by Ryan Bartling, DFG Marine Biologist
Large schools of Pacific herring once again returned to the waters of San Francisco Bay this winter, providing a feast for the bay's many marine mammals and seabirds. The return was also celebrated by the commercial herring fleet.
The spawning biomass estimate for the 2011-2012 season was 60,985 tons, an increase over last season's estimate of 57,082 tons and well above the historical average (1978-1979 season to present) of 49,670 tons. Annual spawning biomass surveys have been conducted by the Department of Fish and Game (DFG) in San Francisco Bay since 1973.
"Another year of favorable ocean conditions likely led to better survival and improved growth for young herring," said John Mello, senior environmental scientist for the Aquaculture and Bay Management Project (ABMP).
The gill net fishery for San Francisco Bay opened with a quota of 1,845 tons on January 2, 2012 and closed on February 27, 2012. During January and February, approximately 88 percent of the San Francisco Bay gill net quota (1,632 tons) was landed. Fresh fish and herring-eggs-on-kelp permits were issued, but no landings were made for these fisheries.
DFG remains committed to providing a sustainable fishery while continuing to protect herring's integral role in both ocean and bay food webs. In order to safeguard the fishery, DFG is once again recommending a conservative 5 percent harvest rate for the upcoming season. If adopted, the quota for the 2012-2013 season would be set at 2,854 tons by the California Fish and Game Commission. This low harvest rate will help minimize fishing mortality, a critical step for continued herring population recovery.
During 2011, the California Fish and Game Commission adopted minor regulatory changes proposed by DFG. These changes included modifications to the fresh fish fisheries in San Francisco and Tomales Bay. Season dates were amended to reflect herring abundance in those bays and the daily market order was increased from 500 to 1,000 pounds. DFG was asked to propose these changes to meet the demands of an emerging market for locally produced and sustainable seafood.
Even with increasing biomass estimates, DFG staff remain concerned about the herring population age structure, specifically the large proportion of younger fish (less than 5-year herring) in the 2011-2012 spawning population. Herring reach reproductive maturity at age 2 and can return to spawn every year, with a large female laying 40,000 to 50,000 eggs in a single year. San Francisco Bay herring can live to be 9 years old. One of the ABMP management goals is to allow the harvest of 4 year old and older herring in the commercial fishery, allowing herring several opportunities to spawn before being caught in the commercial fishery.
Overall, DFG views the continued recovery of the herring population as promising, especially after the historic low biomass estimate for 2008-2009 of 4,833 tons. This low estimate, along with other factors, caused the first-ever complete fishery closure for the 2009-2010 commercial season.
DFG's long-term management goals for the San Francisco Bay Pacific herring population include restoring a healthy age structure that includes all ages of fish, managing commercial harvest to achieve a sustainable fishery, and providing forage to other species that utilize herring as a food source. For more information visit the ABMP Herring Fishery Web page.
