MARINE FISHERY RESOURCES OF NIGERIA: A REVIEW OF EXPLOITED FISH STOCKS TABLE OF CONTENTS

by

G.W.Ssentongo
FAO Fisheries Department Rome
(Consultant to NIR/77/001)

E.T.Ukpe
Federal Department of Fisheries
Lagos

and

T.O.Ajayi
Nigerian Institute of Oceanography
and Marine Research
Lagos

This document has been prepared with financial support from projects INT/81/014 – Development of Fisheries in the Eastern Central Atlantic, NIR/77/001 – Artisanal and Inshore Fisheries Development in Nigeria, and GCP/RAF/215/USA - Support to the CECAF Project

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CONTENTS

LIST OF TABLES

LIST OF FIGURES

PREFACE

In recent years there have been several attempts to review the fishery statistical system and the state of the fishery resources of Nigeria. Nobody has found the exercise easy, for there are discrepancies between the ideal planned statistical sampling scheme and the one effectively operated. And, as details on the current system are not available, it is difficult to determine the accuracy or precision of the reported catch figures and to debias them accordingly. In these circumstances, there still exist discrepancies between reported combined catches of the artisanal and industrial sectors and estimated yield potential of the Nigerian continental shelf.

Some workers have tried to use some results of limited studies, partial sampling and isolated productivity values as rules of thumb, hoping that the inshore fisheries are more or less homogeneous and constant, and also that such results obligingly apply to the entire coastline. The trouble is, however, that the Nigerian marine fisheries are characterized by temporal and spatial variations, and anyone studying them will soon realize the need for more basic data from the various sectors of the fishery.

The complexity of the aquatic ecosystem poses a great challenge to natural science. In the first instance, a comprehensive survey of fishing units and exploited multiple species stocks presents a formidable obstacle. It is therefore understandable that fishery biologists investigating the dynamics of coastal ecosystems have to abstract general principles from the interrelationships of the many species. More recent data on activities of artisanal and industrial fleets reveal rather complicated interactions.

There is not yet enough information to use in formulating rules for managing the industrial and artisanal coastal fisheries. There is, however, enough knowledge to be able to warn against uncontrolled increase in exploitation of available fishery resources without a sound evaluation of consequences. It is true that, in the past, management began purely empirically by trial and error. But it is common knowledge that small-scale large-scale errors can be biologically, financially and socially disastrous. It is hoped that the results and questions presented in this paper will stimulate enough interest in the maintenance of a reliable fishery statistical system on which can be based long-term fishery policies with a sound scientific basis. It is also hoped that the declining catches and catch rates will create increased awareness at high political levels of the importance of rational management of the fisheries in the Nigerian EEZ.

Much of the information presented in this report was collected with the collaboration of the two co-authors, Messrs E.T. Ukpe and T.O. Ajayi, but the presentation of the material, analysis and conclusions drawn are the sole responsibility of the main co-author Mr. G.W. Ssentongo, the FAO Consultant to FAO/UNDP Project NIR/77/001.

SUMMARY

This study reveals the lack of some valuable fishery data without which management of the artisanal and inshore fisheries will prove extremely difficult. But Nigeria has been making efforts to improve biological and catch data of this sector of the fishery. However, the figures obtained are only statistical estimates whose validity is largely dependent on the adequacy of the statistical sampling scheme and the means (technical and financial) effectively available to the Statistics Unit of the Federal Department of Fisheries and the Fisheries Departments of coastal States.

The Nigerian coastline is characterized by a mixture of Pleistocene/Holocene sands and recent muddy silts. The silt muds are deeper off the Kulama River at the axis of the Niger River Delta. East of the Kulama River up to the Cross River estuary, the prevailing pattern is one of alternating sands and mud deposits. West of the Mahin coastal flats (Ondo State) sand deposits are dominant.

The most significant biological features of the hydrographic regime in the Nigerian waters are: the relatively stable thermocline, the steep temperature gradient and the stable oceanographic conditions below the mixed layer throughout the year. There is a definite wind system of the equatorial zone. The season and zone of the northeast trade winds, which is generally dry and less cloudy, is ideal for fishing, whereas the season and zone of the southeast trade winds, which is generally rainy, cloudy and marked with rough sea conditions, is not ideal for offshore canoe fishing.

The present rate of canoe motorization (about 10%) is rational and modest. Overcapitalization of the canoe fishery might give rise to socioeconomic conflicts. The present catch rate of 509 t/trawler/year is proportionate to the estimated yield potential of the trawl fishery. Therefore, any increase in fishing effort of the trawl fishery should be directed in the deeper waters toward the slope to lessen social conflicts with artisanal fishermen and also to reduce fishing pressure in the inshore areas which serve as spawning and nursery grounds for many species.

