ScholarsArchive Collection: Studies in Oregon Ornithology/Yaquina Studies in Natural History

Review : bird predation of juvenile salmonids and management of birds near 14 Columbia Basin dams

Wed, 29 Jan 2003 22:58:59 GMT

Title: Review : bird predation of juvenile salmonids and management of birds near 14 Columbia Basin dams

Authors: Bayer, Range D., 1947-

Abstract: Bird predation of juvenile salmonids and/or bird predation control are reviewed for 14 of the 18mainstem dams on the Columbia and Snake Rivers, but there was little information for some of these dams.California gulls, ring-billed gulls, Caspian terns, double-crested cormorants, American whitepelicans, and several other bird species have been reported as predators of juvenile salmon and steelhead atthese dams. Most estimates of the amount of this predation have been 2% or less of salmonids passing adam. This is less than the percentage of juvenile salmonids killed during dam passage, and it has not beendetermined what proportion of salmonids taken by birds were already dead or mortally injured from dampassage. Thus, it is not clear what portion of bird predation is of viable salmonids that would haveotherwise survived. Further, it appears that most juvenile salmonids in the Columbia Basin are not federallylisted as threatened or endangered, so it is not known what impact bird predation at dams may have on listedsalmonids. Nevertheless, predation may significantly affect certain salmon stocks, so it cannot be dismissedas unimportant.Bird management includes installing wires above the water at dam tailraces. Closely spaced wiresare effective in keeping out flying birds. However, not all areas where birds feed on fish below dams can becovered with wires, the wires have sometimes been placed too far apart to keep out flying birds, andnonflying birds can go under wires. Consequently, Wildlife Services (which was known as AnimalDamage Control prior to 1998) of the U.S. Department of Agriculture has also nonlethally harassed andlethally taken birds at dams after it has been requested to do so. Studies by staff of the U.S. Army Corps ofEngineers have shown that nonlethal and lethal control by Washington Wildlife Services at The Dalles andJohn Day Dams needed to be repeated because birds would return. During 1997-1998, Wildlife Servicesdispersed at least 20,682 birds (mostly gulls) and lethally took at least 3,143 birds at these two dams.Most juvenile salmonids migrate past dams from April through early June, although manysubyearling chinook migrate during July and August. Thus, bird control to protect juvenile salmonidswould be most effective during April-July and perhaps through August for subyearling chinook. Beginningin August, many juvenile American shad are also migrating over lower Columbia dams and then can bemore abundant than migrating salmonids; however, few shad pass Snake River dams and at least onemid-Columbia dam. Washington Wildlife Services' bird control has been during April-Septemberat mid-Columbia dams and apparently during spring through winter at lower Columbia dams, so its controlmay sometimes occur when few juvenile salmonids are migrating.Although bird management at some dams has occurred since at least 1992, it has not yet beendetermined if this control is cost effective (i.e., the costs of bird control are less than the costs of predation).Washington Wildlife Services asserts that the cost of bird predation can be estimated by the cost ofcontrolling predation. With this circular logic, Wildlife Services could spend a considerable amount oftaxpayer or electric ratepayer money controlling predators that may be taking an insignificant number ofviable juvenile salmonids and justify doing so because it has spent so much money. Consequently, it isimportant for there to be realistic evidence for the need or benefits of predator control, so that control iscost effective.Washington Wildlife Services has not been forthcoming in answering general questions about itsactivities at Columbia Basin dams and asserts that a federal Texas court case precludes disclosure ofinformation. However, it seems that Wildlife Services may be using that court case to avoid scrutinybecause the court ruled that Wildlife Services not provide information that could identify cooperators withWildlife Services, not that it withhold all information about its activities. Further, Wildlife Services appearsto have violated this court decision by providing other agencies with reports of its predator control activitiesthat identifies specific cooperators, so Washington Wildlife Services seems to have selectively chosen when to use the court ruling as an excuse to not give out general information.Fish-eating bird control has proceeded very differently in the Columbia Estuary than at ColumbiaBasin dams. In the Estuary, bird predation was quantified in 1997 to establish a need for bird control;agency, tribal, and public consultations about a management plan were conducted, management actionsbegan to be implemented in 1999, and predation reduction began to be quantified in 2000. At dams,Washington Wildlife Services assumed bird predation to be significant, initiated bird management beforethe amount of predation was measured, appears to have done less consultation with the public, otheragencies, or tribes about its management actions; and assumed that its predator control actions havesignificantly reduced predation.

