It is clear that better knowledge of the resources in the area is required as a guide to fisheries development and management in the area. The need for this knowledge may well be urgent in view of the recent trends towards increased fishing in the area.
The meeting noted that a considerable amount of data exists which have so far not been published, in particular on the Congolese fisheries, but perhaps also on the Angolan fisheries, and urges that this information be analysed and made available as soon as possible.
There is a basic need for good data on catch and fishing effort, for each of the two species. So far, data are lacking on the fishing effort in Angola since 1972, and the available data of the earlier years refer only to the total number of boats in the fleet and their tonnage and not to the activity of each boat in each year. Information on boat activity, eventually on a sampling basis, would be extremely valuable. There is, furthermore, need for information on the catches by species, and on the length composition of the catches by species. Sampling for this purpose could be combined with sampling for boat activity in one programme.
In order to better study the movement of the resources, it would be valuable to have statistics of the monthly catch and effort for each of the main fishing ports separately.
With respect to the biology of the species, the only information on growth of S. maderensis dates from 1968. It would be valuable if another investigation on the growth of this species would be undertaken from the data available in Pointe Noire. Regular determination of age composition of the landings of both species would also be desirable, but may be difficult to obtain with the available facilities in the countries concerned.
Some specific studies covering all the historical data of the fishery which might be undertaken by interested scientists having access to the substantial amount of data on the Congolese oceanography and fishery available in Pointe Noire are the following:
(a) a study on the relation between the ecological conditions in Congolese waters and the catch rates of both species of sardinellaIn view of the various difficulties in obtaining the required basic information needed for reliable stock assessment within a reasonable time and the probable need of quick information on the resource potential, the meeting strongly recommends that the possibility of undertaking a quantitative acoustic survey with fishing for species identification in the whole Congo-Angola area of distribution of the sardinella species in order to determine the biomass of each of the two species is seriously investigated, and that such a survey should be undertaken as soon as it appears to be possible. The results of such a survey should be compared with the results of similar surveys done in the West African area, and with the other knowledge on the sardinella resources in that area.(b) a study of the total egg production in Congolese waters (estimated from a density and size composition of the stock of mature fish, and information on fertility and gonadosomatic index), and the possible relation with recruitment, if possible for each of the two species
(c) a study of the available length compositions and age data to determine yearclass strength in successive years, for the interpretation of the fluctuations in catch rates
(d) a study of the comparative fishing power of the purse seiners in Congo, their fishing areas, the fleet behaviour in relation to the size of the fleet, the occurrence of boat saturation, and similar problems, in order to obtain a less biased estimate of fishing effort and the catch per unit of effort
(e) a complete analysis of the results of the tagging experiments carried out in 1970-1972
(f) a detailed comparison of the Congo-Angola area with the West African area, with respect to size of the area of distribution of the fish, the primary productivity of the areas and other relevant oceanographic characteristics, the species composition and density and distribution of the fish species, etc., as a basis for a first estimate of the potential productivity of the Congo-Angola sardinella stocks in comparison with that in West Africa.
Finally, when the need for management of the sardinella resources in the Congo-Angola area arises, it is likely that it will be desirable that the two species are managed separately. The Ad hoc working group therefore suggests that in the not-too-distant future a special study is undertaken on the various aspects, difficulties and possibilities of separate management of the two species, and on the possible ways and consequences of management of the two species together.
