Sitka. . . The Alaska Department of Fish and Game announced today the preliminary guideline harvest
level (GHL) for the 2008 Sitka Sound sac roe herring fishery is 13,796 tons.
This fall the department ran several ASA model runs exploring various biological parameters affecting
the Sitka Sound herring stock and other model parameters to improve the fit of the model to the observed
data. The ASA model uses a long time series of abundance and age composition data from department
surveys conducted during the spring fishery. The best fitting ASA model run included splitting the
maturity schedule estimates for the periods 1978-2001 and 2002-2007. The maturity schedule is the
estimation of what age the herring are reaching maturity and capable of spawning. The model is showing
that during the period 2002-2007 a smaller portion of age-3 through age-7 herring are recruiting as mature
herring to the spawning grounds and the fishery. Maturation of herring is a function of growth and in
recent years younger herring have been growing at a slower rate. The department has selected a more
conservative GHL than that forecast using the ASA model because it is not fully understood how changes
in the environment that are affecting herring growth, maturation and survival will affect the herring
population in future years.
The forecast and quota for the 2008 fishery will be finalized in February, 2008 after a winter test fishery
is completed. The preliminary forecast indicates that the spawning stock will consist of 4% age-3, 6%
age-4, 9% age-5, 13% age-6, 12% age-7, and 57% age-8+.