Pituitary gonadotropin and ovarian gonadotropin receptor transcript levels: Seasonal and photoperiod-induced changes in the reproductive physiology of female Atlantic salmon (Salmo salar)

Infection of postsmolt Atlantic salmon (Salmo salar) with three, six, or 10 preadult and adult sea lice (Lepeophtheirus salmonis) per fish resulted in changes to epithelial structure and at sites in the skin and gill, distant from lice attachment and feeding. In the skin, increased apoptosis and necrosis occurred in the superficial epithelial cells and numbers of mucous cells decreased. In the gill, where no lice were found, uplifting of the epithelium, intercellular swelling, and infiltration by leukocytes occurred in filaments and lamellae. High cell turnover of chloride cells was associated with significantly elevated gill Na+/K+-ATPase activities. Serum chloride levels were elevated in the 3 and 6 lice/fish groups, and the serum Na to Cl ratio was lower in all parasitized groups at 5 days. The results indicate that infection with low numbers of the preadult and adult parasite induced changes characteristic of a stress response. In the low- and medium-infested groups, homeostatic recovery had occurred by 10 days, but recovery was incomplete in the highly infected group. Thus, 10 lice per fish, which is a low infestation level in nature, is stressful and creates a long period during which the overall condition of the skin and gill epithelia may render the fish susceptible to secondary infections.

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Investigating the influence of nitrate nitrogen on post-smolt Atlantic salmon Salmo salar reproductive physiology in freshwater recirculation aquaculture systems

Aquacultural Engineering ◽

10.1016/j.aquaeng.2016.09.003 ◽

2017 ◽

Vol 78 ◽

pp. 2-8 ◽

Cited By ~ 9

Author(s):

Christopher Good ◽

John Davidson ◽

Luke Iwanowicz ◽

Michael Meyer ◽

Julie Dietze ◽

...

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Nitrate Nitrogen ◽

Reproductive Physiology ◽

Atlantic Salmon Salmo Salar

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Temperature-Induced Changes in Acute Toxicity of Zinc to Atlantic Salmon (Salmo salar)

Journal of the Fisheries Research Board of Canada ◽

10.1139/f75-001 ◽

1975 ◽

Vol 32 (1) ◽

pp. 1-10 ◽

Cited By ~ 68

Author(s):

Peter V. Hodson ◽

John B. Sprague

Keyword(s):

Atlantic Salmon ◽

New Brunswick ◽

Salmo Salar ◽

Fish Populations ◽

Acclimation Temperature ◽

Survival Times ◽

Atlantic Salmon Salmo Salar ◽

Zinc Concentrations ◽

Polluted Rivers ◽

Induced Changes

Three groups of Atlantic salmon (Salmo salar) parr were acclimated to water temperatures of 3, 11, and 19 C. When exposed at their acclimation temperature to lethal concentrations of zinc, cold-acclimated salmon survived longer than warm-acclimated salmon. However, the threshold lethal concentration (LC50) of zinc was highest for salmon at 19 C, i.e. there was less toxicity at the high temperature. At test temperatures lower than prior acclimation temperatures, survival times in zinc were longer but the threshold LC50 was lower, i.e. fish were less tolerant of zinc. The opposite results were seen at temperatures above prior acclimation temperatures.The threshold LC50 may be predicted by the equation LC50 = 1.9611 − 0.1873 Ta + 0.8699 Te − 0.0414 Te2 + 0.00004 Ta Te3, where Ta = temperature of acclimation and Te = temperature of exposure.In polluted rivers, zinc concentrations may be most damaging to fish populations during the winter months. Measured concentrations of zinc and copper in the Miramichi River, New Brunswick were highest in winter when estimated toxicity of metal was also greatest.

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