Fishing for prehistoric traces of sockeye salmon in Eklutna Lake

A lately revealed evaluation of sediment layers has discovered no proof of anadromous salmon in Eklutna Lake way back to 1859. Nevertheless, oral historical past and no less than one written document recommend that ocean-reared salmon used emigrate up the Eklutna River to spawn within the lake. Who’s proper?

This query has nice relevance for Eklutna Lake’s future. A dam accomplished in 1929, about 1 half miles above the Previous Glenn Freeway, minimize the Eklutna River in half. Though all 5 species of Pacific salmon are nonetheless discovered within the river under the dam, no salmon has migrated upstream past the dam since 1929.

This derelict dam is being demolished by The Conservation Fund and Eklutna, Inc. Its removing will permit salmon to swim an unknown distance upstream. However not so far as the higher dam, which was constructed on the lake’s outlet in 1955 in affiliation with a federal hydroelectric challenge. The higher reaches of the Eklutna River run dry each summer time as a result of little or no water is allowed to spill out of the lake.

Documenting the previous presence of salmon within the lake is not merely a tutorial train. An settlement signed in 1991 – when the federal hydroelectric facility was purchased by native electrical utilities and the town of Anchorage – stipulated that inside 30 years of the switch date the house owners would pay for the restoration of the Eklutna watershed.

The sort of restoration efforts that can be required will hinge on whether or not or not the Eklutna river and lake provided spawning and rearing habitat for anadromous salmon earlier than the dam was constructed.

The article revealed in Arctic, a peer-reviewed scientific journal, is titled “Evaluating proof for historic anadromous salmon runs in Eklutna Lake, Alaska.” It was written by Michael Loso, Bruce Finney, Richard Johnson, and myself. The lead writer, Loso, previously a professor at Alaska Pacific College and now a Nationwide Park Service geologist, has devoted years to learning Eklutna Valley glaciers.

No salmon in Eklutna Lake?

Fisheries biologists have monitored spawning salmon populations in some Alaska lakes for greater than a century. However the spawning historical past of many lakes is unknown, notably the place no written data exist.

Thankfully, a singular “signature” of spawning salmon is included into the annual sediment layers of lakes by “marine-derived vitamins.” One marine-derived nutrient is a secure isotope of nitrogen. Anadromous fish carry the isotope of their tissues from the ocean to…

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