The effect of a short time exposure to different temperature and salinity regimes on survival of maturing Atlantic salmon and eyed eggs, and changes in blood and seminal plasma during the spawning period

Maturing Atlantic salmon, transferred from brackish water two weeks prespawning, were held under four different temperature and salinity regimes through their spawning period. Values of blood glucose and haematocrit were measured every week during this period. Inorganic components (K+ and Cl-) were analysed from coelomic fluid, blood and seminal plasma. The dry matter of the eggs at spawning, were measured. The mortality of the broodfish and the eyed eggs were also recorded. Cold seawater was the most unfavourable environment to the broodfish, as they suffered high mortalities and high levels of chloride, potassium and blood glucose. These results probably reflected problems with osmoregulation. Cold brackish water appeared to be the best environment to both eggs and broodfish, although the males had problems at low temperatures. The haematocrit values were highest among males, but decreased among both males and females during the investigation period. Neither haematocrit, nor the dry matter of the eggs seemed to be affected by this short time exposure to different water qualities