Iteroparity in Steelhead Trout: Managing for a Diversity of Reproductive Life History Characteristics

What factors affect the frequency and cycle of iteroparity in steelhead trout?  Highly iteroparous populations occur in Kodiak, Alaska and in British Columbia, but few summer steelhead from the mid Columbia and Snake Rivers are iteroparous. Some populations from coastal California streams also have high rates of iteroparity.  Spent spawners (kelts) migrate downstream to the ocean and skip a year, or migrate to the ocean and return after only a brief residence in the ocean.  With harvest and human alteration of the aquatic habitat, understanding the historical information on stocks in many river systems has been difficult.  This symposium will convene scientists from several geographic regions to address case studies and factors affecting the iteroparity life history feature.  We will consider populations from systems with and without hydrodams, and summer and winter run characteristics.  Using information from populations with less controlled river systems we will seek to find features that can be compared across systems such as energy reserves, sex ratios, age of migration, timing and temperature regimes during upstream and seaward migration, and residualism.  This symposium will increase interactions among researchers and managers concerned with population restoration, fish passage structures and designs, and management options to assure viability of steelhead stocks. Sharing of information and future collaborations among diverse parties are among the desired outcomes of this session.