Un-Sound herring stocks

Posted by The Highliner

Posted: October 13, 2008 - 7:39 pm

Comments (0) |

I’m a tad late posting this, but I thought I’d let you know we’ll again see no herring fisheries next spring in Prince William Sound.

Will the roe-rich little shiners ever return?

Here are the dismal details:

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Alaska Department of Fish and Game

Sept. 30, 2008

Based on current herring stock assessment information, the 2008-2009 food and bait fishery and all 2009 spring herring fisheries including the purse seine and gillnet sac roe harvests, the spawn-on-kelp in pound fishery, and the wild spawn-on-kelp harvest are closed. The Prince William Sound herring biomass estimate is below the minimum spawning biomass threshold of 22,000 tons. According to 5AAC 27.365(b) Prince William Sound Herring Management Plan, no fishery may be opened if the estimated spawning biomass is below this threshold level.

Age Structured Assessment (ASA) modeling was used to project the 2009 biomass of Pacific herring. The preliminary PWS herring spawning biomass forecast for 2009 is ~15,000 tons. The preliminary ASA model estimate was calculated using preliminary acoustics data, and the final estimate will be announced after the final acoustics data is available. Hydroacoustic, net sampling, and aerial surveys were conducted in 2008 to assess herring biomass, disease prevalence, age composition, and growth.

Acoustic surveys were conducted during March and April, 2008 with the ADF&G research vessel Solstice and the M/V Auklet, contracted by the Prince William Sound Science Center. The department conducted broad scale surveys in eastern Prince William Sound up to Tatitlek Narrows; north and central Montague Island; and from Sawmill Bay to Whale Bay. Detailed acoustics data were collected on major concentrations of herring in St. Matthews Bay, Port Fidalgo, Two Moon Bay, Whale Bay, and near Bishop Rock. Age composition samples varied by location and sample gear: spawning fish samples (Eastern PWS) were predominately age 4 and age 9, but spawning samples from other locations were predominately younger fish (age 3 and 4). The biomass documented in Whale Bay was mostly juvenile fish (65% age 2).

Herring disease assessment has been included as part of the annual age, sex, and size assessment program the department has completed each spring since 1993. More information on the prevalence of viral hemorrhagic septicemia virus (VHSV) and Ichthyophonus hoferi in the herring population from samples collected in the spring of 2008 will be provided when it becomes available.

Aerial surveys documented a peak biomass estimate of ~10,700 tons of herring versus 770 tons last year (2007), 540 tons in 2006, 4,773 tons in 2005 and 12,305 tons in 2004. The largest biomass estimate (~10,000 tons) was observed in Port Gravina and Port Fidalgo. A total of 33.2 mile-days of spawn were observed in spring 2008, almost double the mile-days observed in 2007. The largest individual spawning event occurred between St. Matthews Bay and Knowles Head with ~14 miles of spawn. Additionally, there was a 5.1 miles of spawn on a single day in the bays of north Montague Island.

The department will collect additional age, sex, and size data along with disease information throughout PWS this fall. Additional updates on the status of the PWS herring population will be announced when new information becomes available.

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