The 2011 acoustic survey biomass estimate is 553,991 metric tons, the lowest observed in the time series and approximately one-third of the 2009 estimate. Only 7.4% of this biomass was observed in Canadian waters.
The methods used to calculate the 2011 estimate have not changed, and are consistent with those presented and reviewed for the years 1995-2009 and used to generate survey biomass estimates during the 2011 stock assessment process. The raw 2011 acoustic survey data suggest that the hake schools encountered were consistently smaller than the average size of schools over the longer time-series.
The survey attributed 63% of the estimated number of hake observed to the 2008 year-class, and a total of 88% to the 2008 and 2009 year-classes combined. While this finding supports the previously estimated strength of these incoming cohorts, it differs substantially from 2011 stock assessment model predictions which, while uncertain, indicated that the 2005 and 2006 year classes would be important contributors to both fishery and survey catches during 2011.
The stock assessment for Pacific hake integrates population information from both the fishery (US and Canadian portions) and the acoustic survey time-series in estimating current stock size and management reference points. As a result, the amount of biomass estimated within the assessment model commonly differs from the corresponding survey estimates. Consequently, this new survey estimate should not be used directly as the best measure of the 2012 stock size, nor to predict total catch levels for 2012, except in the context of a completed and reviewed stock assessment.
The findings from the 2012 acoustic survey biomass are currently being reviewed and will be posted when available.