Trends in wild adult steelhead (Oncorhynchus mykiss) abundance for coastalregions of British Columbia support the variable marine survival hypothesis

Wild adult steelhead (Oncorhynchus mykiss) abundance for rivers in British Columbia was indexed using catch-per-angler-day (CpAD) calculated from data obtained using an angler questionnaire. Mean annual CpAD for primarily win ter-run steelhead in rivers of four rainfall-driven coastal regions of Brit ish Columbia showed similar trends from the fiscal year 1967-1968 to 1989-1 990. After 1989-1990 the trends diverged. The generally remote rivers of th e west coast of Vancouver Island and the Queen Charlotte Islands maintained a steady or increasing trend in CpAD after 1989-1990. The long-term trend for these two regions correlated well with a joint index of winter and summ er upwelling for the Coastal Upwelling Domain for the years that steelhead are at sea and is consistent with studies that relate marine survival of sa lmon to oceanic-atmospheric climate. In contrast with west coast Vancouver Island and the Queen Charlotte Islands, most rivers of the east coast of Va ncouver Island and the lower mainland near Vancouver revealed declining tre nds since 1989-1990. Most of these rivers drain into the Strait of Georgia. Reasons for the discrepancy among regions after about 1990 are discussed. They include high angling pressure related to hatchery supplementation, dif ferences in riverine and marine conditions, and smolt migration distance.