Science Advisory Report  2011/079

Stock Assessment of Subdivision 3Ps cod, October 2011

Summary

• Information available to evaluate stock status consisted of commercial landings (1959 to 2010) and log-book data (1997-2010) in conjunction with information from Canadian research vessel (RV) trawl surveys (1972-2011), sentinel surveys (1995-2011), and a telephone survey of Canadian fish harvesters pertaining to the 2010/11 fishery. Exploitation (harvest) rates were estimated from tagging experiments in Placentia Bay. Consistent with recent assessments, a survey based cohort model (SURBA) was used.
• The total allowable catch (TAC) for the 2009/10 and 2010/11 management years was 11, 500 t. Reported landings during the 2009/10 and 2010/11 seasons totaled 77% and 68% of the TAC, respectively. This is atypical.
• Tagging data and ancillary information indicated that there is a complex of stock components in 3Ps. However, the DFO RV survey covers most of the stock, and survey trends broadly reflect stock trends.
• Gillnet catch rates from both sentinel surveys and logbooks for vessels <35’ suggest stability. However, linetrawl catch rates from these sources indicate recent decline.
• Exploitation rates for 2010 based on tagged cod released in Placentia Bay ranged from 28-33% for large cod (>65cm) and 10-17% for smaller cod (<65cm).
• Estimates of total mortality (ages 5-10) over 2006-10 averaged 0.68 (49% mortality). This high level of mortality is a concern. Total mortality rates reflect mortality due to all causes, including fishing.
• The basis for a limit reference point (LRP) for this stock is BRecovery, defined as the lowest observed SSB from which there has been a sustained recovery. The 1994 value of SSB has been identified as the limit reference level for this stock.
• SSB decreased over the 2004-09 period. The SSB was estimated to be below the LRP during 2008 and 2009. The spawning stock biomass (SSB) in 2011 is estimated to be above the LRP, with a low probability of being below the LRP (0.08).
• A one year projection to 2012 using the cohort model indicated that survey SSB will continue to increase if total mortality is similar to current values (i.e., within ±20%). This increase is due to the recruitment of the relatively strong 2006 year class (YC) to the spawner biomass. The projection also indicated that the probability of being below the LRP in 2012 is low (0.02 to 0.09).
• A three year projection to 2014 indicates subsequent declines in both total biomass and spawning biomass if total mortality is similar to current values (i.e., within ±20%). In 2014 the probability of being below the LRP ranges from 0.03 to 0.56.
• The 2006 cohort is estimated to be relatively strong and is expected to recruit to the 2011 fishery. The 2007 to 2009 cohorts are estimated to be near the 1982-2010 average.

This Science Advisory Report is from the Fisheries and Oceans Canada, Canadian Science Advisory Secretariat, regional advisory meeting of October 25-28, 2011 on the Atlantic Cod in Subdivision 3Ps. Additional publications from this process will be posted as they become available on the DFO Science Advisory Schedule.

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