SOKOINE UNIVERSITY OF AGRICULTURE

FACULTY OF AGRICULTURE

DEPARTMENT OF ANIMAL SCIENCE AND PRODUCTION

BSc. AQUACULTURE

SPECIAL PROJECT REPORT

ABUNDANCE AND COMPOSITION OF SEA CUCUMBERS IN BONGOYO ISLAND,

DAR ES SALAAM

BY

KAIZA, VICTOR

AQU/D/09/T/0006

A RESEARCH REPORT SUBMITTED AS PARTIAL FULFILMENT OF THE REQUREMENTS FOR

THE DEGREE OF BARCHELOR OF SCIENCE IN AQUACULTURE OF SOKOINE UNIVERSITY OF

AGRICULTURE, MOROGORO, TANZANIA.

JUNE, 2012

i

ABSTRACT

Sea cucumbers are benthic marine invertebrates with a high market value in international

market as a result experience rapid over exploitation in many parts of the world

including Tanzania. Over exploitations of this resource in Tanzania led to the

establishment of sea cucumber fishing and trading moratorium in the Fisheries Act no. 22

of 2003. The aim of this study was to assess the sea cucumber species composition,

species density and the size structure of the commercially important sea cucumber in

Bongoyo Island. The study was carried out from 26th

to 30th

March 2012. Six sites were

selected and surveyed during the low tide. Eight species of sea cucumbers were observed

during the study, where one species was not identified. H. Atra, A. Miliaris and H.

Scabra were found to have high densities. There was no significant difference in sea

cucumber abundance among the sampling sites in both locations (P>0.05). However, sea

cucumber species density differ significantly between the North Eastern and South

Western sides of Bongoyo Island (P <0.05). These variations are due to food availability,

predation, shore topography and wave turbulence and made the differences in species

densities, composition and diversity to be significantly different. The estimated sea

cucumber population in the sub-tidal areas of Bongoyo Island was 221,522 individuals.

This population is capable of sustaining the natural regeneration of sea cucumber

resources in areas surround Bongoyo Island. The modal class of H. Scabra was 15 to 16

cm, and the stock size ranges from 9 to 22 cm was composed of sexually matured

individuals. Species composition, diversity and Species densities of sea cucumbers in the

Bongoyo Island are different from site to site and from side to side. And the stock of H.

Scabra is composed of good number of sexually matured individuals. Therefore, from

these findings there is a need for improving the management of sea cucumbers and

establish other initiatives like the aquaculture of sea cucumbers, and ecosystem approach

to the management of sea cucumber resources of Tanzania.

ii

DECLARATION

I, Victor E. Kaiza, do hereby declare to the Senate of Sokoine University of Agriculture

that this Special Project Report is my original work and that it has never been submitted

for a degree in any other university.

……………………………. ……………………………

Victor E. Kaiza Date

iii

COPYRIGHT

No part if this special project may be reproduced, stored in any retrieval system or

transmitted in any form or by any means, electronic, mechanical, photocopying,

recording or otherwise, without the prior permission of the author or University on

behalf.

© Victor Kaiza, 2012

Cell: 0715 900425 / 0766 900 425

E – Mail: vvvkaiza@yahoo.com

iv

AKNOWLEDGEMENT

First of all thanks to God for giving me sounding health for the whole period of my study.

I have great pleasure to acknowledge the Tanzania government for offering financial

support to conduct this research.

I am so thankfully to my supervisor Dr. Hieromin A. Lamtane for his guidance, ideas,

suggestions and encouragement right from the special project proposal preparation to

special project report writing .His timely critics were very instrumental in accomplishing

this study.

Furthermore I would like to thanks the Marine Parks and Reserve Unit for giving me the

permission for undertake this study in Bongoyo Island. Also I would like to thanks the

keepers of Bongoyo Island, Mr. Sandale, Mr Rashid Kilawi and Mzee Khatibu for their

full cooperation during the entire study.

Lastly I would like to express my thanks to my classmates for their encouragement and

help during my study.

v

DEDICATION

This work is dedicated to my mother, Salome L. Kaiza, my sister Antonia and my brother

Winston for their full support in my education at all levels and at all situations. And also

to my late father Edwin M. Kaiza for supporting me when I was young.

vi

TABLE OF CONTENTS

ABSTRACT ........................................................................................................................ i

DECLARATION ............................................................................................................... ii

COPYRIGHT ................................................................................................................... iii

AKNOWLEDGEMENT .................................................................................................. iv

DEDICATION ................................................................................................................... v

LIST OF TABLES .......................................................................................................... viii

LIST OF PLATES ............................................................................................................ ix

LIST OF FIGURES ........................................................................................................... x

