Steelhead Trout, are a Pacific sister fish to the Atlantic Salmon
A recent science publication links their devastating declines not to their fresh water habitat that has been well restored
But rather to their failure to survive on ocean pastures where they spend most of their lives
Steelhead trout are entrenched in the mythos and ethos of the West Coast of North America. They are a giant sea-going Rainbow trout that live alongside the 5 species of Pacific Salmon. They are prized like Atlantic salmon for their sporty nature and are prized by avid sports fishers who hope to catch them on light tackle and experience the thrill of landing the fish that can weigh well over 20 lbs.
Unlike their Pacific Salmon kin they return to their spawning rivers multiple times. Laying eggs in the river gravel and then swimming back out to their ocean pastures to feed and thrive and to return the next year to spawn again. Steelhead can live to a ripe old age of 8 years, spawning for 6 of those years.
A recent study published in the Canadian Journal of Fisheries and Aquatic Sciences (CJFAS) shows that survival of young steelhead trout in ocean environments has also been precipitously declining in spite of very successful efforts in fresh water streams to protect and conserve the fish and their vital habitat. Survival of juvenile steelhead in the ocean has long been considered a possible factor in the decline of these fish but only with great resistance from simple minded fresh water fisheries biologists. They ardently contested any thought that the salt water habitats of the fish could be important. As a result of refusal to engage in studies of the sea-life of the steelhead little his known about their life at sea. They are reported to simply swim with the rest of the schools of Pacific Salmon occupying far pastures hundreds, even thousands, of miles from their fresh water streams.
Sometimes ‘correlation’ does prove ‘causation’
To date long-term survival and abundance trends among Pacific Northwest populations have been largely unknown. Now in this large and comprehensive study the scientists combined many decades of data for 48 different populations of wild and hatchery steelhead trout. The scientists who work for the Washington Department of Fish and Wildlife have shown that declining survival of juvenile steelhead in the ocean is strongly coupled with significant declines in the abundance of adults. In this case the broad scope of the ‘correlation’ comes very close to proving ‘causation.’
“We were able to compile data from multiple reports and databases to document survival in the ocean of Oregon, Washington, and BC steelhead trout and show that these trends paralleled declines in adult abundance and also differ among populations originating from different areas,” says Dr. Neala Kendall, lead author of the study.
“We believe this is the first time these data have been brought together in a single study.”
Populations with particularly cataclysmic declines were those in the Lower Columbia River and in Puget Sound, an inlet of the Pacific Ocean and again streams of the Salish Sea that extends north and south of Seattle, Washington. The study found that among populations in Puget Sound, ocean survival of juvenile steelhead in the 2000s has declined by 77% on average compared to the 1980s; survival averaged 3.1% in the 1980s but dropped to 0.7% in the 2000s.
Surely every Canadian steelhead fisherman knows the fish have all but gone extinct in most of the streams and rivers of the British Columbia Salish Sea watersheds.
The study found parallel trends in adult abundance. Specifically, numbers of adults in Puget Sound steelhead populations in the 2000s have declined by 53% on average compared to the 1980s. The declines in juvenile survival “likely contributed to these fishes’ low abundance,” says Kendall; abundances are so low that Puget Sound steelhead were listed for protection under the Endangered Species Act in 2007.
Steelhead populations in British Columbia included in the study also have all declined in abundance and ocean survival since the 1980s. Declines in survival of juvenile steelhead in ocean environments were not as drastic for populations along the coasts of Washington and Oregon which are not listed under the Endangered Species Act.
Survival and abundance trends, like those generated in this study, can enhance current tools being used to predict changes in steelhead populations. To best conserve steelhead in the Pacific Northwest, especially recovery efforts for Puget Sound populations, “stakeholders and concerned citizens want to better understand why these populations have been struggling and how marine survival has contributed,” Kendall says. “With this information, policymakers and managers can have different expectations about Puget Sound and Lower Columbia steelhead compared to] fish on the coast due to their different marine survival patterns,” she adds.
Kendall sees this study as providing further support for ongoing efforts by natural resource agencies and NGOs to improve steelhead survival and protect the habitats these juvenile trout use upon arriving in the ocean. These include reducing shoreline armoring (e.g., construction of seawalls), protecting and promoting forage fish, understanding the impacts of marine mammals, and decreasing exposure to parasites and chemical contaminants.
The research is part of the Salish Sea Marine Survival Project, a US-Canada collaboration of more than 60 organizations conducting research to understand why salmon and steelhead are dying in the Salish Sea.
The article, “Declining patterns of Pacific Northwest steelhead trout (Oncorhynchus mykiss) adult abundance and smolt survival in the ocean” by Neala W. Kendall, Gary W. Marston, and Matthew M. Klungle was published today in Canadian Journal of Fisheries and Aquatic Sciences. More information: Canadian Journal of Fisheries and Aquatic Sciences (2017). www.nrcresearchpress.com/doi/a … 1139/cjfas-2016-0486
The greater tragedy of this study is that we have at our hands the means to restore the Steelhead ocean pastures to historic health and abundance and in doing so Bring Back those glorious fish. The greatest threat to Steelhead is that almost everyone seems to waiting for someone else to save them. Not I, I have a debt to repay to the Steelhead that Ted and I ran up decades ago and it is time to start giving back to restore and sustain these wonderful fish, join me.