Science Advisory Report 2019/050
Stock assessment of Northern cod (NAFO Divisions 2J3KL) in 2019
- The stock is being assessed using an integrated model (NCAM), which allows quantification of uncertainty in estimated and projected stock status.
- In the current assessment, the estimate of SSB in 2018 has been revised upward from 315 (95% CI = 223-444) to 383 (304-481) Kt. This resulted from a revision of the estimate of natural mortality (M) for 2017 from 0.74 (95% CI = 0.47-1.17) in the previous assessment, to the current estimate for 2017 of 0.53 (95% CI = 0.35-0.78).
- Spawning Stock Biomass (SSB) remains in the critical zone in 2019, at 48% of the Limit Reference Point (LRP) (95% CI = 37-63%). SSB was 398 Kt in 2019 (95% CI = 306-518 Kt).
- Estimated SSB in 2019 is greater than that projected in the previous assessment, resulting from a lower estimate of M in 2017.
- Natural mortality estimated from NCAM for ages 5+ for 2018 was 0.39 (95% CI = 0.24-0.65), which is a return to the levels for 2012-2016 (average 0.32).
- The estimated fishing mortality rate remains low, with an average value of 0.02 over the last 5 years.
- Recruitment (age 2) increased from lowest estimated levels of 36 million fish in 1995 to an average of 265 million in 2012-16. This recent average is 20% of the pre-collapse period of the 1980s.
- Three-year projections with catch ranging from zero to 1.3 times the model estimated catch for 2018 (13,796 t) indicated that the probability that SSB will reach the LRP by 2022 ranges between 6-9%. The probability of the stock in 2022 being greater than 2019 ranged from 63% to 73%.
- Ecosystem conditions are indicative of an overall low productivity state including low levels of phytoplankton and zooplankton, and low abundance of key forage species such as capelin and shrimp. These conditions may negatively impact cod productivity.
- 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.
- Predation by seals was not found to be a significant source of Northern cod mortality in the period 1985-2007. There is no indication that the impact of seal predation has changed since this time.
This Science Advisory Report is from the March 26-29, 2019 Stock Assessment of Northern Cod (Division 2J3KL). 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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