Science Advisory Report 2020/018

Stock Assessment of NAFO Subdivision 3Ps Cod

Summary

• A new integrated state space model resulting from the 2019 3Ps Cod Framework was used to assess the status of the stock and estimate fishing mortality. This model incorporates catch (1959-2019), time varying natural mortality informed by trends in cod condition, and includes abundance indices from bottom trawl surveys conducted by Canada (1983-2005, 2007-2019), France (1978-1991), industry (GEAC, 1998-2005), and standardized catch rate indices from the Sentinel gillnet and line-trawl surveys (1995-2018).
• A new biomass limit reference point (LRP) was determined for the stock based on the relationship between spawning stock biomass (SSB) and recruitment estimated from the model. The LRP is 66,000 t of SSB.
• Spawning Stock Biomass (SSB) at January 1, 2020 is estimated to be 16 kt (12 kt - 21 kt). The stock is in the Critical Zone (24% of Blim (18-32%)) as defined by the DFO Precautionary Approach (PA) Framework. The probability of being below Blim is >99.9%.
• The new model and the revision of the basis for defining the LRP has led to a change in the perception of status of this stock. The stock is now estimated to have been below Blim since the early 2000s.
• The estimated fishing mortality rate (ages 5-8) has ranged between 0.12 and 0.21 since 2010 and in 2019 was 0.21 (0.15–0.30), with an assumed catch of 4453 t.
• Natural mortality was estimated to be 0.49 (0.41–0.58) (ages 5-8) in 2019. Values during the last four years are the highest in the time series.
• Recruitment (age 2) estimates have been below the long term average since the mid-1990s.
• Projection of the stock to 2022 was conducted assuming fishery removals to be within +/- 30% of current levels, assuming a catch of 4453 t for 2019, and with no catch. Under these scenarios, there is a probability >99% that the stock will remain below Blim between 2020 and the beginning of 2022.
• The probability of stock growth to 2022 is 1% or less across catch scenarios (+/- 30% of current levels), and is 16% when there are no removals.
• Natural mortality plays an important role in projections for this stock. If natural mortality rates are appreciably different from those used, projected outcomes will differ from values reported above.
• Bottom temperatures in 3Ps remain above normal, and the spring bloom continues to be reduced in magnitude. Zooplankton biomass in 3Ps was near normal in 2017 and 2018 after four years of low production, with an increased proportion of smaller species. Data were unavailable from 2019. Ongoing warming trends, together with an increased dominance of warm water fishes, indicate that this ecosystem continues to experience structural changes. Reduced growth and condition indicate that cod productivity in 3Ps is reduced.
• Consistency with the DFO decision-making framework incorporating the Precautionary Approach requires that removals from all sources must be kept at the lowest possible level until the stock clears the critical zone.

This Science Advisory Report is from the November 19-22, 2019 Assessment of NAFO Subdivision 3Ps Atlantic Cod. An assessment of 3Ps American Plaice was also conducted during this meeting and a separate advisory report is available for that stock. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Science Advisory Report 2020/018 (PDF, 1,340 KB)

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