February 14, 2011

Neighbors,

For the last ten days, Waterside South Neighborhood Watch residents have been watching the Bay and listening to the cacophony of gulls' cries and sea lion barks associated with this years’s amazing spawning  run of Pacific herring. This is my attempt to address questions many have asked and to consolidate observations shared by others.

What is Going On?

The first week of February has been the normal time for Pacific herring to spawn near the shoreline of Point Richmond between Ferry Point, Keller Beach and Long Wharf.  Herring are oceanic fish which enter San Francisco Bay and hold several weeks in deep water channels awaiting ripening of male gonads and female eggs.  When a school is ready to spawn, male herring initiate spawning by releasing milt in shallow waters where there is suitable substrate for the eggs such as eelgrass, algae and rocks.  A pheromone in the milt triggers spawning by females which exude their adhesive eggs.

Spawning is announced to humans by gulls screaming their excitement to find roe washing ashore on fragments of eelgrass and algae.  The harbor seal colony on Castro Rocks somehow gets the word and with barking sea lions swims in to feast on the fish, which run 8 to 16 inches long.  Ducks fly in to dive underwater and forage to glean roe from the plants.  These diving ducks such as scoters, scaup, ruddy ducks and buffleheads quickly turn to herring eggs from their normal diet of smaller fish, benthic plants and invertebrates such as worms, snails and clams.  Gulls and dabbling ducks such as wigeons and mallards, which are unable to dive, hang out near the shoreline to feed on eggs remaining on kelp and eelgrass fragments washed in to shallow waters after being broken off by the diving ducks.

The presence of marine mammals tells us that herring are underwater spawning whereas their absence suggests that herring have finished spawning and returned to deeper waters of the Bay or the ocean. Diving ducks remain feasting on the eggs during their ten day incubation period, and the gulls hang around to feed on the leftovers.

How Does This Year Compare with Past Experience?

Before the commercial herring roe fishery was introduced in 1973, long time Point Richmond resident George Coles recalls that spawning herring were so abundant that they were easily scooped up by hand along the shoreline.  When the word went out that the herring had arrived, folks would head down to the shore and harvest them for pickling with community barbeques held on the beach.  However, there have been only modest runs in recent decades until last year when there was a moratorium on commercial fishing.  This year, commercial fishing was halted on January 28 when the fleet caught their quota in less than a month.

More Information: Click here for more information about herring biology and the roe fishery.