Behavior of the White Shark, Carcharodon carcharias, and Scalloped Hammerhead, Sphyrna lewini

摘要

Capture records of 109 white sharks caught along the western coast of North America indicate the following life history pattern. Adult females give birth to pups during the late summer and early fall south of the Point Conception to live both inshore or offshore at islands. As females continue to grow, they move back south of Point Conception yet remain offshore probably to give birth to young. It is believed that the areal distribution of the shark is governed by the availability of pinniped prey for adults and possibly the need for pupping grounds with few predators and competitors. The area with the highest abundance of sharks is the coastline within the Point Reyes/Farallon National Marine Sanctuary. A multisensor, computer-interfaced telemetry system has been built. Transmitters have sensors for monitoring swimming speed, depth, surrounding water temperature, and light level. Expansion board hardware converts pulsed telemetry signals to TTL logic. Software has been written to: (1) convert time intervals into sensor values, (2) display 8 channels of sensor values either numerically or graphically, (3) display sensor values of a single channel graphically with high resolution, and (4) store the sensor data on floppy disk. The system will be used to describe predation by the white shark on pinnipeds and orientational behavior in pelagic sharks.