2. FISH RESOURCES

2.1 Characteristics of the Fishing Areas and Fish Resources
2.2 Stock Assessment
2.3 Aquaculture and Inland Fisheries

2.1 Characteristics of the Fishing Areas and Fish Resources

In general the continental shelf off West Africa is less than 20 to 30 nautical miles wide, except in the area between latitudes 24° to 20° North, and the area between Dakar (16° North) and Freetown (8° North) where the shelf is up to about 100 miles wide.

The two major currents in the Region are the cool currents flowing southward down northwest Africa (the Canary Current) and northward up from southwest Africa (the Benguela Current), and both currents gradually flow westwards at about 10° North and 10° South of the Equator. Between these two currents are the Equatorial Countercurrent and its continuation, the Guinea Current, which flow eastwards into the Gulf of Guinea. It is between the cool Canary and Benguela currents that sea temperatures of 27° Centigrade are consistently found. There are seasonal upwellings - and this is essential for resources distribution - in some parts of the Canary current system (roughly from 20° to 10°N), off Ivory Coast, Ghana, Togo, Benin, and off Southern Gabon, Congo and Zaïre.

Morocco has the most extensive coastline of all coastal countries with a length of 1,750 kilometres. Other countries have coastlines generally exceeding 300 kilometres in length. The countries which have smallest coastlines are Zaïre (41 kilometres), Togo (48 kilometres), Gambia (70 kilometres), Benin (120 kilometres) and Congo (156 kilometres). Ports are not frequent along the West African coast, but at least one good port offering adequate unloading and some maintenance facilities is located in most coastal countries.

The most frequently caught fish in the Region are the predominantly pelagic sardinella and horse mackerel (Trachurus) species. Sardinella aurita (round sardinella) is found in the cooler upwelling areas and at depths of 70 to 90 metres when surface waters become warm. Sardinella eba (flat sardine or herring) is found in areas of low salinity, often near river mouths, is rarely found at depth below 40 metres, and does not migrate as much as S. aurita. Horse mackerel (Trachurus trachurus) is found mainly from 25° to 19° North and T. trecae is found a little further South in the latitudes of 22° to 14° North. Both species form dense concentrations which can be caught by high opening bottom trawls in waters down to 200 metres deep. The chub or Spanish mackerel (Scomber japonicus) is found predominantly between 28° to 15° North and undertakes limited migrations in association with horse mackerel. The two species often intermix with little tuna (Euthynnus species), bluefish (Pomatomus species), and scads (Caranx ronchus). The Morocco sardine (Sardina pilchardus) is found off the southern coast of Morocco. The bonga (Ethmalosa fimbriata) occurs in shallow waters and lagoons from Senegal to Sierra Leone, and from Nigeria to the Congo River. The cephalopods (squid, cuttlefish and octopus) are abundant off southern Morocco and northern Mauritania (ex-Spanish Sahara). Another important pelagic stock in the Region is made up of the anchovy (Anchoa guineensis) which is found principally in the Gulf of Guinea.

The demersal fish fauna varies according to sea bed and temperature. In the central tropical area, where warm waters are consistently found, and in waters of less than 50 metres, there is a "croaker" fauna and a "snapper" fauna. The "croaker" fauna predominantly occurs over the soft sea bed and consists of croakers (Scianidae), grunters (Pomadasydae), spadefish (Drepanidae), threadfins (Polynemidae), and soles (Cynoglossidae).

The "snapper" fauna found over the hard sea bed principally consists of sea breams (Sparidae), snappers (Lutjanidae), groupers (Serranidae) and gurnards (Triglidae). Whereas the "croaker" fauna is normally found above the thermocline, the "snapper" fauna can be found both above and below the thermocline. In low salinity waters, particularly near lagoons and river mouths, the demersal fauna consists of large croakers (Pseudotolithus species) and catfish (Arius species).

Important localised stocks of shrimp (Penaeus duorarum) are found mainly in the vicinity of large river mouths or lagoon entrances to the sea, e.g. off the Senegal River, Gambia River, Southern Senegal and Guinea Bissau, Sierra Leone and Nigeria. Penaeus atlantica is a smaller species found in the shallow locations along the coast, and Parapenaeopsis longirostris is found off the Congo and Gabon. Parapenaeopsis atlantica is found in the deeper part of the shelf and on the slope from the Mediterranean to the Southeast Atlantic.

Tuna are common throughout the Region, and the most frequently caught species are skipjack, albacore, yellowfin and bigeye.

