5 3.9+0.5 1.1/18/0.3

a SGR = (ln(wt)-ln(wi))/t*100 where wt is final weight and wi is initial weight and t is time in

days, average SGR value followed by one standard deviation

b t = t test value, df=degrees of freedom and P is the probability value

One final test was conducted at the BF site in March 1997 using plants attached to

PH units. One line of seaweeds from the G site was transferred to the BF site and growth

18

of these plants were compared to a line where the plants had been at the BF site since the

site was started. The plants from the G site grew significantly faster (SGR=6.7+0.6) than

those that had been at the BF site since the site was started (SGR 3.9+0.5) (t=11.2,

d.f.=18, P<0.001). The high growth rate of the plants transferred from the G site would

have to be tested over a longer period of time to see if they are able to maintain this high

rate of growth comparable to that noted at the G site.

The BF site was monitored for growth rates and testing various options until the

end of March 1997. Due to the low growth rates as compared to the G site, the BF site

was not expanded.

Site G maintained high growth rates from June 1996 to March 1997 and this site

was expanded from the original 25 m line to six, 100 m lines. The growth rates for the two

strains were not significantly different (F=2.6, d.f.=1, P=0.11) but there were significant

differences between the months of the study (F=10.9, d.f.=8, P<0.001) (Figs. 5, 6).

Instead of doing pairwise testing for differences between the months the data were divided

into two parts representing the two monsoon periods. This test indicated there were

significant differences between the growth rates of the seaweeds for the two monsoon

periods (t=4.4, d.f.=165, P<0.001). The NE monsoon period had a slightly lower growth

rate of 5.7+0.7%/day (12 day doubling time) relative to the SW monsoon period

(6.4+1.3%/day or 11 day doubling time). Both growth rates, though, are high and were

relatively consistent through time (Figs 5, 6).

Figure 5. Growth rates (SGR, %/day) for seaweeds at the G site.

19

Figure 6. Doubling times (days) for seaweeds at the G site.

A final set of experiments using the bags was conducted in March. This experiment

was to determine if the growth rates are consistent as the bags fill up with seaweeds.

Weights were taken 10 days after placing the bags in the ocean, 19 and then 28 days later.

One kg was placed in the bags at the beginning. The rates were good for the first 19 days

when the bags filled on average to 2650 or 2820 g (green and brown strain averages,

respectively) (Figs. 7, 8). The growth rates were not significantly different between the

first 10 days in the ocean and the time between days 10 and 19 (green strain t=1.9,

d.f.=18, P=0.07; brown strain t=0.7, d.f.=18, P=0.46). During the final 9 days of the trial

(days 19 to 28) the growth rate declined significantly compared to those from the previous

measurement period (green strain t=7.8, d.f.=18, P<0.001; brown strain t=10.6, d.f.=18,

P<0.001). The bags at the end of the trial were on average 3380 and 3730 g for the green

and brown strain, respectively. During this last 9 day measurement period another set of

bags with the brown strain were placed in the water. These bags had 1 kg per bag and the

growth rate was compared between these bags and the bags which were very full to see if

the rates were comparable. The bags with the 1 kg biomass had significantly higher

growth rates than those for the bags which were full (Fig. 9) (t=4.4, d.f.=18, P<0.001).

Figure 10 illustrates the amount of seaweed expected in the bags had the 5.44%/day rate

recorded during the first measurement period for the brown strain been maintained for the

full 28 days of the trial. The actual amount observed is similar to that expected during the

first 19 days of the trial but then, during the final 9 days of the trial, the observed amount

became less than the amount expected since the growth rates dropped. Based upon these

results, the current size of bag being used can fill rapidly to around 3 kg. Up to this weight

20

a high growth rate can be maintained. Beyond 3 kg the growth rates decline as the bags

become very full.

Figure 7. Growth rates (gsgr) and average weight per bag (g) (gwt) for the green strain.

Figure 8. Growth rates (bsgr)and average weight per bag (g) (bwt) for the brown strain.

21

Figure 9. Growth rate for the brown strain over time (bsgr) compared to another set of

bags started with 1 kg on day 19 and measured for 9 days (bnsgr).

Figure 10. Measured average weight per bag (g) (bwt) and the expected weight per bag

(g) (expwt) had the growth rates been maintained at the initial measured rate of 5.44%

day. Data are for the brown strain.

During the NE monsoon season the PH culture method was tested at the G site.

During this season the G site is calm and it was felt that the PH method might work. The

first set of lines were placed in mid December. We thought we were finished with the SW

monsoon period but we still had one more storm which made the site rough. The initial set

of plants were all stripped off of the PH units during this storm. Another set was placed in

January and the seaweeds were observed qualitatively for growth and herbivory damage.