LIST OF APPENDICES .................................................................................................. xi

LIST OF ABBREVIATIONS ......................................................................................... xii

1. INTRODUCTION ......................................................................................................... 1

1.1 Background information ............................................................................................ 1

1.2 Problem statement and justification ........................................................................... 2

1.3 Objectives .................................................................................................................. 3

1.3.1 General objective ................................................................................................. 3

1.3.2 Specific objectives ............................................................................................... 3

1.4 HYPOTHESIS ........................................................................................................... 3

2.0 LITERATURE REVIEW ........................................................................................... 4

2.1 Sea cucumber biology ................................................................................................ 4

2.2 Marine Protected Areas and sea cucumber sustainability .......................................... 4

2.3 Aquaculture of sea cucumbers ................................................................................... 5

3.0 MATERIALS AND METHODS ................................................................................ 7

3.1 Description of the Study Area .................................................................................... 7

3.2 Sampling and Data collection .................................................................................... 7

3.2.1 Sea cucumber species composition ......................................................................... 7

3.2.2 Density of sea cucumber ......................................................................................... 8

3.2.3 Size structure of the commercially important sea cucumber .................................. 8

3.3 Data analysis .................................................................................................................. 9

vii

4. RESULTS AND DISCUSSION .................................................................................. 10

4.1 Results ......................................................................................................................... 10

4.1.1 Species Composition ............................................................................................. 10

4.1.2 The Relative Abundance .................................................................................... 11

4.1.2 Sea cucumber species density ............................................................................ 12

4.1.2 Size structure of H. Scabra ................................................................................ 15

4.2 Discussion ................................................................................................................ 15

5. CONCLUSION AND RECOMMENDATIONS ...................................................... 18

5.1 Conclusion ................................................................................................................ 18

5.2 Recommendations .................................................................................................... 18

REFERENCES ................................................................................................................ 19

APPENDICES .................................................................................................................. 22

viii

LIST OF TABLES

Table 1: Sea cucumber species composition………………………………………10

ix

LIST OF PLATES

Plate 1: Aerial picture of Bongoyo Island………………………………………….9

x

LIST OF FIGURES

Fig. 1: Relative abundance of sea cucumbers in Bongoyo Island…………………….....11

Fig. 2 Relative abundance of Sea cucumber along the South Western Side………….....11

Fig. 3 Relative abundance of sea cucumbers along the North Eastern side………….….12

Fig. 4 Species densities of sea cucumbers at Bongoyo Island……………………….….13

Fig. 5 Species densities of sea cucumbers between two sides of the Island…………….13

Fig. 6 Size composition of H. Scabra from Bongoyo Island……………………….…....15

xi

LIST OF APPENDICES

Appendix 1: Observations of sea cucumber in site A………………………………….22

Appendix 2: Observations of sea cucumber in site B…………………………………..23

Appendix 3: Observations of sea cucumber in site C…………………………………..24

Appendix 4: Observations of sea cucumber in site D…………………………………..25

Appendix 5: Observations of sea cucumber in site E…………………………………..26

Appendix 6: Observations of sea cucumber in site F…………………………………..27

xii

LIST OF ABBREVIATIONS

cm: Centimeter

H’: Shannon Weiner diversity index

Ha: Hectare

km: Kilometer

m: Meter

MPA: Marine Protected Area

no.: Number

P: Probability

1

CHAPTER 1

1. INTRODUCTION

1.1 Background information

In marine habitats of Tanzania, there are several marine resources that are important for

the ecology and the economy of the coastal people. Those marine resources include flora

and fauna that inhabit the marine waters of Tanzania. Marine fauna include vertebrates

and invertebrates that bear high values in fisheries sector. Vertebrates include fish,

batoids and other elasmobranchs and invertebrates include bivalves, mollusks,

crustaceans and holothurians (sea cucumbers). Sea cucumbers are one of the consumed

macro-invertebrate with high economic and nutritional value. However, their fisheries

and export are banned in Tanzania mainland, by the fisheries Act no. 22 of 2003. They

are still operational in Zanzibar, as a commercial fishery for export purpose (Eriksson et

al., 2010). The main exports are to Asian countries.

There are several attempts of culturing sea cucumber so as to fulfill the market demands.

Also Japan and China have managed to establish a commercial sea cucumber aquaculture

(James, 2004). In the Southern Western Indian Ocean countries, the sea cucumber

aquaculture is still in experimental stages (Rasolofonirina et al., 2004). Sea cucumbers

were consumed for thousands of years in Asia. In the Ming dynasty (1364-1644 BC), sea

cucumbers were recognized as ‘tonic’ food and latter recognized as tonic and traditional

medicine (Chen, 2004). Many Asians believe that sea cucumbers are helpful in reduction

of joint pains, arthritis, help to restore correct kidney, intestinal function, reinforce the

immune system and treat certain cancers, sometimes, they can be consumed as

aphrodisiacs (Chen, 2004; Purcell et al., 2010).

