Comparative biology and management of Arctic and European grayling (Salmonidae, Thymallus)

Abstract

The biological and ecological features of Arctic grayling (Thymallus arcticus) relevant to its management and enhancement are reviewed over its range in North America as well as in Asia, and are compared with those for the European grayling (Thymallus thymallus). Populations of both species have declined in some areas where angling pressure has been severe and where major alterations of their habitats have occurred. But native populations of Arctic grayling have been extirpated in eastern parts of its North American range, and nearly so in south-western parts, whereas the range of European grayling has been extended, especially in the United Kingdom and in Finland, by introduction. Furthermore, in contrast to the Arctic grayling, the European grayling, in Scandinavia at least, seems to have been less severely affected by impoundment of rivers and lakes for hydroelectric generation, perhaps because it has been able to successfully reproduce in large rivers below dams, especially those where fluctuation in water level is small.