Download or read book Predation Impacts on Juvenile Salmonids by Double Crested Cormorants Amd Caspian Terns on East Sand Island in the Columbia River Estuary written by United States. Army. Corps of Engineers. Portland District and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Predation Impacts on Juvenile Salmonids by Double crested Cormorants and Caspian Terns Nesting on East Sand Island in the Columbia River Estuary written by Allen Evans (Fisheries biologist) and published by . This book was released on 2016 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Caspian Tern Management to Reduce Predation of Juvenile Salmonids in the Columbia River Estuary written by and published by . This book was released on 2005 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Research Monitoring and Evaluation of Avian Predation on Salmonid Smolts in the Lower and Mid Columbia River 2006 Final Season Summary written by and published by . This book was released on 2009 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study investigates predation by piscivorous waterbirds on juvenile salmonids (Oncorhynchus spp.) from throughout the Columbia River Basin. During 2006, study objectives in the Columbia River estuary, work funded by the Bonneville Power Administration, were to (1) monitor and evaluate previous management initiatives to reduce Caspian tern (Hydroprogne caspia) predation on juvenile salmonids (smolts); (2) measure the impact of double-crested cormorant (Phalacrocorax auritus) predation on smolt survival, and assess potential management options to reduce cormorant predation; and (3) monitor large colonies of other piscivorous waterbirds in the estuary (i.e., glaucous-winged/western gulls [Larus glaucescens/occidentalis]) to determine the potential impacts on smolt survival. Study objectives on the mid-Columbia River, work funded by the Walla Walla District of the U.S. Army Corps of Engineers, were to (1) measure the impact of predation by Caspian terns and double-crested cormorants on smolt survival; and (2) monitor large nesting colonies of other piscivorous waterbirds (i.e., California gulls [L. californicus], ring-billed gulls [L. delawarensis], American white pelicans [Pelecanus erythrorhynchos]) on the mid-Columbia River to determine the potential for significant impacts on smolt survival. Our efforts to evaluate system-wide losses of juvenile salmonids to avian predation indicated that Caspian terns and double-crested cormorants were responsible for the vast majority of smolt losses to avian predators in the Columbia Basin, with most losses occurring in the Columbia River estuary. In 2006, East Sand Island in the Columbia River estuary supported the largest known breeding colonies of Caspian terns and double-crested cormorants in the world. The Caspian tern colony on East Sand Island consisted of about 9,200 breeding pairs in 2006, up slightly (but not significantly so) from the estimate of colony size in 2005 (8,820 pairs). There has not been a statistically significant change in the size of the Caspian tern colony on East Sand Island since 2000. Tern nesting success averaged 0.72 fledglings per breeding pair in 2006, significantly higher than in 2005 (0.37 fledglings per breeding pair), a year of poor ocean conditions. Despite the presumably higher availability of marine forage fishes in 2006, the proportion of juvenile salmonids in diets of Caspian terns (32% of prey items) averaged higher than in 2005 (23% of prey items) and 2004 (18% of prey items). Steelhead smolts were particular vulnerable to predation by East Sand Island terns in 2006, with predation rates as high as 20% on particular groups of PIT-tagged fish reaching the estuary. Consumption of juvenile salmonids by terns nesting at the East Sand Island colony in 2006 was approximately 5.3 million smolts (95% c.i. = 4.4-6.2 million), significantly higher than the estimated 3.6 million smolts consumed in 2005, but still roughly 7 million fewer smolts consumed compared to 1998 (when all terns nested on Rice Island in the upper estuary). Caspian terns nesting on East Sand Island continue to rely primarily on marine forage fishes as a food supply, even in 2005 when availability of marine forage fishes declined due to poor ocean conditions. Further management of Caspian terns to reduce losses of juvenile salmonids would be implemented under the Caspian Tern Management Plan for the Columbia River Estuary; the Records of Decision (RODs) authorizing implementation of the plan were signed in November 2006. The ROD lists as the management goal the redistribution of approximately half of the East Sand Island Caspian tern colony to alternative colony sites in interior Oregon and San Francisco Bay, California (USFWS 2006). Implementation of the management plan is stalled, however, because of the lack of appropriated funds.