Cormorant harassment to protect juvenile salmonids in Tillamook County, Oregon

Fri, 29 Oct 1999 22:58:59 GMT

Title: Cormorant harassment to protect juvenile salmonids in Tillamook County, Oregon

Authors: Bayer, Range D., 1947-

Abstract: The goal of the Oregon Plan is to restore wild coho and wild steelhead runs. Under the federalEndangered Species Act, wild coho salmon along the Oregon Coast are listed as Threatened and wildOregon Coast steelhead are a candidate for listing. Although cormorants have been hazed at theNehalem Estuary for at least 10 years and at the Tillamook and Nestucca Estuaries for at least threeyears, spawning ground counts of wild coho salmon, winter steelhead, and fall chinook have averagedless since hazing began. Thus, hazing does not appear to be useful in recovering wild salmonids.Hazing is not correlated with consistently improved hatchery returns. The survival of Coded WireTag marked coho smolts at the Nehalem was about the same whether hazing occurred or not, thepercent return for coho smolts was not significantly greater at the hazed Nehalem than at the nonhazedSalmon River, and the number of returning adult coho salmon was significantly greater with hazing at theNehalem hatchery but not at the Trask hatchery in the Tillamook Basin. For winter steelhead, the numberof returning adults to the Nehalem and jacks to the Cedar Creek hatchery in the Nestucca Basin did notincrease significantly with hazing, but the number of jacks returning to the Nehalem did.Changes in fisheries subsequent to hazing are mixed. Coho catches increased with hazing atthe Nehalem but not at the Tillamook Basin. Nehalem steelhead catches averaged less with hazing, butchinook fisheries have grown. However, the increase in chinook catches occurred as the number ofwild chinook at spawning areas declined, so the larger catch may be a consequence of a greater harvestof wild chinook rather than hazing.Returns may not have increased with hazing because it was ineffective in substantially reducingpredation, because smolts saved by hazing died anyway, or because other factors such as unfavorableocean conditions may have been much more important in affecting smolt survival than hazing.In any case, hazing does not appear to be a panacea for salmonid recovery, and it has costs.During 1996-1999, the Oregon Legislature spent $100,000 for cormorant hazing, and a biological cost ofhazing is the disturbance of wildlife other than cormorants.

Birds of the Coast Range of Lincoln County, Oregon : v.1. Birds of Thornton Creek

Mon, 29 Oct 1990 22:58:59 GMT

Title: Birds of the Coast Range of Lincoln County, Oregon : v.1. Birds of Thornton Creek

Authors: Faxon, Darrel, 1948-; Bayer, Range D., 1947-

Abstract: Incidental to his outdoor activities such as farming, fern-picking, and horse logging, Darrel Faxon made 17.4 years of detailed observations at Thornton Creek during 1973-1990. He determined bird presence, not bird abundance, and made about 99,800 records, where a record is one bird species found during one day. Depending upon the calendar month, Faxon averaged 19-24 observation days/month, 13-34 bird species/day, and 34-66 species/month. He noted an average of 101 species each year. Faxon found 12 species only during casual observations prior to 1973 and 179 species in 1973-1990. He detected 47 waterbird species, so most birds he noted were terrestrial. 30% of waterbird species and 20% of terrestrial species were recorded in only one year, and just 16% of the waterbird species were seen in 16-18 years. However, Faxon noted the majority (50.4%) of terrestrial species in 16 or more years. For each species, daily relative frequencies of occurrence for each month and average monthly relative frequencies of occurrence for the 1973-1981 and 1982-1990 periods are given. Further, arrival and departure dates are listed for each species for each year, if appropriate. Faxon's records indicate that many migratory terrestrial species are often not present in the 10 days following their arrival or prior to their departure. Thus, determining arrival or departure dates may be very dependent upon daily observation effort. For example, if there are inadequate daily observations, then the actual arrival date may be missed, and it may be several days or a week before the species may re-appear. This inconsistency of presence after their "arrival" results in many species not being found on their "average" arrival date. Although Faxon did not record a spring migration wave, he usually noted a major movement of passerines during August-September. In fall, his records also indicate that some raptors appeared to be migrating through. In addition to his bird observations, Faxon recorded daily precipitation from 1975-1990, and monthly totals are given.

