USING A RANGE OF CAPTURE LIMITS TO DETERMINE TOTAL ALLOWABLE CATCHES.

Abstract

ln order to determine total allowable catch (TAC), the use of a range of catches defined between acceptables mínimum and máximum valúes is proposed. The upper limit of the range should be fixed using biológica! criteria, while social and economic criteria should be considered to fix the lower limit of catch. New valúes of TAC can be estimated using an acceptable level of risk
(chosen by managers), expressed as a probability that the upper limit will be exceeded, and a given level of uncertainty of the current estímate of TAC (e.g. expressed as its coefficient of variation). In addition, the level of risk that TAC will be lower than the inferior limit of catch can be calculated (risk for the fishery). In this way, when the uncertainty in the estimation of
TAC tends to be larger, the new TAC estimates, based on a given mínimum level of risk (e.g. 10%) that current TAC will exceed the upper limit, will tend to be lower and closer to the lower limit of the range yielding a larger level of risk for the fishery. The advantages of the use of a range of catch limits is promote better precisión and accuracy in the results of stock assessment methodologies in order to minimize the risk for the fishery (lower limit). In other words, to minimize the political, economic and social pressure to increase annual quotas.