An examination of catch series and comparative figures of productivity from neighbouring and highly productive coastal systems lead to a maximum potential yield of about 100 000 t for the artisanal fishery sector. The potential yield of shrimp mainly Penaeus notialis is about of 2 500-3 000 t.

Results of various acoustic and trawling surveys led to a potential yield of 15 000-28 600 t for the trawl fishery. In spite of the variability of the estimates, indices of biological productivity of the offshore deeper waters do not appear to indicate a potential yield greater than 50 000 t for the trawl fishery. In these circumstances, the maximum potential yield for the artisanal and industrial marine fisheries is about or slightly less than 150 000 t.

Without a reliable and functioning fishery statistical data system, it would be very risky to formulate viable long-term development schemes and meaningful management strategies for the artisanal sector. There are obvious possible dangers of overinvestment, economic failures and a final decrease in total catch through overfishing. The results of biological productivity studies and catch rates made in the sixties might be questionable and the comparative productivity values used in this report might still not be universally acceptable. Besides, the reported catch magnitudes are also questionable. If all these different indices of yield potential are questionable, then, the contingent and envisaged or projected increase in catch, through various fishery development activities, is also questionable. It should be better to be more apprehensive of projected increases in fish production until the mechanism for biological data and catch sampling are refined. Similarly, it would be very risky to continue acquiring new fish trawlers and shrimpers irrespective of fishing performance of current industrial fleets.

ACKNOWLEDGEMENTS

The authors express their thanks to Alhaji D.D. Apanpa, the Director of Fisheries, Federal Department of Fisheries (FDF), for assisting this study in various ways.

They are very grateful to Mr J.G. Tobor, Director, Nigerian Institute of Oceanography and Marine Research (NIOMR), for providing useful suggestions and for allowing some of his officers to collaborate in this study.

Special thanks go to the following:

Professor B.N. Akpati, Assistant Director (NIOMR, Lagos), with whom we had useful discussion on this work;

Mr. D.A.S. Gnanadoss, Project Manager (FAO/UNDP Project NIR/77/001), who offered useful advice on fishery development activities;

Mr Aderounmu, Assistant Director of Fisheries (FDF), for coordinating well our visits in various coastal States;

Mr. A. Adesioye and Mr Y.O. Oyedeji (FDF) for making available fishery catch statistics;

Messrs M.A. Onabanjo, Chief Fisheries Officer (FDF); Adesanya, Chief Fisheries Officer (Ogun State); T. Agbalajobi, Chief Fisheries Officer (Lagos State); T. Ojo, Chief Fisheries Officer (Ondo State); L.O. Abuah, Chief Fisheries Officer (Bendel State); E.O. Opulah, Chief Fisheries Officer (Rivers State); E.O.E. Odiong, Chief Fisheries Officer (Cross River State); M.A. Afinowi, NIOMR/ARAC (Port Harcourt); P.A. Taggert (FDF); B.S. Moses, Deputy Chief Fisheries Officer (Cross River State); N.E. Nnoli, Project Manager, Ebughu Fishery Terminal; S. Amire, Project Manager, Igbokoda Fishery Terminal; O.A. Sologbade, General Manager Marketing, Almarine (Port Harcourt); Oworitso Sagay (FDF, Port Harcourt); Fidelis O. Otobo, Niger Delta Basin Development Authority; E.E. Obasohan, Fisheries Officer (Bendel State); C. Ike (FDF, Benin City); Ozo Moemeka, Fisheries Officer (Bendel State); and E.E. Eseka (FDF, Warri); Mr Akiwande, Fisheries Officer (FDF, Lagos); Mr Ismail, Fisheries Officer (FDF, Lagos); E.E. Udong, Fisheries Officer (Artisanal Fisheries, FDF, Lagos); N.U. Nsentip, Deputy Chief Fisheries Officer (Cross River State); and T.O. Esan Fisheries Officer (FDF, Lagos) with whom we had informative discussion concerning activities of various marine fisheries.

Finally, we express our thanks to the following Fishing Village “chief” for giving us useful information on historical fishing trends:

1. “Chief” Kotopa, Yovoyan Fishing Village, Badagry, Lagos State;

2. “Chief” I.J. Ijente, Okoroete Fishing Village, Cross River State;

3. “Chief” Asuguo Bassey, Mbe Ndoro Fishing Village, Cross Rivers State;

4. “Chief” A.E.S. Jaja, Opobo Fishing Community, Rivers State;

5. “Chief” D.F. Bobo, Brass, Rivers state;

6. “Chief” Ologhoba Olaghdudu, Oghoye Fishing Village, Bendel State;

7. “Chief” Ariyo Titiola, Oghoye Fishing Village,Bendel State;

8. “Oba” Alajia, Orioke - Iwamimo Fishing Village Ondo State;

9. “Chief” Felix Akingboye, Aiyetoro, Ondo State.