Science Advisory Report 2017/051

Stock Assessment of NAFO Subdivision 3Ps Cod

Summary

• Consistent with recent assessments, a cohort model (SURBA) based on the spring Fisheries and Oceans Canada (DFO) survey was used to infer overall stock trends.
• The 2017 spawning stock biomass (SSB) is estimated to be in the Cautious Zone (54% above Blim) as defined by the DFO Precautionary Approach (PA) Framework. The probability that the stock is in the critical zone is 0.03.
• SSB decreased from 2012, but showed an increase in 2017. However, SSB is concentrated (75% of SSB) in ages 5 and 6, with few older (ages 7+) fish in the population.
• Recruitment has generally been at or above the time-series average since 2005, with particularly strong cohorts produced in 2006 and 2011.
• Estimated total mortality decreased slightly in 2016, but remains high. Over 2014-16, total mortality averaged 0.7 (50% survival per year), however the relative contributions of natural and fishing mortality to total mortality are unknown.
• Projection of the stock to 2020 was conducted assuming mortality rates will be within ± 20% of current values (2014 to 2016 average). Projected SSB shows a continuous decline to 2020 in most cases, with the decrease ranging from 23 to 58% (2017 to 2020). The risk of being below Blim by 2019 ranges from 0.09 and 0.73, and by 2020 from 0.25 to 0.94.
• Ecosystem signals observed in Subdiv. 3Ps in recent years indicate that structural changes are occurring, and overall ecosystem productivity may be low. Although the full impacts of these changes on cod itself are not fully known, they imply that at least some aspects of cod productivity may be impaired.

This Science Advisory Report is from the October 17-18, 2017 Assessment of NAFO Subdivision 3Ps Atlantic Cod. 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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