Some herbivory was noted but the growth appeared to be very good. In mid January,

22

1997 growth studies were initiated on the PH units. Up to 10 plants could be tied to each

PH unit. We examined the effect of tying 1, 2, 3, 4, 6, 8, 10 plants to each unit. Each

treatment was replicated on 10 units or one propagule line. Each unit would contain 1 kg

of plants so for the 1 plant/unit a one kg plant was attached. For the 2 plants/unit each

plant weighed 500 g, etc. The data indicated that the growth rates were lower for the 1, 2,

3 and 4 plants/unit relative to the 6, 8, 10 plants per unit (Table 7). Breakage of plant

parts were noted more frequently in the lower number of plants per unit. For the higher

number of plants per unit (6 through 10 plants/unit) the growth rates were similar. At the

higher number of plants/unit the plants may have been too crowded to maintain a linearly

increasing growth rate. The final weights recorded for these higher number of plants/unit

were as high as 4.8 kg with growth rates being as high as 8.8%/day (Table 7). Based upon

these data we elected to tie on only 6 plants per PH loop since tying on more than 6 plants

did not produce more biomass. The additional time required to tie on the additional plants

was not warranted.

A comparison of 6 plants/unit to bags over the same time period indicated that

plants on the PH units grew significantly faster that those in the bags (PH 8.8%/day and

bags 6.6%/day in February/97, t=7.4, d.f.=18, p<0.001). While growth of the seaweeds on

the PH units was very good the seaweeds are vulnerable to herbivory. On several

occasions the plants on several propagation lines with PH units were eaten by fish

herbivores.

Table 7. Growth rates relative to the number of plants per PH unit.

Number of plants/PH unit SGR (%/d) significant difference

1 4.1+1.1 a

2 4.7+0.8 a,b

3 5.9+1.2 b,c

4 7.1+1.3 c,d

6 8.8+0.8 e

8 7.6+0.6 d,e

10 8.5+0.9 e

a letters a, b, c, d, e reflect significant differences based on ANOVA test

with Bonferroni multiple comparison test (P<0.05). Number of plants/unit

with the same letter are not significantly different.

With the growth rates recorded at the G site during both monsoon seasons, the

estimated production volume for the six, 100 m lines would be about 12,000 kg or more

(12 metric ton or more) of fresh seaweed per month. For a 1/2 ha farm in the Philippines

23

the production volume would be about 10,000 kg or 10 tons (Ruben Baracca Sr., pers.

comm.). The 6 line farm at the G sites would then exceed the production volume of a

typical 1/2 ha farm in the Philippines.

Section 5: Seaweed farm: maintenance and harvesting/drying

The general bag culture methodology is to put from 1/2 to 1 kg of seaweed in the

net bag and than harvest the contents after 14 to 28 days. The bags on a propagule line are

removed from the anchor line and taken to the beach where the seaweeds are easily

removed from the bags and dumped on tarps. Some of the seaweed is put into clean bags

and the rest of the seaweed is dried. The old bags are then buried in the sand for about 1

week. Drying of the seaweeds generally takes 2 to 3 days after which they are no longer

slimy and salt crystals have formed on the surface of the seaweeds.

Due to the extreme differences at the G site during the two monsoon seasons,

different culture strategies are recommended for each season. During the SW monsoon

season the site was rough with fairly steady wave action and periodic strong wave action

while during the NE monsoon the site was calm. During the SW monsoon the wave action

made work at the site somewhat difficult but the waves were advantageous in that they

helped keep the bags clean. Once a week cleaning was generally necessary and the bags

could be in the ocean for about one month before they needed to be buried in the sand for

one week to kill off the algae on the bags. One half kg of seaweed was placed in each bag

and with the growth rates measured during this season (average of 6.4%/day) the

seaweeds were harvested after 3 to 4 weeks(see recommendations for modifications on

the starting weight of seaweeds). At this time the bags contained about 3 kg. Propagule

lines were pulled to the beach and emptied. One half kg was put into clean bags and the

other 2 1/2 kg was dried. During the SW monsoon season the propagule lines at the G site

must be made of 4 mm rope. If fishing line is used it will get twisted due to the strong

waves and will eventually break causing a great deal of unnecessary labor to untangle the

lines. The loops on the propagule lines must also be much smaller than the 25 cm loop

recommended (Barraca, 1996). The larger the loop the more the bag twists due to the

wave action. Small loops, just large enough to loop the bag through should be used on the

propagule lines. The site must also be frequently checked to make sure the anchor lines are

strong and not wearing against coral. The farm site must also be cleaned of debris that

gets tangled on the lines during the storms of this monsoon season.

24

During the NE monsoon the G site is calm. The major difficulty encountered

during this time was algae growing on the bags. At times the algae fouling the bags

formed gassy mats that caused the whole bag to float near the surface. This would expose

the seaweed on one side of the bag excessively to sunlight causing parts of the seaweed to

turn white and die. This is essentially a type of ice-ice. Since the growth rates were still

good during the monsoon season one of two approaches can be taken to deal with the

algae: 1) continue to use bags but clean more often or 2) use PH units since the algae did

not attach itself to the plants. When bags were used 1 kg was placed initially in each bag

and bags were then harvested 2 to 4 weeks later (see recommendations on harvest interval

as related to starting weight of seaweeds). At this time there should be about 2 kg or more

in the bag depending upon how long the bags were left in the ocean. The bags should be

rigorously cleaned two to three times a week. During this season monoline can be used for

the propagule line instead of the 4 mm rope used during the SW monsoon since the G site

is calm during the NE monsoon.