The commercial exports of sea cucumber led to the overfishing of sea cucumber

resources in Tanzania, where by some biological aspects information of sea cucumbers

are still inadequate for the proper management of its fisheries and conservation (Eriksson

2

et al., 2010; Mmbaga and Mgaya, 2004). There is limited information of sea cucumbers

stocks in Marine Protected Areas of Tanzania. Therefore, this study will provide

composition and abundance of sea cucumber stocks in one of the Marine Protected Area

of Tanzania (Bongoyo Island).

1.2 PROBLEM STATEMENT AND JUSTIFICATION

Sea cucumber fisheries provide an income to the artisanal fishers and other actors

involved. Therefore, there is the rapid increase of exploitation of this resource for export

to Asian countries. This will led to over exploitation of sea cucumber stocks in different

parts of Tanzania (Eriksson et al., 2010; Kithakeni, 2002). Sea cucumbers especially

aspidochiroid are detrivorous and provide ecosystem function via nutrient regeneration

through feeding and bioturbation behavior. And their recovery in the ecosystem is very

slow (Eriksson et al., 2010). Therefore the overexploitation will reduce the ecosystem

productivity.

Sea cucumbers are well exploited invertebrates in the marine fisheries in many parts of

the World (Tacio, 2009). There is still inadequate information and poor monitoring and

management of sea cucumbers in Tanzania. Therefore, there is unknown and

unquantified current sea cucumber resources along the Tanzania coast (Mmbaga and

Mgaya, 2004; Kithakeni, 2002). According to Purcell et al. (2010), marine protected

areas (MPA) can be useful for sea cucumber fisheries, because their effective spawning

and fertilization seems to need high densities of spawners, therefore the presence of MPA

will promote recruitment by encouraging dense breeding population that will spawn

successfully. There is unknown present status of sea cucumber resources in Marine

Protected Areas of Tanzania. The findings from this study will provide the information

on the stock conditions of sea cucumbers in the one of the marine protected areas of

Tanzania.

3

1.3 OBJECTIVES OF THE STUDY

1.3.1 General objective

To assess species density and composition of the sea cucumbers in Bongoyo Island.

1.3.2 Specific objectives

To assess the density of sea cucumbers in Bongoyo Island.

To assess the composition of sea cucumbers in Bongoyo Island.

To determine the size structure of commercially important sea cucumber in

Bongoyo Island.

1.4 HYPOTHESIS

(i) There is no significant difference in abundance of sea cucumber within the study sites

(ii) There is no significant difference in abundance of sea cucumbers between the north

eastern side and south western side of the Island.

4

CHAPTER 2

2.0 LITERATURE REVIEW

2.1 Sea cucumber biology

Sea cucumbers belong to the class Holothuroidea. They have orally-aborally elongated

shape with radial symmetrical muscular body, with mouth encircled with tetancles one

end and anus at the other end (Conand, 1998). There are six taxonomic orders of

holothurians (sea cucumber) most commercial species belong to the Aspidochirotida and

a few to the order Dendrochirotida (Purcell et al., 2010). Holothurians are found

throughout all oceans, at all latitudes, from the shore down to deep sea.Theyare usually

benthic (living on the bottom); some species live on hard substrates, rocks, coral reefs, or

asepizoites on plants or invertebrates; most of the species inhabit soft bottoms, on their

surface or in the sediment. They feed on rich organic firm coating surfaces and planktons

(Conand, 1998). Their reproductive biology differs from one species to another. Some are

gonochoristic and some are haemophrodite. They can reproduce sexually by means of

gametes and asexually by fission (Purcell et al., 2010).

2.2 Marine Protected Areas and sea cucumber sustainability

Marine Protected Areas (MPA) in Tanzania provides potential for fisheries and

ecosystem sustainability. Marine Protected Area is the portion of the marine benthos and

water with associated biota, reserved to protect a part or the entire enclosed environment

(Kelleher, 1999). According to Purcell et al., (2010), Marine Protected Areas act as a

management tool for protecting and improving fish stocks in two ways: through larval

supply, this is due to increasing in number of breeding adult in the reserves that allow for

more active spawning, therefore improving fish stock and through ‘spillover’ effect. This

increases the abundance of juveniles and adult in the MPA and surrounding areas

therefore, improving fish stocks. Sea cucumber reproduction depends on several

ecological factors for the success. It needs a high number of effective spawners that are

5

not available in normal fishing grounds (Bell et al., 2008). Therefore, the presence of

MPA encourages the reproduction, growth and development of sea cucumbers.

