On the population biology of the common shrimp Crangon crangon (L.) (Crustacea: Caridea) in the Severn Estuary and Bristol Channel

A 5-year study of the population biology of the common shrimp Crangon crangon (L.) in the Bristol Channel is reported. Samples were collected from three commercial fishermen and from the filter screens of five power stations taking water from the estuary. The Severn Estuary and Bristol Channel were found to contain a single shrimp population which undertook regular seasonal migrations in order to avoid low salinities and to reproduce. Previous studies had assumed that the regions held separate populations which migrated to avoid low winter temperatures.