Science Advisory Report 2017/034
Assessment of the Atlantic Mackerel Stock for the Northwest Atlantic (Subareas 3 and 4) in 2016
- Reported commercial landings in North Atlantic Fisheries Organization (NAFO) subareas 3 and 4 have decreased significantly in recent years. Between 2005 and 2013, they decreased from 54,621 t to 8,663 t before reaching 6,680 t in 2014 and 4,143 t in 2015. In 2016, the TAC of 8,000 t was reached.
- US landings (commercial and recreational) in NAFO subareas 5 and 6 also decreased significantly in recent years. Between 2005 and 2012, they decreased from 43,220 t to about 6,000 t and have remained at that level from 2013 to 2015.
- The issue of unrecorded catches has been investigated using a review of available data on bait needs and recreational fisheries, as well as an online survey aimed at mackerel fishermen. Both approaches show that total catches can reach 150% to 200% of declared catches, and that this ratio varies among regions and years.
- Following its increase in recent years, the length at 50% maturity has remained slightly above the minimum authorized length of 263 mm.
- The age structure in the fishery has contracted considerably since 2000 following the disappearance of fish older than 7 years. However, a slight improvement has been observed since 2013, with an increase of mackerel of ages 5 and 6.
- The abundance index from the egg survey in the southern Gulf reached its lowest level in 2012 (14,568 t), then slowly increased to 52,667 t in 2016. This value remains far below the abundance levels of over 750,000 t observed in the 1980s.
- A “censored” statistical catch-at-age model, calibrated with the abundance index from the egg survey and taking into account the uncertainty due to unrecorded catches, confirms that mackerel spawning biomass has declined due to high exploitation rates and reached its historical minimum in 2012 (20,000 t). According to the model, the 2016 spawning biomass was 40,000 t.
- The Limit Reference Point (LRP) for this stock is a proxy of 40%Bmsy based on F40% derived from a yield-per-recruit analysis. According to the censored model, stock abundance in 2016 was about 40% of the 103,000 t LRP.
- Model projections were used to quantify the risks associated with different catch scenarios. Considering that the stock is in the critical zone, total catches (declared + unreported) should be low enough to facilitate recovery.
- It is particularly important to fill gaps in the biological sampling of the commercial catch in some areas, to accelerate compiling of landing statistics and to improve data collection on unreported catches.
This Science Advisory Report is from the March 8 and 9, 2017, regional meeting on the assessment of the Atlantic mackerel stock in subareas 3 and 4. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada Science Advisory Schedule as they become available.
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