Western Washington Steelhead Trout Abundance and Marine Survival Trends: What's Happening to Our Fish?

Steelhead trout (anadromous O. mykiss) numbers have fallen dramatically in Puget Sound and the Lower Columbia and have also decreased on the coast of Washington State. To better understand the patterns and put them into context, have confirmed the declining steelhead abundance and survival trends in Puget Sound and compared these trends with those in neighboring regions. We will first present abundance and productivity trends (specifically smolt to adult returns; SAR) for hatchery and wild steelhead populations. We found that many coastal populations shared a pattern of declining abundance from the mid 1980s through the mid 90s, and that while many of these populations rebounded in the 2000s, Puget Sound SARs continued to decline and have generally remained below those of other regions. Second, we present correlative analyses on these SARs with factors potentially affecting survival including wild and hatchery steelhead smolt abundance, individual and population life-history characteristics, environmental data, and buffer prey data. We are evaluating hypotheses about spatial variation in mortality, size-selective mortality, predation, and life history variation.