HANDBOOK FOR

SANDFISH FARMING
PREFACE

This handbook aims to disseminate the approach employed by project partners, in a ReCoMaP
funded project, to develop sea cucumber farming as an alternative livelihood for vezo fishers, a
marginalised coastal population, in south-west Madagascar. It is designed to raise awareness,
among future stakeholders, of the factors that can affect the viability of the activity.

Background

In Madagascar, a technique for the in vitro reproduction of sandfish, Holothuria scabra, was
developed during the pioneering work of the Aqua-Lab, a university cooperation project involving
two Belgian universities (ULB and UMSH) and a Malagasy university (IH.SM). In 2009/2010, a small
production unit (hatchery and nursery) allowed the spin-off company, Madagascar Holothurie SA
(MH.SA), to utilise their patent-protected spawning technique to produce approximately 60,000
juveniles per year. At the time of writing, construction is underway for a 20-fold increase in
production, which is expected to achieve significant economies of scale. Furthermore, a number of
other countries are now interested in utilising this technology to develop sandfish farming along their
coastlines.

For private companies, such as MH.SA, two options are available for the grow-out of hatchery-
reared juveniles to market size. The first option is the development of private farms managed by the
company or their business partners. The second option however, which is described in this
handbook, is to work with coastal communities to develop sea cucumber farming as an alternative
livelihood. In the case study of Madagascar, the private company sells sandfish juveniles to families,
who rear them to market size in sea pens constructed in areas adjacent to their village. Once the sea
cucumbers reach market size, they are harvested and sold back to the company for processing and
export.

Two NGOs working in south-west Madagascar (Trans-Mad-Dveloppement and Blue Ventures)

received funding from the Regional Programme for the Sustainable Management of Coastal Zones
of the Indian Ocean (IOC-EU-ReCoMaP) to develop sea cucumber farming as an alternative
livelihood. Their role has been to develop and test effective mechanisms to support the creation of a
network of small-scale mariculture units, which are both economically viable for farmers and
productive enough to sustain a business partnership with the private company.

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The manual is organised into three sections:

Section 1: A guide for operators including technical details and recommendations on:

A) The farming system promoted

B) The role of farmers and the tasks involved
C) The importance of technical and organisational support
D) The key steps to develop community-based mariculture

Section 2: Factsheets on key aspects of sea cucumber farming

Factsheet no. 1: Selection and validation of farming sites

Factsheet no. 2: Pen construction techniques
Factsheet no. 3: Production monitoring techniques
Factsheet no. 4: Methods to calculate optimal rearing densities
Factsheet no. 5: Strategies for control of predators
Factsheet no. 6: Strategies to prevent poaching: the case in Madagascar
Factsheet no. 7: Financial statement for one family owned pen (in US$)

Section 3: An illustrated cartoon for the extension of community-based sea

cucumber farming

This manual is published by ReCoMaP and is currently available in three languages: English, French
and Malagasy.

The authors wish to thank project staff and partners involved in the development of community-
based sea cucumber farming in Madagascar:

De SAN Michel (ProGeCo)

RAKOTOMANJAKA Jos (ProGeCo)
RAJAONARISON Pierre (Dessinateur)
CHAN KITE WAYE Jaco (MH.SA)
GESTIN Pierre-Gildas (MH.SA)
LAVITRA Thierry (MH.SA / IH.SM)
EECKHAUT Igor (MH.SA / UMH)
Dr RABENEVANANA Man Wai et son quipe (IH.SM)
Dr RATSIRISIJA Colin et son quipe (PACP)
SAOTRA Fabien (TMD)
TSIRESY Gatan (TMD)
VORIALY Olmdo (TMD)
MACQUET Frdric (TMD)
HITCHINER Matthew (BV)
BV team
The project coordinators of "community-based sea cucumber farming"
Benjamin PASCAL Georgina ROBINSON
TransMad-Dveloppement Blue Ventures

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GUIDELINES AND RECOMMENDATIONS
ON SEA CUCUMBER FARMING FOR
SUPPORT ORGANISATIONS
The system developed in Madagascar for community-based sea cucumber farming involves three
main stages, each requiring specific facilities:
Spawning, larval rearing and settlement in tanks (hatchery)
Rearing of juveniles in external ponds (nursery)
Grow-out to market size in sea pens (farming)

As the first two stages are highly technical, hatchery and nursery production should be carried out by
a public or private operator, who has access to appropriate technologies and sufficient financial and
human resources. The final stage, however involving the grow-out of hatchery-reared juveniles in
sea pens, can be undertaken by rural communities using simple and accessible technology. A pre-
requisite for the development of community-based sea cucumber farming, is therefore an agree-
ment or partnership between community farmers and a hatchery producing sandfish juveniles.

A) The farming system promoted:

?Sea cucumber farming is carried out in pens constructed from extruded plastic mesh in near
shore coastal areas. It is prudent to start operations with medium sized pens (ca. 1000m2) in
order to simultaneously minimise risk and generate significant revenues, until farmers have
mastered the key parameters for successful farming. The future intensification and expansion
of farms will depend on the performance of the farmers.

?Farmers buy batches of juveniles from a hatchery at an average size of 15 g. Again, it is

necessary to stock medium sized batches of juveniles to limit risk and then progressively
increase the size of the stock during subsequent deliveries. Juveniles can be sold on credit or
a cash-basis, depending on the agreement with the commercial operator.

?During the first grow-out cycle, the initial biomass should be low and sea cucumbers should
be stocked at less than one individual per square meter. 0.5 ind./m2 is a good starting point.
Later on, once the carrying capacity of the site has been determined (see factsheet no 4) the
stocking density can be increased.

