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What Lies Beneath Lake Iliamna?
Large, isolated lake harbors mystery, if no monster
Room for mystery

By Matt Bille

The white sturgeon (Acipenser transmontanus) is the largest known fresh-water fish in North America. The record claim for a white sturgeon, caught in Canada’s Fraser River in 1912, was 20 feet in length and 1,800 pounds. A fish of 1,500 pounds was reported caught in 1928 in the Snake River in the northwestern United States. An 11-foot specimen weighing 900 pounds was found dead on the shore of Seattle’s Lake Washington in 1987.

Sturgeon expert Don Larson, curator of the Sturgeon Page Website, reports sturgeon over 10 feet long are often caught in the Fraser and Columbia Rivers. Larson comments, Most biologists I’ve talked to say that white sturgeon over 20 feet and 1800 pounds is highly probable. 

White sturgeon are not known from Iliamna, but have been found in other Alaskan lakes and in coastal waters as far north as Cook Inlet.  There is a single record of a catch in Bristol Bay, which puts a migration to Iliamna within the bounds of possibility.  It’s also plausible that white sturgeon became trapped in the lake thousands of years ago, when the last glaciers receded, and have developed in isolation.

Sturgeon are bottom-feeders and would rarely be seen near the surface, which fits the Iliamna phenomenon.  The appearance of white sturgeon - gray to gray-brown in color, with huge heads and long cylindrical bodies -match most Iliamna reports. (No one is certain how the species got the name white sturgeon, although some genuinely white specimens have been reported from salt water.)

It may be a distinct sturgeon population has developed, distinguished from the known white sturgeon mainly by unusual size.  Whether this hypothetical type would be different enough to be a new species is unknown.

An estimated 20 million sockeye salmon used to return to the lake from the sea every year.  While conservationists fear the salmon run has been dangerously diminished by overfishing, there is no doubt still enough aquatic food for a small population of predators.  There is also plenty of room.  Iliamna has 15 times the volume of Loch Ness.  At the same time, there is no physical or film evidence for unknown creatures of any kind.

A landlocked population of fish becoming larger than their relatives which are anadromous (dividing their lives between fresh and salt water) would be unusual.  In most cases where a species has become split between freshwater and anadromous populations, as with salmon, the freshwater variety becomes smaller.  However, this rule may not be valid for Lake Iliamna, with its huge size and bountiful food supply.

So what is lurking in Lake Iliamna?  Sturgeons?  Monsters? Tall tales? Or something completely different? 

Excerpt from Shadows of Existence, due out in spring 2005 from Hancock House. Copyright 2004 by Matt Bille. Web publication rights granted to Alaska Science Outreach for educational purposes.  Matt Bille is a science writer in Colorado Springs, CO; Shadows is the sequel to his previously published Rumors of Existence (Hancock House, 1995) about newly discovered, rediscovered, and unconfirmed animal species. Bille welcomes any further information on this topic and may be contacted at

Related Sites

About Science Writer Matt Bille
Monstrous Mysteries, Alaska Magazine


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