2.3 Aquaculture of sea cucumbers

Holothurians are among the mariculture candidates, which are cultured for food or export

to Asian countries (Rasolofonirina et al., 2004). Sea cucumbers that are proven to be

good candidate for tropical countries is Sandfish (Holothuria scabra) and for temperate

Asian countries is Stichopus japonicas because of their good survival, high market value

and higher growth rates. Hatchery of S. Japonicus was recorded in 1950’s and that of H.

Scabra was recorded in 1988 in India (Battalagne, 1999). The reproduction of sea

cucumbers in hatchery is achieved via artificial propagation. Mature broodstocks are

collected from the wild because in most cases, sea cucumbers that are held in captivity

are observed to to have poor gonadal development. For sandfish, the spawning is induced

through thermal stimulation. Air drying and use of water jet also proved to be effective

for S. Japonicus (Battalagne, 1999; James, 2004). Several findings show that the alga can

be used as spawning induction agent in artificial propagation of sea cucumber in a

hatchery, this enhance the fertilization process. The male sea cucumbers are dissected to

remove the gonads and sperms are used for fertilization of eggs (Battalagne, 1999).

Newly hatched larvae are collected and feed with artificial dried micro algae one day

after their hatched and grow up to juvenile stage in 18 days (James, 2004).

Then early juveniles fed with chopped macroalgae (Sargassam densifolium). They are

kept ready for grow-out stage. Depends on the managerial purposes whether for fisheries

as part of stock enhancement or restoration, for small scale mariculture, for sea ranching.

Some studies proved that sea cucumbers especially sandfish can be polycultured in prawn

farms and has higher productivity (James, 2004). Sea cucumber aquaculture is now

practicing in Malaysia, Indonesia, Philliphines, China, Korea, India, Australia and Japan

(James, 2004; Battaglene, 1999; Rasolofonirica et al., 2004). In countries of Western

6

Indian Ocean (WIO), the sea cucumber aquaculture is still in experimental stages. But

several attempts prove to be effective in Madagascar (Muthiga et al., 2010).

7

CHAPTER 3

3.0 MATERIALS AND METHODS

3.1 Description of the Study Area

Bongoyo Island is the Marine Protected Area (MPA) that is under Dar es Salaam Marine

Reserves (DMRs). It lies between 06º43’12” S and 38º16”00”E and is about 8 km north

of Dar es Salaam. The island, which is narrow in the southeast, gradually broadening in

the northwest is uninhibited. The Island area is 80.5 ha, and the intertidal area is 388.5

ha. The area of reef and sea grass beds surrounds the island 284.8 ha (DMR, 2005). These

beds start from the intertidal zone of the island up to shallow water subtidal zone.

3.2 Sampling and Data collection

The study was carried out in six sites of the Island from 26th

to 30th

March 2012. Three

sites were selected from the North Eastern part of the island, and others will be at the

South Western part of the island. Coordinate for each site was obtained by using GPS and

recorded accordingly. And the study was conducted during the low tide. The study was

using Lincoln-Smith transect (Hills and Winkinson, 2004) and was conducted form

seaward to land ward direction and was involving walking, snorkeling, skin diving (free

diving) in both shallower and deeper subtidal area of less than 7 m and in each site three

transects were established at an interval of 50 m. Quadrant of the size of 2 m wide and 5

m long were established in 10 meters interval within a transect. The following data were

recorded in each quadrant, sea cucumber species, density, and body length (in cm).

3.2.1 Sea cucumber species composition

The composition in each site was obtained by identifying each species encountered in a

quadrant of transect and recorded. Species were identified by using identification slates

made from the book of A field guide of Marine and Coastal resources of East Africa by

Richmond (2002). And the species diversity was obtained by using Shannon-Weiner

index (H’), and relative abundance was obtained by using the following formula;

8

RA=Dn/DN×100%

Where;

RA=Relative abundance

Dn=Density of a species

DN=Density of all species

N=total number of individuals

n=number of individuals

3.2.2 Density of sea cucumber

The sea cucumber species densities were obtained by counting each individual species in

each quadrant. Then the number of sea cucumber from all quadrants in transect was

recorded and then the total density of sea cucumber in the study area is calculated using

the following formula:-

T = X * N

Where by:

T = total population

X = mean number per quadrant

N = number of quadrants that fit into the total area (N = total area/quadrant area) (Hassan,

2009).

3.2.3 Size structure of the commercially important sea cucumber

The commercially important sea cucumbers obtained in the area was H. Scabra. Then,

body length was measured using tape measure to the nearest cm.

9

3.3 Data analysis

Data were analyzed by using Microsoft Excel, 2010 package and Statistical Package for

Social Science (SPSS). Kruskal Wallis test was used to test the first hypothesis and Mann

Whitney U-test was used to test the second hypothesis. The size structure of the

commercially important sea cucumber (H. Scabra) was analyzed using Length-frequency

analysis.