The other approach during the NE monsoon is to use the PH units noted above in

the growth studies. During this monsoon season the G site is calm enough that an

excessive amount of seaweed is not lost due to plant breakage using this method. The

growth rates are also in general higher than those noted for seaweeds in the bags but the

plants on the PH units have a higher risk of being consumed by herbivores relative to

plants in the bags. Using the PH units, the seaweeds need only be cleaned once or twice a

week. The method of tying seaweeds onto the PHs is time consuming but the high growth

rates in addition to the less frequent cleaning needed may compensate for the time needed

to tie on the seaweeds. A minor modification to the PH units was tested to eliminate the

tying on of plants. A thin PVC (1/2" diameter high pressure PVC) ring was used instead of

a piece of rope for attaching the plants to the PH loop. The ring was about 5 mm in

thickness and was cut at one point. The ring was then tied to the PH loop, 6 to 10 rings

per loop. The ring could then be easy spread apart a little and the plant slid through the

gap so that it sits in the middle of the ring (Fig. 11). This modification significantly

reduced the amount of time it took to attach plants to the PH units.

25

float

propagule line

seaweed plant

rope loop

pvc

ring

Figure 11. Illustration of the propagule holder (PH) where seaweeds are clipped on the

loop using the PVC ring.

Therefore during the NE monsoon season, either method, bags or PHs, can be

used. When bags were used the starting biomass of seaweed was 1 kg and the bags were

well cleaned 2 to 3 times a week. Harvesting was done every 3 to 4 weeks depending

upon how full we allowed the bags to get. During the rougher SW monsoon only bags

were used at the G site. Seaweeds were stripped from the PH units during the SW

monsoon. The starting biomass was 1/2 kg during the SW monsoon and harvesting took

place 3 to 4 weeks later. Higher yields are obtained if a larger starting biomass is used (see

recommendations on starting weight and harvest interval of seaweeds). During the SW

monsoon bags needed to be cleaned only once per week.

Drying of the seaweeds is best done by emptying the bags and then placing the

seaweeds on drying tables similar to those constructed for drying fish. Local woods can be

used to support the platform made of petioles of the coconut tree. The platform is about 3

feet above the ground and 6 feet wide and any convenient length. The petioles could be

spaced about 1 inch apart if netting is not used and about 6 inches apart if netting is used.

It was found that about 1 square foot was needed to dry one kg of seaweed. At the G site

farm, 2,500 square feet of drying table were constructed to dry the estimated 12 tons of

seaweeds produced from the farm per month. Generally 1 1/2 to 3 days was needed to dry

to the seaweeds to a moisture level of about 1/8 of the original weight of the fresh

seaweed.

A harvest schedule might follow several different patterns. One could harvest daily

or one could do block harvests several times a week or month. In our 6, 100 m line farm

with 20 work days per month, 12 days could be used to change bags at a rate of 500 bags

26

per day. This would cycle through all the bags on the 6 lines in one month. The bags

would be emptied and part of the seaweed biomass dried while the other is returned to the

ocean in new bags. The other 8 days of the month would be used for activities such as

cleaning the bags, storing the dried seaweed, and farm maintenance. For the block harvest,

activities follow a different pattern. On one day 1000 bags would be completely emptied

and all the seaweed in the bags would be put on the drying tables. On the 2 subsequent

days, all the seaweed from 250 bags would be changed into 750 new bags and put in the

ocean. In this way 1500 bags could be processed in the 3 days. This type of processing

could be done each week so that all the bags on the 6 lines would be changed during one

month. The other two days of the week could then be used for the other activities noted

above.

Section 6: Product quality

Three kg of dry seaweed were sent to Mr. Ruben Barraca Sr. in December, 1996.

The following is the analysis report he submitted to OSM on the quality of our seaweeds

produced at the G site. He indicated that seaweed material was of marketable quality

(Ruben Baracca Sr., pers. comm.).

Table 8 Dried seaweed analysis report.

Parameter OSM Maldives Standarda

% moisture content 24.70 30.0

% clean anhydrous weed (CAW) 41.33 41.0

% Gum yield 26.33 29.0

% Gum yield from CAW 63.71 71.0

Gel strength, g 1094g 850 min./1100 target

Viscosity cps 65 25 min./50 target

pH 9.59

a standards provided by Ruben Baracca Sr.

Section 7: Seaweed farm: design considerations

Various designs for the seaweed farm were tested including different anchors at

the ends of the anchor lines and different intermediate supports to the anchor line. All

three styles were tested at Site G.

A general description of the farm used with the bag culture method follows that of

Baracca (1996) and includes anchor line construction and placement at the farm site. The

27

overall design for one anchor line was to have two 100 m ropes running parallel to each

other with a distance of 5 m between the lines. Between the pair of anchor lines are the

propagule lines to which the net bags are attached. Each propagule line was 5 m in length

and had 10 small loops to which the net bags were attached.

