The fishery for, and general biology of, the St Joseph Callorhinchus capensis (Dumeril) off the South-Western Cape, South Africa

Abstract

St Joseph Callorhinchus capensis are caught by a directed gillnet fishery off the coast of South Africa's Western Cape and also incidentally by trawl in shallow water on both South and West coasts. The fishery only became established in the early 1980s and landings have subsequently stabilized at approximately 800 tons per year, almost one-third of which is a by-catch of trawling operations. The gillnet fishery is centred in St Helena Bay and takes very little by-catch. Both trawl and gillnet operations take place in nursery areas of C. capensi and some species of true shark. C. capensi occurs widely off the southern African coast, from 1 to 366 m deep, but large numbers are only caught inshore (<50 m), the only area where immature fish are found. The fork length at 50% sexual maturity is 435 mm in males (3,3 years) and 496 mm in females (4,2 years). Mature fish have an annual onshore/offshore migration, most mature fish aggregating inshore in summer to breed and lay eggs. They then disperse to deep water where unlaid eggs are resorbed and energy reserves accumulated. The largest number of viable eggs recorded was 22. C. capensi primarily live over soft substrata and their diet consists principally of 1 invertebrates associated with such substrata. The relatively fast growth, early sexual maturity and reasonably high fecundity of the species make it a safer fisheries target than most other chondrichthyans.