Life cycles, oceanography and variability: ommastrephid squid in variable oceanographic environments

Exploited populations of ommastrephidsquid are found under a wide range of oceanographic regimes. However, to date most scientific attention has focussed on those found in northern hemisphere western boundary current systems, and these systems have become the paradigm for theoretical work. Dosidicus gigas, in the east central-southeast Pacific, and Martialia hyadesi, in the southwest Atlantic, provide examples of the interactions between squidlifecycles and regional oceanography outside of the paradigm. Illex argentinus, also in the southwest Atlantic, provides a southern hemisphere example of a western boundary current species. These examples are used to highlight the key issues involved in understanding squid population variability within the context of variableoceanographicenvironments. The issues include the fundamental influence of oceanographic variability on population variability, and the importance of a thorough understanding of the lifecycle of the study species in order to detect and understand the relationships between it and the environment. The importance of understanding the relative temporal and spatial scales on which the environmental and biological factors interact is also considered. Overall, a broader understanding of the interactions between oceanographic variability and squidlifecycles is necessary to interpret successfully the adaptation of ommastrephidsquid species to their environment and to allow the effective forecasting and management of fishery resources.

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