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Summary of fisheries and resources information for Somalia

by
N.P. Van Zalinge
FAO Consultant
Via delle Terme di Caracalla
00100 ROME, Italy


ABSTRACT
1. INTRODUCTION
2. THE ARTISANAL FISHERIES
3. THE INDUSTRIAL TRAWL FISHERY
4. THE POTENTIAL INDUSTRIAL FISHERY FOR SMALL PELAGICS
5. BIBLIOGRAPHY


ABSTRACT

Roughly half of the fisheries production from Somalia waters (19,546 tonnes in 1987) is from the artisanal fishermen. Most of the remainder derives from licensed foreign trawlers used for exploiting demersal fish in depths from 20 to 70 m, and deep water lobster and shrimp.

There have been no assessments of the resources available to the artisanal fishermen. Having in mind the relatively small numbers of fishermen and the very low population densities along much of the coastline, it is suggested that the artisanal catch might be substantially increased.

The report contains a preliminary estimate of about 650 tonnes (whole weight) for the potential yield of deep water lobster (Puerulus sewellii and P. carinatus). If this is correct, these species are being fully exploited.

The report also refers to preliminary estimates of about 6,000 to 14,000 tonnes for the potential yield of demersal trawl fish. The annual landings in recent years are given as about 8,000 tonnes, from which it seems that these resources are approaching full exploitation.

The abundance of small pelagics is high off the northeast coast, particularly between Ras Asir and Ras Hafun. These were exploited by Romanian factory trawlers in 1983/84. The most recent estimates of potential yield are given as between 75,000 and 120,000 tonnes.

1. INTRODUCTION

Somalia's northern coastline on the Gulf of Aden from Djibouti to Ras Asir is about 1,000 km long. Its eastern coast extends along the Indian Ocean from Ras Asir to Kenya for about 2,000 km. Coral fringe reef is found in many places. The continental shelf along both coasts is narrow, usually extending not more than between 6 and 30 km from the shore, except in the Ras Asir to Ras Mabber area where the shelf is up to 60 km wide. UNEP (1987) gives the following estimates for the shelf areas.


Km2

North coast shelf

7,000

Ras Asir-Ras Mabber

11,000

Rest of east coast shelf

21,500

TOTAL

39,500

During the south-west monsoon (May to August) currents of generally north-easterly direction are running along both coasts, creating a variable amount of upwelling in the area between Ras Mabber and Ras Hafun and between Ras Asir and Socotra. This upwelling (of cold water) is probably linked to the mass mortalities of fish that are reported to occur occasionally in these areas (Foxton, 1965). At the onset of the north-east monsoon (December to February) these currents turn and flow in the opposite direction.

Roughly half the catch derives from the artisanal fishermen (see Table 1.1). They are relatively few in number, and located at some 25 landing sites. Much of the coastline is remote from settlements and hence only lightly fished.

Table 1.1. Annual marine fish landings by type since 1974

YEAR FISHERY
(tonnes)

ARTISANAL FISHERY
(tonnes)

Fish Landings INDUSTRIAL LANDINGS
(tonnes)

CRUSTACEA
(tonnes)

TOTALS

1974

3,950

1,350

680

5,980

1975

7,900

1,500

950

10,350

1976

7,040

3,400

950

11,390

1977

5,280

3,400

1,150

9,830

1978

3,580

230

20

3,830

1979

4,000

3,080

800

7,880

1980

4,000

8,530

1,800

14,330

1981

4,255

4,792

476

9,523

1982

4,390

3,904

436

8,730

1983

5,280

5,356

559

11,195

1984

7,724

11,363

552

19,639

1985

4,067

11,938

462

16,467

1986

12,653

4,800

802

18,255

1987

8,088

10,748

710

19,546

Source: Ministry of Fisheries and Marine Resources

Note:

1. The landings of Crustacea are from both the artisanal and industrial fisheries

2. Ten Russian (industrial) trawlers were withdrawn in 1977.

3. It seems that purchases by public companies from the artisanal fishermen are sometimes included with the fish landings from the industrial fishery; eg. in 1985.