The ends of the anchor lines have to be firmly secured since a pair of 100 m lines

will hold at times in excess of 2,000 kg of seaweed. Along the length of the anchor lines

additional support can be given in order to secure the anchor line. While the anchor line

must be very secure, the propagule lines with the net bags should be easily detached from

the anchor line. We found it simplest to detach the propagule lines and do the loading and

unloading of the seaweeds in the beach area.

Each anchor line was constructed using one roll (220 m) of 10 mm rope. Knots

were initially placed along the rope at distances of 1 m. Looped through these knots were

4 mm pieces of rope to which the terminal loops on the propagules lines were attached

(see Fig. 12). In the figure the pvc pipe is an 8 cm (3 inch) piece cut from a 3/8" diameter

high pressure pipe. A hole is cut into the pipe through which the rope is thread and then a

knot is placed to secure the pvc piece to the rope. The rope length needed to construct

this loop is about 40 cm. Note that during the calm NE monsoon season the terminal loops

on the propagule lines could just be looped over the pvc pipe if desired. This would

eliminate the step of needing to loop the pvc pipe through the rope loop. Also note that

after knots are placed in the 10 mm rope the actual length of the anchor line is usually less

than 100 m. An alternative method is to not tie knots at one m intervals but rather to tie

thin rope (2 to 2.5 mm) through the 10 mm rope at two places about 1 inch apart and then

in between these two ropes to tie the loop with the pvc piece. This would preserve the

original length of the anchor line rope.

pvc pipe

rope loop through which

pvc pipe is inserted to hold

propagule linerope looped

through knot in

anchor line

Figure 12. Illustration of the loop with the pvc piece used to attach the propagule

line to the anchor line.

28

The final pair of anchor lines then has from 95 to 105, 4 mm rope loops plus pvc

pieces (the number of rope loops is dependent upon whether knots are placed at 1 m

intervals. If knots are place then the line will have about 95 rope loops). This would allow

from 95 to 105 propagule lines (950 to 1050 net-bags) to be attached to this pair of

anchor lines. The total cost of the materials for the anchor line was $45.65. Materials plus

labor was $64.85 (Table 9).

Two styles of anchors were used at the terminal ends of the anchor lines including

concrete blocks and coconut tree logs. The concrete blocks were in the shape of a disk.

They were from 10 to 15 cm thick and 1 meter in diameter. In the middle was placed one

to two holes using 2 cm (1 inch) pvc pipe. Two holes were placed in the large blocks since

these blocks could be used as the anchor for 2 anchor lines. Through the pvc pipe was

threaded thick rope (14 to 16 mm) and knots were placed on both ends. The anchor lines

could then be tied to these thick ropes. It was estimated that each large concrete block

weighed 250 kg. Two and a half bags of concrete along with aggregate, sand and pieces of

3 mm rerod were needed to make four concrete blocks. The total cost of the materials for

4 blocks was $33.28. Materials plus labor was $62.07 (Table 9).

The other style of anchor at the terminal ends of the anchor line was a coconut tree

log about 6 feet tall and sharpened into a point at one end. This log could be driven like a

stake into the substrate if coral, below the sandy surface, was not present. If this log could

be driven to a depth of about 70 to 100 cm, then the anchor was very secure. Generally 3

people were needed to move the log back and forth to drive it into the substrate.

Periodically one person can climb to the top of the log to provide extra weight to drive the

log into the substrate. The total cost for materials was $8.53. Materials plus labor was

$27.73 (Table 9).

Three styles of supports along the length of the anchor line were considered

including coral blocks, rerod and tree logs. The coral blocks were purchased from local

people who did this for a business. Blocks were generally at least 40 cm square. A piece of

8 mm rope about 3.5 m long with a loop on the end was looped around the coral rock.

This unit was then tied around the knots on the anchor lines at 2 m intervals. The block

was placed to the outside of the anchor lines at the maximum distance permitted by the

rope loop. Through time the coral blocks would become buried in the sand and the anchor

line was then secure. It was best to not attach the propagule lines with seaweeds until after

29

the coral blocks were buried. The total cost of the materials was $109.86. Materials plus

labor was $81.06 (Table 9).

The rerod supports were 2 cm (1 inch) in diameter and were 1 m (approximately 3

ft) long. These were driven into the substrate with an 18 lb hammer at a distance of 1 to 2

m from the anchor lines at intervals of 6 m. Rope (6 to 8 mm) was then attached between

the rerod and a knot on the anchor line. For extra support, where the rerod was attached

to the anchor lines, a 5 m piece of rope (6 to 8 mm) was placed between the pair of anchor

lines to essentially secure an 6 m long by 5 m wide section of the anchor line. In places

were coral was either exposed or subsurface, the rerod could be driven into the coral and

the length of the rerod could be shortened as appropriate. Total cost of materials was

$57.59. Materials plus labor was $86.39 (Table 9).

Tree log supports were either coconut tree logs or any other type of strong log

locally available that does not rot or become damaged rapidly in the ocean. These would

essentially be similar to that described above for the anchors. The logs would be driven

into the substrate at 8 m intervals at about a distance of 1 to 2 m from the anchor line.

Rope (6 to 8 mm) would then be attached between the log and the knot on the anchor

line. As with the rerod supports, if extra support was desired rope could be attached

between the anchor lines at the points were the tree log supports were placed. Total cost

of materials was $44.80. Materials plus labor was $83.19 (Table 9).

