Science Advisory Report 2014/001

Stock Assessment of NAFO subdivision 3Ps cod

Summary

• Information available to evaluate stock status consisted of total commercial landings (1959-2012), log-book data (1997-2012), Canadian research vessel (RV) trawl surveys (1972-2013), sentinel surveys (1995-2013), Canadian observer data (1997-2012), results of recent tagging experiments (2009-12) and a telephone survey of Canadian fish harvesters pertaining to the 2012/13 fishery. Consistent with recent assessments, a survey based cohort model (SURBA) was used to infer overall stock trends.
• Reported landings by both Canada and France have been below the TAC since the 2009/10 season, and the proportion of the TAC taken has been decreasing. During the 2012/13 season, less than half (42%) of the 11,500 t TAC was landed.
• Sentinel gillnet catch rates have been very low since 1999, and in 2012 the gillnet index was near the lowest in the time-series. Sentinel linetrawl catch rates from the past four years have also been below average.
• Gillnet catch rates from logbooks of vessels <35' have been stable since 1999, though the 2012 estimate is the lowest in the time-series. Linetrawl catch rates decreased over 2006-10, and have subsequently been relatively stable near the time-series average.
• Although at-sea observer coverage is relatively low for most years and areas (overall, 1.5% for fixed gear; 14% for mobile gears), catch rates from gillnets, line-trawls and otter trawls generally support that recent values are among the lowest in the time-series (1997-2012).
• Average annual exploitation rates based on various size groups of cod tagged and released in Placentia Bay have been variable over 2009-12. In 2011, estimates ranged from 7-14% but increased to 11-21% in 2012, even though the full TAC was not taken in either year.
• Total mortality rates reflect mortality due to all causes, including fishing. Estimated total mortality from a cohort model has been decreasing since 2006, with an average 2010-12 value of 0.44 (36% annual mortality). Current mortality rates are near the time-series average when less than half of the 2012/13 TAC was taken.
• Recent recruitment (2004-09 cohorts) has improved. In particular, the 2006 cohort is estimated to be well above the time-series (1983-2012) average, and preliminary indications are that the 2011 cohort is the strongest in the time-series.
• The basis for a limit reference point (LRP) for this stock is BRecovery, defined as the lowest observed spawning stock biomass (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.
• Over 2009-13, SSB has increased considerably. The 2013 estimate is approximately twice the level of the LRP, and is near the (1983-2013) time-series maximum. The probability of being below the LRP in 2013 is very low (<0.01).
• Three-year projections were conducted assuming future mortality rates will be within ±20% of current values (2010-12 average). Projection scenarios indicate that the 2014 SSB will remain stable or increase slightly from the 2013 estimate. However, by 2016, results indicate SSB will increase to about 3 to 4 times the LRP. The particularly large increase in SSB projected from 2015 to 2016 is highly uncertain, being heavily influenced by the very large preliminary estimate for the 2011 year-class.

This Science Advisory Report is from the October 15-18, 2013 3Ps Cod and Witch Flounder Stock Assessment. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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