4. The values for 1987 are provisional.

At present, there are three main development projects aimed at assisting the coastal settlements. They are operated under aid arrangements with the Ministry of Fisheries and Marine Resources. These are the Somali Marine Products (SMP) on the southeast coast, the North-East Coast Fishing Enterprise (NECFISH) and the North-west Coast Fishery Development (NWFD). Since 1975 the Government's Coastal Development Project has been engaged in retraining nomadic herdsmen to coastal fishing.

The industrial fishery mainly involves the use of foreign owned demersal trawlers. These are operated in the depth range of 20 to 70 m for quality fish, and between 200 to 400 m depth for deep water lobster and shrimp. The statistics for the industrial fishery also includes large pelagics (mainly tuna) caught by Korean longliners (eg. 1,130 tonnes in 1985). None of the industrial catch is marketed for consumption in Somalia.

2. THE ARTISANAL FISHERIES

Location: Fishing is based from some 25 landing sites scattered along the north and east coasts. Between the landing sites the population densities are very low, hence, these grounds are only lightly fished.

Boats: The houri, a rowing boat, is the most commonly used boat in Somalia. Sail boats are found only on the east coast, and are less common than boats equipped with engines. Elmer (1985) carried out a frame survey and counted the numbers of boats shown in Table 2.1.

Table 2.1. Numbers of boats by type counted during 1984

Boat Type

East Coast

North Coast

Total

Motor boats

158

66

224

Sail boats

174

-

174

Houris

271

565

836

Totals

603

631

1,234

Source: Elmer (1985)

Fishermen: The number of fishermen is given as 2,326 (UNEP, 1987) or 2, 619 full-time fishermen and 954 part-time fishermen (Pecker, 1982). Both may be underestimates (Nur Abdulhadir S. Mao, pers. comm.). The membership in 1985 of the 29 marine fishermen's cooperatives was 3,328. Although most cooperatives are apparently not very active, they are the only organizations at village level. In its Yearly Fishery Report (1986/87) the Ministry of Fisheries and Marine Resources put the number of full time fishermen as 4,353 persons, however, this also includes freshwater fishermen.

Gear: A qualitative account of the gears in use is given in Elmer (1985). The most common gears are handlines, troll-lines and mesh nets; while traps, beach seines and cast nets are also used.

Catches: The official landing statistics are given in Table 2.2 for 1985. These should be considered as indicative only, as the system of collecting fisheries statistics is poor. Elmer (1985) gives a figure of 8,300 tonnes for the artisanal landings in 1984, and of about 5,000 tonnes for 1983. Pecker (1982) estimated the landings in 1981 to be 4,477 tonnes. He subdivided the latter into that consumed without sale (925 tonnes), sold fresh (319 tonnes), dried and salted (2,416 tonnes), canned (485 tonnes), sold for resale as chilled or frozen product (257 tonnes) and shrimps and lobsters (75 tonnes).

Table 2.2. Production by cooperatives and settlements and purchases by public companies in 1985.


Production (tonnes)

Totals

Fish and sharks

Shallow-water lobster

Cooperatives:

Ras Kiamboni

53

15

68

Kulmis

119

11

130

Kismayo

260

16

276

Subtotals

432

42

474

Baraawe

97

-

97

El Ahmed

19

-

19

Maka

22

-

22

Jisiira

27

-

27

Mogadishu

432

7

439

Adale

51

-

51

Subtotals

648

7

655

Bander Bayla

505

15

520

Hurdiya

110

-

110

Xaafan

352

-

352

Baargaal

108

-

108

Caluula

468

-

468

Qandala

174

-

174

L/Qoray

64

-

64

Boosaaso

133

-

133

Maydh

4

-

4

Berbera

62

-

62

Hobyo

45

-

45

Sub-totals

2,025

15

2,040

Re-settlements:

