Croissance et survie marines de post-smolts de saumons atlantiques (Salmo salar) : effets de leur origine, de l’alimentation, des structures et des techniques d’élevage

• Main Authors: Gaignon, Jean-louis, Quemener, Loic, Faure, André, Harache, Yves
• Format: Report
• Language: French
• Published: 1997
• Subjects: Salmo salar; post-smolt; eau douce; technique d'élevage; transfert eau de mer; salinité; alimentation; origine; freshwater; rearing technics; seawater transfer; salinity; feeding; origin; Atlantic salmon
• Online Access: https://archimer.ifremer.fr/doc/00713/82483/87306.pdf; https://archimer.ifremer.fr/doc/00713/82483/

Atlantic salmon summer mortalities occured systematically on the coast of Brittany. The effects of various factors were studied and are exposed in the present report : - The origin of the fish as well as the fresh water rearing conditions (water quality, handling and rearing densities) may influence survival of salmon in sea water several months later. - The study of factors associated with the sea cages transfer have shown that (1) the osmotic disturbances after a 35 ppt sea water transfer are much higher than after a 28 ppt salt water transfer and the effect on growth lasts more than two weeks, (2) the transfer in sea cages leads to an arrested growth which is reduced by using wet food, the salt water transfer having no effect by itself, (3) the transport to sea cages reduces the length growth, while the sea cage transfer has only an effect on the condition factor. -The study of factors which may affect the survival rates of Atlantic salmon during summer demonstrated that (1) preventive treatments in order to control diseases associated with mortalities have no effect, (2) it is difficult to prove that the solar radiation exposure have any effect, but (3) that the mortality kinetics depends on the date of the sea cage transfer and (4) survival is linked to the food texture (dry or wet). - Data collected during several years point out that fish reared in circular tanks have clearly higher summer survival than those reared in sea cages. The results are discussed in this paper. We conclude that, if the summer conditions (i.e. the conditions linked with the temperature and the solar radiation exposure) are a discriminating factor for the Atlantic salmon, many other factors also significantly affect the performances during the summer period : their control might increase the summer survival. De fortes mortalités estivales de saumons atlantiques apparaissent systématiquement sur les côtes bretonnes. Les effets de certains facteurs autres que ceux de l’environnement sont étudiés dans le présent rapport :- L'origine ...