(This article was featured in the March 2010 issue of WSC’s newsletter, The Adipose.)
By Dick Burge, WSC VP of Science
Historical WDFW and tribal records show there were large wild steelhead runs in most west side rivers during the early winter months (December, January and February) in Washington and British Columbia. These early runs were equal to and often greater than the late runs of March and April which dominate today. The decline and often loss of this early run due to over harvest is a major reason for the decline of wild steelhead runs since the 1940’s and 1950’s. Genetic studies from other areas show that these individual seasonal runs are different; hence the early run will not recover from recruitment from straying from the other seasonal runs.
The decline of the early winter run has been described in the literature by many authors/researchers as primarily due to the introduction of hatchery fish in the 1960/70’s. A mixed stock fishery developed for the early timed hatchery and wild fish which attracted new fishing effort and increased the harvest of steelhead. The fishery goal for the hatchery runs was to take as many as possible. However, because no controls were imposed on the take of wild fish, and their runs were smaller than the returning hatchery fish, they slowly declined due to overharvest to the depleted populations we have today.
Seasonal run timing (such as the summer, early winter and late winter runs) and the abundance of each run is one of the most important diversity traits of wild steelhead. Healthy seasonal runs help to maintain the total stock health, total annual run size and spatial distribution of steelhead in each river system. The early winter runs were known to migrate higher into the watershed during high winter flows and spawn in these areas. The depletion of the early run means that the winter run survival is dependent almost entirely on the late run.
Steelhead run diversity, such as seasonal runs and the range in years that the fry stay in the rivers and adults stay in the ocean, also protects stocks against catastrophic natural and anthropomorphic damages. If a portion of a run is temporarily damaged by a landslide, summer drought, heavy flooding, heavy sediment input from logging, etc., the run will survive because fish from other seasonal runs and other brood years are still at sea. Protecting and improving the diversity traits of wild steelhead is one of the major keys to maintaining and rebuilding wild steelhead stocks in all rivers.