CDFW Invites You to Report Herring Spawning Activity to Help Monitor Herring Pop

January 7, 2025

The Pacific herring is a small, silvery fish that supports a wide suite of predators, including seabirds, marine mammals, and humans. During its winter spawning period, this forage fish comes close to shore where it is commonly targeted by recreational fishermen tossing throw nets from land and commercial fishermen deploying gill nets from specially equipped aluminum boats.  Herring are targeted for roe (eggs) or food in the commercial gill net fishery, and for bait or food in the recreational fishery.

The California Department of Fish and Wildlife (CDFW) has a long history of managing these fisheries, and now invites you to participate by identifying and reporting Pacific herring spawning activity in California. If you see Pacific herring spawning activity, please email herring@wildlife.ca.gov with the general location information and the date. Photos are highly encouraged!

Reports from the public will aid CDFW in monitoring herring spawning activity as part of the state’s effort to manage the commercial and recreational herring fisheries.

Although areas of shoreline preferred by spawning herring tend to vary over time, the major herring spawning areas in northern California include:

1. Tomales Bay

2. Humboldt Bay

3. Crescent City Harbor

4. San Francisco Bay

Common spawning grounds within San Francisco Bay include:
Richardson Bay and Paradise in Marin County, the San Francisco city waterfront, the shoreline from Point Richmond to Point San Pablo, Crown Beach and Ballena Bay in Alameda County, Bay Farm Island, and Coyote Point.

Herring are unique forage fish that commonly deposit layers of eggs on eelgrass, marine algae, pier pilings, rocky intertidal areas, and jetties, primarily within California’s northern bays and estuaries. The spawning season typically occurs during the winter from about November through March. In San Francisco Bay, anywhere from five to 15 spawn events may occur each season. Eggs hatch approximately two weeks after they are spawned.

Lively gatherings of marine birds are often the first observable indication of herring spawning activity. Congregations of fish-eating birds such as cormorants and pelicans may indicate that herring are preparing to spawn or are actively spawning in the vicinity. In addition to birds, marine mammals such as harbor seals and sea lions may be present during spawning events. Once herring have deposited their eggs and left the area, large active groups of egg-eating birds such as scoters and coots may indicate that a spawn has occurred.

For more information about Pacific herring, take a look at the Pacific Herring Fishery Management Plan and the Pacific Herring Enhanced Status Report. CDFW’s Marine Management News blog has a collection of articles covering Pacific herring spawning events and fishery management news as well.

Questions about this data collection effort can be directed to herring@wildlife.ca.gov. CDFW appreciates any assistance you can provide, thank you!