Table 2.1 Selected data on fishing areas

Country	Coastline (excluding islands) kilometres	Continental width nautical miles	Shelf area thousand square kilometres
Morocco	1,750	6 - 50	60.0
Madeira Islands	·	·	2.0
Canary Islands	·	·	3.0
Ex-Spanish Sahara	1,100	13 - 50	55.1
Mauritania	667	13 - 79	33.9
Senegal	718	8 - 50	23.8
Gambia	70	41 - 50	3.7
Cape Verde	·	·	3.0
Guinea Bissau	300	40 - 105	45.0
Guinea	350	70 - 110	50.2
Sierra Leone	570	15 - 80	30.0
Liberia	537	10 - 35	18.4
Ivory Coast	500	11 - 20	12.2
Ghana	528	13 - 50	27.3
Togo	48	8 - 15	1.2
Benin	120	14 - 15	3.1
Nigeria	669	18 - 35	37.9
Cameroon	346	17 - 50	12.9
Equatorial Guinea	380	12 - 30	10.5
Gabon	739	8 - 40	35.4
Sao Tome and Principe	·	·	2.0
Congo	156	27 - 35	8.6
Zaire	41	27 - 54	1.1
Total	9,964	·	492.4

Source:

FAO Fishery Country Profiles
CECAF Project estimates

2.2 Stock Assessment

Inevitably there is a shortage of necessary data on most of the regional fish stocks which makes even simple stock assessment hazardous, yet in spite of the present uncertain level of our knowledge, some important trends are emerging which will have an impact on resource management and planning and development of fisheries in the Region. There is no discussion of tuna stocks since the terms of reference of CECAF and the CECAF Project are not concerned with such stocks.

Present knowledge of the Region's fish stocks emanates from a number of internationally financed surveys initiated in the 1960's and continuing into the 1970's. Basic information on the demersal resources was collected during the Guinean Trawling Survey, carried out under the aegis of the Scientific, Technical, and Research Commission of the Organization of African Unity. Information on the pelagic resources was collected during the UNDP/FAO Ghana fishery project started in 1963, and in the late 1960's and early 1970's during the UNDP/FAO coastal pelagic resources projects in Senegal, Sierra Leone, Ivory Coast and the Congo, as well as the UNDP/FAO regional fisheries survey which was based in Abidjan. A more recent project which has continued the work of the earlier surveys has been the UNDP/FAO Morocco project. Nevertheless, as a whole, the research carried out by national institutions - of countries both inside and outside the Region - has largely exceeded, according to any standard, that executed by international organizations but it is difficult to achieve a balanced review of the various contributions. In addition to the information gained during the course of the continuing national research and these internationally financed projects, the CECAF Working Party on Resources Evaluation has played a notable role in publishing the latest information on stocks. (The publications appear as FAO Fishery Reports).

Both Sardinella aurita and S. eba are caught by inshore purse seiners and such operations are not believed to have had a significant impact on the different stocks. However off ex-Spanish Sahara, Mauritania and Senegal the intensive operations of foreign-based vessels have undoubtedly had some impact on sardinella stocks, although the extent of this impact is not yet quantifiable due to lack of data. The sardinella stock off Ivory Coast/Ghana/Togo has recently suffered substantial reduction in abundance, and one of the reasons for this reduction may be the intensive high seas fishing of the adult stock seasonally resting offshore in 1972/73.

In spite of intensive exploitation, the horse mackerel stocks do not seem to have yielded lower catches, but increased fishing efficiency may have masked decreasing abundance. Nevertheless considerable caution needs to be expressed in reaching quick and definitive conclusions since, as in the case of the large sardinella fishery, important information on fishing effort and catch rates by area has not been made public by nations catching most of the species, and thus adequate stock assessment is presently impossible.

In contrast to the sardinella and horse mackerel fishery, where so much basic data is unavailable, the state of the Moroccan sardine fishery is relatively well documented. This state of affairs is due principally to the fact that the fish are caught mainly by Moroccan vessels and, in addition, the Moroccan fish stock monitoring service has, over many years, collected key data on the total catch and catch rates of these vessels. Recently the East European nations, including Poland and Bulgaria, have been increasing their catch of the sardine but their fishing operations have been reasonably well documented. In spite of the increased fishing intensity on the sardine stock, it is believed-that the fishery, particularly off central Morocco (Safi-Ifni), is not overexploited although they do not advise that fishing effort exceed the present level. From UNDP/FAO project findings it appears that an increase in fishing effort in Southern Morocco (Agadir to the ex-Spanish Sahara border) is to be encouraged.

The hake stocks are exploited by a number of nations fishing off Morocco, Mauritania and Senegal. The Portuguese have collected the most comprehensive series of data on the species and their records show that catch rates are slowly declining. On the basis of these and other data, it has been recommended that no further increase in fishing intensity on these stocks be permitted.

The sea breams present from Morocco to Zaïre have been intensively fished for some time because of their high market value. In order to protect the sea bream stocks, CECAF agreed on a cod end mesh size limit of 60 millimetres in 1972. Although this regulation has not worked as effectively as intended, data do show that the recent disastrous fall in catch rates has been checked so that the regulation may be having some positive influence for optimal management of this species group. Nevertheless increased fishing effort can definitely not be recommended.

Catch rates of cephalopods have also been declining in the traditionally exploited area off Mauritania. The Third CECAF Working Party on Resources Evaluation (9-13 February 1976) recommended that fishing effort on the stock be reduced to the 1972 level so that catch rates could increase to former levels.

Statistics on the state of the shrimp stocks are poor although catch rates of shrimping operations off St. Louis, South Senegal and Guinea Bissau and other areas such as off Ivory Coast have fallen so much that regulations to control fishing effort are widely believed to be urgently required. It is possible that shrimping grounds off Sierra Leone, Liberia, and Nigeria could withstand a slight increase in fishing intensity.

