THE BY-CATCH OF SHRIMP TRAWL FISHERIES

Wherever shrimp trawling occurs concern is expressed about the wastage and potential impacts of catching and discarding large quantities of incidentally caught organisms (by-catch). Here we draw together the literature on shrimp by-catch and provide an assessment of the state of research. Variability in quantity and composition of by-catch through time and space is large and methods for quantifying shrimp by-catch are mostly imprecise. Consequently, estimates of regional, country and world by-catch are poor. Although a proportion of by-catch is utilised, the majority is discarded at sea. The main obstruction to greater utilisation of by-catch is economic; in most cases target shrimp species are more valuable than the often much greater quantities of small fin-fish caught. Avoidance of by-catch through selective trawl designs is considered a high priority in many fisheries, particularly where the incidental capture of turtles is controversial. Few studies have attempted to analyse the consequences of the shrimp trawl fisheries on populations of species caught as by-catch, especially those species exploited by other fisheries. The incidental catch of the world's shrimp fisheries is enormous and the potential conflicts that this by-catch generates will become an increasingly important issue for fisheries managers. Gaps in our current knowledge of by-catch are highlighted and possible directions for future research are discussed.