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A Telemetric Study of the Behavior of Free-Swimming Pacific Angel Sharks, Squatina californica





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Nine Pacific angel sharks were tagged near Santa Catalina Island, California, with single-channel or multichannel ultrasonic transmitters incorporating various combinations of sensors to measure swimming speed, depth, light, and temperature. The sharks were tracked for periods of 13 to 25 h and were found to be basically nocturnal, apparently cuing on decreased light intensity averaging 7 lux (range, 1-16) to begin swimming activity which peaked at dusk and midnight. Mean of maximum rate of movement for each shark was 490 m/h. The tagged sharks moved an average of 4 km (range, 2-9) during the trackings and collectively occupied a home area of approximately 150 ha. The sharks swam at depths ranging from 27 to 100 m and readily crossed thermoclines. The number and size of individuals seen at the tagging site changed with season.