The structures noted above could be used in various configurations. The best

configurations would use combinations of concrete/log end anchors in conjunction with

rerod/log supports. The coral blocks are not recommended since the taking of the blocks

damages the local reefs in addition to being more costly and not as strong in comparison

to rerod or logs. In our G site we have several lines with both coconut tree logs plus rerod

supports. In areas where there is coral rock under the sand the logs could not be driven

into the sand. In these places rerod could be driven into the coral. In addition, depending

upon the size of the waves and strength of the current at the site, the intervals between

supports or the size of the end anchors could be modified. The site were we have the

above farm design configurations is very rough during several months of the SW

monsoon. The site is near the reef and while the current is not strong, during several

months each year the waves are sizable.

30

table of costs table 9

31

Section 8: Economic Analysis

Three analyses were performed in our evaluation of the economics of farming

seaweeds in the Maldives. The first portion of each of the following tables assumes the

farm is a business venture where farmers are hired at a set salary. The other portion of the

table ("no labor") is where the farm is owned by the individual(s) and labor costs are not

factored into the cost of making or maintaining the farm. In the third analysis, the cost to

produce one ton of dry seaweed is calculated.

Table 10 summarizes the values in Table 9 under Section 7: Design considerations,

except that here the cost of the bags are added in. The cost of the bags is the major

expense in establishing a farm averaging 66% of the cost for a farm where labor is costed

in. At this time this is a fixed cost since these bags are purchased from the Philippines. In

the future, the bags could be locally constructed and hence form another local industry for

the Maldives. Because the bags constitute such a large fraction of the overall cost of

making a farm, whether one chooses to use concrete blocks or logs changes the cost of

the farm only by a small fraction. The cost for making one line including labor and

materials ranges from $575 to $636. Materials alone would range from $498 to $559.

Note that each bag requires a float. In Laamu we put out a reward for children to

bring in discarded flip flop shoes and waste styrofoam found on the beaches. We combined

our need for material to make floats with a reward system for cleaning up the local

beaches. The response was tremendous and for about 400 rf ($34) we were able to

purchase enough material from the children for making 8,000 floats. The children were

happy with their monetary compensation, we received material to make floats for many

bags and the beaches were cleaned up.

32

Table 10. Cost of farm construction per 100 m anchor line. The upper half of the

table assumes farmers are paid a set salary of 1500 rf per month ($128)

while the lower half (no labor) assumes the farmers own the farm and no

labor costs are paid

anchor line bagsa farm design anchor supports total

($) ($) anchor/supports ($) ($) ($)

64.85 399.00 concrete/blocks 62.07 109.86 635.78

concrete/rerod 86.39 612.31

concrete/logs 83.19 609.11

logs/blocks 27.73 109.86 601.44

logs/rerod 86.39 577.97

logs/logs 83.19 574.77

no labor

45.65 399.00 concrete/blocks 33.28 81.06 558.99

concrete/rerod 57.59 535.52

concrete/logs 44.80 522.73

logs/blocks 8.53 81.06 534.24

logs/rerod 57.59 510.77

logs/logs 44.80 497.98

a cost of bags is $3.00 per 10 bag unit or one propagule line. Since bags have

to be buried in the sand each month more than 1000 bags are needed for a 100 m

line. In this costing it is assumed that 133, 10 bag units are needed per 100 m

line where 1000 bags could be in the ocean and 33, 10 bag units in rotation or

be available as replacement bags for damaged bags. If bag units are considered

only for burying in the sand (i.e. no replacement bags for damaged bags) than

only 125, 10 bag units would be needed if the bags are buried in the sand for

one week.

Using the cost of making a farm from Table 10 an overall evaluation of what the

business owner or farmer (no labor) might expect is provided in Table 11. Several

assumptions were made in constructing this economic analysis including:

1) materials used to make the farm would have to be replaced over a 2 year (24

month period) and so farm material costs are divided by 24,

2) labor charges were assumed to be 1500 rf per person per month,

3) price per kg of raw seaweed is 1 rf (this would be equivalent to $683/MT of dry

seaweed assuming 1 MT of dry seaweed can be produced from 8000 kg of raw

seaweed). This price is reasonable when selling directly to a company using the

seaweed. If the farmers sell to a middle person they will likely get 50 laari per kg

of raw seaweed and their profits would be less,

4) a line is 100 m long with 1000 bags,

5) production volume estimated using a doubling time of 2 weeks (SGR 5%/day),

6) each ha farm has 20, 100 m lines,

7) the farm starts with 1 kg of seaweed per bag and,

33

8) there are 10 people managing a one ha farm.

Profit per ha would range from $1610 to $1661 depending upon the farm design

desired. If the farm is owned by the farmer, then the profit to the farmers would range

from $2954 to $3005 (Table 11). Since it is assumed that 10 farmers are needed to

manage a one ha farm then this would mean that each individual would receive from $295

to $300 (3462 to 3522 rf) (Table 11).