Dan Cadale

560

-

560

Dan Baday

235

-

235

Dan el Ahmed

167

-

167

Sub-totals

962

-

962

Totals

4,067

64

4,131

Purchases by public companies:

Xaabo (at Boosaaso)

1,434

-

1,434

Somali Marine

425

52

477

Products (at Kismayo)

Fish Retail Market (at Mogadishu)

180

-

180

Totals

2,039

52

2,091

Grand Totals

6,107

116

6,223

Source: Ministry of Fisheries and Marine Resources

Catch per Unit Effort: The official statistics system does not presently provide for the estimation of catches per unit effort. If it is assumed, however, that each boat was used for 200 days per year during 1984 then the mean catch per unit effort in that year would have been 33.6 kg/boat/day.

Species Composition: Comprehensive data on the species compositions in the catches is not available. A useful qualitative description is given in UNEP (1987).

The principle large pelagic fish include yellowfin tuna (Thunnus albacares), longtail tuna (Thunnus tonggol), bigeye tuna (Thunnus obesus), bonito (Sarda orientalis), skipjack (Katsuwonus pelamis), Spanish mackerel (Scomberomorus commerson). On the north coast between Bosaso and Ras Asir tunas are caught seasonally (mainly in November and March) for canning. Along the southeast coast March to June is the main season for Spanish mackerel and October to November for tuna.

The main demersal species in the catches are the emperors (Lethrinidae), groupers (Serranidae), snappers (Lutjanidae), grunts (Pomadasyidae) and threadfin breams (Nemipteridae), lizard fishes (Synodontidae) and goatfishes (Mullidae). Sharks are very important contributing some 40 percent of the artisanal catch (Elmer, 1985).

The predominant small pelagics are the Indian oil sardine (Sardinella longiceps), rainbow sardine (Dussumieria acuta), scads (Decapterus russelli, D. macrosoma), mackerel (Trachurus indicus) and anchovies (Engraulis japonicus and Stolephorus indicus). These species are mainly distributed off the northeast coast between Ras Asir and Ras Mabber. Part of the stock migrates seasonally into the Bosaso to Ras Asir region. Elsewhere the small pelagics are scattered and do not form the basis of any fishery.

Shallow-water lobsters of the genus Panulirus (P. ornatus, P. versicolor, P. penicillatus, P. dasypus and P. japonicus) occur in the near-shore waters along the entire coast of Somalia. They are more heavily exploited in the southern part of their range, probably in connection with the presence of the cold store belonging to the SMP project in Kismayo (Losse, 1968). They are caught mainly by diving, and throughout the year except during the monsoon period. Gillnets are only used occasionally.

Small quantities of shallow water shrimp are found particularly in the mouth of the Juba River and Bircao estuary. Among the more common species are Penaeus indicus, P. monodon, P. semisulcatus, Metapenaeus monoceros and M. stebbingi (Losse, 1968). Negligible quantities have been landed so far. In 1987 the Somali Marine Products purchased an 11 m shrimp trawler for use in the Juba estuary.

Areas of Fishing Grounds: The area of grounds exploited directly by the artisanal fishermen is unknown. Having in mind the limited seaworthiness of most of the boats, it seems unlikely that fishing would take place beyond about 5 km from shore. The product of this value and the length of coastline gives a very rough estimate for the exploited area of 15,000 km2.

Productivities per Unit Area: Using the area of the fishing grounds given above, the annual productivity per unit area was 0.41 tonnes/km2 in 1985.

Resource Assessments: None.

3. THE INDUSTRIAL TRAWL FISHERY

Location: The trawling grounds as indicated in Johnsen (1984) are shown in figure 3.1. When fishing exclusively for fish the vessels are operated in the depth range of 20 to 70 m and at 200 to 400 m when operated for deep water lobster and shrimp.

Figure 3.1 Approximate location of identified trawling grounds on the Somali coast.