Plate 1: Aerial picture of Bongoyo Island; A, B, C, D, E and F are the sites that were

surveyed during the study.

10

CHAPTER 4

4. RESULTS AND DISCUSSION

4.1 RESULTS

The results were observed and recorded as they appeared in the appendices.

4.1.1 Species Composition

Table 1: Sea cucumber species composition

SITES SITE A SITE B SITE C SITE D SITE E SITE F

COORDINATES 6

0 41’ 48.64’’ S

390 15’ 39.88’’E

60 42’ 05.61’’ S

390 16’ 03.35’’ E

60 42’ 25.45’’ S

390 16’ 23.52’’ E

60 41’27.32’’ S

390 15’ 40.46’’ E

60 41’49.48’’ S

390 16’ 00.85’’ E

60 42’ 22.07’’ S

390 16’ 26.88’’ E

SPECIES

A. Miliaris + + + + + +

A. Mauritiana - - - + + +

B. Subrubra - - - - + -

H. Scabra - + + + + +

H. Leucospilota + - - + - -

H.Atra - + + - + +

H. Edulis + - + + - +

Unknown + - - - - -

Diversity (H’) 1.330 0.950 1.332 1.359 1.494 1.226

Table 1shows presence-absence and diversity index of sea cucumber species in Bongoyo

Island. Only one species (A. Miliaris) appeared in all sampling sites. Site E and B were

observed to have the highest and lowest diversity index respectively.

11

4.1.2 The Relative Abundance

Fig.1: Relative abundance of sea cucumbers in Bongoyo Island

Figure 1 shows the general relative abundance of sea cucumber species in Bongoyo

Island. H. Atra and B. Subrubra were found to have the highest (29%) and lowest (1%)

relative abundance respectively.

Fig. 2 Relative abundance of Sea cucumber along the South Western Side

A. miliaris26%

A. mauritiana6%

B. subrubra1%

H. scabra19%

H. leucospilota4%

H. atra29%

H. edulis12%

Unknown3%

A. Miliaris24%

H. Scabra20%

H. Leucospilota5%

H.Atra27%

H. Edulis18%

Unknown6%

12

Figure 2 shows relative abundances of sea cucumber species along the South western side

of Bongoyo Island. H. Atra and H. Leucospilota were observed to have the highest and

lowest relative abundance respectively.

Fig. 3 Relative abundance of sea cucumbers along the North Eastern side

Figure 3 presents the relative abundances of sea cucumber species along the North

Eastern side of Bongoyo Island. H. Atra, also was observed to have the highest relative

abundance and B. Subrubra was found to have the lowest relative abundance.

4.1.2 SEA CUCUMBER SPECIES DENSITY

Statistically, there was no significant difference in species density among the sampling

sites in the North-Eastern side and South-Western side of Bongoyo Island (Kruskal-

Wallis, P > 0.05). However, there was significantly different in species density between

the South Western side and the North Eastern side of the Island (Mann Whitney, U-test,

P < 0.05).

A. Miliaris28%

A. Mauritiana12%

B. Subrubra2%

H. Scabra19%H. Leucospilota

3%

H.Atra31%

H. Edulis5%

13

Fig. 4 Species densities of sea cucumbers at Bongoyo Island

Figure 4 show species densities of sea cucumber from six sampling sites. H. Atra had the

highest density in three sampling sites followed by H. Scabra and A. Miliaris.

Fig. 5 Species densities of sea cucumbers between two sides of the Island

Generally, there was higher density of species North western side of the Island compared

to the South western side (Figure 5). In both sites H. Atra and A. Miliaris had the higher

0

1

2

3

4

5

6

7

8

9

Site A Site B Site C Site D Site E Site F

Spe

cie

s d

en

sity

(in

d/1

00

m2

) A. Miliaris

A. Mauritiana

B. Subrubra

H. Scabra

H. Leucospilota

H.Atra

H. Edulis

Unknown

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

South Western North Eastern

Spe

cie

s d

en

sity

(in

d/1

00

m2

)

A. Miliaris

A. Mauritiana

B. Subrubra

H. Scabra

H. Leucospilota

H.Atra

H. Edulis

Unknown

14

density compared to other species. H. Leucospilota contributed the lowest density in both

sites.

