Assessment and management techniques for migratory annual squid stocks: The Illex argentinus fishery in the Southwest Atlantic as an example

Assessment methodology for squid fisheries is presented, extending previous work by considering migration between adjacent fishing grounds. The methods are based on standard Leslie-De-lury analysis but make different assumptions about stock movement and the relation between stock abundance and catch per unit effort. The new methodology is applied to data from the Illex argentinus fishery in the Southwest Atlantic, south of 45 degrees S. Retrospective assessments for the 1987-1991 fishing seasons are presented, focusing on estimates of recruitment and spawning biomass. Management of the fishery around the Falkland Islands is based on effort control. The objective is to maintain the spawning biomass above a threshold level, thus avoiding high probabilities of low recruitment in the following season. The estimates of spawning biomass and recruitment from the analyses are used to estimate an appropriate threshold level of spawning biomass.