Research Document - 2012/022

Assessment of lobster off the coast of eastern Cape Breton and the eastern and south shores of Nova Scotia (LFAs 27-33)

By M.J. Tremblay, D.S. Pezzack, C. Denton, M. Cassista-Da Ros, S.J. Smith, A.RReeves, ASilva, and SArmsworthy

Abstract

Lobster Fishing Areas (LFAs) 27-33 are located on the Atlantic coast of Nova Scotia, stretching from the northern tip of Cape Breton Island in the north to Barrington Bay (Shelburne County) in the south An assessment of the status of these LFAs was conducted in 2011 The assessment is for the seasons ending in spring 2010 Indicators of stock health come primarily from the catch rate (CPUE) in commercial traps, or in Fishermen and Scientists Research Society (FSRS) traps Other data inputs include commercial landings and lobster sizes Analysis of the sizes of lobsters in FSRS traps versus those captured in commercial traps indicates they are comparable, with the exception of LFA 33 during the fall season In LFA 27, indicators of stock health are positive Landings in 2010 in LFA 27 (2,568 t) and the mean for the last 3 years (2,532 t) were above the median for 1985 to 2004 (1,996 t) CPUE abundance indicators for sublegals, legal sizes and ovigerous (“berried”) females are positive The increase in the abundance indicators for ovigerous females and sublegals is consistent with the expectations from the increase in Minimum Legal Size (MLS) in LFA 27 from 70 to 76 mm carapace length (CL) (1998-2002) and from 76 to 81 mm CL (2007-2009) In LFAs 28-32, indicators of stock health for lobsters are mainly positive Landings in 2010 in LFAs 28-32 (3,866 t) and the mean for the last 3 years (4,224 t) were well above the median for 1985 to 2004 (822 t) CPUE abundance indicators for sublegal and legal sizes indicate substantial increases A CPUE index for sublegals increased from 2002 to 2007 and declined recently, but the mean of the last 3 years is still above the median for 2000 to 2007 An egg index for LFA 31a was substantially higher in more recent years (2008 to 2010) compared to 2002 to 2003 In LFA 33, indicators of stock health are positive Landings in LFA 33 for the 2009-10 season (3,377 t) and the mean for the last 3 years (3,126 t) were above the median for 1984-85 to 2003-04 (2,071 t) CPUE abundance indicators are positive or neutral Unstandardized commercial CPUE from available logs in LFA 33 CPUE has trended upwards since the 1990s A temperature-corrected abundance index for sublegals (76-80 mm CL) increased from 1999-00 to 2008-09 Unstandardized CPUE of sublegals in FSRS traps increased from the 2000-01 season, while unstandardized CPUE of legal sizes fluctuated without trend.

An index of exploitation rate (ER) has been stable or declined slightly in all assessment units It is concluded that the current levels of exploitation do not threaten sustainability in any of the assessment units under current environmental conditions

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