Science Advisory Report 2023/013
Assessment of Northern Shrimp (Pandalus borealis) and Striped Shrimp (Pandalus montagui) in the Eastern and Western Assessment Zones, February 2023
Summary
- The last full assessment was completed in 2021. This assessment has updated the stock status for Pandalus borealis and P. montagui in the Eastern Assessment Zone (EAZ) and Western Assessment Zone (WAZ), to incorporate survey and fishery data from the last two years. Limited predator-prey information, potential redfish competition, and oceanographic data were reviewed for additional ecosystem context.
- Pandalus borealis and P. montagui are distributed broadly over the Northwest Atlantic Ocean. The associated assessment areas, including the EAZ, WAZ and Shrimp Fishing Area 4 (SFA4), are connected through larval dispersal, but rates of exchange of adults are less understood. These linkages need to be considered to interpret fluctuations in biomass within and among assessment areas, even within the same year.
- The ocean climate in the NW Atlantic experiences fluctuations at decadal time scales, with potential impacts on availability of optimal Pandalid habitat and/or predator-prey interactions in the EAZ/WAZ. In 2022, bottom temperatures in the EAZ were lower than the 2006–2021 average for the first time since 2017, but they remained relatively high in the WAZ after the record high in 2021.
- The emergence of a large biomass of juvenile redfish in the EAZ over the last three years may have indirect (competition) and/or direct (future predation) impacts on the shrimp population. The magnitude and duration of these impacts are unknown.
- In both the EAZ and WAZ the stocks are currently assessed relative to established Limit Reference Points (LRPs) and previously proposed Upper Stock Reference points (USRs) in accordance with DFOs Precautionary Approach (PA) Framework.
Eastern Assessment Zone – Pandalus borealis
- Total catch varied without trend around 6,000 t from 1997 through 2022/23. Catch statistics in 2022/23 are preliminary.
- The fishable biomass index in 2022 declined to the lowest value in the time series (36,911 t). This was below both the long term mean (2009–2021; 63,642 t) and reference period mean (2009–2019; 62,849 t).
- The female spawning stock biomass index (SSB) in 2022 declined to the lowest value in the time series (23,771 t). This was below both the long term mean (2009–2021; 40,374 t) and reference period mean (2009–2019; 39,459 t).
- Both the reported and potential exploitation rates were the highest in the time series. The reported exploitation rate index for 2022/23 was 19.4% with 67% of the Total Allowable Catch (TAC) taken. Should the entire 2022/23 TAC of 10,732 t be taken, the potential exploitation rate index would be 29.1%.
- Pandalus borealis stock in the EAZ is currently above the established LRP (15,800 t), but below the proposed USR. Based on the proposed USR of 31,600 t, this would place the stock in the Cautious zone with a 98.3% probability.
Eastern Assessment Zone – Pandalus montagui
- Total catch in 2022/23 was 1,419 t, 101.4% of the 1,400 t TAC. Catch statistics in 2022/23 are preliminary.
- The fishable biomass index in 2022 was 14,325 t. This was above both the long term mean (2009–2021; 12,397 t) and reference period mean (2009–2019; 11,715 t).
- The female spawning stock biomass index (SSB) in 2022 was 10,428 t, above both the long term mean (2009–2021; 8,267 t) and reference period mean (2009–2019; 7,644 t).
- The reported exploitation rate index for 2022/23 was 9.9% with 101.4% of the TAC taken.
- Pandalus montagui stock in the EAZ is currently well above the established LRP (3,100 t) and the proposed USR (6,100 t). This would place the stock in the Healthy zone with a 93.1% probability.
Western Assessment Zone – Pandalus borealis
- Total catch in 2022/23 was 318 t, which is 8.0% of the 3,958 t TAC. Catch statistics in 2022/23 are preliminary.
- The fishable biomass index in 2022 was 23,939 t. This was above the long term mean (2014–2021; 19,994 t) and reference period mean (2014–2019; 18,223 t).
- The female SSB index in 2022 was 15,899 t, above both the long term mean (2014–2021; 11,402 t) and reference period mean (2014–2019; 10,243 t).
- The reported exploitation rate index for 2022/23 was 1.3% with 8.0% of the TAC taken. Should the entire 2022/23 TAC of 3,958 t be taken, the potential exploitation rate index would be 16.5%.
- Pandalus borealis stock in the WAZ is currently well above the established LRP (4,100 t) and the proposed USR (8,200 t). This would place the stock in the Healthy zone with a 98.8% probability.
Western Assessment Zone – Pandalus montagui
- Total catch in 2022/23 was 11,195 t, which is 92.6% of the 12,096 t TAC. Catch statistics in 2022/23 are preliminary.
- The fishable biomass index in 2022 was 104,737 t and was the highest in the time series. This is well above the long term mean (2014–2021; 56,440 t) and reference period mean (2014–2019; 56,079 t).
- The female SSB index in 2022 was 61,058 t, above both the long term mean (2014–2021; 30,937 t) and reference period mean (2014–2019; 30,698 t).
- The reported exploitation rate index for 2022/23 was 10.7% with 92.6% of the TAC taken. Should the entire 2022/23 TAC of 12,096 t be taken, the potential exploitation rate index would be 11.5%.
- Pandalus montagui stock in the WAZ is currently well above the established LRP (12,300 t) and the proposed USR (24,600 t). This would place the stock in the Healthy zone with a >99.9% probability.
This Science Advisory Report is from the February 15–16, 2023 regional peer review on the Stock Assessment of Northern Shrimp (Pandalus borealis) and Striped Shrimp (Pandalus borealis) in the Eastern Assessment Zone and Western Assessment Zone for the 2023-24 fishing season. 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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