Finding 'Lost Sharks' Under the Golden Gate Bridge

In the deep waters underneath the Golden Gate Bridge, right next to the city of San Francisco, live mysterious sharks -- from small leopard sharks to giant seven-gills weighing over 300 lbs.

When people think of sharks, they usually think of great white sharks, hammerheads, or whale sharks. But these large sharks represent a very small percentage of the sharks in our oceans.  There are many other shark species that are much less famous, but much more common.  These species are often called 'lost sharks' because they are "data deficient" - often ignored even by science. 


There are more than 500 species of shark -- and more than 25% of these species are under threat of extinction.

Bay Area Study of Elasmobranchs (BASE)

​​In collaboration with the Monterey Bay Aquarium, we are carrying out a long-term study of the shark populations of San Francisco Bay.  The study involves tagging sharks with brightly colored tags that ask fishermen to report when and where these sharks were caught again.


Sharks are part of a larger group of cartilaginous fishes called elasmobranchs, which includes rays and skates.


Elasmobranchs are a group of animals as diverse as any other animal group. They include apex predators like the great white, plankton-eaters like the whale shark, and many small sharks that live deep in the ocean. Elasmobranchs play diverse and complex roles in their ecosystems that scientists are still striving to understand.

Elasmobranchs (sharks and rays) are commonly caught as incidental by-catch by sportfishers.  BASE provides a chance for those fishermen to help scientists create an important database of elasmobranch information from the San Francisco Bay.

BASE is helping scientists learn the movement patterns and long-term population trends of common sharks and rays in the bay.  We can use this information to look for correlations with things like fishing pressure, weather patterns, pollution, habitat loss, and food supply fluctuations. 


Best of all, by tagging hundreds of sharks that are later caught by fishermen, BASE gives us an opportunity to connect with local fishermen, party boat captains, and fishing guides and get them involved in important real-world science. 

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