Resistance of Underyearling and Yearling Atlantic Salmon and Lake Trout to Supersaturation with Air

Abstract

Juvenile Atlantic salmon Salmo salar and lake trout Salvelinus namaycush of different sizes were exposed for 96 h to water supersaturated with air. Underyearlings (Atlantic salmon shorter than 66 ± 8 mm [mean total length ± SD] and lake trout shorter than 96 mm) were resistant to high dissolved-gas pressures. The level of supersaturation causing 50% mortality was lower for yearling Atlantic salmon (148 ± 17 mm long) than for underyearling Atlantic salmon, and sensitivity to supersaturation was greater in lake trout 96 ± 1 to 153 ± 17 mm long than in those 23 ± 1 to 46 ± 4 mm long. Incidence of cutaneous emphysema and other signs of gas bubble disease increased as supersaturation increased. The number of bubbles and number of sites with bubbles were higher in the older fish. Among fish 150 ± 17 mm long, Atlantic salmon seemed to be less resistant to gas supersaturation than did lake trout.

Acute effects of gas supersaturation on Atlantic salmon smolt in two Norwegian rivers

“…In a study where Atlantic salmon was exposed to TDG supersaturation at 15 cm water depth in laboratory settings, acute mortality occurred from 117% TDG and no mortality occurred at B 110% TDG (Krise & Herman, 1991). There are at least six factors that may explain differences in mortality between our study and the study by Krise & Herman (1991). These factors may to some extent also be valid for other studies that find different susceptibility toward TDG supersaturation for single species.…”

“…These factors may to some extent also be valid for other studies that find different susceptibility toward TDG supersaturation for single species. (1) The Atlantic salmon in River Otra is a relict landlocked population, whereas the Atlantic salmon from Lake Evangervatnet and in the laboratory study (Krise & Herman (1991) are anadromous populations. Although the landlocked and anadromous populations constitute the same species, physiological differences could potentially have formed over the 9000 years since the populations were separated (Hutchings et al, 2019).…”

“…Relatively few studies have investigated effects of TDG supersaturation in Atlantic salmon, despite its distribution in rivers that are often exploited for hydropower purpose. In a laboratory study with 15 cm deep tanks, sub-yearling Atlantic salmon were less tolerant to TDG than lake trout (Salvelinus namaycush Walbaum, 1792) (Krise & Herman, 1991). Here, Atlantic salmon mortality commenced from 114% TDG, and 50% mortality occurred after 96 h at 117% TDG for parr (mean length 14.8 cm) and 118 to 122% for smaller parr and fry (6.6-2.3 cm).…”

A Simple Apparatus for Maintaining Gas‐Supersaturated Seawater in the Laboratory for Experimental Purposes

“…An earlier experiment by Krise and Herman (1991) targeted specific saturation levels by aerating a supersaturated water supply. Treatments ranged from 8 to 210 mm Hg (SD ¼ 18 mm Hg) and were highly variable, fluctuating two to three times more than the variation experienced with our system.…”

“…As a result, a great deal of research has been conducted to understand the effects of gas saturation on aquatic organisms (Weitkamp and Katz 1980;Elston 1983;Brisson 1985). Inter-and intraspecific differences in symptoms of gas bubble disease (GBD) are known to occur from interactive effects of gas saturation levels, organism age or size, and water temperature (Dawley and Ebel 1975;Krise and Herman 1991;Saeed and Al-Thobaiti 1997).…”