Download or read book Bioenergetics based Predator prey Relationships Between Piscivorous Birds and Juvenile Salmonids in the Columbia River Estuary written by Donald E. Lyons and published by . This book was released on 2010 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation focuses on the predator-prey relationship between two species of avian predators, Caspian terns (Hydroprogne caspia) and double-crested cormorants (Phalacrocorax auritus), and one of their important prey types, juvenile salmonids (Oncorhynchus spp.), in the Columbia River estuary of Oregon and Washington states during the period 1998 - 2007. I used a data-rich bioenergetics framework to estimate juvenile salmonid consumption by these two avian predators, assessed impacts to at-risk salmonid populations by estimating salmonid mortality rates due to avian predation, and estimated potential demographic benefits to salmonids if avian predation were reduced. The managed relocation of the Caspian tern colony from Rice Island to East Sand Island, lower in the Columbia River estuary, reduced tern predation on salmonids from over 11 million smolts consumed annually to 4 - 7 million, but those benefits accrued primarily to sub-yearling Chinook salmon (O. tshawytscha). Combined consumption of juvenile salmonids by Caspian terns and double-crested cormorants in the Columbia River estuary was ca. 7 - 15 million smolts per year during 2006-2007, causing an 8 - 17% mortality rate among smolts migrating through the estuary, with higher mortality rates for steelhead (O. mykiss) and coho salmon (O. kisutch). Under a potential management scenario to reduce avian predation by both species, improvements in the average annual population growth rate ([lambda]) of salmonids ranged from 0.4% for sub-yearling Chinook to 3.1% for coho. These improvements are generally less than what is possible from altered hydropower system operation within the Columbia Basin for salmonid populations that are more severely affected by dams. For a few salmonid populations, reduced avian predation might contribute to stabilizing the population ([lambda] = 1), but would need to be part of a broader recovery strategy to ensure population growth and recovery ([lambda] > 1). Climate was an important factor modulating Caspian tern predation on salmonids, with greater consumption of smolts occurring in years of cooler ocean conditions and higher Columbia River flows. Climate did not contribute to variation in consumption of salmonids by cormorants, perhaps due to the larger effect of growth in the size of the cormorant colony during the study period. Due to current trends in colony size (terns: stable, cormorants: increasing) and the planned dispersal of a portion of the tern population, cormorant predation will likely be a more significant mortality factor for Columbia Basin salmonids in the future than will tern predation. A critical unknown factor remains; that is the degree to which reductions in avian predation on salmonids might be compensated for by other salmonid mortality factors.

Download or read book Caspian Tern Management to Reduce Predation of Juvenile Salmonids in the Columbia River Estuary written by U.S. Fish and Wildlife Service and published by . This book was released on 2005 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Research Monitoring and Evaluation of Avian Predation on Salmonid Smolts in the Lower and Mid Columbia River 2008 Draft Season Summary written by and published by . This book was released on 2009 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes investigations into predation by piscivorous colonial waterbirds on juvenile salmonids (Oncorhynchus spp.) from throughout the Columbia River basin during 2008. East Sand Island in the Columbia River estuary again supported the largest known breeding colony of Caspian terns (Hydroprogne caspia) in the world (approximately 10,700 breeding pairs) and the largest breeding colony of double-crested cormorants (Phalacrocorax auritus) in western North America (approximately 10,950 breeding pairs). The Caspian tern colony increased from 2007, but not significantly so, while the double-crested cormorant colony experienced a significant decline (20%) from 2007. Average cormorant nesting success in 2008, however, was down only slightly from 2007, suggesting that food supply during the 2008 nesting season was not the principal cause of the decline in cormorant colony size. Total consumption of juvenile salmonids by East Sand Island Caspian terns in 2008 was approximately 6.7 million smolts (95% c.i. = 5.8-7.5 million). Caspian terns nesting on East Sand Island continued to rely primarily on marine forage fishes as a food supply. Based on smolt PIT tag recoveries on the East Sand Island Caspian tern colony, predation rates were highest on steelhead in 2008; minimum predation rates on steelhead smolts detected passing Bonneville Dam averaged 8.3% for wild smolts and 10.7% for hatchery-raised smolts. In 2007, total smolt consumption by East Sand Island double-crested cormorants was about 9.2 million juvenile salmonids (95% c.i. = 4.4-14.0 million), similar to or greater than that of East Sand Island Caspian terns during that year (5.5 million juvenile salmonids; 95% c.i. = 4.8-6.2 million). The numbers of smolt PIT tags recovered on the cormorant colony in 2008 were roughly proportional to the relative availability of PIT-tagged salmonids released in the Basin, suggesting that cormorant predation on salmonid smolts in the estuary was less selective than tern predation. Cormorant predation rates in excess of 30%, however, were observed for some groups of hatchery-reared