Off Morocco the trumpet fish (Macrorhamphus species) could withstand increased exploitation. This fish is pelagic and shoaling and, although small and not easily sold for human consumption, could provide additional supplies to the numerous Moroccan fishmeal factories. The UNDP/FAO Morocco project findings indicate that the standing stock of trumpet fish is equal to or greater in size than the sardine stock. Off Mauritania there are certain extensive densities of Capros aper which could also form the basis for a fish-meal industry. This species could be one of many localised fish stocks around the coasts that might withstand higher exploitation rates.

Throughout much of the coastline there are small localised stocks of bonga (Ethmalosa fimbriata). Although there are indications that bonga stocks may not be fully exploited, their limited distribution (brackish waters, of relatively limited area) suggests that stocks are possibly not very large. The grunt (Brachydeuterus sp.) catches can probably be increased along almost the whole coastline south of Senegal. Off the Ivory Coast and Ghana, the anchovy (Anchoa guineensis) and mackerel (Scomber japonicus) can be more intensively exploited.

Satisfactory stock assessment in the Region will always be hazardous as long as catch and effort data for the various fishing divisions are not collected systematically. Indeed, until the most important fishing nation in the Region, the Soviet Union, supplies these data, such stock assessment will be impossible.

This inability to collect good data in previous years was due in part to the lack of insufficient jurisdiction of marine fishing waters. However now that fishing limits have been substantially extended, and the important fishing waters off ex-Spanish Sahara are now controlled by Morocco and Mauritania, it is possible that data collection will improve. Certainly all coastal countries that have agreements with foreign nations fishing in their waters will be able to exert pressure through legal agreements on fishing operators to provide more information and permit inspection of catch and effort data.

2.3 Aquaculture and Inland Fisheries

The CECAF Project is not required by its terms of reference to become involved in inland freshwater fisheries, although it is involved in brackish water fisheries. Nevertheless the production from inland waters is very substantial and obviously has an important impact on the distribution, marketing, trade and consumption of fish throughout West Africa, and for this reason the estimated data for freshwater production in the CECAF Region are presented in Table 2.2.

Table 2.2 Estimates of production of inland fish (1973)

thousand tons
Country	Catch
Morocco	· · ·
Mauritania	10.0
Senegal	20.0
Gambia	0.8
Guinea Bissau	· · ·
Cape Verde	· · ·
Guinea	· · ·
Sierra Leone	· · ·
Liberia	4.0
Ivory Coast	11.0
Ghana (Volta Lake)	35.8
Togo	3.0
Benin	19.1
Nigeria	49.6
Cameroon	18.0
Equatorial Guinea	· · ·
Gabon	0.4
Sao Tome and Principe	· · ·
Congo	6.0
Zaire	110.1
Total	287.8

Source:

Welcomme (1975)
CECAF Project estimates

The extensive lagoons along the West African coast are often of a delicate biological nature and, when disturbed, can often be disadvantageously upset. For example the construction of a port in Cotonou caused changes in marine currents to be such that a seasonal outflow from the nearby lagoon became permanent, with the result that the lagoon's salinity changed and fish catches dropped. These coastal lagoons provide very valuable fish resources which can be extracted with little difficulty by nearby residents and where small canoes which need not withstand wave action can be cheaply built. The lagoons are very often intensively fished by traps as well as by nets of various types. Because of the ease of access and the high surrounding population, the lagoons pose especial fish resource management problems.

Brackish water and/or marine aquaculture is not as yet practised on any significant scale in West Africa. All experimental programmes are in their infancy and are mainly aimed at perfecting techniques. In Morocco, the Government of South Korea has agreed to assist the Office National des Pêches with initiating an experimental marine aquaculture programme. The Government of Senegal intends to encourage the aquaculture of oyster and grey mullet, but as yet has not formulated any action plan. Sierra Leone has an agreement with the International Development Research Centre of Canada for a joint programme of oyster culture. The programme is still at an early stage but so far has been proceeding successfully.

The Fishery Research Unit of the Department of Fisheries, Ghana, is undertaking a project in the Keta Lagoon to determine the most suitable material on which oyster spat may collect, with a view to establishing an experimental oyster farm. The Unit is also attempting to introduce lagoon shrimping techniques that have proved successful for catching the shrimp in the lagoons and estuaries of Senegal and Gambia. The Nigerian Federal Department of Fisheries administers a brackish water fish culture station at Buguma in the Niger Delta and, at that station, some important work has been undertaken and published on clams, mullet, oysters, shrimp and brackish water and marine finfish. The FAO Aquatic Resources Improvement and Environment Service has proposed two models of fish farm management procedures for demonstrating intensive production for the brackish water fish farm, and a project proposal for UNDP funding has been drawn up for 'Investment feasibility studies on the reclamation of swamplands for fish farm development in the Niger Delta'. The Centre de Recherches Océanographiques at Pointe Noire, Congo, has had encouraging results from preliminary trials with mussel and oyster culture.