In view of the possible existence of interaction between S. aurita and B. capriscus the working group examined existing knowledge on the latter species, and more especially new information obtained since the review made at the last special working group meeting on the evaluation of demersal stocks in the Ivory Coast-Zaire Sector (FAO, 1979a).
With regard to biology, it is confirmed that the main spawning period occurs in the minor hot season (November-December). A large amount of information is provided on sexual maturation, feeding and growth of this species (Appendix 4). B. capriscus feeds on benthos and pelagic organisms though the latter, which contains Clupeidae eggs and larvae, may only be supplementary. It has been possible to make an initial estimation of the growth of B. capriscus: individuals of 14 cm being a little more than one year and those of 21 cm being slightly more than two years old.
Many predators on the species have recently been identified: seriola, tuna, groupers and sharks feed readily on B. capriscus (especially the juveniles).
It appears that recently B. capriscus is decreasing in abundance in the region, judging from catches and cpue data obtained in Ghana (Ansa-Emmim, 1979) and in Togo and also from surveys by the trawler CHALCI off Ivory Coast in 1978 and 1979 (unpublished).
During the cold season B. capriscus is low in the catches of coastal trawlers and seiners. The working party has put forward a hypothesis to explain this phenomenon. It is possible that fish caught by trawlers and purse seiners in the hot season at depths of less than 30 to 80 m move from the cold coastal waters as a result of upwelling during the third quarter of the year and join the pelagic offshore stock present throughout the year (Figure 7). This latter portion of the stock has been identified in Guinea (FAO, 1979b). In Ivory Coast it would correspond to the non-identified pelagic concentration detected offshore (at a depth of 100 to 200 m) in February 1979 at the 20-40 m layer.
The working group noted the progress achieved in the knowledge on B. capriscus and adopted the recommendations of the special working party for evaluation of demersal stocks in the Ivory Coast-Zaire sector (FAO, 1979a). The working group particularly stressed the need for research on B. capriscus during the cold season by echo-integration and trawling and on the study of their feeding habits. The working group also recommends that a study on the discards of B. capriscus be undertaken.