fall Chinook salmon released downstream of Bonneville Dam. Implementation of the federal plan 'Caspian Tern Management to Reduce Predation of Juvenile Salmonids in the Columbia River Estuary' was initiated in 2008 with construction by the Corps of Engineers of two alternative colony sites for Caspian terns in interior Oregon: a 1-acre island on Crump Lake in the Warner Valley and a 1-acre island on Fern Ridge Reservoir near Eugene. We deployed Caspian tern social attraction (decoys and sound systems) on these two islands and monitored for Caspian tern nesting. Caspian terns quickly colonized the Crump Lake tern island; about 430 pairs nested there, including 5 terns that had been banded at the East Sand Island colony in the Columbia River estuary, over 500 km to the northwest. No Caspian terns nested at the Fern Ridge tern island in 2008, but up to 9 Caspian terns were recorded roosting on the island after the nesting season. There were two breeding colonies of Caspian terns on the mid-Columbia River in 2008: (1) about 388 pairs nested at the historical colony on Crescent Island in the McNary Pool and (2) about 100 pairs nested at a relatively new colony site on Rock Island in the John Day Pool. Nesting success at the Crescent Island tern colony was only 0.28 young fledged per breeding pair, the lowest nesting success recorded at that colony since monitoring began in 2000, while only three fledglings were raised at the Rock Island tern colony. The diet of Crescent Island Caspian terns consisted of 68% salmonid smolts; total smolt consumption was estimated at 330,000. Since 2004, total smolt consumption by Crescent Island terns has declined by 34%, due mostly to a decline in colony size, while steelhead consumption has increased 10% during this same period. In 2008, approximately 64,000 steelhead smolts were consumed by Caspian terns nesting at Crescent Island. Based on smolt PIT tag recoveries on the Crescent Island Caspian tern colony, the average predation rate on in-river migrants from the Snake River (all species and run types combined based on interrogations at Lower Monumental Dam) was at least 1.4%. Predation rates on PIT-tagged steelhead smolts were greater than those for other salmonid species; 6.0% of wild steelhead smolts from the Snake River were consumed by Crescent Island terns. The double-crested cormorant colony on Foundation Island in the mid-Columbia River consisted of at least 360 pairs nesting in trees in 2008. The proportion of juvenile salmonids in stomach samples collected from cormorants nesting on Foundation Island during the peak of the smolt out-migration was about 45% of prey biomass.

Download or read book Salmon Recovery on the Columbia and Snake Rivers written by United States. Congress. Senate. Committee on Environment and Public Works. Subcommittee on Drinking Water, Fisheries, and Wildlife and published by . This book was released on 1999 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Final Work Plan written by RTR / BLE JV and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Health and Safety Plan written by RTR / BLE JV and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Double crested Cormorant Management written by and published by . This book was released on 2003 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Inform Columbia River Basin Hatchery Operations and the Funding of Mitchell Act Hatchery Programs written by and published by . This book was released on 2010 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Benefits to Columbia River Anadromous Salmonids from Potential Reductions in Predation by Double crested Cormorants Nesting at the East Sand Island Colony in the Columbia River Estuary written by Donald E. Lyons and published by . This book was released on 2014 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Predation on juvenile salmonids (Oncorhynchus spp.) during out-migration to the Pacific Ocean is considered a factor potentially limiting the recovery of threatened and endangered anadromous salmonid populations from the Columbia River basin. We examined the potential benefits of reductions in predation by double-crested cormorants (Phalacrocorax auritus) nesting at the large colony on East Sand Island (rkm 8) in the Columbia River estuary to three distinct population segments (DPSs) of steelhead (O. mykiss), four evolutionarily significant units (ESUs) of Chinook salmon (O. tshawytscha), and one ESU of sockeye salmon (O. nerka). All eight of these salmonid populations originate from either the Columbia Basin upstream of Bonneville Dam (rkm 235) or the Upper Willamette Basin, and are listed as either threatened or endangered under the U.S. Endangered Species Act. The East Sand Island double-crested cormorant colony, averaging ca. 12,600 breeding pairs during 2007 – 2012, is the largest colony for this species in western North America, and cormorants from this colony have been documented to consume millions of salmonid smolts per year. We estimated cormorant predation rates using recoveries of smolt passive integrated transponder (PIT) tags on the East Sand Island cormorant colony. Under the framework of a simple deterministic, age-structured, matrix population growth model for salmonid populations, we translated potential changes in smolt survival due to reductions in cormorant predation into increases in the average annual population growth rate at the level of the salmonid distinct population segement (DPS) or evolutionarily significant unit (ESU). Estimates were produced for a range of reductions in cormorant predation and for a range of levels of compensatory mortality for smolts."--From summary.