The mean number of individual sea cucumber for all six sites in the area of 100m2

was

7.7778. Therefore, the population of the sea cucumber in Bongoyo Island can be

estimated as follows,

From the formula, T = X*N , where N = 𝐴𝑟𝑒𝑎 𝑜𝑓 𝑡𝑕𝑒 𝑆𝑒𝑎 𝑔𝑟𝑎𝑠𝑠 𝑏𝑒𝑑𝑠 𝑎𝑛𝑑 𝑟𝑒𝑒𝑓 ,𝐴

10 𝑡𝑖𝑚𝑒𝑠 𝑡𝑕𝑒 𝑎𝑟𝑒𝑎 𝑜𝑓 𝑞𝑢𝑎𝑑𝑟𝑎𝑡 ,𝑎

Since,

A = 284.8 ha and a = 0.01 ha

Then, T = 7.7778 * 248.8

0.01

T = 221512 individuals

Therefore, the estimated sea cucumber population in Bongoyo Island is 221,512

individuals.

15

4.1.2 SIZE STRUCTURE OF H. SCABRA

Fig. 6 Size composition of H. Scabra from Bongoyo Island

Figure 6 gives the size frequency distribution of H. Scabra. The size structure indicates a

unimodal distribution with a modal class of 15 – 16 cm. Minimum and maximum size of

H. Scabra was 9 and 22 cm respectively.

4.2 DISCUSSION

Only seven sea cucumber species was observed during the survey, and one sea cucumber

species with was not identified, the specie has a soft body, which is violet in color and

scattered dots which are orange colored and with a size about 0.5 cm. B. Subrubra and A.

Mauritana were only observed along the North Eastern Side. Others were observed in all

sides of the Island. However H. Scabra was the most cryptic species during the survey.

They were not easily seen because, they tend to bury and camouflaging themselves in

sediments (Wolkenhauer et al., 2009). Then, other species were bit observable during the

survey. The population of sea cucumber was estimated to be 221,522 individuals. This

population in the Subtidal area of Bongoyo Island which is about 284.8 ha is equivalent

to 777.8 individuals ha-1

. That density is above the minimum density range for successful

16

reproduction of tropical sea cucumbers, which ranges from 10 to 40 individuals ha-1

(Bell

et al., 2008). Therefore, this population is effective for enabling the regeneration of sea

cucumbers stocks in the areas surround Bongoyo Island. The composition of sea

cucumber was not uniformly distributed along the shores of Bongoyo Island; different

individual species were more diverse in one place than the other due to food availability,

shore topography, predation and wave turbulence (Mercier et al., 1999; Sloan and von

Bodungen, 1980). Those factors also affect their density from one site to another and

made the species densities to be different among individual sea cucumber species of the

Island.

The sea cucumber species composition at Bongoyo Island varies from one site to another.

Variation of species is probably due to the physiographic nature of the study sites. South

Western side of the Island is composed of narrow sea grass beds, coral reef patches and

dead corals. Little sedimentation and decomposition of matters was observed along this

side. Higher species composition, species diversity and species densities of sea cucumber

were observed along the North Eastern side due to habitat heterogeneity. The North

Eastern side of the island has a wider tidal reef in which there are very few sea grasses

patches and a lot of decomposing sea weeds. According to Purcell et al. (2010) sea

cucumbers prefer an area with high abundance of detritus, microalgae and sometimes

planktons. Therefore, they became more abundant along the North Eastern side of the

Island.

Different sites were observed to have microhabitat that could affect the density of sea

cucumber. Species of star fish and crown of thorn star fish (Acanthaster plancii) which

are one of the possible predators of sea cucumber were more observed South Western

Side of Bongoyo Island. The site was more affected by invasive sea weeds including

green algae, Ulva species and brown algae). Also dead corals were observed during the

survey. Some of the dangerous corals (Fire corals – Millepora species) were also

observed from Site A. According to Kithakeni and Ndaro (2002), H. Scabra at Dar es

17

Salaam attains sexual maturity at 16.8 cm; therefore the sea cucumber stock of Bongoyo

Island has a high frequency of mature sea cucumber stocks. Therefore, this sea cucumber

stock is slightly under exploited.

18

CHAPTER 5

5. CONCLUSION AND RECOMMENDATIONS

5.1 CONCLUSION

The composition, diversity and abundance of sea cucumbers vary from one site to another

and between two sides of Bongoyo Island. This is due to nature of habitats prevailing

around the Island. Estimated population of sea cucumber was 221512. The stock of H.

Scabra is partially dominated by sexually mature individuals.

5.2 RECOMMENDATIONS

Due to the present status of sea cucumber on one of the marine protected area, the

following are recommendations to the Marine Parks and Reserve Unity, the Directory of

Fisheries and other fisheries and wildlife stakeholders:-

The sea cucumber fishing moratorium alone is not sufficient in managing sea cucumber

stocks of Tanzania. The proper management should be improved so as to reduce the

opportunistic fishing of sea cucumber inside and outside the marine protected areas.

More research should be done concerning sea cucumber ecology and stock status along

the coast of Tanzania so as to obtain sufficient information concerning the sea cucumber

stocks and the problems which are facing them.

