Fisheries management and research for Loligo gahi in the Falkland Islands

Two squid species have been the subject of targeted fisheries in the southw est 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 argentinus, 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 demograp hy and distribution of the Falkland Islands L. gahi population demonstrated ontogenetic descent with a probable associated coastward spawning migratio n. The L, gahi fishery concentrates by area and does not follow the migrati on pattern, indicating that the closed population assumption of the assessm ent model is invalid for much of the period assessed. Research has confirme d the variable nature of recruitment of microcohorts to the fishery overstr etching the single-recruitment assumption of the Leslie-DeLury model. But r esearch has also shown that there are periods of residency of L. gahi on th e fishing grounds. The current assessment procedure uses these periods of r esidency to derive estimates of population depletion and therefore stock si ze. In this paper the salient features of the fishery for L, gahi are prese nted, and the crucial links between resource assessment, biological researc h, and management advice are discussed. Finally, directions for further res earch, needed to refine assessments and achieve some predictability of popu lation processes, are identified.