Research Document - 2013/049
The Atlantic mackerel (Scomber scombrus L.) in NAFO Subareas 3 and 4 in 2011
By Grégoire, F., Beaulieu, J.-L., Gendron, M.-H., and Lévesque, I.
Abstract
In 2011, preliminary landings of Atlantic mackerel (Scomber scombrus L.) in the Northwest Atlantic totalled 9,845 t, which represents major decreases of 39,577 t and 55,768 t from 2010 and 2009. In eastern Canada, 8,544 t were landed with 7,320 t (86%) in Newfoundland. These landings are the lowest since 1963. Most of the landings off the west coast of Newfoundland were from unit areas 4Rb and 4Rc with respective totals of 3,378 t and 1,575 t. On the east coast of Newfoundland, the most important landings were from unit areas 3Kh and 3Ki with respective values of 271 t and 133 t. In addition to this decline of the commercial landings, mackerel have almost disappeared from the multidisciplinary groundfish surveys conducted annually on the Scotian Shelf. Moreover, the mean lengths of the by-catches of the summer survey are decreasing since the beginning of the 1990s. Mean lengths of the line and gillnet catches are decreasing for a few years and remain below historical averages. The condition index seems strongly related to the Cold Intermediate Layer (CIL) temperatures. The growth of the dominant year-classes is less important than that of other classes which seems to indicate the presence of an inverse relationship with density. Maturity at age has varied little over the years unlike the maturity at length with the highest proportions of maturity that were observed during the years 2000. Since the early 2000s, Canadian landings have been greatly dominated by fish from the 1999 year-class. Between 2000 and 2003, fish from this year-class have accounted for between 41% and 77% of all catches in numbers, which had not been observed since the late 1960s. Nevertheless, the relative significance of this year-class dropped sharply beginning in 2005 in favour of the 2003, 2005, 2007, and 2008 year-classes which disappear of the fishery after a few years only. Catches in the order of 50,000 t have been supported in the past by the strong 1999 year-class. It is uncertain that catches of that level can be realized in the years to come with the year-classes presently available to the fishery.
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