Description: Some 290 species of squids comprise the order Teuthida that belongs to the molluscan Class Cephalopoda. Of these, about 30-40 squid species have substantial commercial importance around the world. Squid fisheries make a rather small contribution to world landings from capture fisheries relative to that of fish, but the proportion has increased steadily over the last decade, with some signs of recent leveling off. The present overview describes all substantial squid fisheries around the globe. The main ecological and biological features of exploited stocks, and key aspects of fisheries management are presented for each commercial species of squid worldwide. The history and fishing methods used in squid fisheries are also described. Special attention has been paid to interactions between squid fisheries and marine ecosystems including the effects of fishing gear, the role of squid in ecosystem change induced by overfishing on groundfish, and ecosystem-based fishery management.

Description: The North Pacific Ocean population of the neon flying squid Ommastrephes bartramii, which undertakes seasonal north–south migrations, consists of autumn and winter–spring spawning cohorts. We examined life history differences between the 2 cohorts in relation to the oceanographic environment. The differences could be explained by seasonal north–south movements of the following 2 oceanographic zones: (1) the optimum spawning zone defined by sea surface temperatures; and (2) the food-rich zone defined by the position of the transition zone chlorophyll front (TZCF). The 2 cohorts use the food-rich zone in different phases of their life cycles. The spawning grounds for the autumn cohort occur within the subtropical frontal zone (STFZ), characterized by enhanced productivity in winter due to its proximity to the TZCF, whereas the spawning grounds for the winter–spring cohort occur within the subtropical domain, which is less productive. As the TZCF shifts northward in spring, the autumn cohort continues to occur in the productive area north of the TZCF, whereas the winter–spring cohort remains in the less productive area to the south until it migrates into productive waters north of the TZCF in the summer or autumn. Consequently, the autumn cohort grows faster than the winter–spring cohort during the first half of its life cycle, whereas the winter–spring cohort grows faster during the second half. This growth pattern may be responsible for differing migration patterns; males of the autumn cohort do not have to migrate given their early fast growth in the STFZ, whereas those of the winter–spring cohort must migrate to the food-rich subarctic frontal zone to compensate for their slow growth. These biological and ecological differences between the 2 cohorts suggest flexibility of their life history response to oceanographic environments.