Methodology to Estimate Bycatch and Discards

Abstract

FAO Fisheries Technical Paper 339 (1994) provided the first estimation of global bycatch and discards, however, the estimated discards of 27 million tons have been abolished at FAO Consultation Meeting in Tokyo (1996). This was attributed to application of its discard ratios, total discard/landing of target species, to total landing with little respect to multi-species fisheries, which resulted in over-estimates of fishing effort and, consequently, discards. In order to determine the methodology for estimation of discards in multi-species fisheries in Asia, it is important to take into account; (1) it is difficult to segregate target and bycatch species, and (2) discards of species are not necessarily correlated to landing of single species positively. Therefore, the realistic approach is to define discard ratios as total discard/total landing and species discard ratios, if necessary, also against total landing in each fishing sector. Several methods to estimate bycatch and discards have been proposed recently with increasing concern to by-catch and discard issues, while information of by-catch in multi-species fisheries is scarce. Researches on characteristic discards in multi-species fisheries in the Region must be promoted for the regional fisheries to contribute in the international fisheries management.