With hundreds of thousands of young salmon now making their way toward the ocean, the Oregon Department of Fish and Wildlife is ramping up efforts to make sure they get there and aren’t picked off by hungry birds along the way.
For the next month and a half, volunteers assisting ODFW staff will haze cormorants to keep them from feasting on salmon smolts as the young fish run the gauntlet through five coastal estuaries on their way to the Pacific Ocean.
Cormorants are large seabirds that inhabit Oregon’s estuaries during the spring and summer. They are voracious eaters and can consume up to two pounds of fish per day … roughly the equivalent of about 12 salmon smolts when the fish are released as juveniles from ODFW’s hatcheries at Tillamook, Nehalem, Hebo, Alsea and Coquille.
The fish include coho and fall and spring salmon as well as winter and summer-run steelhead. Most the ocean-bound migrants are hatchery fish, though coastal coho from the Alsea are primarily wild fish that are listed as threatened under the Endangered Species Act.
“Coho are kind of at the top of our list” for protection against the hungry cormorants, said Lindsay Adrean, ODFW’s avian predation coordinator.
Cormorants have been identified by sportsmen’s groups and others as a potential threat the outbound migration of salmon and steelhead.
Members of those organizations are assisting in the hazing program by providing manpower and equipment needed for daily hazing chores while ODFW provides fuel and oversight. Hazing generally consists of a person in a small boat interrupting the birds’ feeding patterns by driving toward them while they are in the water foraging for fish. At times, pyrotechnics are used to scare the birds away.
“Cormorants will eat what’s most abundant,” Adrean said. “The idea is to move the cormorants towards the lower estuary and ocean where they will have many other kinds of fish to choose from. This also provides the salmon with extra time to disperse, making them less vulnerable to predation.”
The young fish are believed particularly vulnerable as they pause, and adjust, during that transition from the freshwater of their birth to saltwater.
The cormorants have “just started to come back to the area” in recent days to feed and nest, Adrean said.
Fishery managers are “seeing a lot of high mortality in the estuary,” Adrean said. The hazing efforts are being choreographed to match the timing of planned hatchery releases.
The hazing in the coastal streams has been conducted on and off, and with varying intensity, since 1988, particularly in Nehalem and Tillamook bays.
Volunteers will be working in Tillamook and Alsea bays and mouths of the Nehalem, Nestucca and Coquille rivers through the end of May. Manpower is being provided by the Port of Nehalem, Port of Bandon, North Coast Salmon and Steelhead Enhancement Fund, and Alsea Sportsmen’s Association.
In addition to improving salmon out-migration the hazing project will help ODFW gather baseline information about cormorant population trends and the effectiveness of hazing. It’s a tricky proposition, according to Adrean, because cormorants are protected under the Migratory Bird Treaty Act, so extra care must be used to ensure the birds are not injured or killed.
At the same time, cormorant populations have been increasing on East Sand Island near the mouth of the Columbia River. Population surveys indicate there are about 2,300 cormorant breeding pairs in the estuaries between Tillamook Bay and the Rogue River, and 12,000 breeding pairs on East Sand Island.
Researchers want to know how future changes in the distribution of cormorants might impact coastal salmon populations. A management plan is being developed in hopes of reducing predation by double-crested cormorants based on East Sand. Researchers estimated that cormorants consumed an estimated 22.6 million out-migrating juvenile salmonids in the Columbia River estuary. That consumption includes wild fish from 13 stocks of salmon and steelhead that are listed under the ESA.
“We hear a lot from people who think cormorants are having an impact, so that’s what we’re working on,” said Adrean. “We’re trying to find the right balance. That’s the key.”
“We’re not trying to keep the birds from foraging,” Adrean said. But, the hazing is aimed at forcing the birds focus away from migrating salmon.