Most Threatened and Endangered Pacific Coast Salmon Populations Increased After Listings

Most Pacific Coast salmon and steelhead listed under the Endangered Species Act have increased in abundance over the past 25 years, arresting earlier declines. These findings were published in new research by NOAA Fisheries scientists who have studied the species.

The scientists examined trends in 28 population groups, called distinct population segments, within five species of salmon and steelhead listed from 1989 to 2007. These groups represent specific geographic areas and genetic characteristics, and are the smallest units that can be listed under the Act. The scientists found that a majority of the population groups protected as threatened or endangered increased in abundance. None disappeared into extinction. Protected population groups also increased faster than unprotected populations of the same species.

"At the time of the salmon listings, there was a path toward recovery and a path toward extinction," said Michael Ford, lead author of the new research published in Fish and Fisheries. Ford recently retired as a research scientist at NOAA's Northwest Fisheries Science Center. "So far, we have avoided extinction and even succeeded in moving many populations in the right direction, but most are still far from complete recovery."

Habitat Focus Proves Successful

The turnaround in listed salmon abundance is striking, considering that the population of West Coast states has grown by nearly 10 million in the same period. That adds demand on the water and other resources salmon also rely on, the scientists said. Large-scale environmental trends, such as declining stream flows and increasing stream temperatures, continue to worsen in ways that affect both salmon populations and local communities.

The findings suggest that the region's focus on improving habitat and involving communities in salmon recovery has proved successful. Salmon in the Northwest averaged higher abundance trends than those in California, the study found. Salmon in California are closer to the southern edge of their range and exposed to greater climate stress.

The listed population groups have yet to recover to the point where they no longer need protection. However, some-such as Snake River fall-run Chinook, Hood Canal summer chum, and Oregon Coast coho-have increased dramatically since their listing. These trends indicate that these listed population groups are on the path to recovery. Recovering salmon populations to self-sustaining levels is critical to restoring the great economic and environmental benefits they once provided, when millions surged up West Coast rivers every year.

Salmon Cross Boundaries

Many important successes under the Endangered Species Act have come when local communities, states, tribes, and others have embraced tools the Act provides to help conserve salmon, said Jennifer Quan, Regional Administrator of NOAA Fisheries' West Coast Region. "Local communities have taken on major roles in making improvements happen," she said. "This is how environmental stewardship should work, with communities making them work."

Since salmon cross many boundaries as they migrate between their spawning streams and the ocean, the Act allows for recovery strategies to do the same. NOAA Fisheries' West Coast Region completed the agency's first Safe Harbor Agreement in 2016, for example. It improved conditions for endangered coho salmon and threatened Chinook salmon and steelhead in Sonoma County, California, across ranches, wineries, and other lands.

The Agreement assures landowners that recovering species will not limit their land use. The region has continued to pioneer additional Safe Harbor Agreements and similar Habitat Conservation Plans to benefit salmon and communities across the West Coast.

Trends in Other Factors

Besides abundance, the study examined other factors affecting listed population groups of salmon and steelhead, including hatchery releases, harvest, and environmental indicators.

Hatchery releases and harvest impacts have remained relatively stable for most populations, the study found. Harvest rates were generally lower on listed population groups than unlisted population groups. While hatchery releases support commercial, tribal, and sport fisheries vital to the regional economy and culture, some also help restore naturally spawning populations of threatened and endangered population groups. Such conservation hatcheries are credited for increasing the abundance of threatened Snake River fall-run Chinook salmon, for instance.

However, hatchery fish can also undermine natural populations by diluting the adaptations that help them survive. Nearly all listed population groups retain at least some populations made up mostly of naturally spawning fish that remain free of hatchery influences, the research found.

The study found that some threats to salmon have increased over the past 25 years such as;

• Predation by marine mammals
• Reduced stream flows and snowpack levels
• Increasing stream temperatures

The increases in many salmon population groups despite these trends indicates that local salmon recovery efforts have improved local conditions for salmon.

As previous studies have indicated, the researchers also found that changing ocean conditions affect the survival of adult salmon, which is a large factor in driving salmon abundance.

The research demonstrates that protection under the Endangered Species Act combined with investments in restoration can turn declining salmon population groups around, said Steve Lindley, coauthor of the research who recently retired as research scientist at NOAA's Southwest Fisheries Science Center. However, he said, "It takes time to reverse the accumulated damage to salmon habitats, and progress can be prevented or temporarily reversed by prolonged periods of poor environmental conditions, such as with populations in California that have experienced severe droughts in the last decade."