 |
Thymallus arcticus montanus
The native population of Arctic Grayling residing in the Big Hole River of Montana is the last remnant of fluvial (river-dwelling) grayling that once occurred throughout the upper Missouri River drainage. Grayling have been stocked in lakes throughout Montana in an attempt to prevent complete extinction of the population, such as occurred with the only other population in the lower 48 states, formerly of Michigan, but obviously these stocked individuals are not fluvial populations.
 |
|
| |
|
Arctic grayling spawn in the spring, April-June, depending on water temperatures. As is the case with lake trout, grayling are dispersal spawners over gravel or rocky areas, not nest or redd builders. When females are ready to spawn, males swim along side of them to fertilize the eggs as they fall into crevices amongst the rocks. Hatching occurs between 11 and 22 days depending on temperature conditions.
Grayling embryos and fry show a more rapid development
compared to spring-spawning rainbow and cutthroat trout under the same conditions.
Arctic grayling are endangered because of a number of threats. Grayling do not coexist well with other salmonids besides those it coevolved with, such as cutthroats and whitefish in Montana. Thus, non-native trout are of major concern. As an example, brown and rainbow trout have replaced grayling in much of its native habitat in the upper Missouri River basin. Arctic grayling are also highly vulnerable to anthropogenic effects, mainly agriculture and development. Due to increased usage of water from streams and rivers, movement of grayling is restricted and higher water temperatures become a severe hazard. Additionally, runoff associated with the same conditions increases turbidity. All these factors limit both viable habitat and spawning conditions for grayling. Major conservation plans are being formed to help prevent the extinction of the fluvial population of grayling in the Big Hole River of Montana.
References:
Brown, C.J.D. 1971. Fishes of Montana. Big Sky Books, Bozeman, Montana.
Behnke, R.J. 2002. Trout and Salmon of North America. The Free Press, New York, NY.
|