Aquaculture of sea cucumber should be emphasized and practiced in different potential

sites for stock enhancement and improving productivity. Hatchery production of sea

cucumber seeds (larvae) should be employed so as to allow the large scale mariculture of

sea cucumbers.

19

REFERENCES

Bell, J.D., Purcell, S.W. and W.J. Nash.(2008). Restoring small-scale fisheries for

tropical seacucumbers. Ocean and Coastal Management, 51: 589–593.

Chen, J. (2004). Present status and prospects of sea cucumber industry in China. In:

Advances in sea cucumber aquaculture and management. LovatelliA., Conand C.,

Purcell S., Uthicke S., Hamel J.-F. and M. Mercier (eds). FAO Fisheries Technical

Paper. No. 463.FAO, Rome. pp. 25–38.

Conand, C (1998). Holothurians: Sea cucumber, Class Holothuroidea In: Carpenter, K.E

and Niem, V.H. (eds) FAO species identification guide for fishery purposes: The

living marine resources of the Western Central Pacific. Volume 2. Cephalopods,

Crustaceans, Holothurians and Sharks. Rome, FAO. 1998.

DMR (2005). Dar es Salaam Marine Reserves; General Management Plan. Marine Parks

and Reserves Unit.

Eriksson, B. H., de la Tore-Castro, M., Eklof, J. and Jiddawi, N. (2010). Resorce

degradation in the sea cucumber fishery in Zanzibar, Tanzania: a need for

management reform. Aquatic Living Resources.23:.387–398.

Hassan, M.H. (2009). Stock assessment of holothuroid populations in the Red Sea

watersof Saudi Arabia. SPC Beche-de-mer Information Bulletin #29 – June 2009.

Hill, J and C. Wilkinson (2004). Methods for ecological monitoring of the coral

reef.Australia Institute of Marine Science.

James, B.D. (2004). Captive breeding of the sea cucumber, Holothuria scabra, from

India.. In: Advances in sea cucumber aquaculture and management. A. Lovatelli,

C. Conand, S. Purcell, S. Uthicke, J., F. Hamel and A. Mercier, (Eds.). FAO,

Rome.

20

Kelleher, G. (1999). Guidelines for Marine Protected Areas. IUCN, Gland, Switzerland

and Cambridge, UK.xxiv +107pp.

Kithakeni, T and S.G.M. Ndaro (2002). Some Aspects of Sea Cucumber, Holothuria

scabra (Jaeger,1935), along the Coast of Dar es Salaam. Western Indian Ocean

Journal of Marine Science,1:163–168.

Mercier, A., Battaglene, S.C. & Hamel, J.F. (1999).Daily burrowing cycle and feeding

activity of juvenile sea cucumbers Holothuria scabra in response to environmental

factors. SPC Info. Bull.No. 12: 29.

Mmbaga, T.K. & Mgaya, Y.D.(2004). Studies on sea cucumber in Tanzania and the gaps

towards resource inventory and management. In: Advances in sea cucumber

aquaculture and management. A. Lovatelli, C. Conand, S. Purcell, S. Uthicke, J.,

F. Hamel and A. Mercier, (Eds.). FAO, Rome.

Muthiga, N., Ochiewo, J. And J. Kawaka (2010). Strengthening capacity to sustainably

manage sea cucumber fisheries in the Western Indian Ocean.SPC Beche de Mer

Information Bulletin (30) March 2010.

Purcell, S.W., Lovatelli, A. & M. Vancellos (eds) (2010). Managing Sea cucumber

fisheries with an ecosystem approach. FAO Fisheries and Aquaculture Technical

Paper, 520.

Rasolofonirina, R., Mara,E. and Jangoux, M. (2004). Sea cucumber fishery and

mariculture in Madagascar, a case study of Toliara, southwest Madagascar.. In:

Advances in sea cucumber aquaculture and management. A. Lovatelli, C. Conand,

S. Purcell, S. Uthicke, J., F. Hamel and A. Mercier, (Eds.). FAO, Rome.

Sloan, N.A. & von Bodungen, B. (1980).Distributionand feeding of sea cucumber

Istichopus in relation to shelter and sediment criteria of the Bermuda

Platform.Mar. Ecol. Prog. Ser. 2: 257–264

21

Tacio, H.D. (2009). Sea cucumber hatchery and culture to tackle overfishing.[Internet]

available from <http://www.gaiadiscovery.com/marine-life-latest/sea-cucumber-

hatchery-and-culture-to-tackle-overfishing.html> visited 18th

January 2012.

