Insights into the ocean migration, behavior, and ecology of steelhead kelts from Prince of Wales Island, Alaska

Although steelhead (Oncorhynchus mykiss) is a culturally and recreational important species throughout North America, less is known about its ocean than its freshwater ecology. To provide insights into migratory routes and habitats occupied by steelhead in the North Pacific Ocean, we attached pop-up satellite archival tags (PSATs) to female steelhead kelts from three watersheds on the east coast of Prince of Wales Island, in southern southeast Alaska. PSATs successfully recorded extensive westward post-spawning migrations of nine female kelts across the Gulf of Alaska to areas near the Alaska Peninsula and Aleutian Islands. From the months of June to October, tagged steelhead occasionally dived to 10–20 m, but spent approximately 90% of their time in surface waters (< 4.5 m). During this same time period, 90% of all tag-recorded temperatures were between 8.7 and 12.8°C. These results corroborate past research on other North American steelhead populations, demonstrating that steelhead kelts predominantly occupy surface waters with sea-surface temperatures of 5–15 °C while transiting to and occupying purported feeding grounds in the western Gulf of Alaska and Aleutian Islands. Taken together, these results suggest that steelhead kelts originating from rivers throughout this species’ North American range occupy similar habitats in the North Pacific Ocean. While we only studied the ocean ecology of a limited number of steelhead kelts from southern Southeast Alaska, our results are pertinent for other populations throughout the northern west coast of North America, and provide better understanding of this species’ ocean ecology.