Dark clouds gathered last Tuesday morning, and many of us hoped for a storm. Yet, the not-so-still waters at Berkeley’s Aquatic Park didn’t roil from raindrops; they bubbled from thousands of small jumping fish.
According to Dr. Peter Moyle, Distinguished Professor Emeritus with the Department of Wildlife, Fish, and Conservation Biology at UC Davis, these little silver fish were juvenile topsmelt (Atheriopsis affinis). Full-size topsmelt can be as long as 14.5 inches.
Despite their name, topsmelt are not true smelt. Instead, they are members of the silversides family, Atherinopsidae — the same family that comprises jacksmelt, which are bigger, and grunion, which are famous for their mating “runs” up sandy beaches in Southern California.
The finger-length fish have been schooling and leaping at the north end of the park’s main lagoon, close to foot of Addison Street. According to the Aquarium of the Pacific, these fish can tolerate varying salinity levels, and may move into estuaries during spring and summer and return to open water in the fall and winter.
It’s unknown how long their spectacle will continue, but one bicyclist in the park said he had observed the jumping fish for about 10 days.
Other park-goers expressed their surprise that the fish had not attracted flocks of hungry birds.
During my visits to the estuary last week, I observed a couple of curious pelicans and cormorants. An immature Bonaparte’s gull seemed to show the most interest; it flew several passes over the fish. The fish seemed to jump when the bird came close.
Says Dr. Moyle: “These are among the most common fish in shallow bays along the coast. If you see a tern with a fish in its beak, chances are pretty good it will be a topsmelt.”
Back in the Berkeley estuary, Dr. Moyle explains why the topsmelt might be jumping: “They feed mainly on algae, so the leaping is probably to escape from fish predators.”
“Or,” he adds, “They could just be happy fish.”
Watch the fish in action in the two short videos below:
Special thanks to Steven Donaldson for getting Berkeleyside “hooked” on this story — and to Dr. Moyle, Lawrence Ray, Rusty Scalf, John Greenleigh.
Elaine Miller Bond is photographer for The Utah Prairie Dog: Life Among the Red Rocks (University of Utah Press) and author of Dream Affimals (Sunstone Press) and Affimals (LIT Verlag). You may have seen her presenting her “Diary of a Hummingbird’s nest” at Uncharted Berkeley Festival of Ideas last month.
Catch up with more of Elaine Miller Bond’s remarkable nature stories created for Berkeleyside.