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?Juveniles can be stocked on a regular basis, ensuring that the carrying capacity of each site is
not exceeded (otherwise the growth of sea cucumbers will slow or stop)

1) One option is to stock juveniles on a regular basis (e.g. quarterly) so that cohorts of different
ages and sizes coexist simultaneously in the pen. This helps to maintain the total biomass as
close to the carrying capacity of the site as possible. In this case, large sea cucumbers will
always present and thus the pens will need to be permanently guarded at night to prevent
theft.

2) Another option is to stock a large number of sea cucumbers (ideally at the start of the hot
season to optimise the initial growth of juveniles) and wait until they are harvested before re-
stocking the pens. This will avoid the need to guard the pens at night during the first months
of grow-out as the market value of juveniles is virtually nil until they reach a size of 100-150g.

?Sandfish reared in sea pens can reach market size (350-400g) between five and twelve
months later, as the length of the grow-out period varies between different sites and seasons.
However, as the growth of sea cucumbers within each batch is not uniform, it is sensible to
schedule the harvest and sale of a specific batch over a few months. Once a sufficient
number of sea cucumbers exceed the agreed market size, the commercial operator should
come to purchase the sea cucumbers. As they pay in cash, this is the ideal time for any
financial transactions to take place between farmers and the operator, for example, re-
payment of credit for juveniles and purchases of new batches of juveniles (the rates should be
based on the value of the product sold).

Comment n1: Once key parameters are known and understood (biomass / optimal density growth
rates, predation levels, prevalence of theft ...), farmers may consider expanding the size of their
operation by building new pens and increasing the number of juveniles stocked.

Comment n2: It is possible that after several production cycles, farmers may notice the appearance
of juvenile sea cucumbers in the vicinity of their pens. These are the offspring of their stock which
have reproduced in the wild. If this happens, farmers can add increase their production by collecting
the juveniles and stocking them in their pens for on-growing.

B) The role of farmers and the tasks involved

Control of theft

The sandfish, Holothuria scabra, is one of the most commercially valuable species of sea cucumber,
forming the basis of a complex fishery and trade, involving a large number of operators along the
value chain. Farming sites are likely to attract poachers, especially at night when the sea cucumbers
emerge from the sediment and are more vulnerable. One of the key parameters for successful
production is therefore the organisation of an effective surveillance system. Farmers will need to
operate a rota (either within or between farming groups) to ensure that there is a permanent pres-
ence guarding the pens at night. This is the most important and time consuming activity for farmers.

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Control of predation

If the pens are experiencing high rates of predation from crabs, farmers should organise regular
searches for crabs at night (crabs are often more active at night). Two or three people per pen can
easily carry out this task for about an hour during each spring tide. To be effective, it is essential to use
a strong light (hurricane lantern) and other equipment to catch the crabs (nets, spears, gloves, etc.).

Two or three days prior to a delivery of juveniles, a more intensive search should be conducted both
day and night to eliminate predators. Newly stocked juvenile sea cucumbers are the most vulnerable
to predation during their first few weeks of grow-out.

Other maintenance tasks

Apart from the above nightly tasks, the remainder of the work to be done only requires a limited
investment of time, so farmers are able to pursue other economic activities in addition to sea cucum-
ber farming. Pen maintenance can be carried out by a single person in less than four hours per week
(or during one or two spring low tides).

Maintenance tasks consist of:

?
? Brushing the sides of the pen to maintain adequate water exchange and make it easier to
detect holes or tears in the mesh
? Repairing pens
? Controlling predators

These features make sea cucumber farming:

a predominantly nocturnal activity in which men will play a key role!

an activity that can rapidly achieve economies of scale once operations expand (as the
burden of nightly surveillance does not increase)
a moderate risk activity!

C) The importance of technical and organisational support

One of the roles of extension workers is to identify farmers who are motivated, professional, and
efficient, with the ability to improve their standard of living significantly through mariculture. By
engaging their interest, the achievements and success of these first farmers will act as a catalyst for
the expansion and replication of farming villages, thus promoting the development of the sector.

The selection, training, and supervision of the first farmers is therefore of upmost importance. The
extension process relies on having technicians permanently present in the villages, to regularly
monitor production and facilitate consultation with local residents.

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The role of training, monitoring and organisational support

From a technical and organisational point of view, the key message that is emerging for successful
farming today, is that it is the detail that counts." Whether it is preventing poaching or controlling
predators, the farmers who are the most thorough and organised will generally fare better. Regular
visits to the pens, combined with vigilance and hard work will yield results.

A key role for technicians is to assess the work of the farmers; therefore it is important to put tools for
monitoring and evaluation in place. To encourage farmers to develop good practices, the focus
should be on providing constructive advice and supporting famers in their work rather than compen-
sating for their potential weaknesses.

If it is not possible to have technicians permanently in the field, then a representative from the village
can support their role. This local intermediary must be your eyes and ears in the absence of techni-
cians, especially for assessing the participation of famers in surveillance and predator control. They
can also facilitate liaison between the commercial operator and farmers to schedule deliveries of
juveniles, sales of market sized sea cucumbers and other necessary collective actions (building pens,
monitoring production, meetings, etc).

Institutional support to create a secure operating environment

It should be noted that assuring 24/7 surveillance of their pens will be extremely difficult for farmers.
There will always be unforeseen events which will occasionally leave the pens vulnerable to theft
(such as unfavourable weather or sickness)

In addition to carrying out surveillance at night, farmers must work with you to establish a secure
operating environment (legitimising the farms among local residents, deterring theft, mobilising
public authorities, etc). This is the only way in which mariculture can develop harmoniously, espe-
cially during the early stages.