Boats: In the mid 1970's SOMALFISH, a Somali/USSR joint venture company operated ten factory trawlers of about 680 GRT. This venture collapsed in 1977. Subsequently the exploitation has largely involved the licensing of foreign vessels from Italy, Japan, Greece, Singapore and Egypt. A Somali/Italian joint venture (SOMITFISH) operated three Italian built trawlers from 1981 to 1983. These have since been rehabilitated with one of the vessels returned to the fishery in 1987.

Catches: The catch weights are given in Table 3.1 for 1985 and in Table 3.2. for 1987. (The values for 1986 were not available to the author). The basic data were as recorded at the point of transhipment (e.g. Djibouti or Berbera). They are as whole weight in the case of the lobster, and as packaged weights for the fish. Generally fish larger than 1.5 kg were gutted, headed and tailed before packing (Johnsen, 1984).

Table 3.1. Production by demersal trawlers in 1985

Vessels

Production (tonnes)

Fish

Deep Water Lobster

Totals

Italian trawler

1,141

172

1,313

Italian trawler

603

75

679

Japanese trawler

3,120

53

3,173

Japanese trawler

2,526

23

2,549

Remaining 7 trawlers

1,078

23

1,101

NECFISH trawlers

60

-

60

Totals

8,528

346

8,875

Source: Ministry of Fisheries and Marine Resources.

Note:

1. The two NECFISH trawlers were engaged in experimental fishing

2. The values given for lobster also contain mostly unknown quantities of deep water shrimp (e.g. 86 tonnes of shrimp were caught in 1985, mostly from the two Italian vessels).

Table 3.2. Production by demersal trawlers in 1987

Vessels

Production (tonnes)

Fish

Deep Water Lobster

Totals

Vessel 1

465

112

577

Vessel 2

740

93

834

Vessel 3

1,413

73

1,485

Vessel 4

1,081

72.

1,153

Vessel 5

1,058

40

1,099

Vessel 6

803

55

858

Vessel 7

1,643

126

1,769

SOMITFISH (1 vessel)

1,245

-

1,245

Totals

8,448

571

9,020

Source: Ministry of Fisheries and Marine Resources

Note: The values given for lobster contain unknown quantities of deep water shrimp.

Catches per Unit Effort: Data on fishing days and numbers of hauls are recorded by onboard observers, but have not yet been analysed. Data collected during a 40 day cruise in March/April 1983 with the F/V CUSMAAN GEEDI (length 67 m) provided the estimates of catch rates given in Table 3.3.

Table 3.3. Catches per unit effort determined for the F/V CUSMAAN GEEDI in March/April 1983 and other related data.

Target Species Group

No. of Fishing Days

Depth Range
(m)

No. of Hauls

Mean Duration of Hauls
(min)

Weight of Retained Catch
(tonnes)

Mean Catch per Haul
(kg/haul)

Mean Catch per Hour
(kg/haul)

Lobster

30

240-400

236

104 (11)

52.60

223 (217)

129

Fish

5

34-43

46

105 (10)

36.56

795 (356)

454

Source: Estimated from data in Johnsen 1984.

Note:

1. The values in brackets are standard deviations.

2. The horizontal width of the trawl nets were 30 m for the lobster trawl and 33 m for the fish trawl.

3. The fishing grounds were Nos. 8, 11, 14 and 20 when fishing for lobster and Nos. 9 and 10 when fishing for fish; see Figure 3.1.

4. The catches per unit effort given when the target group is lobster include Puerulus spp. only. The quantities of species not included (mainly squids and cuttlefish) generally did not exceed 50 kg/haul.

Species Composition: Species group categories are recorded by observers on board the vessels and at the point of transhipment but these data have not been analysed. It is only the high value species that are retained from the catches. Johnsen (1984) refers to the spangled emperor (Lethrinus nebulosus) being 40-60 percent of the catches when trawling for fish during a 40 day cruise in March/April 1983. Apart from the emperors the catches include groupers (Serranidae), snappers (Lutjanidae), breams (Sparidae), and goatfish (Mullidae). Cuttlefish (Sepia spp.) are also an important component of the catches from the shallow grounds.

