Ultrasonic tags reveal seasonal movements in red king crab (Paralithodescamtschaticus)

Abstract

The red king crab was introduced to the Barents Sea in the 1960s and has spread widely both in Norwegian and in Russian waters, entailing a need to acquire knowledge of the biology and behaviour of the crab in these areas. Twenty crabs of both sexes were tagged with ultrasonic coded acoustic transmitters and released at three sites in Porsangerfjord, Finnmark, Norway. Ten acoustic receivers were placed in a non-uniform grid in the experimental area, allowing us to track individual crabs for ca. 12 months. Results on seasonal movements according to depth and sex throughout the year are presented as well as long‐term observations on individual crab behaviour. Daily movement speed of individual crabs is also calculated. Being a small introductory experiment, this study provides valuable information on the behaviour of a successful introduced species, essential knowledge for the understanding of the species and for pinpointing further investigations on the crab’s impact on the native ecosystem.