The development of mariculture-based activities should not be a source of conflict for the local
community. Both farmers and extension workers need to give careful consideration to marine
resource use issues and the wider political and economic implications of the activity, especially
during the early stages of implementation (selection of farmers, designation of mariculture zones
and spatial planning).

In summary, the role of extension workers is to:

Initiate dialogue with the village, foster communication and relay relavent information
Identify good farmers and train them in farming techniques.
Supervise activities (site selection, pen construction, optimisation of spatial planning) and
coordinate the smooth delivery and sale of sea cucumbers.
Carry out monitoring of production at night with farmers
Explain key parameters (density and survival) to farmers so they understand the principles
of monitoring
Monitor the economic performance of their farms in relation to their husbandry practices.

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D) The key steps to establish community-based sea
cucumber farming

1) Identification of potential sites

A sound approach in site selection is to utilise traditional ecological knowledge of fishers to identify
sites which support, or previously supported, sandfish populations.

Ideally, before the development of farming activities, the suitability of the site can be assessed via the
use of test plots to empirically evaluate growth rates and the carrying capacity of the site (see Fact
Sheet No. 1)

Areas prone to influxes of fresh water, strong currents or waves should be avoided. The sediment
should be deep enough (at least 40 cm) to allow the solid construction of pens. The substrate should
never dry out completely, even during spring low tides. A good site will have a minimum water depth
of 10 - 50 cm during the lowest tide. The site should be characterised by soft, sandy-muddy sedi-
ment, which is often (but not exclusively) found in close proximity to mangroves.

For security reasons, sites that are within sight of the village offer an advantage, as during the day,
farmers can keep an eye on the pens and the daily traffic around them, without needing to be
physically present.

2) The selection of villages for consultation

Small villages can offer a number of advantages. In general, solidarity is often stronger and con-
flicts are rarer or easier to resolve by the villagers. The risk of theft is therefore more manageable.

The development of community-based sea cucumber farming will inevitably lead to a change in
marine resource use. For other resource users, the designation of areas for mariculture will trans-
late into a net loss of access. It is therefore necessary that changes in land use are negotiated and
accepted by all stakeholders in the area.

Different compensatory measures, whether symbolical or physical, (sacrifices, ceremonies, financial

compensation - either upfront or in the form of local taxation, fees or land lease), can be imple-
mented in collaboration with the first few farmers who enter into mariculture, for the benefit of the
wider community. Above all, it is a case of legitimising changes in marine resource use, preventing
any disagreements and avoiding the definitive and unequal ownership of the mariculture area.
Although compensation should originate from the farmers, it should not so great that it affects the
profitability of sea cucumber farming.

Caution! Territorial land use rights that come into play in the development of mariculture can be
complex and interconnected among various groups of coastal residents! The development of
compensatory measures must be taken into account. To avoid conflicts (manipulation by certain
groups, imposition of illegitimate measures, etc.), it is more prudent to spend time consulting all

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parties involved. It is not the role of an external operator to develop such measures, let alone to
enforce them. It is up to the local authorities to make such decisions. Caution is therefore essential.
Although it is advisable to involve local government in these processes, it does not necessarily
guarantee legitimacy. Compensatory measures therefore do not have to be formal; they can simply
be local agreements which lack legal recognition.

3) Selection of farmers
Preliminary screening

Farmers must be hardworking, dedicated people with an entrepreneurial sprit. Sea cucumber
farming commits farmers to long cycles and requires an initial investment, regular expenses (pur-
chase of juveniles) and income generation that is potentially significant but sporadic (for example
every two or three months). To ensure that profits are generated regularly, the work must be carried
out methodically, including a systematic nightly surveillance program.

These features contrast with the economic pattern that characterises most small-scale fisheries, in
which income is generated almost daily and where fishing effort can be tailored to meet cash flow
requirements. During the start-up phase, farmers cannot rely on a single activity to meet their needs.
It is only after the first two or three farming cycles they can consider specialising in mariculture. It is
preferable that each farming unit comprises several active members in a group (4-5 people),
preferably from the same family, sharing the risks, workload (maintenance and surveillance) and the
benefits.

It is essential that all candidates involved in the screening process are aware of these characteristics.
It is therefore important to conduct selection interviews with all candidates to discuss these issues and
evaluate their understanding of risk before they start farming. Scenario-based role playing is a useful
tool to assess how people will react and cope with different situations.

It is very important to clarify the details of how the work will be carried out and how risk will be shared
among the parties involved. Even the most dedicated and serious farmers should have some
recourse to compensation in the event that their farms are affected by a natural disaster. However,
they must also understand that they will be held responsible for theft, regardless of the reasons for a
default in surveillance. Simplified contracts can be drawn up to formalise the roles and responsibili-
ties of each party.

Creation of contracts

Once the selection process is complete, the creation of contracts with farmers will help to clarify the
exact nature of the support given, define the duties and responsibilities, and in addition, regulate the
commercial partnership with the hatchery supplying juveniles who may, in return, demand the
exclusive right to buy back all production.

Formal contracts should be sufficient to justify the exclusion of "cheaters" who resell part of their
production to other traders instead of the company supplying the juveniles. It is very important that
the contract terms are understood and accepted before the start of the activity.

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Secondary selection based on economic performance criteria

During the second farming cycle, it is advisable to implement measures based on performance
criteria, through which farmers can either be incentivised or excluded. For example, at the end of
the 2nd or 3rd grow-out cycle, farmers who have not reached minimum targets (e.g. harvesting and
selling 50% of their sea cucumbers) can be excluded from the activity whereas farmers who have
exceeded targets (e.g. who have sold 70% or more of their stock) can be incentivised to build a
second pen (through prizes or donations of equipment).

