Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

1998 ◽  
Keyword(s):  
Great Lakes ◽  
Baltic Sea ◽  
Early Life ◽  
Lake Trout ◽  
Life Stage ◽  
Early Life Stage ◽  
Early Mortality ◽  
Thiamine Pyrophosphate ◽  
Critical Threshold ◽  
Early Mortality Syndrome

<em>Abstract</em>.—Dietary amprolium, a thiamine antagonist, was fed to lake trout <em>Salvelinus namaycush </em>broodstock from April to October before spawning to determine its effect on egg and tissue concentrations of thiamine, thiamine monophosphate, and thiamine pyrophosphate. The thiamine concentration of eggs from fish fed no amprolium was 61.8 nmol/g, whereas the concentration of thiamine in fish fed 0.05 and 0.10% amprolium was 4.02 and 1.71 nmol/g (<EM>P </EM>< 0.01), respectively. In lake trout fed 0.10% amprolium beginning in August, egg free thiamine concentration was reduced to 11.6 nmol/g. No sign of early mortality syndrome was observed in sac fry from eggs in this study, which suggests that thiamine concentrations in the egg were not low enough to be below a critical threshold or that factors other than thiamine are involved in early mortality syndrome.

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

1998 ◽  
Keyword(s):  
High Risk ◽  
Great Lakes ◽  
Baltic Sea ◽  
Salmo Salar ◽  
Strong Correlation ◽  
Early Life ◽  
Life Stage ◽  
Early Life Stage ◽  
Yolk Sac ◽  
Normal Behavior

<em>Abstract</em>.—Since 1974, feral Baltic salmon <em>Salmo salar </em>populations have suffered from yolk sac fry mortality caused by the M74 syndrome. This syndrome affects yolk sac fry originating from specific females, and the mortality in affected family groups is usually 100%. Since 1990–1991, disturbances in the behavior of spawning migrating Baltic salmon have been observed. This study found a strong correlation between wiggling behavior in adult female Baltic salmon and the development of M74 in their offspring. Moreover, the ovarian thiamine concentrations in wiggling females were found to be significantly lower than those of females with normal behavior. In addition, eyed eggs and yolk sac fry that subsequently developed M74 contained only 13% (0.24 nmol/g) and 6% (0.11 nmol/g), respectively, of the thiamine concentrations detected in viable progeny sampled during the same periods. Eyed eggs with thiamine concentrations below a threshold limit interval of 0.36–0.77 nmol/g were found to have a high risk of developing M74 at the yolk sac fry stage.

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

1998 ◽  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Lake Trout ◽  
Life Stage ◽  
Lake Ontario ◽  
Early Life Stage ◽  
Fertilization Success ◽  
Thiamine Pyrophosphate ◽  
Predictive Index ◽  
Early Mortality Syndrome

<em>Abstract</em>.—Reproductive success and vitamin B<sub>1 </sub>(thiamine pyrophosphate, thiamine monophosphate, and free thiamine) concentrations were assessed in feral female lake trout <em>Salvelinus namaycush </em>from Lake Ontario and Lake Manitou. We monitored fertilization success, survival to hatch, incidence of blue-sac disease, other anomalies, and lake trout early mortality syndrome (EMS). Fertilization and hatching success were high, whereas mortality from blue-sac disease and other anomalies was low in egg batches from both lakes. There was no mortality from EMS in families from Lake Manitou. However, EMS occurred after hatching in the offspring of 48% of the females collected from Lake Ontario. We measured thiamine in liver, red blood cells, eggs, and developing embryos. Relative to fish collected in reference lakes, females in Lake Ontario had depressed hepatic, red blood cell, and egg thiamine concentrations. Although more extensive investigation of thiamine balance is required, it may be possible to use red blood cell thiamine pyrophosphate as a predictive index for EMS susceptibility in offspring. Total thiamine concentrations in developing embryos declined by 50% between fertilization and swim-up. Free thiamine reserves declined most rapidly, whereas levels of thiamine pyrophosphate increased between the eyed embryo and hatch stages. A high proportion (67%) of lake trout families in which the initial egg free thiamine reserves or embryonic concentrations of thiamine pyrophosphate levels were <0.8 nmol/g exhibited EMS. Below this threshold (0.8 nmol/g), the occurrence of EMS was variable (0–100%) and only weakly related to free thiamine concentrations (<em>r</em><sup>2</sup> = 0.32, <EM>P</EM> = 0.014). This observation implies the possibility of additional interactions with other factors.

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

1998 ◽  
Keyword(s):  
Great Lakes ◽  
Baltic Sea ◽  
Early Life ◽  
Lake Superior ◽  
Life Stage ◽  
Early Life Stage ◽  
Whole Body ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Sampling Times

<em>Abstract</em>.—Smelt <em>Osmerus mordax </em>and alewives <em>Alosa pseudoharengus </em>were collected from Lakes Huron and Michigan in spring and fall and from Lake Superior in spring to determine the activity of thiaminase, a thiamine-destroying enzyme, in those species. Greater thiaminase activity was found in the viscera (1,902 pmol • g<sup>-1</sup> • min<sup>-1</sup> for smelt and 1,705 pmol • g<sup>-1</sup> • min<sup>-1</sup> for alewives) than in the eviscerated body (180 pmol • g<sup>-1</sup> • min<sup>-1</sup> for smelt and 235 pmol • g<sup>-1</sup> • min<sup>-1</sup> for alewives). The average whole body thiaminase activity when all of the samples were pooled was 362 pmol • g<sup>-1</sup> • min<sup>-1</sup> for smelt and 357 pmol • g<sup>-1</sup> • min<sup>-1</sup> for alewives. Large differences were found in thiaminase activities between smelt and alewives from different locations in the Great Lakes region and at different sampling times. These differences may be species-, location-, or season-specific.

Early Life Stage Mortality Syndrome in Fishes of the Great Lakes and Baltic Sea

1998 ◽  
Keyword(s):  
Baltic Sea ◽  
Salmo Salar ◽  
Early Life ◽  
Life Stage ◽  
Early Life Stage ◽  
Mortality Rates ◽  
Yolk Sac ◽  
The Mean ◽  
The Baltic ◽  
Related Mortality

<em>Abstract</em>.—Since 1974, feral salmon <em>Salmo salar </em>populations of the Baltic Sea have suffered from a yolk sac fry mortality known as the M74 syndrome. Mortality rates of 40–95% have been recorded during the 1990s in compensatory rearing stations along the east coast of Sweden. The M74 syndrome has been linked to the offspring of specific females and associated with low thiamine (vitamin B<sub>1</sub>) concentrations in both female tissues and their progeny. This study evaluated the effect of thiamine treatments on mortality and thiamine concentrations in progeny with and without M74. Eggs and newly hatched yolk sac fry were immersed in water containing thiamine at concentrations of 100, 500, or 2,000 mg/L. Hardening of eggs in water containing thiamine at 500 or 2,000 mg/L completely eliminated M74-related mortality, whereas treatment with thiamine at 100 mg/L only partially reduced M74 mortality. The mean thiamine concentrations at the yolk sac fry stage (21–23 d after hatching) in untreated normal and M74-affected groups were between 0.70–1.0 and 0.19–0.26 nmol/g, respectively. At the same sampling, the mean thiamine concentrations in groups in which eggs were waterhardened in thiamine at 500 or 2,000 mg/L were between 0.8 and 9.4 times higher than the concentrations in the untreated groups. A thiamine threshold limit interval of 0.34–0.47 nmol/g was estimated for the development of M74 in yolk sac fry.

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