Science Advisory Report  2014/030

Assessment of the Atlantic Mackerel stock for the Northwest Atlantic (Subareas 3 and 4) in 2013

Summary

• Reported commercial landings in NAFO subareas 3 and 4 have decreased significantly in recent years. Between 2005 and 2010, they decreased from 54,621 t to 38,753 t before reaching 11,400 t in 2011, 6,468 t in 2012, and 7,431 t in 2013.
• US landings (commercial and recreational) in NAFO subareas 5 and 6 also decreased significantly in recent years. Between 2005 and 2010, they decreased from 43,220 t to 10,635 t before reaching 1,463 t in 2011, 6,019 t in 2012, and 5,250 t in 2013.
• Age at 50% maturity has varied little over the years. However, length at 50% maturity has varied and in most cases it is greater than the minimum authorized length of catch of 250 mm. The fact that catches may target immature fish represents an additional pressure for the stock.
• Mackerel condition in June and the gain in condition during summer, both apparently related to the temperature of the cold intermediate layer (CIL) and to the abundance and phenology of key copepod species, decreased since 2003 and 2009 respectively, the 2003 value being among the lowest of the series. Mackerel recruitment success appears to be favoured by high abundance and an early development of the copepod Calanus finmarchicus.
• The abundance index from the egg survey dropped significantly between 1993 and 1998. Following an increase caused by the arrival of the strong 1999 year-class, the index dropped again from 2002 to reach since 2005 the lowest values of the series, which reflects the collapse of the stock.
• A sequential population analysis calibrated with the abundance index from the egg survey indicates that the mackerel spawning biomass has been declining since the mid-2000s to reach in 2013 the historical minimum.
• According to the sequential population analysis, this decline in biomass was caused by fishing mortality levels several times higher than the historic sustainable levels. Two previous declines in the biomass associated with large increases in fishing mortality had not caused such a severe decline of the stock. It is likely that the stock is currently in a situation of recruitment overfishing.
• Given the critical situation of the stock, the priority is for its reconstruction: (1) According to the projections based on the average sustainable fishing mortality from the analytical assessment, annual catches in 2014 and 2015 should not exceed 800 t; (2) In the current situation of the stock, it is even more important to know and control the bait and recreational fisheries.

This Science Advisory Report is from the March 4, 2014 on the Assessment of the Atlantic Mackerel in subareas 3 and 4. 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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