Center for Biological Diversity

Protecting endangered species and wild places through
science, policy, education, and environmental law.



Contact: Jeff Miller (510) 845-4675 or Dave Hogan (619) 574-6800, Center for Biological Diversity
Rich Nawa (541) 472-9627, Ecologist, Petition Author, Siskiyou Project
More Information: Lamprey web, and photos

Eleven conservation organizations in California, Oregon, and Washington today petitioned the U. S. Fish and Wildlife Service to list four species of lampreys as threatened or endangered under the federal Endangered Species Act. Lampreys are ancient jawless fish that superficially resemble eels, but are not related. The four lamprey species petitioned for are the Pacific lamprey, river lamprey, western brook lamprey, and Kern brook lamprey.

These lampreys spend most or all of their life cycles in a broad distribution of Pacific coast rivers and streams, except for the Kern brook lamprey, which are limited to a small portion of the San Joaquin River Basin in California. Pacific and river lamprey are primarily concentrated in medium and large sized low-gradient Pacific streams, while western brook lampreys, which are distributed from the Sacramento River basin northward into British Columbia, prefer the small tributaries.

"As with Pacific salmon populations, all of the lamprey species petitioned for have been heavily impacted by water developments, poor agricultural and forestland management practices, and rapid urbanization of many watersheds," said Jeff Miller, spokesperson for the Center for Biological Diversity.

Large concentrations of adult and larval lamprey were once an important and dependable high-fat food source for many birds, fish, and mammals, especially seals and sea lions. Adult pacific lampreys function as a buffer to reduce predation on adult migrating salmon by seals and sea lions and by other fish and gulls that otherwise might prey more heavily on young salmon. For example, feeding studies at the mouths of the Klamath and Rogue Rivers found that lamprey were the food item for 92 to 96 percent of sea lion feeding observations. Similar to salmon, lampreys also play an important ecological role in transporting nutrients such as nitrogen to freshwater ecosystems.

Somewhat like salmon, adult lampreys dig depressions in gravel beds in freshwater streams to spawn. However, not all species are anadromous (migrating to freshwater for spawning), nor are they all parasitic on other fish, as commonly believed. Information regarding efforts to control non-native Atlantic coast sea lamprey, which entered the Great Lakes in 1921 through the St. Lawrence Seaway, has led to unfounded prejudice toward native west coast lamprey species. The Pacific lamprey has co-adapted with its prey, which can include salmon as well as other marine fish species. Of the four lamprey species being petitioned by conservationists, only the Pacific and river lampreys produce parasitic adults that attach to other fish during these lampreys' shorter marine life stages.

The scarcity of lampreys became a conservation concern in the early 1990s when tribal fish managers, Oregon Department of Fish and Wildlife (ODFW) and other researchers noted that populations of Pacific lamprey were declining to perilously low numbers. Similar to Pacific salmon declines, Pacific lamprey show a dramatic declining trend throughout their range from California to the Columbia River portions of their range.

Pacific lamprey range from Baja California north through Alaska and around the Pacific Rim to Japan. Although there is no qualitative data, Pacific lamprey are in decline throughout California and the large runs of literally millions of lamprey described as great "wriggling masses of lampreys" that once characterized streams such as the Eel River have largely disappeared. Annual counts of Pacific lampreys at the Red Bluff Diversion Dam on the upper Sacramento River have declined from 38,492 in 1972 to 107 or less since 1996. Small numbers of Pacific lamprey persist in San Francisco Bay tributaries such as Coyote Creek, Alameda Creek, and Sonoma Creek. Pacific lampreys persist in the Salinas River and its tributaries, and in Malibu Creek and the Santa Clara River in southern California. The species is generally rare along the southern coast and has been extirpated from many streams in the urbanized southern end of its range, such as the Los Angeles and San Gabriel Rivers.

The distribution of the small parasitic river lamprey extends from the Sacramento River to southeast Alaska. Trend data is unavailable from California but it is likely the species has declined, along with the decline of suitable spawning and rearing habitat in the lower reaches of larger rivers. There are historical records of the species from the lower Sacramento-San Joaquin drainage and San Francisco Bay tributaries such as Coyote Creek, Alameda Creek, Napa River, and Sonoma Creek. River lamprey have been extirpated from Cache Creek, but still spawn in some Russian River tributaries and the Trinity River in northern California.

The non-parasitic Western brook lamprey is distributed from the Sacramento-San Joaquin drainage to southeastern Alaska. Populations likely occur in many streams along the California coast, especially in large rivers or their tributaries. However, it is unlikely that they can withstand severe pollution or habitat changes, so they are probably restricted to less disturbed sections of streams. Western brook lampreys have been extirpated from the Los Angeles River in southern California and the Putah and Cache Creek tributaries to the Sacramento River. Populations are still present in northern California in the Russian River, Navarro River, and the Eel River above Pillsbury Reservoir.

The Kern Brook lamprey is endemic to the San Joaquin River and a handful of its tributary drainages on the east side of the San Joaquin Valley. Probable populations are thinly scattered throughout the San Joaquin drainage and isolated from one another. This fragmented distribution makes local extirpations likely, without hope of re-colonization.

In the Pacific Northwest, human impacts to the freshwater habitats of lampreys have been severe and cumulative. Counts of Pacific lamprey at Ice Harbor Dam on the Snake River declined from 50,000 in the early 1960s to less than 1,000 during the 1990s. Counts at Winchester Dam on the North Umpqua River in Oregon declined from 46,785 in 1966 to less than 50 annually since 1995. Counts at Gold Ray Dam on the Rogue River, Oregon have ranged from 155-2,370 since 1993, but abundance is believed to be far below historical numbers.

Lamprey are vulnerable to habitat losses due to reduced river flows, water diversions, dredging, streambed scouring, channelization, inadequate protection of stream side vegetation, chemical pollution, and impeded passage due to dams and poorly designed road culverts. Introduction of exotic fish predators such as small mouth bass has also been a factor in the decline of lamprey.

Poor passage on dams contributes to Pacific lamprey declines by limiting access to historical spawning locations. For example, dams such as Bonneville, Dalles, John Day, and McNary Dams on the lower Columbia River have caused significant mortality of lampreys and blocked passage. Ironically, passing lamprey through the turbines at these dams may be less harmful than the current fish screens. According to Rich Nawa, staff ecologist for the Siskiyou Project, "in some cases it may be the dams that will need to be removed."

In addition to the four lamprey species petitioned for, the petition notes at least four other localized (or endemic) species in the upper Klamath Basin and upper Sacramento/Pitt River system that are of particular concern. Unless sufficient conservation measures are adopted these endemic lamprey may need to be petitioned at a future time, according to Nawa. They include: Miller Lake lamprey, Pit-Klamath Brook lamprey, Klamath River lamprey, and non-anadromous Pacific Lamprey in the upper Klamath Basin.

The eleven petitioning conservation organizations are: Klamath-Siskiyou Wildlands Center, Siskiyou Regional Education Project, Umpqua Watersheds, Friends of the Eel, Environmental Protection Information Center, Native Fish Society, Center for Biological Diversity, Northcoast Environmental Center, Umpqua Valley Audubon Society, Washington Trout, and Oregon Natural Resources Council.


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