Table 11. Costs, profits and income for a seaweed farm. The upper half of the table

assumes farmers are paid a set salary of 1500 rf per month ($128) while the lower half (no

labor) assumes the farmers own the farm and no labor costs are paid. Units are USD ($)

unless otherwise noted.

farm design material labor sales profit per month profit

anchor/support cost per moa per mob per moc per lined per hae rff

concrete/block 26.49 64.00 171.00 80.51 1610.20 18871

concrete/rerod 25.51 64.00 171.00 81.49 1629.80 19101

concrete/logs 25.38 64.00 171.00 81.62 1632.40 19131

logs/block 25.06 64.00 171.00 81.94 1638.80 19207

logs/rerod 24.08 64.00 171.00 82.92 1658.40 19436

logs/logs 23.95 64.00 171.00 83.05 1661.00 19467

no labor

concrete/block 23.29 0.00 171.00 147.71 2954.20 34623

concrete/rerod 22.31 0.00 171.00 148.69 2973.80 34853

concrete/logs 21.78 0.00 171.00 149.22 2984.40 34977

logs/block 22.26 0.00 171.00 148.74 2974.80 34865

logs/rerod 21.28 0.00 171.00 149.72 2994.35 35094

logs/logs 20.75 0.00 171.00 150.25 3005.00 35219

a cost is per 100 m line and assumes replacement of materials over a 2 year period

b assume 1/2 person month per 100m line @ 1500 rf/mo (11.72 rf per $1)(this is equivalent to 10

people per ha

c assume 2 kg per bag of seaweed produced for sale per month at 1 rf per kg raw seaweed. This is

equal to $683/MT of dry seaweed assuming 1 MT of dry seaweed can be produced from 8000 kg

of raw seaweed. This price is reasonable when selling directly to a company using the seaweed. If

the farmers sell to a middle person they will likely get 50 laari per kg of raw seaweed and the profit

would then be less than half that noted here.

d profit per line (100 m line) are sales minus labor and materials

e profit per ha are profit per line multiplied by 20

f profit in the local currency (rf) is on a per month and per ha basis. For the "no labor" option

where the farm is owned by the farmers, the per farmer income would be the profit divided by

however many farmers are needed to manage the 1 ha farm. Where the farmers are paid a salary,

10 farmers are assumed to be managing a 1 ha farm. Conversion to rf is 11.72 rf per $1.

34

Since growth rates change per month the farm owner or farmers might receive a

variable amount depending upon the month. Using the lowest cost farm design (log

anchors and log supports), profit per month per ha can be generated using the same

assumptions noted above except the production volume varies with the growth rate (Table

12). With growth rates as low as 3% the 10 farmers managing the farm would still exceed

the set salary of 1500 rf earned if they were hired labor for a farm (Table 12). As the

growth rates increase so do the profits so that during some months the farmers could net a

very respectable salary. An assumption made throughout this analysis is that the farmer is

willing to put in the extra hours of labor to harvest the larger biomass produced from

seaweeds growing at the higher rates.

Table 12. Profits in relationship to seaweed growth rates from a one ha log anchor/log

support farm design.

Growth Profit per month per ha ($)

(SGR) business pays farm labor farmers own farm (no labor)

3% 219 1563

4% 868 2212

5% 1661 3005

6% 2231 3575

7% 2688 4032

8% 3359 4703

9% 3681 5025

Another way to consider the economics of seaweed farming is to determine how

much it costs to produce a ton of dry seaweed. Using the lowest cost farm design (log

anchors and log supports), two growth rates corresponding to the average for the NE and

SW monsoon seasons, harvest intervals of 2, 3, or 4 weeks and 3 labor rates (1500, 1800,

and 2000 rf per month), the cost to make a ton of dry seaweed was calculated. The higher

the growth rate the lower the cost per ton (Table 13). The cost per ton also drops as the

harvest interval increases due to the exponential growth of seaweeds (see

recommendations on harvest interval). As the labor rate goes up so does the cost per ton.

Even at the highest labor rate, lowest growth rate and shortest harvest interval, the cost

per ton is below $400.

35

Table 13. Cost to produce one ton of dry seaweed depending upon the labor rate, seaweed

growth rates and harvest interval (for details on the effects of initial weight of seaweed

used, growth rates, and harvest intervals see recommendations).

Labor Rate per Month

Growth

Rate

(%/day)

Harvest Interval

(weeks)a

$128 (1500 rf)

$154 (1800 rf)

$171 (2000 rf)

Cost per ton ($)b

5.7c 2 285 326 353

3 246 282 306

4 176 202 219

6.4d 2 241 276 299

3 203 233 253

4 139 160 173

a harvest interval - the number of weeks between taking the excess seaweed out of the bags to dry. The

amount left in the bags would be 1 kg since this was the starting weight

b cost per ton of seaweed produced in Laamu. To ship to Male by dhoni is estimated to cost 25 rf per 80

kg bag or $27 per ton (based upon discussions with villages in Thundi)

c average growth rate during the NE monsoon period

d average growth rate during the SW monsoon period

Section 9: Environmental Impact

The areas where the seaweed farm was established had a substrate of bare white

sand. Therefore the actual substrate was not altered due to seaweed activities such as farm

construction or farm maintenance activities.

