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 Fishery Bulletin written by and published by . This book was released on 2012 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Canadian Journal of Fisheries and Aquatic Sciences written by and published by . This book was released on 2013 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Avian Predation on Juvenile Salmonids in the Columbia River written by Allen Evans and published by . This book was released on 2015 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: "To address concerns over the impact of avian predation on juvenile salmonids in the Columbia River Basin, we evaluated predation probabilities on steelhead, yearling Chinook salmon, and subyearling Chinook salmon by piscivorous birds from 11 different breeding colonies. Salmonid smolts were tagged and released as part of survival studies using the Juvenile Salmonid Acoustic Telemetry System, a network of hydrophones that provided detections of acoustic-tagged fish at various spatial and temporal scales during seaward migration. Fish were released and tracked during passage through a 251 kilometer (km) section of the lower Snake River and lower Columbia River in 2012, a 192 km section of the lower Columbia River in 2014, and a 184 km section of the middle Columbia River during 2014. Detections of tagged smolts at telemetry arrays, coupled with the recovery of tags on nearby bird colonies, were used to quantify where avian predation occurred, when it occurred, and the cumulative impact of predation by colonial waterbirds on the survival of tagged fish. Results were also used to estimate unaccounted for smolt mortality (total smolt mortality - mortality due to colonial waterbirds), which was due in part to factors other than bird predation (e.g., piscine predation, mortality during dam passage, and other non-avian mortality factors)."--From summary.
Download or read book Avian Predation on Juvenile Salmonids in the Lower Columbia River written by and published by . This book was released on 1998 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors initiated a field study in 1997 to assess the impacts of fish-eating colonial waterbirds (i.e., terns, cormorants, and gulls) on the survival of juvenile salmonids in the lower Columbia River. Here the authors present results from the 1998 breeding season, the second field season of work on this project. The research objectives in 1998 were to: (1) determine the location, size, nesting chronology, nesting success, and population trajectories of breeding colonies of fish-eating birds in the lower Columbia River; (2) determine diet composition of fish-eating birds, including taxonomic composition and energy content of various prey types; (3) estimate forage fish consumption rates, with special emphasis on juvenile salmonids, by breeding adults and their young; (4) determine the relative vulnerabilit2048 different groups of juvenile salmonids to bird predation; (5) identify foraging range, foraging strategies, and habitat utilization by piscivorous waterbirds; and (6) test the feasibility of various alternative methods for managing avian predation on juvenile salmonids and develop recommendations to reduce avian predation, if warranted by the results.
Download or read book Avian Predation on Juvenile Salmonids in the Lower Columbia River written by and published by . This book was released on 2000 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors initiated a field study in 1997 to assess the impacts of fish-eating colonial waterbirds (i.e., terns, cormorants, and gulls) on the survival of juvenile salmonids in the lower Columbia River. Here the authors present results from the 1998 breeding season, the second field season of work on this project. The research objectives in 1998 were to: (1) determine the location, size, nesting chronology, nesting success, and population trajectories of breeding colonies of fish-eating birds in the lower Columbia River; (2) determine diet composition of fish-eating birds, including taxonomic composition and energy content of various prey types; (3) estimate forage fish consumption rates, with special emphasis on juvenile salmonids, by breeding adults and their young; (4) determine the relative vulnerability of different groups of juvenile salmonids to bird predation; (5) identify foraging range, foraging strategies, and habitat utilization by piscivorous waterbirds; and (6) test the feasibility of various alternative methods for managing avian predation on juvenile salmonids and develop recommendations to reduce avian predation, if warranted by the results.
Download or read book Environmental Assessment written by and published by . This book was released on 2003 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Review written by Range D. Bayer and published by . This book was released on 2003-01-01 with total page 98 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 Seabird Predation on Juvenile Salmonids in the Columbia River Estuary written by and published by . This book was released on 1999 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A System wide Assessment of Avian Predation on Juvenile Salmonids in the Columbia River Basin Based on Passive Integrated Transponder Tag Recoveries written by Brad A. Ryan and published by . This book was released on 2005 with total page 266 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 Pre decisional Environmental Assessment written by Wildlife Services (U.S.) and published by . This book was released on 2003 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Influence of the Columbia River Plume on Predator prey Interactions written by Elizabeth M. Phillips and published by . This book was released on 2018 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oceanographic processes that aggregate prey and facilitate the transfer of energy to higher trophic levels often influence marine predator-prey interactions. Buoyant discharge from the Columbia River forms a large freshwater plume bounded by convergent fronts in the northern California Current. These oceanographic features aggregate zooplankton and attract coastal pelagic fish species (CPS) including northern anchovy (Engraulis mordax). Juvenile salmon (Oncorhynchus spp.) use the Columbia River plume as they migrate to sea and experience elevated mortality during early marine residence. Seabirds including sooty shearwaters (Ardenna grisea) and common murres (Uria aalge) use the plume to forage, consuming CPS and juvenile salmon, and the Columbia River plume may influence predator-prey interactions and juvenile salmon survival. This dissertation examined the influence of the Columbia River plume on distributions of seabirds and fish prey, and characterized conditions that influence juvenile salmon predation risk. Chapter 1 provides a general introduction to the Columbia River plume ecosystem. Chapter 2 demonstrates the disproportionate occurrence of murres, shearwaters, CPS, and juvenile salmon in plume waters, the positive relationship between turbid plume waters and seabird densities, and the aggregation of seabirds in the plume when surface area is low. Chapter 3 used satellite telemetry and a high resolution hydrodynamic model of plume circulation to demonstrate the ability of murres and shearwaters to track the north-south movements of the plume, and the movement of seabirds towards biophysically active plume boundaries when surface areas exceed a threshold of ~1,500–4,000 km2. Chapter 4 compared murre distributions observed from ship, plane, and satellite telemetry data perspectives, and identified similarities and differences in seabird spatiotemporal distributions that can inform species distribution models. Chapter 5 documented a relationship between low plume surface areas and increased juvenile coho and Chinook salmon predation risk from seabirds, and the mediating role of CPS in predator-prey interactions near the plume. Taken together, the results of this dissertation demonstrate that variation in Columbia River plume surface area and river discharge influences predator-prey interactions and juvenile salmonid predation risk. Chapter 6 offers a synthesis of the results and recommendations for future research aimed at informing Pacific salmon ocean ecology, management, and conservation.
Download or read book Predator prey Relationships Between Fish eating Birds and Atlantic Salmon written by P. F. Elson and published by . This book was released on 1960 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt:
