Research Document - 2011/004
The status of the Northern shrimp (Pandalus borealis) resource off Labrador and northeastern Newfoundland as of March 2010
By D.C. Orr, P.J. Veitch, D.J. Sullivan, and K. Skanes
Abstract
Updates of northern shrimp (Pandalus borealis) assessments were performed for NAFO Div. 2G, Hopedale + Cartwright Channels as well as Hawke Channel + Div. 3K, which correspond to shrimp fishing areas (SFA) 4, 5 and 6, respectively. Status of the resource in each area was inferred, in part, by examining trends in commercial catch, effort, catch-per-unit effort (CPUE), fishing pattern and size/sex/age composition of the catches. Fisheries independent data include an autumn multispecies research bottom trawl survey into SFAs 5 and 6 (1996-09). The Northern Shrimp Research Foundation, in partnership with Fisheries and Oceans Canada, conducted a shrimp based research survey into Div. 2G (SFA 4) during each of the past five summers (2005–09). Surveys in SFAs 4-6 provide information on distribution, abundance, biomass, size/ sex composition and age structure of shrimp.
Catches increased from 22,000 t in 1994 to over 114,000 t by 2007-08 due mainly to increases in Total Allowable Catch (TAC). The TAC for the 2009-10 management year was set at 120,345 t and catches for that year equaled 80,700 t. The TAC was not met due to operational/ commercial constraints.
Annual catches within SFA 6 increased from 11,000 t during 1994-96 to 80,700 t by 2007-08. The TAC for the 2009/10 management year was set at 85,725 t. Catches for the 2009-10 management year equaled 45,100 t as of April 7, 2010. Spatial distribution of the resource and large vessel fishery changed little over recent years. The spatial distribution of the small vessel fishery increased from 1998 to 2007 then decreased to 2009. The large (>500 t) vessel CPUE remained at a high level between 1995 and 2006 after which it decreased to 2009. The small vessel (<100 ft) CPUE increased to 2003, remained high until 2007 and then decreased to 2009.
Biomass and abundance indices (total, fishable and female) from fall multi-species surveys generally increased from 1997 to peak levels in 2006 but have since decreased by 50%. These indices dropped below the long term average in 2009. Recruitment indices have been variable, peaking in 2006, but have since declined to the long term average. The apparently strong 2004 year class (2006 index) did not lead to increased fishable biomass. The relationship between recruitment index and fishable biomass is uncertain.
Even though catches remained high over the period 2004–07, the exploitation rate index decreased as a result of increased fishable biomass over the 2003–06 period.
In terms of the precautionary approach framework, SSB is presently within the cautious zone at 97% of the provisional upper stock reference point (USR).
Catches within SFA 5 (Hopedale + Cartwright Channels) increased from 15,000 t in 1997-2002 to around 23,000 t in 2004-05 and 2008-09. The 2009-10 TAC was set at 23,300 t and 24,900 t were taken. CPUE has been trending upward from 1992 to 2001 and has been above the long term average since 1995. Percent total area fished within SFA 5 for the large (>500 t) vessel fleet to obtain 95% of their catch increased from 5–11% over the period 1985–2006, but has since decreased compared to the long term mean. It is a concern that the area fished has been decreasing while the CPUE is being maintained at a high level, suggesting the resource may be locally aggregated.
The SFA 5 survey fishable biomass index declined by 17% from 2006 to 2008. Fishable biomass in Cartwright Channel decreased by 40% in 2009; however, broad confidence intervals in 2009 indicate uncertainty. Recruitment in the short-term, while uncertain appears average. The exploitation rate index is approximately 20%, slightly above the long term mean. In terms of the precautionary approach framework, SSB in SFA 5 was in the healthy zone in 2008, well above the provisional USR.
Catches within SFA 4 increased from 4000 t in 1994 to 9,600 t by 2004-05. Approximately 10,700 t of shrimp were caught against a 11,320 t TAC during 2009-10. CPUE has increased since 2004-05 and is now well above the long term mean.
The NSRF-DFO research survey biomass indices (female and fishable) have been increasing throughout the five-year time period. The recruitment index increased from 2005 to 2008 and has changed little in 2009. Exploitation rate index has decreased from 16% in 2005 to 6% in 2009. In terms of the precautionary approach framework, SSB in SFA 4 was in the healthy zone in 2009, well above the provisional USR.
In conclusion, the resource appears to have been decreasing in the south but increasing in the north.
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