The cormorant/fisherman conflict in Tillamook County, Oregon

Sat, 29 Oct 1988 22:58:59 GMT

Title: The cormorant/fisherman conflict in Tillamook County, Oregon

Authors: Bayer, Range D., 1947-

Abstract: The cormorant/fisherman issue is not limited to Tillamook County in1988-1989 but is symptomatic of a widespread conflict of some fishermenwith fish-eating animals.Predators, specifically cormorants, have been blamed for the "ruin" ofthe Tillamook fisheries, but the effects of cormorant predation have beenexaggerated. Actually, current salmon and steelhead catches are similar to orgreater than many catches prior to 1972, when several "predators" (includingDouble-crested Cormorants) were not protected by law. Although it is clearthat cormorants can eat some smolts in Tillamook Bay, it is unreasonable toassume that they eat as many as has been suggested. For example, when figuresthat appeared in a Tillamook newspaper are added up, cormorants in TillamookBay in 1988 were suggested to eat nearly three times as many smolts as werereleased there!Because a few Tillamook County fishing guides and fishermen felt thatcormorants were destroying their salmon and steelhead fisheries, theypressured the Oregon Department of Fish and Wildlife (ODFW) into giving thempermits to harass (but not kill) cormorants in the spring of 1988 on publicwaters of Nehalem and Tillamook Bays. The permittees were not supervised tobe sure that they did not disturb or harm nontarget wildlife (i.e., wildlifeother than the targeted cormorants) or did not kill cormorants.After the ODFW announced in late November 1988 that they would not beissuing cormorant harassment permits in 1989, a few Tillamook fishing guidesand fishermen worked to pass House Bill 3185 during the 1989 OregonLegislative session. House Bill 3185 would have allowed cormorantharassment along the entire Oregon Coast any time during the year, but theBill failed. Then, in July 1989, the Oregon Fish and Wildlife Commissionrefused to consider granting harassment permits to fishing guides andfishermen. Thus, cormorant harassment in 1989 was not legalized, althoughsome harassment apparently occurred illegally.Cormorant harassment in Tillamook County does not currently meet therequirements to justify an animal damage control program. For example, onecriterion of such a program is that there be minimal compensatory predation(i.e., prey saved from the controlled predator is taken by noncontrolledpredators). But if cormorants are harassed, there are many other predatorsthat could eat the "saved" smolts, including adult coho and chinook salmon,steelhead, cutthroat trout, and striped bass that may eat millions of salmonand steelhead smolts along the Oregon Coast each year.Current information indicates that documented smolt losses from cormorantpredation may not compensate the economic, biological, aesthetic, and socialcosts of harassment. Biological costs include disturbance to nontargetwildlife such as waterfowl or threatened and endangered birds like the BaldEagle and Brown Pelican; disturbance would unavoidably accompany cormorantharassment. One social cost of interest is that predator control ofcormorants to "save" salmon is arbitrary and capricious, since salmon arethemselves a significant predator of young Dungeness crabs and fish importantto other Oregon commercial and sports fishermen.Alternatives to cormorant harassment exist and would address all smoltpredation, not just that by cormorants. These alternatives include changinghatchery practices, so that smolts survive better after release. These alternatives should be at least considered.Biologists may have somewhat defused the cormorant harassment issue ifthey were more able to communicate with nonbiologically-trained fishermen, buteven so, there are a few fishing guides and fishermen who refuse to believeany information that does not agree with their own opinions.