Selawik Refuge staff surgically implant a radio transmitter in a sheefish, September 2007.

Sheefish, a large, highly desirable whitefish, are abundant on the Selawik Refuge in northwest Alaska.

Renowned for its tremendous size, fighting ability, and fine eating qualities, the sheefish is a large whitefish found in the vast northern drainages of Siberia and North America.  In Alaska, the largest sheefish occur in the Selawik and Kobuk river drainages in the northwest part of the state, where local residents eagerly catch them throughout the year.

Despite their high profile and their importance as a subsistence food, much is still not known about sheefish. The U.S. Fish & Wildlife Service and Alaska Department of Fish and Game have launched several projects in recent years to learn more about the spawning habits of these unique fish. About 240 sheefish in northwest Alaska now carry radio transmitters in their abdomens, surgically implanted by biologists in 2004-08.

Already these transmitters have yielded important information about where sheefish are—and are not—spawning.  In 2008, spawning on the Kobuk River took place between the Mauneluk and Reed rivers, concluding by October 1.  On the Selawik Refuge, sheefish that had been radio-tagged in the Tagragvik River in 2007 were nowhere to be found in that river in 2008.  Instead, several of these fish were detected on the upper Selawik River spawning grounds.

This fall scientists had the rare opportunity to observe spawning sheefish on the upper reaches of the Selawik River in the Selawik Refuge.  Spawning began September 21 and occurred in faster-moving stretches of water. The Selawik River spawning area is located downstream from a large landslide (or “thaw slump”) that continues to spill mud and silt into the river during summer months. Concern exists about the effect this sediment might have on sheefish eggs.  Supported by the Selawik Refuge, scientists are exploring ways to study this in more detail.

Stay tuned for exciting updates as we unravel the mysteries of sheefish!