Shrimp fishing areas (SFA) 4-6 Northern Shrimp (Pandalus borealis) stock assessment in 2023

Abstract

Status SFA 4: The 2023 spawning stock biomass (SSB) index is above the Upper Stock Reference point (USR) with a 68% probability, with the stock remaining in the Healthy Zone. SFA 5: The 2023 SSB index is above the Limit Reference Point (LRP, with a 99% probability), but below the USR (with a 60% probability), moving the stock from the Healthy Zone to the Cautious Zone. SFA 6: The 2023 SSB index is below the LRP with a greater than 99% probability, with the stock remaining in the Critical Zone. Trends SFA 4: There have been general increases in biomass indices from time-series (2005–23) lows in 2018. Fishable biomass (FB) and SSB indices increased by 2% and 13% respectively from 2022 to 2023. SFA 5: There have been general decreases in biomass indices and they are currently amongst the lowest values in the time series (1996–2023). FB and SSB indices decreased by 17% and 8% respectively from 2021 to 2023. SFA 6: FB and SSB indices have remained at or near time-series (1996–2023) lows without trends since 2016. The FB index did not change from 2021 to 2023, and the SSB index decreased by 13% from 2021 to 2023. Ecosystem and Climate Change Considerations The Newfoundland and Labrador (NL) ocean climate varies on near-decadal timescales with cooling and warming phases known to impact ecosystem productivity. The current warming phase of the climate has been ongoing since about 2018 and has likely contributed to the improved conditions that have been observed at the lower trophic levels (i.e., phytoplankton, zooplankton). The NL bioregion continues to experience overall low productivity conditions, with total biomass well below pre-collapse levels (late-1980s), and has returned to a finfish dominated structure. Due to lack of data, conditions in 2G (SFA 4) are unknown. Under current ecosystem conditions, fishing and predation have been potential drivers of the stock in 2H (~SFA 5), while predation has been the stronger potential driver in 2J3KL (~SFA 6–7). Per capita net production of shrimp in 2J3KL remains lower in recent years than in the late-2000s. This trend is likely associated with impacts from predation, fishing, and ocean climate. No major changes in per capita net production of shrimp would be expected within the next 1–3 years based on these associations. Stock Advice The application of conversion factors to account for new survey vessels resulted in a revision of the biomass and exploitation rate indices (ERIs) in SFA 5 and 6 (1996–2021), and recalculation of the LRPs and USRs. The new vessels generally catch more shrimp than the CCG Needler and fewer shrimp than the CCG Teleost. These differences in catchability impact biomass indices and therefore the interpretation of past ERIs and calculations of current ERIs. The impact of this change represents annual changes of past FB indices’ values (1996–2021) ranging from -7.4– 18.9% for SFA 5 (median of -7.1%), and ranging from -6.6–21.7% for SFA 6 (median of - 1.0%). SFA 4: The ERI ranged between 6.8% and 36.7% from 2005/06 to 2022/23 and the preliminary ERI was 10.8% in 2023/24. If the Total Allowable Catch (TAC) is taken in 2023/24, the ERI would be 18.4%. SFA 5: The ERI ranged between 6.6% and 31.5% from 1997 to 2022/23 and could not be calculated for 2023/24 due to no survey occurring in 2022. If the 2023/24 TAC is maintained and taken in 2024/25, the ERI would be 25.9%. SFA 6: The 2018 rebuilding plan states a maximum ERI of 10% while the stock is in the Critical Zone. If the 2023/24 TAC is maintained and taken in 2024/25, the ERI would be 10.7%.