The catches of deep water lobster principally include two species; Puerulus sewellii and Puerulus carinatus. The former were reported to occur on the fishing grounds north of about latitude 7°N, and the latter south of 10°N (Johnsen, 1984).

The Andaman lobster (Metanephrops andamanicus) were caught in small quantities in greater than 300 m depth off the northeast coast. The deep water shrimp (Heterocarpus spp.) is an important by-catch in some areas. Small quantities of sand lobster (Thenus orientalis) are caught by the industrial fleet in depths up to 100 m (Noor, 1987).

Areas of Fishing Grounds: The areas of the trawling grounds depicted in Figure 3.1 are given in Table 3.4, along with related information. The total area of the grounds suitable for catching deep water lobster and shrimp is 4,696 km2, while the total area of the trawl grounds in shallow waters is 8,608 km-.

Table 3.4. Areas of the trawling grounds

Ground Number

Areas of Grounds
(km2)

Trawlable Depth Range
(m)

Dominant Species Caught

1

480

255-285

Puerulus carinatus

2

137

20-40

Penaeidae

3

755

250-320

Puerulus carinatus

4

86

240-300

Puerulus carinatus

5

755

20-52

Fish

6

755

30-60

Fish

7

1,303

21-58

Fish

8

285

240-400

Puerulus carinatus/sewellii

9

1,269

24-56

Fish

10

1,338

19-54

Fish

11

1.526

260-400

Puerulus carinatus/sewellii

12

1,543

40-69

Fish

13

583

20-46

Penaeidae, Fish

14

154

300-390

Puerulus sewellii, Heterocarpus spp.

15

583

22-42

Fish

16

446

280-400

Puerulus sewellii, Heterocarpus spp.

17

171

26-70

Fish

18

171

25-57

Fish

19

343

200-390

Puerulus sewellii, Heterocarpus spp.

20

621

240-320

Puerulus carinatus

Source: Johnsen (1984)

Productivities per Unit Area: The values from dividing the above areas into the catches for 1987 gives 0.12 tonnes/km for the deep water lobster grounds, and 0.98 tonnes/km for the inshore trawling grounds.

Resources Assessments:

1. Commercial trawling by the Somitfish owned F/V Cusmaan Geedi Raage was monitored during a 40-day cruise in March/April 1983 (Johnsen, 1984). It appeared that south of Eil (7°N) only Puerulus carinatus occurs, while north of Ras Hafun (10°N) only P. sewellii occurs. In the intermediate area both species were found.

Using the swept area method and assuming the trawl net was 100 percent efficient, the biomass of lobster on the 4,696 km2 of grounds exploited by the company was estimated as 639 tonnes for P. carinatus and 1,094 tonnes for P. sewellii (Johnsen, 1984). The associated estimates of biomass per unit area was determined as 0.37 tonnes/km2 for the two species combined.

The above-mentioned author did not estimate the potential yields. A very rough estimate is provided, however, by using the following equations from Garcia et al (1987);

MSY = B M2/ (2 M - (Y/B)) (based on Schaefer model)
MSY = MB exp ( (Y/MB)-1) (based on Fox model)

where MSY is the maximum sustainable yield, M is the natural mortality coefficient, B is the measured biomass and Y is the annual catch (at the time of the biomass determination). Here Y is given the value of 400 tonnes and M the value 0.7 (from Sanders, 1981). The resulting estimates for the potential yield (=MSY) from using the two equations for both species combined are respectively 726 tonnes and 621 tonnes. These are equivalent to 0.15 and 0.13 tonnes/km respectively.

2. Estimates of potential yield for the demersal trawl resources based on a review of the available survey reports are provided in UNEP (1987). Particular reference is made to the Spanish trawler F/V Isla de Lanzarote used in an extensive stratified random sampling survey of the east coast from February to May 1981, and the Norwegian R/V Dr. Fridtjof Nansen used in two limited duration surveys of the grounds between Ras Asir and Ras Mabber in March and August 1984.

