Science Advisory Report  2016/028

An assessment of Northern Shrimp (Pandalus borealis) in Shrimp Fishing Areas 4-6 and of Striped Shrimp (Pandalus montagui) in Shrimp Fishing Area 4 in 2015

Summary

• Resource status of Northern Shrimp in Shrimp Fishing Areas (SFAs) 5 and 6 was updated based on DFO fall multi-species trawl survey data (1996‑2015). Resource status for Northern Shrimp and Striped Shrimp in SFA 4 was updated based on Northern Shrimp Research Foundation (NSRF)-DFO summer trawl survey data (2005‑15).
• Trawl survey data for SFAs 4‑6 provided information on shrimp distribution, length frequencies, and biomass. Trends in fisheries performance were inferred from total allowable catch (TAC), commercial catch to date, fishery catch per unit effort (CPUE) and fishing patterns.
• Precautionary Approach (PA) reference points have been revised from the previous assessments, in accordance with refinements in the biomass estimation method. The PA framework itself has not changed.

Environment and Ecosystem

• The regional Composite Climate Index declined for the fifth year in a row to seventh lowest in 66 years, indicating a continued regional cooling trend since 2010 which is a departure from broader warmer-than-average conditions across the north Atlantic.
• As in 2014, the seasonal cycle of surface sea temperature was characterized by a colder than average spring which, combined with a delayed retreat of sea ice, resulted in later than average onset of the spring phytoplankton bloom. This may lead to stronger shrimp productivity in the medium term.
• Fall bottom temperatures in SFA 6 were above normal, resulting in near normal and above normal areas of the potential thermal habitat for shrimp in Northwest Atlantic Fisheries Organization (NAFO) Divisions 2J and 3K, respectively.
• Environmental forcing, predation and fishing are correlated with subsequent shrimp production. The build-up of shrimp until the mid‑2000s occurred during a period with a combination of favorable environmental conditions and reduced predation.
• Shrimp per-capita production has declined since the mid‑2000s. Environmental conditions and increasing predation pressure appear as important drivers for the recent decline. However, recent departures in environmental conditions from the decadal trend may lead to increased shrimp per-capita production over the medium term but are unlikely to trigger a rapid rebuilding of the resource.

SFA 6 Pandalus borealis

• Commercial catch has been about 50,000 t over the past two years. It is expected that the 2015/16 TAC of 48,196 t will be taken.
• Large and small-vessel standardized CPUE have varied without trend since 2010 around the long-term mean.
• Fishable biomass index declined from 785,000 t in 2006 to 138,000 t in 2015 which is the lowest in the time series. There was a 41% decline between 2014 and 2015.
• Female spawning stock biomass (SSB) index declined from 466,000 t in 2006 to 89,000 t in 2015 which is the lowest in the time series. There was a 35% decline between 2014 and 2015.
• The exploitation rate index ranged between 5.5% and 21.4% from 1997 to 2015/16, and has averaged 18.3% in the last five years. The 2015/16 exploitation rate index will be 20.7% if the TAC is taken.
• The female SSB index is currently close to the limit reference point (LRP), in the Cautious Zone of the Integrated Fisheries Management Plan (IFMP) PA Framework, with a 20% probability that it is in the Critical Zone. If the 48,196 t TAC is maintained and taken in the 2016/17 season, the exploitation rate index will be 34.9%.

SFA 5 Pandalus borealis

• Commercial catch has been about 23,000 t over the past five years. It is expected that the 2015/16 TAC of 23,300 t will be taken.
• Standardized large-vessel CPUE over the last four years has been stable at high levels.
• Fishable biomass index has been relatively stable since 2010, and was 148,000 t in 2015.
• Female SSB index has changed little since 2010, and was 83,000 t in 2015.
• The exploitation rate index has varied without trend around 15% from 1997‑2015/16.
• Female SSB index is in the Healthy Zone within the IFMP PA Framework. If the 23,300 t TAC is maintained and taken in 2016/17, then the exploitation rate index will be 16%.

SFA 4 Pandalus borealis

• Commercial catch increased from approximately 10,000 t from 2005/06‑2011/12 to about 15,000 t in the past three years.
• Large-vessel standardized CPUE fluctuated without trend near the long term mean.
• The fishable biomass index varied without trend from 2005 to 2015 with the 2015 point estimate at 91,000 t, which represents a decrease of 13% from 2014.
• The female SSB index for 2015 was 58,000 t, representing a decrease of 18% from 2014.
• The exploitation rate index reached 16.5% by 2015/16.
• Female SSB index in 2015 was in the Healthy Zone within the IFMP PA Framework with a 40% probability of having been in the Cautious Zone.

SFA 4 Pandalus montagui

• Commercial catch of P. montagui, taken as by-catch in the P. borealis fishery, increased from 280 t in 2008 to 4,700 t in 2012 and declined to 2,135 t in 2015. The by-catch limit of 4,033 t has not been taken in the past three years.
• Fishable biomass index for 2015 was 47,000 t, an increase of 52% from 2014.
• Female SSB is unknown.
• If the by-catch limit had been taken, the exploitation rate would have been 8.6% in 2015/16.
• There is no IFMP PA Framework for this resource.

This Science Advisory Report is from the April 6‑8 and April 11‑12, 2016 Assessment of Northern and Striped Shrimp. Additional publications from this meeting will be posted on the DFO Science Advisory Schedule as they become available.

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