Interactions and Potential Causes to the M74 Syndrome Affecting Sea-Run Baltic Salmon (Salmo salar) Populations
Baltic salmon (Salmo salar) populations originating from the Swedish East Coast have suffered from the reproduction disorder M74 since 1974. Between 1992–96 the mean frequency of M74 in Swedish compensatory rearing stations varied between 50 and 80%. The highest recorded incidence of M74 was in 1993...
| Main Authors: | , , |
|---|---|
| Other Authors: | |
| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.517.1800 http://www.npafc.org/new/publications/Technical Report/TR4/page 42-44(Amcoff).pdf |
| Summary: | Baltic salmon (Salmo salar) populations originating from the Swedish East Coast have suffered from the reproduction disorder M74 since 1974. Between 1992–96 the mean frequency of M74 in Swedish compensatory rearing stations varied between 50 and 80%. The highest recorded incidence of M74 was in 1993 when 96 % of all family groups from the River Ume developed M74. Since 1997 the mean annual frequency of M74 in Swedish compensatory rearing stations has been about 25%. Finnish and Estonian Baltic salmon have also demonstrated development of M74 in the 1990s. Several factors have been hypothesized to be involved in the aetiology including loading of man-made pollutants, lowered levels of antioxidant compounds and large-scale changes of the food web with accompanying alterations of the nutritional quality of the basic prey species for Baltic salmon (Norrgren et al. 1993a; Börjeson and Norrgren 1997). However, today it is evident that the primary cause of M74 is a deficiency in thiamine (Vitamin B1) due to a poor maternal transfer (Amcoff et al. 1998a). M74-similar syndromes (EMS and Cayuga Syndrome) also affect several salmonid species in the North American Great Lakes (Fisher et al. 1995: Fitzsimons 1995; Marcquenski and Brown 1997). Thiamine is essential as a co-factor for three enzymes necessary in carbohydrate metabolism: the transketolase in the non-oxidative part of the penthose phosphate shunt; the pyruvate dehydrogenase complex in the junction between the glycolytic pathway and the citric acid cycle; and the a-ketoglutarate dehydrogenase complex in the citric acid cycle. The pentose phosphate shunt produces NADPH and |
|---|