On the problem of identifying and assessing populations of Falkland Island squid Loligo gahi

Abstract

Patterns of catches of Loligo gahi around the Falkland Islands in the years 1982-1986 initially suggested a simple population structure with one stock peaking in the fishery in autumn and another peaking in spring. Management of two seasons was therefore imposed in 1987. This pattern has proved highly variable, with the result that, for some years, it seems as if up to four cohorts are present in two separated northern and southern fishing areas. In this paper, evidence from fishing vessel and scientific observer data is examined for these different population structures. The conclusion is that the simplest structure that fits the observed data is of two main cohorts recruiting during a year to a single fishing area, albeit with considerable geographic heterogeneity, with a smaller recruitment episode sometimes present at the end of the year. The recruitment of these cohorts to the fishery is not, however, coincident with current management seasons.