The objective of this secondary triage is to exclude, early on, any dishonest farmers who sell their
production elsewhere or unproductive farmers, who occupy farming sites and utilise materials that
other farmers could put to better use and absorb valuable inputs of juveniles in vain. On the other
hand, performance-based criteria are necessary to avoid farmers wasting their time, or worse,
falling into debt by persevering at an activity that they are unable to master.

On the other hand, it is in everyones interest to support the best farmers to construct a second pen
and increase their production. With an expansion of the farming area, the workload will only
increase marginally and the economic success of these farmers will encourage others to achieve a
similar level of results.

4) Monitoring production
To assess the performance of farms, regular monitoring is essential. It will allow problems to be
identified early on, so that farmers can be helped to make the correct choices to resolve the prob-
lem.

Monitoring should be carried out every two weeks, during spring low tides. The technicians, accom-
panied by the farmers, should count all sea cucumbers in the pen and weigh a sample (e.g. 25% of
the total) to determine the growth rate (factsheet no 3). As sandfish tend to burrow during the day,
monitoring should be carried out at night when the sea cucumbers are active.

A decrease in the number of sea cucumbers during the first three months may indicate predation
(probably by crabs) or escape/loss of sea cucumbers from the pens due to strong currents or dam-
aged pens. Later on, once the average weight of sea cucumbers exceeds 100g, a reduction in the
number of sea cucumbers almost certainly indicates that a theft has occurred (either from poaching
or internal theft whereby the farmers have discretely sold their sea cucumbers to other traders). Once
sea cucumbers attain a certain size they are able withstand predatory attacks from crabs and
although occasional marks may be visible on the body wall, attacks rarely result in mortality.

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5) Problem solving and adaptation of farming practices to local
conditions
Adaptation of farming techniques

Depending on the problem encountered, if it increases costs for farmers and in turn affects the
viability of their farms, certain practises may be unavoidable to resolve the problem.

Key problems Potential solutions

?
Sediment re-working (efficiency to be confirmed ?)
Slow growth rates ?
Sediment enrichment (techniques to validate ?)

High mortality rates (predation ?

Construction of a juvenile nursery (protected enclosure)
from crabs) ?
Organisation of predator control (day and night)
?
Use of crab traps

Theft of sea cucumbers ?

Strong coordination at village level
?Reinforcement of surveillance
?Construction of an elevated guard platform
?Systematically reporting thefts and requesting
government assistance in investigations
?
Role of government: establishment of a system of
traceability for farmed product (certificates of origin
for wild sea cucumbers and inspections).

Adaptation of the farming model

Other adaptations of the farming model are possible based on different biophysical and socio-
economic characteristics. They should be assessed on a case by case basis in consultation with
farmers. Two standard models are available:

Farming model Advantages Disadvantages

1) Farming in consecutive ? No surveillance needed ? Limited profitability

cycles (extensive) : for the first few months ? Irregular income
A new batch of juveniles are ? Farmers can pursue other ? Extensive model requires
stocked after each harvest economic activities more space

2)Farming in continuous cycles ? Optimisation of space ? Permanent surveillance

(intensive) : ? Increased profitability required
Batches of juveniles are stocked at ? Regular and evenly ? More time consuming
regular intervals throughout the spread income
year. Different cohorts grow
simultaneously in the pen

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Farming in consecutive cycles is a form of extensive mariculture. This model is suited to sites
where growth rates are slow and/or the carrying capacity of the site is low or sites where a large area
suitable for sea cucumber farming is available. Grow-out time to market size will be longer and sites
will have a lower profitability per unit area than sites which can support an elevated biomass. In this
case, sea cucumber farming can provide a complementary source of income. With longer grow-
out periods (10-12 months) until sea cucumbers reach market size, farmers will be less likely to
specialise in mariculture and income generation will be infrequent. In this scenario, it is desirable to
stock sea cucumbers at the start of the hot season to optimise their growth during the first few
months.

Farming in continuous cycles is preferable in order to optimise site potential, especially at sites
where the available surface area for sea cucumber farming is limited. This method allows an
intensification of production by maintaining the total biomass close to the carrying capacity of the
site. Batches of juveniles are stocked regularly, as soon as market size sea cucumbers have been
harvested. Although the workload is higher and more time consuming (nightly surveillance,
predator control) the profitability is higher. Farmers will be more driven to specialise in mariculture

.The farming model however is not definitive and it is always possible to re-evaluate the choice of
model employed, based on the capacity and performance of farmers. In addition, the models
outlined here can undoubtedly be improved as sea cucumber farming practices evolve. Hybrid
models can be considered, for example by scheduling juvenile inputs shortly before the harvest and
sale of the previous cohort or by incorporating fallow periods into the farming system

.In conclusion, the strategy of the support organisation should take into account that :

The growth rate of sea cucumbers is higher during the hot season than then the cold season.
?

Production cycles are long and often do not correspond with the mentality of fishers
?

The terms and conditions of a commercial partnership with a hatchery must clearly
?
understood and respected. The sustainability of community-based sea cucumber farming
depends on the existence of a functional hatchery, which may in turn depend on being able to buy
back sea cucumbers for processing an export, in an exclusive partnership with communities.

Pro-active prevention of theft and nightly surveillance are indispensable to the success of
?
community-based sea cucumber farming

Sea cucumber farming is an activity that can rapidly achieve economies of scale
?

The size of mariculture units must take into account financial viability, social equity and marine
?
resource use issues.

Effective community involvement is essential to provide farmers with a degree of security and to
?
legitimise the exploitation mariculture zones.

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The above also applies to government involvement

Empowerment of farmers can only be achieved through an effective partnership with a

hatchery in which the buy-back of sea cucumbers and re-supply of juveniles becomes routine.