Seaweed pieces from the bags were rarely seen on the substrate. In contrast, in

areas where the PH units were used seaweed pieces were seen either near the site or

washed up on the beach. With either culture method, though, seaweeds were never seen to

establish themselves in or around the site. The pieces simply died or were eaten by fish or

other herbivores.

The physical seaweed farm structure (anchor lines, bags, etc.) provided structure

for small fish which would often be seen along the lines or around the bags. Whether the

seaweed farm actually promoted increases in the populations of these small fish or whether

they simply attracted the fish is not known.

36

Section 10: Recommendations

To provide a basis for several of the following recommendations a background in

growth rates of seaweeds is provided so that the relationship between starting weight of

the seaweed, harvest interval and amount of harvestable seaweed can be understood.

Seaweeds generally follow an exponential rate of growth, at least for a given time interval

(Fig. 13). For example if the weight is doubled in 2 weeks than in another 2 weeks it

would double again. Figure 13 illustrates the exponential rate of growth for several

different starting weights with a growth rate of 6.4%/day (equal to a doubling every 11

days which was the average doubling time recorded in the SW monsoon season). If you

start with 0.5 kg and have a growth rate of 6.4%/day then after 11 days you would have 1

kg and then in another 11 days, 2 kg and then at the end of the month or a 28 day period

about 3 kg or a little less than 3 doublings. If you start with 2 kg then you would have a

similar set of doublings and after 28 days you would have about 12 kg. So starting weight

will have a large impact on how much you will be able to harvest per bag. Figure 13 can

also be used to illustrate the basics for harvest interval. If you harvest every 2 weeks than

you slide back to the beginning of the curve to estimate how much you can harvest during

the second, 2 week interval. For example, if you placed 2 kg in the bag to begin with and

harvested after 2 weeks than you would get approximately 5 kg. You could take 3 kg to

dry and return the remaining seaweed to the bag for another grow out period. You would

get the same amount during the next 2 week interval or a total of 6 kg to dry. In contrast

if you left all of the seaweed in the bag another 2 weeks for a total of 4 weeks you would

be on the part of the curve at day 28 or about 12 kg. If you retain 2 kg in the bag you

could harvest 10 kg to dry or 4 more kg than if you harvested every 2 weeks. There would

also be a savings in labor in not having to process the bags so frequently. These points on

harvest frequency and starting weight are examined further below.

37

Figure 13. Amount of seaweed in the bag over time in relation to the starting

weight (0.5, 1, 1.5, 2 kg). Growth rate used was 6.4%/day (average growth rate

for the SW monsoon period).

As indicated above the starting weight of the seaweed placed in the bags is

important. Figure 14 illustrates the amount you can have in a bag after 28 days and the

amount you can harvest (final weight minus initial weight) relative to the starting weight

of seaweeds used (the growth rate used is 6.4 %/day which is the average rate recorded

for the SW monsoon period). The goal is to have a very full bag after one month or 28

days and then process the bags only once per month. For example, if you place 0.5 kg in

the bag initially you would have 3 kg in the bag after 28 days and could harvest 2.5 kg. If

you started with 1 kg you would have 6 kg in the bag and could harvest 5 kg. Because of

the size limitations of the bag currently being used, the maximum the bag can hold is

estimated to be about 3 to 4 kg (note the growth rates slowed between 3 to 4 kg in the

bag (see section of growth). Based upon Figure 14, 0.5 kg (1/2 kg) would be a good

starting weight during the SW monsoon season. With this starting weight about 3 kg of

seaweed would be in the bag after 28 days. Some seaweed is then taken out to dry (2.5

kg) and the rest (0.5 kg) is put in a new bag and returned to the ocean. It is likely that

putting a larger amount in the bags currently being used would not net a significantly great

yield since the growth rates drop as the bags fill beyond 3 kg (see section on growth

rates).

38

Figure 14. Final weight and harvestable amount relative to the starting weight of

seaweeds used. Assumed are a 28 day harvest cycle and 6.4%/day growth rate

(average growth rate during the SW monsoon period).

Figure 15 illustrates the same information as Figure 14 except the growth rate is

for the NE monsoon season. For the NE monsoon period where the growth is a little

slower than the SW monsoon, one could start with 0.6 kg per bag. Then at the end of the

month you would have 3 kg in the bag and could harvest 2.4 kg.

Figure 15. Final weight and harvestable amount relative to the starting weight of

seaweeds used. Assumed are a 28 day harvest cycle and 5.7%/day growth

rate.(average growth rate during the NE monsoon period).

39

As illustrated above if you could put 2 kg in a bag and wait 28 days to harvest you

could have about 12 kg in the bag. This would allow you to dry 10 kg and retain 2 kg in

the bag. The current bag size is too small for growing 12 kg of seaweed per bag per

month. Because of the potential benefits of using a larger bag size not only in harvesting

more seaweed biomass but also in processing a fewer number of bags (labor savings), the

following culture method modification is recommended for field testing.

Bags should be constructed which could hold maximally 4, 6, 8, 10, 12 kg.

