This study reveals wide gaps in the available fishery biostatistical information and it is realized that without reliable additional data, management of the artisanal and coastal inshore fisheries will prove extremely difficult.
The estimation of total fish landings in the remote and extensive brackishwater areas (fringed by mangrove) fished by artisanal fishermen is one of the most difficult problems facing fishery biologists. The catch-reported figures are only statistical estimates and their validity is largely dependent on the adequacy of the sampling scheme and the means effectively available to the statistical unit of the Federal Department of Fisheries and the Fisheries Departments of coastal States.
The statistical system used by Nigeria has been reviewed by FAO Headquarters and the CECAF Project and modifications have been proposed in order to reduce the deficiencies observed. There are discrepancies between the ideal planned sampling scheme and the one effectively operated. In these circumstances, the estimated catch magnitudes might be biased. The fact that there are no regular periodical estimates of number of motorized canoes, non-motorized canoes, fishing gears and fishermen by fish landing sites raises a question on the reliability of the raising factors used in deriving total catch. The point is that, at present, it is very difficult to establish the confidence limits of the estimated annual catch of the artisanal fisheries.
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 2 500–3 000 t. Trawling and acoustic surveys are subject to great variability. Longhurst (1965) estimated the potential of trawl catches at 15 000 t whereas using the results of the FAO/USSR vessel FIOLENT, Robertson (1977) estimated at 28 600 t the demersal fish stocks for the surveyed area. In spite of variability of these estimates, the potential yield of the trawl finfish fishery is not likely to exceed 50 000 t. In these circumstances, the maximum potential yield for the artisanal and industrial marine fisheries is about or slightly less than 150 000 t.
The conclusions reached in this study lead to the following management guidelines:
Compilation of basic data on all fishing units is recommended. Consideration should be given to compilation of information on fishing villages, gears, number of canoes (motorized and non-motorized), number of fishermen (part-time and full-time) in the creeks and along the coast for all the coastal States. This exercise should be repeated periodically and, if possible, the accuracy checked by aerial surveys.
Analysis of the profitability of the present-day canoe fishery is recommended. Such an analysis on a sample of canoes for a sample of fish landing sites in all coastal States could provide a quick and reasonable measure of the economic state of the artisanal sector.
Collection of data on catch rates of the small-scale fishermen by type of fishery in all coastal States by sampling the catch of the artisanal fisheries is recommended, as is collection, compilation and standardization of catch per unit effort data of various fishing units in the creeks, estuaries and coastal waters for use in resource evaluation.
Refinement and continuation of systematic sampling for nominal catch data from randomly selected fishing villages in all coastal states is recommended, with stricter coverage checks in major production centres. The reasons for continuing fisheries surveys is to obtain information on the distribution of appropriate species and indices of their abundance. An attempt should be made to avoid as much as possible the use of broad common names which could refer to more than one species. The recording of weight, value of catch and number of fishing gears as well as gear characteristics should be improved and maintained.
Mapping of the main rich fishing grounds along the coast is recommended. Such information can also be obtained from progressive artisanal fishermen and from industrial vessels operating in coastal waters. Additionally, the logbooks of all fish and shrimp trawlers should provide information on location of rich fishing grounds.
Precise documentation on migration patterns of commercially important species harvested by both the artisanal fishermen and offshore industrial fleets is needed. This would require a more long-lasting programme, which should be initiated as soon as possible.
Collection of information on selectivity for size by species in various gears deployed in the creeks and coastal inshore waters is recommended. Length measurements of the sampled catch of the artisanal fishermen in all coastal States should be taken.
The fishery administrators should take the necessary regulatory measures to lessen conflicts between artisanal fishermen and the industrial fleets exploiting the shallow inshore areas of the Nigerian shelf and also to reduce the fishing pressure there in order to save the fish stocks from collapsing.
