Monitoring the Movements of Snow Crab (Chionoecetes Opilio) with Ultrasonic Telemetry

In May 1986 ultrasonic transmitters were attached to male and female snow crabs (Chionoecetes opilio} by divers in Bonne Bay, Newfoundland. An array of three to four omnidirectional hydrophones was set up underwater, roughly 50 meters from the shore, to receive the ultrasonic signals. On shore, a computer monitored the time that the signals were received at each hydrophone and automatically recorded the data every 10 minutes on a 24 hours per day basis. The data collected by the time delay tracking system was used to plot detailed maps of movement of the male and female crabs over several days. No clear pattern of diurnal movement of the male crab was apparent over the tracking period. The patterns of movements differ for the male and female crabs. This could indicate different strategies of movement for each sex at particular life stages.