Bibliography of the Maurice Lamontagne Institute

Chantale MÉTHOT

GRÉGOIRE, F., C. LÉVESQUE, J.-L. BEAULIEU, C. MÉTHOT, M.-H. GENDRON, 2007. Résultats du relevé des œufs de maquereau bleu (Scomber scombrus L.) réalisé dans le sud du golfe du Saint-Laurent en 2006 ; Results of the Atlantic mackerel (Scomber scombrus L.) egg survey conducted in the southern Gulf of St. Lawrence in 2006. MPO, Secrétariat canadien de consultation scientifique, Document de recherche ; DFO, Canadian Science Advisory Secretariat, Research Document, 2007/073, 76 p .

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A survey for assessing the spawning biomass of Atlantic mackerel (Scomber scombrus L.) by egg sampling was conducted in the southern Gulf of St. Lawrence between June 28^th and July 8^th, 2006. Some very low egg abundance, less than 10 eggs/m², was recorded at nearly 75 % of the sampled stations. The highest abundance was recorded at stations located west of the Magdalen Islands. These stations were associated to water temperatures (0-10 m layer) varying between 9.3 °C and 12.3 °C. The mean egg production for the entire sampled area was calculated at 7.4 eggs/m², and total production at 5.12 x 10¹¹ eggs. A spawning biomass of 54,133 t was associated with this egg production, which represented the lowest recorded value since 1979. The 2006 survey was conducted towards the end of the spawning season as indicated by the daily egg production curve, the high water temperatures, between 9.3 °C and 16.7 °C, and the presence of larvae at just about every station. When considering these results, the assessed biomass for 2006 is associated to the portion of the stock that reproduced at the very end of the spawning season rather than the entire stock. In order to improve the mackerel abundance assessment, it is suggested that the survey be conducted at more appropriate dates. The 2006 survey could not be conducted earlier due to a conflict in time management for vessels. It is also suggested that the survey cover the Scotian Shelf due to the recent changes in mackerel migration routes.

GRÉGOIRE, F., C. LÉVESQUE, J.-L. BEAULIEU, C. MÉTHOT, M.-H. GENDRON, 2007. Pêche et biologie du maquereau bleu (Scomber scombrus L.) des sous-régions 3 et 4 de l’OPANO en 2006 ; Atlantic mackerel (Scomber scombrus L.)fishery and biology for NAFO Subareas 3 and 4 in 2006. MPO, Secrétariat canadien de consultation scientifique, Document de recherche ; DFO, Canadian Science Advisory Secretariat, Research Document, 2007/067, 136 p .

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In 2006, preliminary landings of Atlantic mackerel (Scomber scombrus L.) in the Northwest Atlantic totalled 96,272 t, which represents a decrease of 66 t from 2005 and 12,547 t from 2004. In eastern Canada, 38,155 t were landed, with 34,884 t in Newfoundland alone. The actual landings made in Canadian waters in 2006 should be higher because fishery data from New Brunswick, Prince Edward Island and Nova Scotia were not all accounted for at the time of the assessment. In 2006, American landings totalled 58,117 t, an increase of 17,100 t compared with 2005. By considering the catches made by foreign vessels in American and Canadian waters, the sharing of the resource between both countries would total 75 % in favour of the United States if this calculation was based on total landings made between 1960 and 2005, and 52 % based on the average annual landings proportion of each country. When only considering domestic American and Canadian landings, these values would total 64 % and 70 % respectively in favour of Canada. Most of the landings off the west coast of Newfoundland were from unit areas 4Rd, 4Rb and 4Rc with respective totals of 8,159 t, 3,139 t and 2,617 t. On the east coast of Newfoundland, the most important landings were from unit areas 3Kh, 3Lb and 3Kd with respective values of 11,705 t, 3,265 t and 3,243 t. The other significant unit areas, with over 1,000 t each, were 3La on the east coast of Newfoundland and 4Tf in the Magdalen Islands with 1,912 t and 1,046 t respectively. Since the early 2000s, Canadian landings have been greatly dominated by fish from the 1999 year-class. Between 2001 and 2004, fish from this year-class have accounted for between 45 % and 77 % of all catches in numbers, which had not been observed since the late 1960s. Nevertheless, the relative significance of this year-class has dropped sharply in 2005 and 2006 in favour of the 2003 year-class. From 2002 to 2003, annual landings attributed to the 1999 year-class varied from 4,927 t to 35,970 t. They decreased from 30,792 t and 24,805 t in 2004 and 2005 to only 6,429 t in 2006. Although there are still uncertainties associated with fishery statistics, it appears that the dominant 1999 year-class no longer contributes very much to the fishery or to the reproductive stock. Therefore, total landings in 2007 are not likely to exceed that of recent years and the TAC, which far exceeds the highest recorded landings, should be brought back down to 50,000 t. However, it is highly likely that landings of this magnitude will not be sustainable if post-1999 year-classes are of only average abundance.