Eagles, Salmon Linked

Nature

The past three years of high water will depress salmon populations in the Missouri River near Helena, biologists say, and they speculate that the annual migration of eagles through the area may move elsewhere.

Hundreds of eagles pause in their migration each year to feast on spawning kokanee salmon below Canyon Ferry Dam, drawing thousands of viewers.

But high water in 1995, 1996 and 1997 resulted in large volumes being released from Canyon Ferry Dam. That water flushed fish, including most of the kokanee salmon, over Hauser Dam, then over Holter Dam and into the Missouri River.

The state has stocked about 150,000 kokanee in Hauser, but those fish are only about 4 inches long and won’t spawn for about three years.

A similar situation occurred more than a decade ago in Glacier National Park, where eagles used to feed on salmon running upstream from Flathead Lake. But the Flathead salmon population collapsed when the mysis shrimp was introduced in the lake, and the eagles abandoned Glacier to search for other food sources.

So far, there seems to have been little change in the Missouri River migratory pattern, however. A one-day count last week turned up 75 to 80 eagles. The viewing is expected to peak this week.