Seaweed placed in these bags should be tested over a 28 day period for growth. The bag

which produces the greatest amount of harvestable seaweed should then be used in the

following farm design. In the following illustration of a modified farm design a bag which

can hold up to 12 kg is assumed.

A 10 mm rope could have our loop design (Fig. 12) placed every 0.5 m to which

the larger bag would be attached (Fig. 16). The opening of the bags could be at the

bottom since the bags would be opened and closed on the beach. An opening at the

bottom would also require only one knot to secure the bag and floats would not be lost

because the top of the bag has no opening. The bag could be 3 feet long and 2 feet wide.

There would be no propagule lines but rather a series of anchor lines placed 1 meter apart.

The anchor line would have coconut trees anchors at each end and then additional coconut

tree logs every 25 m to which the anchor line would be directly tied to. There would be

not additional supports attached to the anchor line. So for a 100 m anchor line you would

have four, 25 m units between logs to which 50 large bags would be attached per unit or a

total of 200 bags per 100 m anchor line (Fig. 16). From this anchor line you might be able

to harvest 10 kg per bag per month or a total of 2000 kg. Since the original design with

smaller bags has 5 m between sets of anchor lines you could have 6 lines for the larger

bags in a comparable area so that the total would be 1200 bags for the 6 lines (Fig. 17). At

2000 kg per line of harvestable seaweed you could harvest from 6 lines, 12000 kg from

the 1200 bags. In contrast, from the original design of 10 bags per propagule line and

1000 bags per set of anchor lines you would harvest a total of 2.5 kg per bag per month or

a total of 2500 kg (this assumes a starting weight of 0.5 kg and then harvesting at the end

of the month as illustrated in Figure 14).

40

each bag represents 10 bags

25m

distance between bags is 0.5m

Figure 16. Anchor line for a large bag seaweed farm.

5m

100m

Figure 17. Spacing of anchor lines for a large bag seaweed farm.

Whether one can effectively use a bag than can contain 12 kg of seaweed needs to

be determined. But any larger size bag which maintained a growth rate similar to that

noted for the bags currently being used would increase the amount of harvestable seaweed

biomass as well as reduce the number of bags needing to be processes for a comparable

amount of biomass.

Other recommendations would include:

1) construct anchor lines perpendicular to shore in the G site. The anchor lines are

currently placed parallel to the shore with one set near the beach and the other set further

out. With this configuration, to place the 20 lines for a one ha farm would require 1000 m

of linear shoreline. Placing the lines perpendicular to shore would allow more lines to be

placed for a given linear distance of shoreline. The logistics of placing the lines

perpendicular need to be worked out as coral is found further out and the water depth

increases as ones moves further from the shore.

41

2) large scale testing at the BF site. The BF site is a large area with several ha of lagoon

space available. It is also further from the reef and hence is not very rough during the SW

monsoon season. Fish herbivory might be overcome by increasing the amount of biomass

at the site. Bags and PH units should be tested on the scale of a least one, 100 m anchor

line. PH units could likely be used the entire year at this site if fish herbivory can be

overcome.

3) expand current farm operations and evaluate new sites in Laamu atoll plus other atolls.

Evaluate new sites first for a 12 month period and then develop the best sites.

4) develop a high quality drying, baling and packing facility in Laamu atoll.

5) develop strain of K. alvarezii best suited for the Maldivian environment

6) develop local industries which use carrageenan.

7) expand seaweed farming operations using other species of seaweed.

Section 11: Literature Cited

Adams, T. and R. Foscarini (eds). 1990. Proceedings of the regional workshop on

seaweed culture and marketing. South Pacific Aquaculture Development Project,

FAO GCP/RAS/116/JPN, FAO Field Document 1990/2.

Barraca, R. 1996. Feasibility study of farming, processing and exporting of Eucheuma

(seaweeds). Report for FAO TCP/MDV/4452.

Barraca, R. 1990. Agronomy protocol. Pages 34-36 In: Proceedings of the regional

workshop on seaweed culture and marketing, Adams, T. and R. Foscarini (eds),

South Pacific Aquaculture Development Project, FAO GCP/RAS/116/JPN, FAO

Field Document 1990/2.

Holloway, S. 1992. Harvesting the Bounty of the Reefs: An Evaluation of Mariculture

Candidates for the Republic of Maldives, Oceanographic Society of Maldives, Box

2075, Male, Republic of Maldives.

Llana, E. 1991. Production and utilization of seaweeds in the Philippines. Infofish

International 1/91:12-17.

42

Lewis, R. S. Holloway, and A. Shakeel. 1992. Preliminary survey of sea cucumber and

seaweed resources in Laamu atoll, Republic of Maldives. Oceanographic of

Maldives, Box 2075, Male, Republic of Maldives.

Neushul, M., C.D. Amsler, D.C. Reed, and R.J. Lewis. 1989. The Introduction of

Marine Plants for Aquacultural Purposes. Department of Biological Science,

University of California, Santa Barbara; Presented at Aquaculture '89, UCLA,

USA.

Russell, D. 1982. Introduction of Eucheuma to Fanning Atoll, Kiribati, for the purpose

of mariculture. Micronesia 18:3544.