Sheefish (Stendous leucichthys nelma) 

The Tarpon of the North

Color:	Silvery sides darkening to blackish-green along top Large silver scales	Sheefish or Inconnu have also been called the “Tarpon of the North” due to their resemblance.  Yet, the primarily sub-arctic species are the largest members of the whitefish family.  The largest Sheefish are found in the Kobuk River and Selawik drainages along the southern slopes of the western Brooks Range.  There is absolutely nowhere else where the fish can be caught as large as 30 to 40 pounds or more.
Size:	Average 15 to 25 lbs in Kobuk, Up to 40+ Average 5 to 12 pounds elsewhere
Method:	Cast and slowly retrieve in deep water Jigging near the bottom from a boat Large, shiny ¾ oz. to 1 oz. spoons Large, weighted flies
Gear:	Medium-action spinning and fly rods
Range:	Largest by size and population found in the sub-arctic Kobuk River Smaller populations in Yukon and Kuskokwim River drainages
Season:	Mostly July to October
Taste:	Excellent, white meat that rivals halibut
Record:	53 lbs, Pah River, by Lawrence E. Hudnall, 1986
Back Issues:	Jan / Feb 2003 October 2003

Appearance

Sheefish have a streamline shape and an elongated head.  Most of a Sheefish’s body is shimmering silver, but it does become darker blue to greenish grey on the back and white along the underside.  The mouth, when fully open, is nearly square and many describe the fish as having a bucket mouth.  The scales, which are larger than most other fish their size, are speckled with varying numbers of small black dots.  A 30-pound Sheefish will usually have scales the size of nickels along its lateral line. 

Location

The largest Sheefish population, both in individual size and number, resides in the Kobuk and Selawik River drainages.  Sheefish in this area commonly grow over 30 pounds and it’s not uncommon or difficult to catch one about 40 pounds.  The record was taken on a tributary of the Kobuk, the Pah River, and weighed in at 52 pounds.  Native nets on the Kobuk have caught Sheefish between 60- and 80-pounds.  Other smaller populations of Sheefish are found in the Koyukuk, Yukon and Kuskokwim River drainages.

Diet

Sheefish reach large sizes by constantly preying on other fishing.  Surprisingly, their mouths are void of any teeth; only a light sandpapery texture around the inside.  Sheefish can open their bucket-shaped mouth almost as large as the width of their body.  Prey includes almost any type of fish that they can fit down their throat, and they do so through a quick sucking motion.  Cisco and grayling are two of their favorites.  Unlike salmon, Sheefish continue to feed while heading upstream to spawn.  But their appetites do lessen and feeding nearly stops when close to actual spawning. 

Angling Method

Sheefish primarily stay close to the bottom of the river.  When resting, they feed in deep, slow water or back eddies.  Some of the best fishing holes in the Kobuk River can be as deep as 15 feet.  The most effective way to catch a lot of Sheefish is to fish deep with large, heavy spoons or flies.  The fish are also attracted to shiny colors, which means lures or weighted flies shouldn’t be a dull color.  Casting from shore works just as well as jigging from a boat.  Due to the feeding nature of a Sheefish, with its deep inhaling action, hooks should be barbless.  Frequently, the fish will have the hook lodged well into the rear of their mouth or delicate gillrakers.  Removing the hook is a delicate process as once the gills start bleeding, they usually don’t stop. Being prepared with barbless hooks and an elongated pair of extraction pliers (or similar tool) is recommended.

Life History

In the spring, following breakup, the Sheefish begin their migration from their wintering grounds.  Most adults will head to spawning areas while others will move only to nearby feeding grounds.  The amount of time spent migrating and the overall distance traveled depends on the river.  For some, such as those in the Upper Yukon, the migration will only last a few weeks, while others will spend over four months in the Lower Yukon River.  The Koyukuk River population will travel as many as 1,000 river miles to spawn.

Sheefish are picky when it come to choosing a site for spawning; they prefer water between four to eight feet deep, over gravel of different sizes, and fast current.  The fish also prefer cold water for spawning and, for this reason, usually spawn in September or October.  A 12-pound female can carry 100,000 eggs while a 50-pounder may contain nearly 400,000 eggs.  The females release the eggs on the surface (where they can sometimes be seen rolling) while the males swim below and fertilize the eggs.  The eggs sink to the bottom and adhere to the gravel.  After spawning, Sheefish make a rapid return to their wintering grounds.  Biologists believe that a mature individual will join the annual spawning runs perhaps only every other year or perhaps less depending on population.

Sheefish are one of the slowest growing fish in the arctic and their growth, age and size varies greatly among different populations.  Those found in the Kuskokwim populations grow the fastest.  By the age of two, they are usually 16 inches.  Their growth then slows and by the age of eight they average 30 inches and weigh 14 pounds.  Although Sheefish in the Kobuk River and Selawik area are the largest, they grow the slowest.  A 10 year old fish in this population will only weigh 10 pounds.  However, they enjoy a long lifespan, usually living well past 20 years old and reaching sizes of 20 to 30 pounds.  Sheefish between 60- and 80-pounds have been netted by Alaskan Natives in the Kobuk River.  The key to their size is probably due to their wintering grounds, the enormous Selawik Lake.  The lake, which is more of a brackish bay of Kotzebue Sound, thrives with fish found delectable by the “Tarpon of the North.”

Fish Alaska Magazine