Science Advisory Report  2012/031

Assessment of the Atlantic Mackerel Stock for the Northwest Atlantic (Subareas 3 and 4) in 2011

Summary

• Reported landings in NAFO subareas 3 and 4 have increased substantially, from 16,080 t in 2000 to a historical high of 54,621 t in 2005. Between 2006 and 2010, landings decreased from 53,649 t to 38,753 t, before reaching 8,544 t in 2011.
• From 2000 to 2006, landings in the USA commercial fishery increased from 5,649 t to a maximum of 56,640 t. Between 2007 and 2010, they decreased from 25,547 t to 9,891 t, before reaching a historical low of 500 t in 2011.
• Age at 50% maturity has varied little over the years. However, length at 50% maturity decreased in the 2000s, and subsequently increased in 2010 and 2011.
• The spawning biomass index measured by egg surveys dropped substantially between 1993 and 1998. Following an increase caused by the strong year-class of 1999, the index dropped again to reach historical lows since 2005.
• In 2009 an additional egg survey was conducted on the Scotian Shelf and the south coast of Newfoundland. Egg densities found during the survey were very low, suggesting that spawning biomass on the Scotian Shelf was not very abundant.
• For the first time, a sequential population analysis was used to assess stock abundance. This analysis indicates that the biomass of the Canadian Atlantic mackerel contingent has been declining since the mid-2000s, reaching a very low value in 2011.
• This biomass decrease was caused by a lack of recruitment combined with historically higher-than-sustainable fishing mortalities. On two past occasions, biomass decreases associated with large increases in fishing mortality caused the population to decline.
• Given that stock abundance should not increase in the short term, the fishing mortality rate should be lower over the next few years compared to that of 2011. Therefore, in order to bring back this rate to the average sustainable level from 1968 to 1992, catches in 2012 and 2013 should not exceed 9,000 t.

This Science Advisory Report is from the April 18, 2012 Assessment of the Atlantic mackerel in subareas 3 and 4. Additional publications from this process will be posted as they become available on the Fisheries and Oceans Canada Science Advisory Schedule.

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