The project coordinators of "community-based sea cucumber farming

Benjamin PASCAL Georgina ROBINSON

TransMad-Dveloppement Blue Ventures

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FACTSHEETS
FACTSHEET N1 SELECTION AND VALIDATION OF FARMING SITES

Preliminary identification

1) Use traditional ecological knowledge for fishers to identify sites where wild Holothuria
scabra are found (or were previously found).
2) Restrict site selection to areas where the sediment is soft and sufficiently deep, notably
more than 40cm before a solid substratum is reached, so that the stakes and mesh can
be solidly embedded (a crow-bar or iron bar can be used to test sediment depth).
3) Assess the compactness of the top layer of sediment in order to choose the softest areas.
4) Avoid areas exposed to waves, strong currents and influxes of fresh water.
5) Select sites closest to populated areas to facilitate surveillance during the day and at
night

Empirical validation

Where possible, consider using replicated test plots to validate the suitability of selected sites
based on their natural carrying capacity. This is done by:
1) Building a series of small 4m pens covered with a protective top-net (like the nursery
pens)
2) Stocking a batch of juveniles at a relatively high density (for example, 10 juveniles/m)
3) Weighing the sea cucumbers every seven days to monitor their growth
4) Calculating the carrying capacity of the site (see information sheet n4)
5) Determining the optimal density for the culture system chosen (consecutive or continuous
cycles)

Note: the method illustrated in the following example can be adapted to specific constraints
(pen size, number of juveniles stocked, etc.) To ensure that the results are representative, a
minimum of 5 test plots should be constructed per site.

Example: In a 4 m test plot, 40 juvenile sea cucumbers with an average weight of 15g are
stocked. The following results were recorded during monitoring:

T=0 => biomass = 40 ind. x 15 g / 4m = 150 g/m

T=7 => biomass = 40 ind. x 18 g / 4m = 180 g/m
T=14 => biomass = 40 ind. x 25 g / 4m = 250 g/m
T=21 => biomass = 35 ind. x 32 g / 4m = 280 g/m
T=28 => biomass = 35 ind. x 36 g / 4m = 315 g/m
T=35 => biomass = 30 ind. x 44 g / 4m = 330 g/m
T=42 => biomass = 30 ind. x 44 g / 4m = 330 g/m

The above data shows that some sea cucumbers disappeared, maybe due to predation from
crabs or due to mortality post-transfer. However, the exercise demonstrates that the total
biomass does not increase beyond day 35, indicating that the natural carrying capacity of the
site is 330g/m2. At this site, it should be possible to rear sea cucumbers at a density of 1
ind./m2 until they reach an average size of 330g utilising the consecutive stocking model. In
order to grow sea cucumbers to a market size of 500g using this method, the density should be
reduced to 0.66 ind./m2 (calculated as 330/500).

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SPECIFICATION SHEET FOR FIELD TECHNICIAN
Assessment of the quality of potential sandfish farming sites
Based on sediment study done by Thomas Plotieau and Igor Eeckhaut
(University of Mons Belgium)

To identify potential farming sites, three key parameters must be taken into consideration:
survival rates, growth rates and physical characteristics. Some background information is
given below for each factor to allow technicians to optimise the success of future farming
operations by selecting the best grow-out sites.

Identify factors that promote survival:

The most straightforward indicator is a knowledge of the previous or present existence of

Holothuria scabra populations.
It is essential that the site remains submerged even during the lowest spring tides
Finally, the abundance of crabs (species such as Thalamita crenata) should alert
technicians to increased risks of mortality due to predation (especially for juveniles).

Assess factors that promote growth:

1) Sites with a high proportion of fine sediments should be selected preferentially: the
fraction of fine sediment can be measured with a 500 micron sieve and high precision
electronic scales. In the absence of laboratory equipment, the technician can estimate
the fineness of the sediment by releasing a handful of sediment at the water surface. For
fine or muddy sediment, which are ideal for growth, it will disperse in a cloud; if not, the
sediment is likely to be granular or sandy which is less favourable for sea cucumber
farming. In addition:

Well protected areas (such as bays and coves in large lagoon systems or areas
close to mangroves) will generally be subject to natural sedimentation which is
likely to promote growth, as opposed to areas that are subject to significant water
movements (strong currents, reef flat areas inside a fringing reef, etc).
The presence of certain species such as the black brittle star (Ophiocomina nigra)
can indicate coarser sediments which are unfavourable for sandfish growth.
The presence of seagrass beds and/or the sea urchin Tripneustes gratilla can
indicator sediment that is favourable for sandfish growth.

2) Sediment with a high proportion of quartz appears to be very favourable for

sandfish growth. If it is complicated and expensive to conduct tests to analyse the mineral
composition of sediments, it is still assess the proportion of carbonate, which in general,
is inversely proportional to the amount of quartz. Simply measure the difference in weight
between a sample of dry sediment weighed before and after adding acid (e.g. vinegar). It
is anticipated that carbonate dominated sediment (e.g. > 80%) may result in slow
growth.

Note : the colour of the sediment is not a relevant indicator.

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SPECIFICATION SHEET FOR FIELD TECHNICIAN

Assess factors that will optimise farming efficiency:

Pens should be built in areas with a soft sediment and a minimum depth of 30cm to
ensure that the construction is sturdy.
The accessibility and proximity of farming areas in order to encourage regular
monitoring, maintenance and in particular, facilitate guarding of the pens.
Assess the security of the site and minimise risk factors by investigating the potential for
theft (pre-existing conflicts, economic alternatives, proximity to police stations, etc.) and
concealment (presence of sea cucumber traders, quantities traded, etc).