Download or read book The Devil s Cormorant written by Richard J. King and published by University of New Hampshire Press. This book was released on 2013-09-22 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: Behold the cormorant: silent, still, cruciform, and brooding; flashing, soaring, quick as a snake. Evolution has crafted the only creature on Earth that can migrate the length of a continent, dive and hunt deep underwater, perch comfortably on a branch or a wire, walk on land, climb up cliff faces, feed on thousands of different species, and live beside both fresh and salt water in a vast global range of temperatures and altitudes, often in close proximity to man. Long a symbol of gluttony, greed, bad luck, and evil, the cormorant has led a troubled existence in human history, myth, and literature. The birds have been prized as a source of mineral wealth in Peru, hunted to extinction in the Arctic, trained by the Japanese to catch fish, demonized by Milton in Paradise Lost, and reviled, despised, and exterminated by sport and commercial fishermen from Israel to Indianapolis, Toronto to Tierra del Fuego. In The DevilÕs Cormorant, Richard King takes us back in time and around the world to show us the history, nature, ecology, and economy of the worldÕs most misunderstood waterfowl.

Download or read book The Behavior and Ecology of Pacific Salmon and Trout written by Thomas P. Quinn and published by University of Washington Press. This book was released on 2018-08-06 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Behavior and Ecology of Pacific Salmon and Trout combines in-depth scientific information with outstanding photographs and original artwork to fully describe the fish species critical to the Pacific Rim. This completely revised and updated edition covers all aspects of the life cycle of these remarkable fish in the Pacific: homing migration from the open ocean through coastal waters and up rivers to their breeding grounds; courtship and reproduction; the lives of juvenile salmon and trout in rivers and lakes; migration to the sea; the structure of fish populations; and the importance of fish carcasses to the ecosystem. The book also includes information on salmon and trout transplanted outside their ranges. Fisheries expert Thomas P. Quinn writes with clarity and enthusiasm to interest a wide range of readers, including biologists, anglers, and naturalists. He provides the most current science available as well as perspectives on the past, present, and future of Pacific salmon and trout. In this edition: Over 100 beautiful color photographs of salmon and troutUpdated information on all aspects of the salmon and trout life cycleExpanded coverage of trout

Download or read book Piscivorous Colonial Waterbirds in the Columbia River Estuary written by Yasuko Suzuki and published by . This book was released on 2012 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Caspian terns (Hydroprogne caspia) and double-crested cormorants (Phalacrocorax auritus) nest in large colonies on East Sand Island in the Columbia River estuary, the largest known colonies for the two species in the world. Both species of piscivorous colonial waterbirds have been identified as predators with a significant impact on the survival of juvenile salmonids (Oncorhynchus spp.) listed under the U.S. Endangered Species Act. To better understand and address issues related to seabird-fisheries interactions in the Columbia River estuary, I conducted studies related to the ecology, conservation, and management of these two species of piscivorous waterbirds. I evaluated the demographics and inter-colony movements of Caspian terns belonging to the Pacific Coast metapopulation, with special emphasis on two breeding colonies, one on East Sand Island in the Columbia River estuary and the other on Crescent Island in the mid-Columbia River, based on re-sightings of color-banded individuals. Apparent annual adult survival at both colonies was high, and age at first reproduction was greater than previously reported for the species. Colony site philopatry of breeding adults at both colonies was high; however, some individuals prospected for breeding colonies over much of the Pacific Coast region and moved to other colonies over distances of up to 3,000 km. Some terns from the large colony in the Columbia River estuary responded quickly to the availability of new colony sites as distant as 550 km from the estuary, and established successful breeding colonies within less than a year of the new sites becoming available. The Caspian tern colony on East Sand Island appears to be an important source colony for a number of smaller, less productive colonies distributed over an extensive area from the Salton Sea, California to the Copper River Delta, Alaska, an