22

APPENDICES

Appendix 1: Observations of sea cucumber in site A

SEA CUCUMBER RESULTS OF THE BONGOYO ISLAND

SITE A COORDINATES 60 41’ 48.64’’ S 39

0 15’ 39.88’’E

TRANSECT 1 TRANSECT 2 TRANSECT 3

INDIVIDUAL SPECIES Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

A. Miliaris 1 1

A. Mauritiana

B. Subrubra

H. Scabra

H. Leucospilota 1

H. Edulis 1 1

H. Nobilis

H. Fuscogilva

T. Ananas

Unknown 1

Nature of the substratum coral sand sea grass rocky coral sea grass sea grass rocky corals Corals sand sand

Total 1 0 2 1 0 1 0 1 0 0 0 0

SIZE STRUCTURE OFH.Scabra

INDIVIDUALS LENGTH

NIL

23

Appendix 2: Observations of sea cucumber in site B

SITE B COORDINATES 60 42’ 05.61’’ S 390 16’ 03.35’’ E

TRANSECT 1 TRANSECT 2 TRANSECT 3

INDIVIDUAL

SPECIES Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

A. Miliaris 1

A. Mauritiana

B. Subrubra

H. Scabra 1

H. Leucospilota

H. Atra 1 1 1

H. Edulis

H. Nobilis

H. Fuscogilva

T. Ananas

Unknown

Nature of the substratum rocky sea grass rocky sand rocky rocky rocky muddy rocky/dead corals rocky rocky rocky

Total 1 0 1 0 1 0 0 1 0 0 0 1

SIZE STRUCTURE of H. Scabra

INDIVIDUAL LENGTH (cm)

1 19

24

Appendix 3: Observations of sea cucumber in site C

SITE C COORDINATE 60 42’ 25.45’’ S 39

0 16’ 23.52’’ E

TRANSECT 1 TRANSECT 2 TRANSECT 3

INDIVIDUAL SPECIES Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

A. Miliaris 1

A. Mauritiana

B. Subrubra

H. Scabra 1 1

H. Leucospilota

H.Atra 1

H. Edulis 1

H. Nobilis

H. Fuscogilva

T. Ananas

Unknown

Nature of the substratum rocky sea grass rocky sea grass rocky/dead coral rocky sand sand rocky sea grass rocky rocky

Total 1 0 2 0 0 0 0 0 1 1 0 0

SIZE STRUCTURE of H. Scabra

INDIVIDUAL LENGTH (cm)

1 16

2 22

25

Appendix 4: Observations of sea cucumber in site D

SITE D COORDINATES 60 41’27.32’’ S 390 15’ 40.46’’ E TRANSECT 1 TRANSECT 2 TRANSECT 3

INDIVIDUAL SPECIES Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

A. Miliaris 1 1 1 1 1

A. Mauritiana 1

B. Subrubra

H. Scabra 2

H. Leucospilota 1

H. Edulis 1

H. Nobilis

H. Fuscogilva

T. Ananas

Unknown

Nature of the substratum muddy rocky rocky sand sea grass sea grass sand rocky sea grass Muddy rocky rocky

Total 2 1 0 0 0 1 0 2 0 0 1 2

SIZE STRUCTURE OF H. Scabra

INDIVIDUAL

LENGTH

(cm)

1 13

2 11

26

Appendix 5: Observations of sea cucumber in site E

SITE E COORDINATE 60 41’49.48’’ S 390 16’ 00.85’’ E

TRANSECT 1 TRANSECT 2 TRANSECT 3

INDIVIDUAL SPECIES Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

A. Miliaris 2 1

A. Mauritiana 1 1 1

B. Subrubra 1

H. Scabra 1 1

H. Leucospilota

H. Edulis

H. Nobilis

H. Atra 1 1 1 1 1

H. Fuscogilva

T. Ananas

Unknown

Nature of the substratum rocky rocky rocky rocky rocky rocky rocky rocky rocky Rocky rocky rocky

Total 3 1 2 1 2 1 1 0 1 0 1 1

SIZE STRUCTURE of H. Scabra

INDIVIDUAL

LENGTH

(cm)

1 17

2 15

27

Appendix 6: Observations of sea cucumber in site F

SITE F COORDINATE 60 42’ 22.07’’ S 390 16’ 26.88’’ E

TRANSECT 1 TRANSECT 2 TRANSECT 3

INDIVIDUAL SPECIES Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

A. Miliaris 1 1

A. Mauritiana 1

B. Subrubra

H. Scabra 1 1 1 1

H. Leucospilota

H.atra 3 1 1 2 3

H. Edulis 1

H. Nobilis

H. Fuscogilva

T. Ananas

Unknown

Nature of the substratum rocky rocky rocky rocky rocky rocky rocky/sea grass rocky rocky rocky rocky rocky

SIZE STRUCTURE OF H. Scabra

INDIVIDUAL

LENGTH

(cm)

1 18

2 15

3 20

4 9

28

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Name of Student: KAIZA, Victor

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