Terms of Reference

Update of indices of abundance to 2019 of Witch Flounder (NAFO Div. 4RST), Winter Flounder (NAFO Div. 4T) and White Hake (NAFO Div. 4T) assessed and managed by DFO Gulf Region

Regional Science Response Process – Gulf Region

December 10, 2019
Moncton, New Brunswick

Chairperson: Gérald Chaput

Context

Full peer-reviewed stock assessments of groundfish species in the southern Gulf of St. Lawrence are now mostly conducted on a multi-year cycle with monitoring continuing on an annual basis. Following on the advice of DFO (2016a) and as identified in the respective peer reviewed stock assessments for Witch Flounder (DFO 2017a) and Winter Flounder (DFO 2017b), an update of indicators of stock status would be completed at the end of the year 2019, mid-way in the five-year assessment and fisheries management cycle.

An update of indicators of status for White Hake was requested from DFO Fisheries and Aquaculture Management, Gulf Region. For White Hake, the most recent stock status information is from the Recovery Potential Assessment 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) 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 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.

Objective

The objectives of the meeting are to review the indicators of abundance to 2019 for the following species:

• Witch Flounder (Glyptocephalus cynoglossus) of NAFO Divs. 4RST; review and advise on whether the agreed indicator has exceeded the species specific threshold value that would recommend a full assessment earlier than the prescribed multi-year assessment cycle. As concluded in DFO (2017a), as the Witch Flounder stock of NAFO Divs. 4RST is projected to increase in abundance and have a low probability (< 30%) of being below the LRP by 2021, a re-assessment would be recommended before 2021 if the stock status indicator (30+ cm biomass index) signaled a decline of the SSB to below the LRP.
• Winter Flounder (Pseudopleuronectes americanus) of NAFO Div. 4T review and advise on whether the agreed indicator has exceeded the species specific threshold value that would recommend a full assessment earlier than the prescribed multi-year assessment cycle. DFO (2017b) concluded that as the stock was below the LRP and expected to remain there even in the absence of fishing, a re-assessment would be recommended before 2021 if the stock status indicator (commercial-sized Winter Flounder, >= 25 cm, in units of trawlable biomass) signaled an increase in abundance to a level above the LRP.
• For White Hake (Urophycis tenuis), of NAFO Div. 4T, review and advise 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) and review the distribution information of adult White Hake in the southern Gulf relative to the distribution recovery objective proposed in DFO (2016b).

Expected Publications

• Science Response

Expected Participation

• Fisheries and Oceans Canada (DFO) (Ecosystems and Oceans Science, and Ecosystems and Fisheries Management)

References

DFO. 2016a. Guidelines for providing interim-year updates and science advice for multi-year assessments. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2016/020.

DFO. 2016b. Recovery Potential Assessment for White Hake (Urophycis tenuis): Population of the Southern Gulf of St. Lawrence. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2016/034.

DFO. 2017a. Stock assessment of Witch Flounder (Glyptocephalus cynoglossus) in the Gulf of St. Lawrence (NAFO Divs. 4RST) to 2016. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2017/036.

DFO. 2017b. Stock assessment of Winter Flounder (Pseudopleuronectes americanus) of the southern Gulf of St. Lawrence (NAFO Div. 4T) to 2016. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2017/022.

Swain, D.P., Savoie, L., and Cox, S.P. 2016. Recovery potential assessment of the Southern Gulf of St. Lawrence Designatable Unit of White Hake (Urophycis tenuis Mitchill), January 2015. DFO Can. Sci. Advis. Sec. Res. Doc. 2016/045. vii + 109 p.