Science Advisory Report 2019/013

Assessment of Northern Shrimp on the Eastern Scotian Shelf (SFAs 13-15)

Summary

• As of November 15, 2018, 2410 mt of the 2600 mt Total Allowable Catch (TAC) for 2018 had been landed.
• The 2018 total biomass estimate showed stability at 23,449 mt (± 4,724 mt, 95% Confidence Interval (CI)) from the 2017 estimate of 23,382 mt (± 6,376 mt, 95% CI).
• The Eastern Scotian Shelf Shrimp stock has declined since 2014, as the 2009-2012 year classes have reached the end of their expected life span.
• The 2018 Spawning Stock Biomass (SSB, females) point estimate increased 2% to 12,599 mt and it remains below the Upper Stock Reference (USR, 14,558 mt). Based on the precautionary approach the Eastern Scotian Shelf Shrimp stock is considered to be in the Cautious Zone.
• The 2017 TAC (2600 mt) was maintained in 2018 to reflect declining fishable and spawning stock biomass resulting from the low recruitment contributions from 2009-2012 year classes. The unchanged precautionary TAC helped to further reduce both total and female exploitation to values of 10% and 12%, respectively.
• Belly-bag index values for 2016 and 2017 were consistent and low, suggesting poor recruitment over the past two seasons. However, the value for 2018 shows an increase in recruitment relative to the past two years.  
• The abundance index for both Age 2 and Age 4 Shrimp decreased in 2018, which is consistent with the low belly-bag Age 1 abundance index values found in 2017 (i.e. 2016 year class) and 2015 (i.e. 2014 year class), respectively.
• The 2013 year class increased the index of abundance for Age 5+ Shrimp in 2018.
• Ecosystem indicators were primarily influenced by temperature trends as two of three sympatric species trends were not updated for 2018.  The consistent decrease in temperatures and an increase in Snow Crab recruitment in the last few years, suggest that conditions are currently favourable for cold water species such as Shrimp.
• The overall mean summary indicator increased in 2018 and is in the yellow zone after being in the red zone for the past two years due to increases in indicators representing abundance, productivity, ecosystem characteristics, and a decrease in indicators representing fishing effects.
• While Age 4+ males decreased in 2018, it is uncertain whether this will translate into a decrease in the total biomass index in 2019. The 2013 year class is expected to recruit to the SSB at least until 2020.
• Continuation of a status-quo TAC will help to maintain low exploitation rates and to protect more of the 2013 year class as it recruits to the SSB.

This Science Advisory Report is from the December 13, 2018, Stock Assessment of Eastern Scotian Shelf Shrimp in Shrimp Fishing Areas (SFAs) 13-15. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

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