The Rise of Salmon Predators and Parasites

Fishery managers are also responsible for more direct attacks on salmon populations, through the introduction of species that eat them. There are at least five non-native species of fish that eat juvenile salmon that have been introduced to the Columbia River, and we are now unlikely to be able to get rid of any of them, even if we take out the dams.38

For example, in the 1980s, the Washington Department of Fisheries introduced walleye into the Columbia River above Grand Coulee Dam. By the 1990s, the walleye had spread to the Snake River and were supporting trophy-sized walleye fisheries. Unfortunately, walleye are voracious predators, and eat juvenile salmon and sturgeon.39

Fishery managers are not promoting programs to exterminate shad and walleye. They are promoting programs to exterminate squawfish, which are, ironically, native fish. In the squawfish management program, because electric ratepayers are picking up the tab, cash bounties are paid for catching squawfish. Unfortunately, unlike mackerel and shad, which can be a gourmet item, most people don't like the taste of squawfish. But they have not gone to waste. They are ground up and fed to the juvenile salmon at the hatcheries.

The recent and headlong rush to "restore the natural ecosystem" has even produced programs to increase salmon predators. The fishery managers placed "Level 1" priority for 1997 BPA funding on a program "directed at learning more about the status of, and options for restoring, populations of Pacific lamprey". Why electric ratepayers should pay for this is unclear, but the motivation is: "Pacific lamprey were an important component of the natural ecosystem, but their numbers have declined dramatically in recent years".40

While there is little research on the effect of lamprey populations in the Columbia River, research in Canada suggests that lamprey feed on juvenile salmon and cause significant mortality.41 If there were more lampreys in the Columbia River, they’d be eating more salmon. If, as some claim, the dams are making life difficult for lamprey, we ought to be happy if our goal is to have larger salmon populations.

In any event, the fishery managers are taxing citizens of the Pacific Northwest $5 million a year to kill one salmon predator (squawfish), and $334,560 to reintroduce another (the lamprey).42 Right now, squawfish are politically unpopular, while politically-potent tribes cite a historic practice of harvesting lamprey. The impact of restoring lamprey on endangered salmon does not seem to be considered; citizens who pay for the lamprey program have no idea how their money is being spent.

Salmon diseases have also spread rapidly in recent years throughout the Columbia River Basin, sometimes through poor hatchery practices. Ceratomyxa shasta, a small worm that preys on salmonids, used to be rare. As recently as twenty years ago, it was only found in the Lower Columbia, below the Deschutes River. Now it can be found as far upstream as the Hell’s Canyon complex.43 Fish tuberculosis and bacterial kidney disease (discussed in greater detail in Chapter 6) also have spread rapidly.

The overall impact on these diseases is presently ignored in salmon recovery programs, in that no one has even attempted to estimate the extent to which overall survival has dropped, and whether and to what extent this drop can be offset by any means. It is possible that until salmon evolve with greater resistance to these diseases, salmon populations may be permanently depressed. Efforts have been made to reduce the spread of disease from hatchery operations, but no one has assessed whether there has been any improvement in overall disease levels.

All salmon have to migrate through the Columbia River estuary, which is rife with predators. Islands at the mouth of the Columbia River, favored by birds, are littered with the identification tags (called “PIT” tags) that scientists have put into salmon. Populations of cormorants, Caspian terns, and other fish-eating birds have increased in recent years, but until very recently, no attempts have been made to quantify the impact on Columbia River salmon.44

Radiotagging studies by Oregon State University researcher Carl Schreck have discovered that cormorants and terns eat 30-40% of the smolts that make it to the mouth of the Columbia River.45 Cormorants take an especially heavy toll. A single cormorant can consume up to twenty pounds of smolts in a single prolonged feeding session. In 1997, Oregon State University researchers focused on the Caspian tern population on Rice Island, which was created by the U.S. Army Corps of Engineers from dredged material. The population has increased 600% in the past 12 years, and it appears that during 1997, the terns on this one island ate between six and twenty million juvenile salmon.46

No one has prepared any comprehensive review of whether total estuarine bird populations are higher or lower than historical levels and what effect this might have on salmon abundance. It certainly seems as if putting a breeding pair of weasels on Rice Island might produce tens if not hundreds of thousands of additional adult salmon, a singularly cost-effective approach to salmon recovery.

38 U.S. Army Corps of Engineers, "Interim Status Report", at 2-4.

39 J. Lilly, Letter to the Editor, Northwest Steelheader, Summer 1996. Mr. Lilly, like many recreational fisherman up and down the rivers of the Columbia Basin, believes that dam turbines have been wrongly blamed for the salmon's decline. "I would like to know", he asks, "who . . . is able to count dead fish coming out of turbines".

40 CBFWA, Public Review (Draft) FY 1997 Anadromous Fish Recommendations, May 15, 1996, at 9.

41 R. Beamish & C-E. Neville, “Pacific salmon and Pacific herring mortalities in the Fraser River plume caused by river lamprey (Lampetra ayresi)”, Can. J. Fish. Aquat. Sci. 52: 644-50 (1995).

42 BPA, “Fish and Wildlife Budget Tracking Report, Fourth Quarter, Fiscal Year 1996, Dec. 23, 1996, at 13 (1996 funds “in process or obligated).

43 G. Bouck, pers. comm. (Nov. 20, 1996).

44 BPA, “Interim Research, Monitoring, and Evaluation Program to Support the FCPRS Biological Opinion and Recovery Plan”, at 37 (Nov. 15, 1995 Draft).

45 C. Schreck, Memo to D. DeHart, W. Weber & B. Schmidt, Oct. 16, 1996.

46 B. Rudolph, "Birds Getting Fat on Salmon Recovery Dollars", NW Fishletter, Oct. 28, 1997.

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