In recent weeks, visitors have reported finding dead sharks that have washed up on beaches along San Francisco Bay, including Crown Beach in Alameda. James Frank, a naturalist at Crown Beach’s Crab Cove Visitor Center, has provided some good information about the phenomenon.
Essentially, shark die-offs are common in late spring and early summer. The phenomenon was first reported in 1967 by Ron Russo, then the East Bay Regional Park District’s chief naturalist, now retired. The district maintains a database for reporting washed-up sharks to the California Department of Fish and Wildlife. The district also collaborates with researchers from Fish and Wildlife and UC San Francisco, all working to pin down the exact cause.
A parasite called Miamiensis avidus seems to be the culprit. It has been known to infect captive aquaculture fish and is not uncommon in the wild. But it seems to have an especially strong effect on leopard sharks in San Francisco Bay. There’s an informative article on the topic in the Oct. 27, 2017, edition of National Geographic. The sharks present no threat to people, but Frank advises people to avoid trying to “rescue” them, since the sharks will not survive. Sending them off into deeper water makes it harder for the district to keep accurate records.
The most helpful thing that park visitors can do if they encounter a shark, bat ray or other fish washed up on a park district shoreline is to report it to the Crab Cove Visitor Center. The phone number is 510-544-3187. Please provide the date, species if known and location. In cases of less commonly affected species that wash up on the shore, the district may collect and send samples to researchers for further analysis. Staff may not be able to follow up with each call but will call back if there are additional questions.
Alameda: The Crab Cove Visitor Center is at 1252 McKay Ave. off Alameda’s Central Avenue. It’s open from 10 a.m. to 5 p.m. Wednesdays through Sundays, with an aquarium and exhibits about the cultural and natural history of San Francisco Bay. The center hosts Family Nature Fun Time from 2 to 3 p.m. every Saturday and Sunday, then fish feeding time at the aquarium from 3 to 3:30 p.m.
If you’d like to help keep the shoreline pristine, the center needs volunteers for a post-July 4 beach cleanup from 10:30 a.m. to noon July 7, coordinated by naturalist Morgan Guenther. Bring buckets and gloves, or borrow them from the center.
Berkeley: Up the hill at Tilden Nature Area near Berkeley, insects and arachnids are the focus of a couple of programs at the Environmental Education Center. Naturalist Trent Pearce will lead an insect expedition from 2 to 3 p.m. every Saturday in July. These are short walks to meadows and fields in search of our six-legged friends. All ages are welcome.
Eight-leggers — itsy-bitsy spiders — are the stars of a program from 1 to 2 p.m. July 7 and again July 21, led by naturalist Jenna Collins. Bring your magnifying glass for a walk around the Little Farm in search of the littlest ones.
Or you can talk with the animals during a program from 11 to 11:30 a.m. every Sunday in July and August, meeting at the Little Farm classroom. Learn how various animals find their food and avoid predators. The center and Little Farm are at the north end of Tilden’s Central Park Drive. For information, call 510-544-2233.
Antioch: Out at Black Diamond Mines Regional Preserve in Antioch, the underground Greathouse Visitor Center will be closed for construction through mid-September. During this time, the Sidney Flat Visitor Center, which is in the group of buildings to the left as you enter the park, will be open on weekends from 10 a.m. to 4:30 p.m. Most naturalist-led programs meet in the parking lot at the end of Somersville Road. Tours of the Hazel-Atlas mine are canceled till fall. For information, call 888-327-2757, ext. 2750.
Online: All summer long, there are lots of things to see and do in the regional parks. Check out the park district’s website at ebparks.org for a full schedule.
Ned MacKay writes a regular column about East Bay Regional Park District sites and activities. Email him at nedmackay@comcast.net.