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FACTSHEET N2 PEN CONSTRUCTION TECHNIQUES

Once favourable sites have been identified and farmers have been selected, two options can be
considered to construct the pens: circular or square pens.
Circular pens have the advantage that they are more resistant to currents and also they
provide a larger surface area per linear metre of mesh used. They are therefore less
expensive to construct than square pens.
However, square pens are more advantageous when they are constructed in an adjoining
fashion. With this type of construction, the area occupied by the pens is optimised and spatial
planning is more straightforward.
Care should be taken at this stage to incorporate channels between groups of pens to allow access
by canoes or boats.

Pen construction

The materials to construct pens should be prepared ashore. Plastic mesh with a minimum mesh size
of 8mm should be cut to a minimum width of 75cm. Wooden stakes measuring 1m in length, (using
wood that will not rot in seawater) are ideal however at sites where there is a hard substrate
underlying the sediment, galvanised steel stakes can be used, although this is an expensive option.
Pen construction should be carried out during spring low tides. Two or three days work is sufficient to
build a pen with a team of people.

1- Using a measuring tape, rope and some stakes, hammer stakes into the 4 corners and use
rope to outline the area of the pen
2- Use a narrow shovel to dig trenches at least 30 cm deep along the rope outlining the
perimeter of the pen.
3- As the trench progresses, start to insert the mesh into the trench, ensuring that is pulled taut
along its length.
4- As the mesh is rolled out along the trench, hammer in stakes at 1 metre intervals, alternating
between the interior and exterior of the pen to support the mesh.
5- Use 2mm cord or cable ties to attach the mesh to the stakes. The mesh should be attached
to the stakes at the base and the top and then stitched along the length of the stakes to secure
it.
6- Backfill the trench and compact the sediment to ensure the mesh is well buried.

Construction of a nursery

At sites which suffer from high levels of predation, the construction of a covered enclosure to act as a
nursery for juveniles is indispensable. To determine the correct area needed, the formula to
calculate rearing density (factsheet no 4) is used by setting with the target weight at which juveniles
should be transferred out of the nursery of the juveniles at 50g. Once sandfish reach this size, they
are less vulnerable to predation by crabs.

The construction method for the nursery is similar to the main pen, with two main differences:
The stakes should be inserted only along the interior of the pen and the stakes must be flush
with the top of the net.
A net with a mesh size of 1cm square should be used to cover the top of the nursery.
Cord should be used to stitch the top net securely to the sides of the pen, ensuring that there

20
are no gaps for even small crabs to enter.

Whenever access to the nursery is needed, for example to capture crabs or count juveniles, the top
net can be partially unstitched and pulled back, ensuring that it secured again once the work is
completed.

21
FACTSHEET N3 MONITORING PRODUCTION (COUNTING AND
WEIGHING AT NIGHT)

The sandfish, Holothuria scabra, actively feed on the sediment surface at night, however during the
day, they often remain buried. Therefore all activities such as counting, weighing and harvesting
need to be carried out at night, during spring low tides. This is also an ideal opportunity to search for
and capture any crabs.

The following equipment is needed to carry out monitoring at night: a hurricane lantern and extra
torches, plastic containers to collect the sea cucumbers, weighing scales, writing materials
(preferably waterproof) and a stable surface for weighing (a folding table is ideal).

Monitoring protocol :

1) Light the hurricane lantern, gather all the equipment and wade out to the pens, setting up the
table in the centre of the pen.

2) Farmers should form a line and walk slowly upstream (to avoid stirring up the sediment and
reducing visibility) using the hurricane lantern to illuminate the search area. An empty
plastic bowl or bucket can used to collect and count of all of the sea cucumbers that are
found.

3) Once placed in the containers, the sea cucumbers will release water held inside their bodies
and deflate. This water should be emptied out of the container periodically to that sea
cucumbers are weighed once they have emptied out internal water to standardise the
weighing procedure.

4) A representative sample (25%) of sea cucumbers are weighed one at a time, as quickly as
possible, before being replaced in a separate container filled with water until the sample is
complete. A clipboard can be used to record the data.

5) Once the monitoring is completed, the sea cucumbers can be returned to the pen :
a. Return them to the areas where they were found
b. Handle them gently - avoiding damaging their skin or throwing them back into the water.
c. Place them with their ventral (white) side face down
d. Take care not to group them all in one place

Note : to monitor juveniles in the nursery pen, the method is the same however great care should be
taken not to step on or damage juveniles. Once monitoring is completed, the top net must be
carefully replaced and stitched to prevent crabs from entering.

22
FACTSHEET N4 METHODS FOR CALCULATING
OPTIMAL REARING DENSITIES

In order to calculate optimal rearing densities, the following variables need to be known:

? Surface area (S) = 4 m

? Number of sea cucumbers stocked (n) = 50
? Initial weight (Wi) = 15 g
? Target weight (Wt) = 350 g
(note: the target weight (Wt) can either be the market size of sea cucumbers or the size at which
juveniles should be transferred out of the nursery).

By plotting growth rate data from the test plots, the curve of the graph will enable determination of:
? The maximum average weight (Wmax g) that the sea cucumbers attain before growth slows
and stops due to density-dependant effects (illustrated by the point at which the graph starts
to /level off)
? The time taken to reach the maximum weight (t in days)

growth rate of sea cucumbers

45
Ps= 40
35
30
25
Weight
20
15
10
5
0
15

45
30
days

T=40j
duration of growth
1) Calculation of the carrying capacity of the site

To calculate the carrying capacity (Ccap) of the sediment at the farming sites, the following formula
should be applied :
Ccap = Wmax x n / S

So for the above example

Ccap = 40g x 50 sea cucumbers / 4m = 500 g/m

23
2) Calculation of the optimal stocking density for consecutive farming cycles

Therefore us, to determine the optimum stocking density (D) on the site tested previously, the critical
biomass is divided by the target harvest weight (g) (or the average weight at which juveniles should
be transferred from the nursery into the grow-out pen).

