Évaluation de la crevette nordique (Pandalus borealis) et de la crevette ésope (Pandalus montagui) dans la zone de pêche de la crevette (ZPC) 4 en 2022 et évaluation d'un point de référence limite (PRL) proposé pour la crevette ésope dans la ZPC 4

Abstract

Resource status of Northern Shrimp (also known as Pink Shrimp) and Striped Shrimp were assessed based on Northern Shrimp Research Foundation (NSRF)-DFO summer trawl survey data (SFA 4) and commercial catch data. It is recognized that Northern Shrimp are distributed broadly over the Northwest Atlantic Ocean, including SFA 4, and all of these areas are connected through larval dispersal. Rates of exchange of adults are less understood. Preliminary research demonstrates localized genetically distinct pools that may be linked to smaller-scale oceanographic profiles (i.e., gyres). These linkages need to be considered to interpret dynamics within and among assessment areas. There is a spatial scale mismatch between the assessment unit and the dynamics of the wider population. Northern Shrimp in SFA 4 is currently assessed relative to a Limit Reference Point (LRP) and Upper Stock Reference point (USR) in accordance with DFO’s Precautionary Approach (PA) Framework. The majority of the population of Striped Shrimp spans the Eastern Assessment Zone (EAZ), Western Assessment Zone (WAZ) and SFA 4. The extent of movement between these zones are unknown; therefore, understanding resource dynamics as a whole requires integrating information from across the entire range. Environment & Ecosystem Environmental conditions in the Northwest Atlantic experience fluctuations at decadal time scales, with potential impacts on availability of optimal Pandalid habitat. A composite climate index remained high and indicated that 2022 was the ninth warmest of the time series (1950-present), continuing the ongoing warming trend since 2018. The Spring phytoplankton bloom in SFA 4 in 2021 was the earliest in the time series but returned to more normal timing in 2022. Multiple analyses suggest that thermal habitat available to Pandalid Shrimp in SFA 4 has been favorable since the late-2010s. Limit Reference Point for SFA 4 Striped Shrimp In accordance with DFO’s PA Framework, an LRP for Striped Shrimp based on the combined survey data time series (2005–22) of SFA 4, EAZ, and WAZ was developed from a spatiotemporal model that created a new fishable biomass index (FBpop) to determine the stock status in SFA 4. The adopted LRP is based on FBpop and was calculated as the average of o the lowest fishable biomass at which the stock increased and remained above the geometric mean for a period of at least 3 years, o the lowest observed fishable biomass in the time series, and o 40% of the geometric mean of the fishable biomass index throughout the time series. SFA 4 Northern Shrimp Northern Shrimp Fishable Biomass (FB) and female spawning stock biomass (SSB) indices were unusually high in 2021. Despite a year-over-year decrease in 2022 (by 47% to 79,500 t for FB, and by 55% to 51,300 t for SSB), the recent trend suggests continued increases from a historic low in 2018. The Exploitation Rate Index (ERI) ranged between 5.8% and 36.7% from 2005/06 to 2021/22 and was 15.3% in 2022/23. If the Total Allowable Catch (TAC) is taken in 2022/23, the ERI will be 16.3%. In 2022, Northern Shrimp in SFA 4 was in the Healthy Zone within the PA Framework, just above the USR, with a 53% probability of being in the Cautious Zone. SFA 4 Striped Shrimp In SFA 4, Striped Shrimp Fishable biomass and SSB indices have increased since 2021, by 25% (to 38,800 t) and 37% (to 30,600 t) respectively and are above the long-term means (2005–21) of the survey time series. The ERI ranged between 0.8% and 23.3% from 2005/06 to 2021/22 and was 9.0% in 2022/23. If the TAC is taken in 2022/23, the ERI will be 10.4%. In 2022, Striped Shrimp biomass (FBpop) was estimated to be 5 times the LRP. Other indices of stock health, including the potential predator index, total egg production index, and SFA 4 specific fishable biomass index showed no cause for concern. Striped Shrimp in SFA 4 is considered in a healthy state in the PA Framework.