Science Response 2020/008

Updated indices of abundance to 2019 for Winter Flounder from NAFO Div. 4T, Witch Flounder from NAFO Divs. 4RST and White Hake from NAFO Div. 4T

Context

Fisheries and Oceans Canada (DFO) Ecosystems and Fisheries Management has instituted a multi-year management approach for the Winter Flounder stock of the southern Gulf of St. Lawrence (sGSL; NAFO Div. 4T) and the Witch Flounder stock of the Gulf of St. Lawrence (GSL; NAFO Div. 4RST). The last full assessments of the Winter Flounder stock of the sGSL (Surette and Rolland 2019) and the Witch Flounder stock of the GSL (Ricard and Swain 2018) were completed in March 2017 with advice for the May 2017 to May 2022 fisheries period. Following on the advice of DFO (2016a) and as identified in the respective science advisory reports for Winter Flounder (DFO 2017a) and Witch Flounder (DFO 2017b), an update of indicators of stock status is to be provided at the end of the year 2019, mid-way in the five-year assessment and fisheries management cycle. In line with this advice, this Science Response Report, resulting from the Science Response Process of December 12, 2019, provides an update of indices of abundance to 2019 for Winter Flounder of the sGSL and Witch Flounder of the GSL, assessed and managed by DFO Gulf Region. For both Winter Flounder and Witch Flounder, the analysis of the indicator relative to an identified trigger value is presented to determine if a full stock re-assessment may be warranted earlier than March 2022, the next scheduled assessments of the five-year stock assessment cycle for these two species.

DFO Fisheries and Aquaculture Management has also requested an update of indicators for the White Hake population of the sGSL (NAFO Div. 4T). The most recent stock status information is from the Recovery Potential Assessment (RPA) of the Southern Gulf of St. Lawrence Designatable Unit completed in 2016 (DFO 2016b; Swain et al. 2016). DFO (2016b) indicated that the estimated spawning stock biomass (SSB) of White Hake in 2013 was about 30% of the proposed abundance recovery target (12,800 t, 40% of the SSB producing the maximum surplus production of recruits) and that the estimated SSB has been below the abundance recovery target since 1995. Additionally, DFO (2016b) proposed a distribution recovery target corresponding to the return of White Hake to inshore waters of the southern Gulf of St. Lawrence, the areas where they predominantly occurred in summer from the 1970s to the mid-1990s. A review and advice on the status using an indicator of adult abundance (or SSB) from the September multi-species research vessel survey relative to the proposed abundance recovery target (DFO 2016b) is presented. The distribution information of adult White Hake in the sGSL relative to the distribution recovery objective proposed in DFO (2016b) is also presented.

Science Response 2020/008 (PDF, 974 KB)

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