ISSN:
1095-8649
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Grayling Thymallus thymallus in Lake Aursjøen, Norway, showed a remarkably uniform growth pattern throughout life, whereas brown trout Salmo trutta showed far more variation. In addition, a narrower age-length interval of maturation was found in grayling. The restricted life history variation in grayling is discussed and it is suggested that all grayling of Lake Aursjøen experience similar environmental conditions as juveniles, which induces low phenotypic variation. In contrast the existence of several spawning populations, adapted to as many as 28 different tributaries, may have created large life history variation in Aursjøen trout. Logistic models revealed that both age and length had significant, simultaneous effects on the maturation of both species. Furthermore, the sexes of trout differed in maturation patterns, i.e. males matured earlier and at smaller sizes than female conspecifics, but no difference was found between the sexes of grayling. In addition, larger sex-specific growth differences were found in trout. An absence of early maturing males in grayling and their presence in trout is discussed as a possible explanation of the restricted life history variation found between sexes of grayling. Male grayling experienced a larger mortality rate than did females, whereas no such differences were found in trout. It is suggested that grayling males invest more in reproduction than do females, due primarily to large investments in breeding behaviour. The equal mortality rates found for both sexes of trout, albeit males starting to spawn earlier than females, is probably explained by a female-selective fishing mortality.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1095-8649.1996.tb01490.x
Permalink