D = Ccap / Wt

Following on from the previous example: D = 500 g/m / 350 g = 1.43 sea cucumber/m
Thus in a pen with a total surface area of 900 m, 1285 sea cucumbers per cycle could be reared to
market size (in a consecutive farming model)

3) Calculation of growth rates : another key parameter

Growth rates will vary from site to site, even if the carrying capacities are identical. To calculate the
growth rate at each site, you must again collect reliable data from initial test plots or from monitoring
production during previous farming cycles.
growth rate of sea cucumbers in test plots
Weight (g)
45
Wmax=40
Wt2=
35
30
25
Wt1=20
15
10
5
0
45
days

t1=11d t2=27d

time (days)

Gr = (Wt2 Wt1) / (t2 t1)

Note : growth rates are independent of the carrying capacityof the site

4) The continuous stocking model : optimisation of production

Using information generated from the above parameters, it is possible to optimise production, by
rearing different cohorts of sea cucumbers (different ages and sizes) in the same pen simultaneously.
The following table gives an estimation of the numbers of sea cucumbers to stock, the frequency of
stocking and the length of the grow-out period which can be used as a guideline to intensify
production.

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For a total biomass of 100kg per pen
Target market size = 350 g Target market size = 500 g

Growth No. to Frequency of Grow-out No. to Frequency of Grow-out

rate stock deliveries period stock deliveries period
0,5 g/day 118 every 6 months 670 day 85 every 8 months 970 day
1 g/day 118 every 2 months 335 day 85 every 4 months 485 day
1,5 g/day 118 every 2 months 223 day 85 every 3 months 323 day
2 g/day 145 every 2 months 167 day 104 every 3 months 242 day
2.5 g/day 164 every 2 months 134 day 121 every 3 months 194 day
3 g/day 160 every 2 months 112 day 104 every 2 months 162 day

Comment : to support a total biomass of 100kg, a site with a carrying capacity of 100g/m2 would
require 1000m2 whereas a site with a twice the carrying capacity (200g/m2) would require half the
area (500m2) in order to support the same quantity.

Example :

A farmer with a 2500 m pen has an average growth rate of 1.5 g/day and a carrying capacity of
300g/m. According to the table above, to grow sea cucumbers to an average market size of 500g
in continuous cycles, he should ideally stock juveniles every 3 months.

The number of sea cucumber to be delivered will be determined as follows:

First calculation the total biomass (Btot) the pen can support
Btot = 300 g/m x 2500 m = 750 000 g or 750kg

The number of sea cucumber to be delivered every 3 months is calculated by referring to the table
above
n = 85 x (750 000 / 100 000) = 637 juveniles per input

25
FACTSHEET N5 PROCEDURES FOR PREDATOR CONTROL

(These instructions can be added as an appendix to the contracts signed by team leaders)

To doregularly (every spring tide)

Brush the sides of the pen to promote good water exchange and make it easier to see any
holes in the net. At the same time check for and remove any crabs
? Check the nursery pen very carefully including the top and sides
Repair any holes
To adequately protect the juveniles from predation by crabs, the nursery should be com-
pletely closed and inaccessible to crabs for two months. A single crab can kill approximately
30 juveniles per month
Hunt for crabs in the pen at least once per tidal cycle using a hurricane lantern with 1L
fuel until the fuel runs out. Use spears, gloves and crab nets, carefully checking all sides
of the pen.
Bait can be positioned upstream, farmers start by moving downstream then after coming
back against the current any crabs should be concentrated around the bait so they can be
easily captured. Afterwards, the bait can be replaced in traps around the pens.
Bait the traps and place them around the pens, for example every 3 metres.

To do during the spring tide before a delivery of juveniles

Use a mask to search for and capture any crabs in the nursery and check the base of
the net then re-secure the top net. This should be done a few times during the tide during
the day with a mask and at night with a lamp.
Carefully check all sides of the nursery at low tide and at high tide with a maskrepair
any holes.

To dojust before a juvenile delivery

Intensify the search for crabs

Open the nursery and re-work the surface layer of the sediment (this makes it easier for the
juveniles to bury and helps to eliminate crabs and their burrows).

To dothe day of the delivery

Continue to check for crabs (using a mask during the day and at lantern at night) making
sure that crabs do not enter the nursery while the top net is pulled back
Regularly check the sides of the nursery pen and ensure the top net is securely
fastened
Monitor the juveniles regularly without opening the top net. If the remains of juveniles are
found beware! It is likely that crabs have been shut inside with the juveniles!

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FACTSHEET N6 PREVENTION OF THEFT: THE CASE IN MADAGASCAR

(These instructions can be added as an appendix to the contracts signed by team leaders)

In Madagascar, groups of farmers involved in sea cucumber mariculture have agreed to guard
their pens against theft at night and are contractually bound to do this. Due to mistrust between
different farming groups, it is not possible to organise a communal rota, instead each group
sends at least one person every night to guard their pen. In the days leading up to a sale of sea
cucumbers (when incidents of theft have been much higher) the pens must be guarded until
daybreak. Normally, farmers guarding the pens are able to remain on the beach during the low
tide and return to their houses once the tide covers the pens. However the risk of theft remains!

