Research Document - 2012/158
Assessing the status of the cod (Gadus morhua) stock in NAFO Subdivision 3Ps in 2011
By B.P. Healey, E.F. Murphy, J. Brattey, N.G. Cadigan, M.J. Morgan, D. Maddock Parsons, and J.C. Mahé
Abstract
The status of the cod stock in Northwest Atlantic Fisheries Organization (NAFO) Subdivision 3Ps was assessed during a regional advisory process (RAP) held during October of 2011. Stock status was updated based upon information collected up to spring 2011. Principal sources of information available for the assessments were: a time series of abundance and biomass indices from Canadian winter/spring research vessel bottom trawl surveys, inshore sentinel surveys, science logbooks from vessels <35 ft, reported landings from commercial fisheries, oceanographic data, and tagging studies. Total landings for the 2010-2011 management year (April 1 to March 31) were 7,800 t or just 68% of the total allowable catch (TAC). Though this is the second consecutive year that the TAC was not fully taken, it is unusual. Industry participants indicated this discrepancy was primarily due to reduced profitability, additional market considerations, and some reduction in fish availability offshore. The 2011-2012 fishery was still in progress at the time of the RAP with provisional landings to date totaling of 2,600 t. The removals through recreational fishing are unknown since 2007, but based on previous estimates are thought to be a small fraction (~1%) of the commercial landings.
A complex of stock components are exploited in Subdiv. 3Ps. Thus the impact of fishing at specific TAC levels on all components cannot be quantified. However, the Fisheries and Oceans Canada (DFO) research vessel (RV) survey covers most of the stock, and it is thought that survey trends broadly reflect overall stock trends.
The abundance and biomass indices from the 2011 DFO RV spring survey were both lower than those in 2010, and both are presently below the time-series (1983 to 2010) average. The 2006 year-class is estimated to be well above average, and survey results for this year-class are comparable to the 1997 and 1998 year-classes, each of which contributed to stock growth and supported commercial fisheries for several years. The gillnet catch rates from inshore sentinel surveys and logbooks for vessels <35 ft suggest stability. However, recent line-trawl catch rates from these sources indicate decline.
Spawning stock biomass (SSB) estimated from a survey based cohort model decreased in recent years and was estimated to be below the limit reference point (LRP) during 2008 and 2009. Thereafter, SSB has increased, and in 2011 is estimated to be above the LRP, with a low probability of being below the LRP (0.08). A one year projection to 2012 using the cohort model indicated that survey SSB will continue to increase if total mortality is similar to current values (i.e., within ± 20%). This increase is due to the recruitment of the relatively strong 2006 year class (YC) to the spawner biomass. The projection also indicated that the probability of being below the LRP in 2012 is low (0.02 to 0.09). A three year projection to 2014 indicates subsequent declines in both total biomass and spawning biomass, and in 2014 the probability of being below the LRP ranges from 0.03 to 0.56, depending upon the assumed mortality.
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