With recent sightings of white sharks making local headlines, the Discovery Channel’s Shark Week on the horizon and the pupping season for local shark species underway, now is an ideal time to take a deeper look at San Francisco Bay’s largest predator, the sevengill shark, Notorynchus cepedianus.
The sevengill shark gets its name from having seven gills on each side of their pectoral fins; most sharks have only five gills. Photo courtesy of the Aquarium of the Bay
By Kati Schmidt
With recent sightings of white sharks making local headlines, the Discovery Channel’s Shark Week on the horizon and the pupping season for local shark species underway, now is an ideal time to take a deeper look at San Francisco Bay’s largest predator, the sevengill shark, Notorynchus cepedianus.
Sevengill sharks are one of five native species in San Francisco Bay: the others are leopard, soupfin, spiny dogfish, and brown smoothhound sharks. Not just a clever name, sevengill sharks have seven gills on each side of their pectoral fins; most sharks have only five gills. Locally, they reside in bays such as San Francisco, Monterey and Tomales, but are also found in the South Atlantic, Pacific and Indian Oceans.
"Sevengill sharks are great to work with," says Christina J. Slager, director of animal care and exhibits for Aquarium of the Bay. "Even though they’re the Bay’s apex predators, at Aquarium of the Bay, they’re like goofy aquatic puppies, waiting to be fed."
Sevengill sharks are ovoviviparous, meaning they give live birth versus laying eggs, with 80 to 100 young born per pregnancy. Gestation for this animal can last up to two years. It is thought that San Francisco Bay may be the primary pupping ground on the west coast for Sevengills.
The species is one of two in the cow shark family—the other being the sixgill shark—found along the California coast. The animal was heavily fished in San Francisco Bay in the 1930s and 40s, until the fishery collapsed. However, interest in shark fishing was reignited in the mid 1970s following the release of Jaws—arguably the worst ocean film ever created, in terms of its impact on the public’s perception of sharks.
While sevengill sharks are common in San Francisco Bay, little is known about their behavior and ecology. In one of its leading conservation impact programs, Aquarium of the Bay’s biologists began working with the Biotelemetry Lab at the University of California, Davis in 2008, implanting transmitters into sevengills to collect valuable information on the sharks’ life patterns, basic ecology and issues that endanger their existence. Initial findings indicate a previously undocumented travel pattern in and out of the Bay. Further analysis is currently underway and will be released later this summer.
Aquarium of the Bay exhibits sevengills, along with all local shark species, in its Under the Bay exhibit tunnels. In addition to viewing these animals, visitors have the unique opportunity to watch the Aquarium’s Animal Care staff pole feed them underwater each Thursday and Sunday at 11:30 a.m.
As San Francisco Bay’s Aquarium, a strong emphasis is placed on extending visitors’ connection to marine animals and habitats to help protect them for future generations. In its No Fins, No Future: Support AB 376 exhibition, which opened in April, the Aquarium is providing public education and an action station in support of Assembly Bill AB 376, which would ban the possession, sale, trade and distribution of shark fins in California. Aquarium visitors can sign personalized postcards in support of AB 376, which the Aquarium is mailing to the bill’s authors, Assembly members Paul Fong (D-Cupertino) and Jared Huffman (D-San Rafael). To date, nearly 4,300 postcards have been signed and sent in support of this monumental piece of legislation.
Coming up in July and August, Aquarium of the Bay is leading a variety of events inside and outside its doors to deepen individuals’ connections with sharks. Throughout July and August, Aquarium educators will be leading "Fintastic! Shark Discovery" outreach programs at library branches throughout San Francisco. This program will culminate with a special evening encounter of sharks on film and in discussion on Tuesday, August 2, from 6 – 8 p.m. at San Francisco’s Main Library. In partnership with the Natural Resources Defense Council and famed freediver William Winram, an evening event will be held at Aquarium of the Bay on Thursday, July 28. Lastly, throughout the Discovery Channel’s Shark Week run, July 30 – August 7, the Aquarium will host a variety of events, culminating with the ever-popular Family Sleepover on August 6, aimed at replacing fear of sharks with fascination. The full schedule of events, details on the Aquarium’s shark care and research efforts and much more can be found at www.aquariumofthebay.org.
Kati Schmidt is the Public Relations Manager for Aquarium of the Bay and The Bay Institute, nonprofit organizations dedicated to protecting, restoring and inspiring conservation of San Francisco Bay and its watershed. A Bay Area native and aspiring Great American novelist, Kati enjoys the professional and personal muses found from strolling and cycling along, and occasionally even swimming in San Francisco Bay and beyond.
“Even though they’re the Bay’s apex predators, at Aquarium of the Bay, they’re like goofy aquatic puppies, waiting to be fed.” Photo courtesy of the Aquarium of the Bay