A/ Suggestions on reinforcing pro-active measures to combat theft :

(to implement and integrate into farmer contracts in villages where the level of security is not
sufficient)

1) As soon as sea cucumbers reach an average weight of 150g it is imperative to guard the
pens every night without fail!
2) Surveillance should be carried out at both low and high tide, throughout the night
3) Farmers who do not participate in the surveillance should pay a fine to the other farmers

Other suggestions:

If a watchtower is constructed, two or three people must stay there each night. They can
take it in turns to sleep, but not all at the same time.
Three people from different teams can act as guards between two successive monitoring
periods (when the sea cucumber are counted) and take responsibility for the stock during
this period. After each count, the team of guards can rotate once the sea cucumbers are
all accounted for and it is certain that no theft has occurred. The numbers of days that
each person guards the pens should be recorded and balanced out over the year.
If certain people are absent (for valid reasons) one of the three guards must remain there
permanently throughout the cycle. He will be the guarantee for the team and the person
responsible if a theft occurs.
If the surveillance cannot be carried out for legitimate reasons (storms, heavy rain, force
majeure) the sea cucumbers should be recounted as soon as the surveillance is resumed.

B/ Steps to follow is a theft is discovered

If a theft is discovered or suspectedon a mandatory basis and as quickly as possible!:

1) Count all remaining sea cucumbers at night and compare the result to the previous
count.
2) File a declaration of theft to the village authorities, the mayor and the district police (with
their signature).
3) Carry out an investigation with people in the village who may have seen something
(people that work at night, traders, transport companies, village security patrols, etc.).

27
FACTSHEET N6 PREVENTION OF THEFT: THE CASE IN MADAGASCAR

If the thieves were caught red-handed or in possession of stolen sea cucumbers:

Call as many witnesses as possible to corroborate the theft
Make a written record of the incident with the village authorities in which the thief (or thieves)
and witnesses are identified
Apply local conventions or laws and ensure that the thieves reimburse the famers loss, or
If no consensus is reached, the case should be passed onto law enforcement
officershowever a written account should be recorded at each stage of the investigation.
If suspicions or information lead to the identification of a suspect, the following steps should
be carried out in order:
Hold a conflict resolution meeting in the village to shed more light on the affair: ask specific
questions and record all statements in a transcript signed by all legal authorities and
traditional leaders and the people involved in the case (victims, suspects, witnesses)
In the situation that the matter is not resolved at the village level, the fine may be made to the
municipality in the presence of the mayor and then proceed to court for unresolved cases
(see theoretical procedures outlined in local agreements that were created at the start of the
mariculture activity).
If there are no suspicions or information which allow a suspect to be identified :

Caution : this indicates that there is a big problem with security and the organisation of the farmers.
Their working methods should be reassessed and any future collaboration should be seriously
considered!

Comments for the attention of support organisations and extension workers

The role of technical or project leadership should be to provide advice and support throughout the
process. Technical support is not designed to replace the need for famers to manage these types of
problems themselves. It is dangerous and counter-productive to do so!

If the procedures outlined above are not followed the project must make the famers in the village
understand that they can no longer support them. It is the only leverage the project has to negotiate
and put pressure on the famers to react to restore a safe operating environment and regain
confidence with industry partners.

The type of advice that follows can be given by the project to ensure that the above procedures are
carried out effectively:

-Alert the maximum number of official authorities (village, municipality/district, police, fisheries
department, industry partners, etc) and create official documents.
-Record very precisely all statements made during meetings in signed minutes of the meeting so the
information can be recalled at a later date.
-Treat suspects as innocent until proven guilty rather than rely on evidence that may be deliberately
misleading
-Follow procedures in local laws or conventions that have been established
Based on the procedures carried out by the farmers and meeting minutes recorded at each stage of
the investigation, the support organisation can then help to mobilise government authorities so that
they can take over the investigation. It is important that the regional fisheries department, the police
and fisheries patrols are involved in treating cases of theft and furthermore show their presence on
the ground.

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FACTSHEET N7 FINANCIAL STATEMENT FOR
ONE FAMILY OWNED PEN (IN US$)

The following example is based on an experienced farmer who has already demonstrated positive
results with a small mariculture unit and has decided to expand his farm to consist of a large 2500
m2 square pen and a 100m2 nursery pen. The financial statement is based on the following
assumptions: the pen (including the plastic net and wooden stakes) costs approximately US$2.5 per
linear metre, the juvenile price is US$0.20 and the sale price for market size sea cucumbers (400g) is
US$ 1 (ex works).

Conservative assumptions for growth rate and survival are employed. The grow-out period for 15g
juveniles to reach market size is 400g is 8 month, at a site with a carrying capacity of 600g/m2. The
example is based on 3 deliveries of 1200 juveniles per year. The overall survival rate, after taking
into account mortality from predation and minor thefts is 75%, which translates into the sale of 900
market sized sae cucumbers per input.

The following balance sheet illustrates the example of an expanding sea cucumber farm.
Attention the first year the farmer has to disburse 1,035 $ at the beginning and a second pack of
juvenile for 240 $, before any profit. This has to be sorted it out with a loan, donors support ..

Items Price per unit Per cycle TOTAL

(8 months)
$ $ $

Operational costs
Juvenile purchase (1 200 juveniles) 0,20 $/piece 240
Kerosene and maintenance (hurricance 2,5 $/month 20 260
lamp)

Sales revenue
Sale of 900 sea cucumbers 1 $/piece 900 900

Gross profit 640

Depreciation (over 1 cycle)

Pen 50x50m 500 $ 36

(5yr lifespan, i.e. 14 cycles)
Nursery pen 5x20m 200 $ 25
(3yr lifespan, i.e. 8 cycles)
Hurricane lantern 35 $ 7
(2yr lifespan, i.e. 5 cycles)
Equipment (masks, traps, crab nets, etc) 40 $ 8
(2 yr lifespan, i.e. 5 cycles) 76

Net profit for 1 cycle 564

Net profit per month (with sales every 4 months) 138

29
FACTSHEET N7 FINANCIAL STATEMENT FOR
ONE FAMILY OWNED PEN (IN US$)

30
Sandfish
village farming

R. PIERRE
29