During the Spanish survey 144 trawl stations were carried out on the east coast (and a few on the north coast). Only the quantities of species having commercial importance such as groupers (Serranidae, 16.2% of the catch), emperors (Lethrinidae, 35.5%), snappers (Lutjanidae, 12.8%), Spilotichthys pictus (23.7%) and Pseudupenaeus indicus (11.8%) were recorded. Assuming that the trawl net was 100 percent efficient, the all species density was estimated as 1.2 tonnes/km.

The Spanish survey also caught some deep water shrimp (Heterocarpus tricarinatus) along the eastern coast south of Mogadishu, and in some isolated spots in the Ras Hafun area, at depths ranging from about 180 to more than 300 m. Catches were generally low (averaging 6 kg/hr), but were high at a few stations (up to 259 kg/hr).

The surveys with the R/V Dr. Fridtjof Nansen involved 17 stations in March and 21 in August 1984. Species of high commercial value formed 50 percent or less of the total demersal catch, and were found in densities of 3.5 and 1.9 tonnes/km respectively. The lower value is explained as representing the situation during the time of extreme upwelling.

The following mean density values derived from other surveys are strictly not comparable as they were often the result of aimed fishing on the highest concentrations (UNEP, 1987).

R/V Thetus (1966)

North Coast

2.3 t/km2

East Coast

4.8 t/km2

Italian operations (1978-79)

East Coast

0.95-1.3 t/km2

They show however, that a density of between 1 and 2 tonnes/km2 is likely to be in the correct range. Applying these densities to the shelf areas (24,500 km2 and 3,200 km2 for the east and north coasts respectively) gave biomass estimates of 24,500 to 49,000 tonnes for the east coast and 3,200 to 6,400 for the north coast (UNEP, 1987). These estimates relate to commercially important species only.

The above report also contains the very preliminary estimates of potential yield shown in Table 3.5. These are based on the potential yield being either 20 percent of the biomass (conservative) or 25 percent of the biomass (radical).

Table 3.5. Estimates of potential yield.

Location

Potential Yields ('000 tonnes) with following Exploitation Regime

Radical

Conservative

East Coast

6-12 (-24)

5-10 (-20)

North Coast

0.8-1.6 (-3.2)

0.65-1.3 (-2.6)

Source: UNEP (1987)

Note: The values in brackets are the most optimistic, but less likely estimates

4. THE POTENTIAL INDUSTRIAL FISHERY FOR SMALL PELAGICS

Location: Off the northeast coast, principally between Ras Asir and Ras Hafun.

Boats: Two Romanian factory ships, F/V Glabucet (88.3 m) and F/V Bahlui (102 m) were operated on the above grounds between November 1983 and October 1984. The purpose was to investigate the feasibility of establishing a pelagic trawl fishery for small pelagics.

(Subsequently the Romanian Government submitted a proposal for a joint venture, which envisaged employing five Romanian factory ships. The venture was not approved and the resource has since remained largely unexploited).

Gear: The vessels were used with pelagic trawl nets having horizontal openings of 80 to 100 m, and vertical openings of about 35 m, when towed at a speed of about 5 knots.

Catches, Efforts and Catches per Unit Effort: The catch from the two vessels during the above-mentioned period was 6,112 tonnes from 641 trawl hauls or 997 trawling hours. The mean catch per unit effort was 42.4 tonnes/day (6.1 tonnes/trawling hour), with monthly variations between 11.1 and 56.9 tonnes/day (1.1 to 12 tonnes/trawling hour).

(The production from industrial fishing in 1985 included 240 tonnes of small pelagics from the Romanian trawler F/V Semenic.)

Species Composition: The catch composition was 48 percent of Sardinella longiceps, 21 percent of Scomber japonicus, 20 percent of Etrumeus teres, and 7 percent of Decapterus spp. Fifty percent of the catch was frozen, 45 percent was converted to fishmeal, and 21 tonnes of oil was produced.

