UC Davis Research Project 7

Sevengill shark movements within San Francisco Bay Estuary


Sevengill sharks are common inhabitants of estuaries and bays from southeastern Alaska to the southern end of Baja California. They are a top predator in this system feeding on fish and other elasmobranchs as adults. Very little is known about their movements or reproduction in this area. It hypothesized that San Francisco Bay is the primary pupping grounds for west coast sevengills.


To gain knowledge of sevengill movements within San Francisco Bay and to detect potential habitat preferences and migration patterns of sevengill sharks. This will provide much needed information for management and conservation of this large predatory species.


Sevengill shark movements will be actively tracked using continuous Vemco transmitters implanted in the abdominal cavity of the sharks (Fig. 3). Tracks will be attempted on individual sharks for a period up to 72 hours. An additional 20 sharks will be implanted with coded Vemco transmitters and those sharks will be tracked using the monitor array in San Francisco Bay.  


The field portion of this study is complete and the data is being prepped for publication, although the tags have more than five years of battery life remaining and are currently being detected at all bridges in the Bay. There is also a mini-documentary produced by David McGuire called “City of the Shark” that will be used for research fundraising purposes. A second year of the study is being planned.