The North Fork Skykomish River and its tributaries are home to one of the best remaining strongholds of wild anadromous and freshwater fish in the Puget Sound basin. Many miles of cold, clean water that are sheltered by mature and old growth forests provide excellent spawning and rearing habitat.

According to the report, "Conservation Priorities: An Assessment of Freshwater Habitat for Puget Sound Salmon", almost all of this area is priority refugia for wild salmon. The Conservation Priorities report concludes “regional efforts to protect and restore Puget Sound salmon will fall short unless we protect the last remaining best habitat first.” Wilderness designation would protect the forests and streams of the North Fork Skykomish area and ensure its continued vitality.

The North Fork Skykomish is an unusual river in the Puget Sound Basin in that anadromous fish can swim far upriver. Bear Creek Falls, at 1400’ elevation is a partial barrier, but many fish including Steelhead and Bull Trout climb it and continue as far as Deer Falls. At 2100’ elevation, Deer Falls is only five miles from the Cascade crest. Popular fishing holes abound and anglers are particularly drawn to Troublesome Hole and Stairstep Hole.

Steelhead

The most well known and abundant anadromous fish in the North Fork Skykomish are winter and summer run steelhead. Steelhead are sought after by anglers and provide the predominant sport fishing on the North Fork. These seagoing trout, close relatives of salmon, are strong swimmers and are able to climb Bear Creek falls and reach the upper North Fork and many tributaries, which provide their main spawning area. It is sometimes possible to see several dozen fish at once just below the blocking falls on such tributaries as West Cady, Goblin or Troublesome Creeks. These concentrations of fish attract osprey, eagles, otters and other wildlife.

Bull Trout

Bull trout (sometimes referred to as Dolly Varden) are federally listed as a threatened species, and require extremely cold, pure water to spawn successfully. The North Fork Skykomish high mountain spawning areas are one of their most important refuges in the Puget Sound Basin. Bull trout populations here are among the healthiest in the Cascades, and they are often seen in the river's upper reaches.

Salmon

Three species of salmon are commonly found in the North Fork Skykomish. Puget Sound Chinook, or king salmon are federally listed as threatened, and are one of the largest salmon species. The North Fork represents an important refuge and water source for their downstream spawning areas. An occasional Chinook ascends Bear Creek Falls, but most spawn below it. In the North Fork, the lower three miles have the greatest concentration of spawning grounds.

Humpback, or pink salmon runs occur only during odd numbered years. 2001 was an especially plentiful year for Pink Salmon in the North Fork Skykomish, with hundreds shimmering through the town of Index, amazing residents and visitors alike.

Silver, or coho salmon are also found in the North Fork and are considered by many to be the most flavorful salmon. They often appear in the Skykomish in greater numbers than the other species. Since they are plentiful and tasty, they provide a great attraction for anglers, bringing many people to the Skykomish every year. Coho spawn in the main stem of the North Fork Skykomish, in the lower reaches of Lewis, Howard and West Cady creeks, and in other tributaries.

A fourth salmon species, sometimes found in the North Fork but more often downstream, is chum salmon, which are abundant and provide an important source of food for eagles and other wildlife.