area with limited and ephemeral nesting opportunities. Environmental contaminants have been a conservation concern for wildlife in the Columbia River estuary, especially species that consume fish and are therefore likely to bioaccumulate persistent organic pollutants. I measured and compared levels of polychlorinated biphenyls (PCBs) in eggs and chicks of Caspian terns and doublecrested cormorants, as well as their primary prey fish types, at colonies on East Sand Island and farther up-river. Based on differences in tern and cormorant diet composition at the various study colonies, higher PCB levels in eggs and chicks were associated with diets dominated by resident freshwater and estuarine fishes. PCB levels in prey fish were positively correlated with lipid content; however, PCB levels in the livers of chicks were negatively correlated with chick fat scores, suggesting that chick fat reserves are a sink for ingested PCBs. Lower PCB levels in terns and cormorants from East Sand Island compared to colonies farther up-river reflected diets with a higher proportion of marine forage fishes at East Sand Island; marine forage fishes had lower average levels of PCBs than their resident freshwater and estuarine counterparts. In order to explore non-destructive techniques for managing nesting colonies of double-crested cormorants, I evaluated habitat enhancement and social attraction, two techniques that have proven effective for relocating Caspian tern colonies to sites where impacts on fish stocks of conservation concern would be minimal. Cormorants were attracted to nest and successfully raised young at test plots on East Sand Island and on islands in the estuary with a previous history of cormorant nesting or unsuccessful nesting attempts. On an island with no history of cormorant nesting or prospecting, however, no cormorants were attracted to nest. My results suggest that attraction of nesting cormorants using these techniques is dependent on the previous history of cormorant nesting or nesting attempts, the frequency and intensity of disturbance by potential predators, and the presence of breeding cormorants nearby. While habitat enhancement and social attraction have potential as methods for redistributing nesting cormorants away from areas where fish stocks of concern are highly susceptible to predation, successful establishment of new colonies using these techniques will likely require a focus on sites with a history of cormorant nesting. Findings from this dissertation raise some concerns over the management of Caspian tern and double-crested cormorant colonies on East Sand Island in order to redistribute parts of these colonies to alternative sites and mitigate the impact of those piscivorous colonial waterbirds on ESA-listed salmonids. East Sand Island has supported source colonies of piscivorous colonial waterbirds for many smaller colonies throughout the region and is close to an abundant and relatively uncontaminated food supply. Also, alternative colony sites that can substitute for East Sand Island are not readily apparent, especially for double-crested cormorants. Therefore, management of Caspian tern and double-crested cormorant colonies on East Sand Island to benefit Columbia Basin salmonids needs to proceed cautiously and reversibly because of the implications for the region-wide populations of these piscivorous colonial waterbirds.

Download or read book Avian Predation on Salmonids in the Columbia River Basin written by Daniel D. Roby and published by . This book was released on 2021 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary goal of this report is to assemble and summarize results from previous published and unpublished studies of avian predation in the Columbia River basin (CRB) and to present results from retrospective analyses of data from previous studies to identify long‐term patterns and trends. Results of these analyses are vital for assessing the efficacy of management initiatives to reduce predation impacts on Endangered Species Act‐listed juvenile salmonids by Caspian terns and double‐crested cormorants in the CRB and to inform an adaptive approach that ensures that management objectives are fully achieved and sustained into the future. These analyses are also essential for evaluating how management actions have and will continue to affect populations of piscivorous colonial waterbirds in the CRB and throughout the Pacific Flyway, populations of native species that are protected by the Migratory Bird Treaty Act. Finally, we hope that this report will serve as a comprehensive repository of results from research, monitoring, and evaluation of avian predation during 1997–2019 and provide a single‐source document on the topic for regional managers, stakeholders, researchers, and the public.