Bill Carter clips a sheefish fin while Frank Berry, Jr. records data, upper Selawik River, August 2005. Photo by Susan Georgette.

This landslide in spring 2004 continued to pour mud and sediment into the upper Selawik River during last year's field season, August 2005. Photo by Bill Carter.

Sheefish

Surprising results are in from a recent study of sheefish in the Selawik National Wildlife Refuge.  Spawning sheefish were far more abundant—four to nine times more abundant—in 2004 and 2005 than a similar study found ten years earlier.  Smaller and presumably younger fish accounted for most of the increase, leading biologists to speculate that unusually good conditions at some point in these fishes’ early lives spurred this population growth. 

Sheefish, also called inconnu, are the largest whitefish found in northwest Alaska.  They are an important and highly desirable subsistence food caught both under the ice and in open water. Sheefish are long-lived, living up to 35 years old.

Researchers’ preliminary estimate of the 2005 population of spawning sheefish in the Selawik River was a whopping 46,472 fish. The 2004 estimate was 23,480 fish.  This compares to slightly fewer than 5,200 spawning sheefish estimated in 1995 and 1996.

Ray Hander of the U.S. Fish and Wildlife Service, Fairbanks Fish and Wildlife Field Office, led the study which used a mark-recapture methodology to estimate the spawning population of sheefish.  Local Selawik residents Frank Berry, Jr., Lawrence Foster, Sr., Elvie Stoney, and Artemus Coffin participated in the field work, providing critically important knowledge of the local area and conditions.  Catching fish for the study proved to be unexpectedly challenging because a large landslide in the far upper reaches of the Selawik River in spring 2004 transformed the normally clear water river into a muddy, silt-laden one. 

Little is known about long-term cycles of sheefish abundance or their complex life history. Few if any other sheefish populations have multiple spawning population estimates like the Selawik River. Scientists have few biological clues as to what might account for the population explosion in the Selawik River, and far more questions than answers.  Is the same increase in spawning sheefish happening elsewhere?  Was the earlier spawning estimate unusually low, or is this one unusually high?  Is this related to climate change?  Biologists hope that a combination of further research and observations by local subsistence fishermen might help shed light on these questions.