Science Advisory Report  2015/018

Assessment of Northern Shrimp (Pandalus borealis) in Shrimp Fishing Areas 4-6 (NAFO Divisions 2G-3K) and of Striped Shrimp (Pandalus montagui) in Shrimp Fishing Area 4 (NAFO Division 2G)

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 (1996‑2014). 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 (2005‑14).
• 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.

Environment and Ecosystem

• Data from SFAs 5 and 6 indicate that shrimp constitutes an important part of the diet of many groundfish species. In recent years the fraction of shrimp in the diets has declined, while another key forage species, Capelin, has been increasing. Relevant data from SFA 4 are lacking.
• In SFA 6, total biomass of fishes that are potential shrimp predators has increased. As a consequence, their consumption of all types of food was estimated to have tripled since the late 1990s, and has remained around that level since 2010. Estimates of total predation on shrimp peaked in 2011 and have since declined to be around twice the level of the mid-2000s. Future trends will depend on the trajectory of predator biomass and availability of alternative prey, like Capelin.

SFA 6 Pandalus borealis

• Commercial catch has been about 60,000 t over the past four years. It is expected that the 2014/15 TAC of 48,196 t will be taken.
• Large vessel standardized CPUE has varied without trend since 2010 while small vessel CPUE has been increasing.
• Fishable biomass index declined from 421,000 t in 2011 to 216,000 t in 2013, the lowest in the time series, and increased slightly to 233,000 t in 2014.
• Female spawning stock biomass (SSB) index declined from 250,000 t in 2011 to about 136,000 t in 2013 and 2014, the lowest level in the series.
• Climate-driven changes (e.g., time of phytoplankton bloom) and increases in predation pressure suggest low recruitment to the fishable biomass in the medium term.
• The exploitation rate index ranged between 5.6% and 22.3% from 1997 to 2014/15, and has averaged 18.3% in the last five years. The 2014/15 exploitation rate index will be 22.3% if the TAC is taken.
• Female SSB index, at its lowest level in the time series, was assessed to be below the midpoint of the cautious zone within the Integrated Fisheries Management Plan (IFMP) Precautionary Approach (PA) Framework. If the 48,196 t TAC is maintained and taken in the 2015/16 season, the exploitation rate index will be 20.7%.

SFA 5 Pandalus borealis

• Commercial catch had been about 23,000 t over the past five years. It is expected that the 2014/15 TAC of 20,970 t will be taken.
• Standardized large vessel CPUE increased over the last 4 years.
• Fishable biomass index has been relatively stable since 2010, and was 116,000 t in 2014.
• Female SSB index has changed little since 2010, and was 60,000 t in 2014.
• Climate-driven changes (e.g., time of phytoplankton bloom) and increases in predation suggest low recruitment to the fishable biomass in the medium term.
• The exploitation rate index has varied without trend and averaged 18% since 2010.
• Female SSB index was assessed to be in the Healthy Zone within the IFMP PA Framework. If the 20,970 t TAC is maintained and taken in 2015/16, then the exploitation rate index will be 18.1%.

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 two years.
• Since 2010, large vessel standardized CPUE fluctuated above the long term mean.
• Fishable biomass index has been relatively stable since 2010, and was 134,000 t in 2014.
• Female SSB index has changed little since 2010 and was 89,800 t in 2014.
• Prospects for recruitment to the fishable biomass are uncertain.
• Since 2010, the exploitation rate index has shown an increasing trend, and reached 11.2% by 2014/15.
• Female SSB index was assessed to be in the Healthy Zone, within the IFMP PA Framework.

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 1,200 t in 2014. The by-catch limit of 4,033 t has not been taken in the past two years.
• Fishable biomass index has doubled since 2010 and was 34,100 t in 2014.
• Female SSB is unknown.
• Prospects for recruitment to the fishable biomass are unknown.
• The exploitation rate index would have been 11.8% in 2014/15 if the by-catch limit had been taken.

This Science Advisory Report is from the February 17-23, 2015 Assessment of Northern and Striped Shrimp. 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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