Fisheries management and research for Loligo gahi in the Falkland Islands

Abstract

Two squid species have been the subject of targeted fisheries in the southwest Atlantic since the early 1980s.The two fisheries have been managed in Falkland Islands waters since 1987 and provide an annual license revenue to the Falkland Islands government equivalent to some $35 (U.S.) million.The real-time assessment of the two species, Loligo gahi and Illex avgcntinus, is based on the Leslie-DeLury assessment model.The model assumes a single recruitment event before the start of the period used in fitting the model, and a closed population during the period.Early research on the demography and distribution of the Falkland Islands L. gahi population demonstrated ontogenetic descent with a probable associated coastward spawning migration.The L. gahi fishery concentrates by area and does not follow the migration pattern, indicating that the closed population assumption of the assessment model is invalid for much of the period assessed.Research has confirmed the variable nature of recruitment of microcohorts to the fishery, overstretching the single-recruitment as- sumption of the Leslie-DeLury model.But research has also shown that there are periods of residency of L. gahi on the fishing grounds.The current assessment procedure uses these periods of residency to derive estimates of population depletion and therefore stock size.In this paper the salient features of the fishery for L. gahi are presented, and the crucial links between resource assessment, biological research, and management advice are discussed.Finally, directions for further research, needed to refine assessments and achieve some predictability of population processes, are identified.