BASIC ECOLOGY OF CORYPHAENA-HIPPURUS (PISCES, CORYPHAENIDAE) AND ABUNDANCE OF OTHER LARGE PELAGIC ORGANISMS IN THE PACIFIC OF COSTA-RICA

Catch records, reproductive biology, length population structure, and feeding were studied for Coryphaena hippurus (dorado) and other large pelagics. Historical data, sampling on landing sites and experimental fishing for six months were employed. Dorado represented more than 75% of capture in surface long lines. Other species of importance were Istiophorus platypterus (sail fish) and Carcharhinus falciformis (shark). Analysis of landing statistics, curves of CPUE vrs. effort and net monthly changes in catch, indicate that C. hippurus presents a strong ''pulse'' and is a resource that responds positively to fishing pressure. No significant statistical relations were found between CPUE and surface temperature or the initial, mid and final depth of the termocline. Experimental fishing yielded an adult and sexually mature stock. The monthly length structure and the gonadal analysis reflect a bimodal reproductive pattern, with a recruitment peak between September and October, resulting from spawning in January and February. Exocoetidae was the best represented family in numbers and weight of prey found.