Répartition spatiale, cycle saisonnier et croissance de Mysis litoralis (Banner, 1948) (Mysidacea) dans un fjord subarctique

• Published in: Canadian Journal of Zoology
• Main Authors: Ladurantaye, Réjean de, Lacroix, Guy
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1980
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Arctic; subarctique*
• Online Access: http://dx.doi.org/10.1139/z80-100; http://www.nrcresearchpress.com/doi/pdf/10.1139/z80-100

An isolated and practically unknown population of Mysis litoralis was sampled biweekly with plankton nets in the Saguenay fjord, in May–October 1975 and April–May 1976. In April and May, this arctic mysid is almost absent upstream and occurs mainly in the central and lower parts of the fjord. From June to October, it is restricted in distribution to the lower part of the fjord. There, M. litoralis inhabits deep waters (100–200 m)of< 5 °C in May and June, but is found mainly in shallower (up to 5 m) and warmer waters from July to October, regardless of the age of individuals. The vertical salinity range in the fjord is 2–3‰. Reproductive activity occurs only once a year, in late October or early November, and young mysids, then averaging a length of 3.8 mm. are released from the brood pouch in April–May, There is evidence that the number of young (33–113) in the marsupium varies with the size of the female. From June to September individuals of the new stock grow rapidly to a length of 15 mm. As early as October, almost all the individuals have attained the average length of the parental stock, and are sexually mature, apparently due to the favourable temperature and food conditions of the downstream area. Some individuals of the breeding population may survive to the following year.