No abstract

Cephalopods have become an important global food source, but their sustainable management is challenged by unique life history characteristics associated with short lifespans and semelparous reproduction, high natural mortality rates, rapid and often nonasymptotic growth, and complex population structures. Weak stock-recruitment relationships together with the time-consuming work required for age validation and high-volume annual age determinations make traditional age-based modelling impractical. We propose that the best method for cephalopod assessment involves innovative depletion models, fitted with in-season data on catch numbers and fishing effort, to produce realistic estimates of stock biomass. A “fast lane” assessment approach is suggested that includes high-frequency data collection for separate, in-season stock assessments of each cohort to ensure sustainable exploitation of these short-lived resources. However, most cephalopod fisheries are data-poor and/or lack the infrastructure and resources needed to apply depletion methods; therefore, we also present alternative assessment methods that have been recently applied worldwide. We also offer suggestions for further research on the remaining challenges of cephalopod stock assessment and management.

The spatial and temporal distribution patterns of cuttlefish abundance and the relationships between cuttlefish abundance and environmental variables in the French Atlantic coast, the English Channel, and adjacent waters were studied using both geographical information system and statistical methods. Cuttlefish have a clear general annual migration pattern, consistently occurring in broadly the same areas in different years. The strength of the Atlantic currents into the west part of the English Channel and the south part of the Celtic Sea may be the dominant influence on the timing of cuttlefish migration to these areas. Local abundance shows a positive correlation with SST, although it is difficult to determine if this reflects any causal link. Cuttlefish expand their distribution further north in the spawning season in warm years and shift south in cool years. The centre of high abundance in offshore deep water shifts north in warm winters and south in cool winters.