During the last cruise it was determined that surface trawling at night-time was most productive, enabling almost clean catches of Sardinella longiceps. During the day-time the best catches were taken with the footrope 4 to 5 metres from the bottom, associated with a false footrope in contact with the bottom.

Area of Grounds: The fishing location was between Cape Guardafui and Cape Hafun (from 10°48' to 11°55'N) in depths of 20 to 200 m. The area of the grounds was reported as 750 sq.n.mile (2,570 km2).

Productivity per Unit Area: The value obtained from dividing the catch obtained in the period November 1983 to October 1984 by the above-mentioned area is 2.38 tonnes/km.

Resource Assessments:

1. Using the catch rates obtained during the prospection cruises with the Romanian vessels and estimates of the volume of sea swept by the gear, the volume occupied by the fish, and an assumed catching efficiency of 0.5326, the biomass of the stock was determined as 131,000 tonnes. The potential annual yield was assumed to be a third of the biomass, or 43,700 tonnes per year. It was presumably on the basis of these values that the Romanian Government sought approval for a joint venture to deploy a fleet of five factory trawlers.

Age determination on fish from monthly samples showed that the catch of Sardinella longiceps contained more than 85 percent of 3-year old fish. In the case of Scomber japonicus the catches were of 1 and 2 year old fish, while for the other two species 2 and 3 year old fish were predominant. Although length-frequency distributions are presented in the paper, they were not separated into different age groups. Only in the case of Sardinella longiceps, modal progression analysis was applied, and the von Bertalanffy growth parameter K was calculated to be about 0.5 per year.

(Information Source: Report from the Romanian Institute for Marine Research at Constanza, titled "The results of the Romanian research following the fishing prospecting cruises in the waters of the Somali Democratic Republic from November 1983 to October 1984").

2. The Norwegian R/V Dr. Fridtjof Nansen was used for acoustic surveys, along the entire coast five times between March 1975 and November 1976. It was found that the main concentrations of fish occurred off the northeast coast between Ras Asir and Ras Hafun, which is an area of great productivity due to the upwelling between Ras Mabber and Ras Hafun. In the latter area, however, no great densities of pelagic fish were encountered. The survey of the Ras Asir to Ras Hafun area was repeated in February/March and August 1984 (see Figure 4.1) and produced estimates of 245,000 and 115,000 tonnes respectively for the biomass of small pelagics. The drop in stock estimates between the two dates was attributed to an offshore migration of the fish to avoid oxygen-depleted upwelled waters closer inshore (Stromme, 1984).

The dominant species in the high density aggregations was Sardinella longiceps (Indian oil sardine). Other species caught were Decapterus russelli and D. macrosoma (scads), Dussumieria acuta (rainbow sardine), and Etrumeus teres (round herring).

Using the Beddington and Cooke (1983) relationship between MSY and the virgin biomass, an M = 0.8, a K = 0.5 and a recruitment age of 1 year, it was determined that the exploitation rate was 23 percent of the initial biomass. Applying this exploitation level to the above biomass values gave annual yield estimates of about 55,000 and 25,000 tonnes respectively; Stromme, (1984). It was suggested that in view of the environmental conditions prevailing in the area the higher estimate was the more probable, although as the species involved are relatively short-lived, large variations in stock size from one year to another can be expected.

In a more recent interpretation (UNEP, 1987) the same author assumes the potential yield to be 50 percent (radical) and 30 percent (conservative) of the biomass. When applying these values to the higher estimate of biomass (245,000 tonnes) the estimates of potential yield obtained are 120,000 tonnes (radical) and 75,000 tonnes (conservative).

5. BIBLIOGRAPHY

Anon., (1984). The results of the Rumanian research following the fishery prospecting cruises in the waters of the northeastern costs of the Somali Democratic Republic from November 1983 to October 1984. The Rumanian Institute for Marine Research, Constantza.

Beddington, J.R. and J.G. Cooke, (1983). The potential yield of fish stocks. FAO Fish. Tech. Pap., (242): 47p.

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