Science Advisory Report 2020/041

Assessment of St. Mary’s Bay Longhorn Sculpin (Myoxocephalus octodemspinosus)

Summary

• Landings of St. Mary’s Bay Longhorn Sculpin peaked at 235 t and 229 t in 2011 and 2012, respectively, but declined to 29 t in 2019.
• Since 2011, landings of Winter Flounder bycatch in the Sculpin fishery have increased steadily and exceeded Sculpin landings in 2019. Other landed species include unspecified skates, Haddock, and Atlantic Halibut.
• Crustaceans represented 74% of all discarded bycatch (1999–2019 average) and included American Lobster, Jonah Crab, and Rock Crab. Winter Flounder discards represented 40% of all discards in 2018 and 2019.
• The average size of Longhorn Sculpin and the percentage of fish >23 cm (size-at-50% maturity) in the fishery catch-at-size declined during the early (1999–2006) and more recent (2009–2019) periods of the fishery, and they have both been below the long-term average since 2015.
• Although the overall spatial distribution of Longhorn Sculpin from the DFO Summer Research Vessel (RV) Survey does not appear to have changed, there has been a notable decrease in survey catches on the eastern Scotian Shelf and the outer Bay of Fundy since 2000. 
• Biomass indices for survey strata in 4X and stratum 490 (adjacent to St Mary’s Bay) have been below the long-term mean (1970–2019) since 2010.
• The average size of Longhorn Sculpin and percentage of fish >23 cm in DFO Summer RV Survey catches show a declining trend in survey strata in 4X and stratum 490 from 1970 to 2019, but the decline is steeper for stratum 490, especially since 2000.
• In season exploitation rates were above 30% in 2006 and from 2009–2015, and potentially as high as 75–76% in 2011 and 2012, when landings were highest.
• The median of the Catch Per Unit Effort (CPUE) time series was used as a proxy of biomass at maximum sustainable yield (BMSY). The Limit Reference Point (LRP) was calculated as 40% of BMSY. The 3-year median CPUE is used for determining stock status.
• The CPUE declined rapidly to levels approaching 40% of the time series median (LRP proxy) in 2006 and 2019, in close proximity to the Cautious/Critical zone boundary.
• Additional indices to monitor the stock were identified and support the conclusion that the stock is approaching the Cautious/Critical zone boundary.

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  This Science Advisory Report is from the April 15, 2020, St. Mary’s Bay Sculpin Review. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

  

  Science Advisory Report 2020/041 (PDF, 1,106 KB)

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