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Research Monitoring And Evaluation Of Avian Predation On Salmonid Smolts In The Lower And Mid Columbia River Final 2012 Annual Report
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Book Synopsis Research, Monitoring, and Evaluation of Avian Predation on Salmonid Smolts in the Lower and Mid-Columbia River, Final 2012 Annual Report by : Ken Collis
Download or read book Research, Monitoring, and Evaluation of Avian Predation on Salmonid Smolts in the Lower and Mid-Columbia River, Final 2012 Annual Report written by Ken Collis and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study continues investigations of predation by piscivorous waterbirds on juvenile salmonids (Oncorhynchus spp.) from throughout the Columbia River Basin.
Book Synopsis Research, Monitoring, and Evaluation of Avian Predation on Salmonid Smolts in the Lower and Mid-Columbia River, 2006 Final Season Summary by :
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.
Book Synopsis Research, Monitoring, and Evaluation of Avian Predation on Salmonid Smolts in the Lower and Mid-Columbia River, 2008 Draft Season Summary by :
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.
Book Synopsis Avian Predation on Juvenile Salmonids in the Columbia River by : Allen Evans
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.
Book Synopsis Avian Predation in the Columbia Plateau Region, Management, Monitoring, and Evaluation by : Ken Collis
Download or read book Avian Predation in the Columbia Plateau Region, Management, Monitoring, and Evaluation written by Ken Collis and published by . This book was released on 2020 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The primary objectives of this study in 2019 were to: (1) implement and evaluate the Inland Avian Predation Management Plan (IAPMP; USACE 2014), including adaptive management actions, in order to dissuade Caspian terns (Hydroprogne caspia) from nesting on Crescent Island, Goose Island, and elsewhere in Potholes Reservoir to reduce tern predation on Endangered Species Act (ESA)-listed juvenile salmonids (Oncorhynchus spp.); (2) investigate the distribution, colony size, and smolt impacts of unmanaged piscivorous colonial waterbirds (i.e. California gulls [Larus californicus], ring-billed gulls [L. delawarensis], American white pelicans [Pelecanus erythrorhynchos]), and double-crested cormorants [Phalacrocorax auratus] to help identify immerging avian predation issues in the Columbia Plateau region (CPR) that may be of concern to resource managers; and (3) calculate aggregate estimates of avian predation (i.e. consumption by all predator species and colonies combined within a specific river reach) and estimates of reach-specific survival of juvenile salmonids during downstream passage. Collectively, these objectives address several management-relevant questions needed to maximize the benefits to ESA-listed salmonids in managing piscivorous colonial waterbirds, while also maintaining a multiyear avian predation dataset in the Columbia River basin."--Project Objectives (pages 6-7).
Book Synopsis Avian Predation on Salmonids in the Columbia River Basin by : Daniel D. Roby
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.
Book Synopsis Avian Predation on Juvenile Salmonids in the Lower Columbia River by : Ken Collis
Download or read book Avian Predation on Juvenile Salmonids in the Lower Columbia River written by Ken Collis and published by . This book was released on 2000 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Avian Predation on Juvenile Salmonids in the Lower Columbia River by :
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.
Book Synopsis Monitoring and Evaluation of Smolt Migration in the Columbia Basin by :
Download or read book Monitoring and Evaluation of Smolt Migration in the Columbia Basin written by and published by . This book was released on 2008 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: The combined juvenile and adult detection histories of PIT-tagged wild salmonids migrating through the Federal Columbia River Power System (FCRPS) were analyzed using the ROSTER (River-Ocean Survival and Transportation Effects Routine) statistical release-recapture model. This model, implemented by software Program ROSTER, was used to estimate survival on large temporal and spatial scales for PIT-tagged wild spring and summer Chinook salmon and steelhead released in the Snake River Basin upstream of Lower Granite Dam from 1996 to 2004. In addition, annual results from wild salmonids were compared with results from hatchery salmonids, which were presented in a previous report in this series (Buchanan, R.A., Skalski, J.R., Lady, J.L., Westhagen, P., Griswold, J., and Smith, S. 2007, 'Survival and Transportation Effects for Migrating Snake River Hatchery Chinook Salmon and Steelhead: Historical Estimates from 1996-2003', Technical report, Bonneville Power Administration, Project 1991-051-00). These results are reported here. Annual estimates of the smolt-to-adult return ratio (SAR), juvenile inriver survival from Lower Granite to Bonneville, the ocean return probability from Bonneville to Bonneville, and adult upriver survival from Bonneville to Lower Granite are reported. Annual estimates of transport-inriver (T/I) ratios and differential post-Bonneville mortality (D) are reported on a dam-specific basis for release years with sufficient numbers of wild PIT-tagged smolts transported. Transportation effects are estimated only for dams where at least 1,000 tagged wild smolts were transported from a given upstream release group. Because few wild Chinook salmon and steelhead tagged upstream of Lower Granite Dam were transported before the 2003 release year, T/I and D were estimated only for the 2003 and 2004 release years. Performance measures include age-1-ocean adult returns for steelhead, but not for Chinook salmon. Spring and summer Chinook salmon release groups were pooled across the entire Snake River Basin upstream of Lower Granite Dam for this report. Annual estimates of SAR from Lower Granite back to Lower Granite averaged 0.92% with an estimated standard error (dSE) of 0.25% for wild spring and summer Chinook salmon for tagged groups released from 1996 through 2004, omitting age-1-ocean (jack) returns. Only for the 1999 and 2000 release years did the wild Chinook SAR approach the target value of 2%, identified by the NPCC as the minimum SAR necessary for recovery. Annual estimates of SAR for wild steelhead from the Snake River Basin averaged 0.63% (dSE = 0.15%), including age-1-ocean returns, for release years 1996 through 2004. For release years when the ocean return probability from Bonneville back to Bonneville could be estimated (i.e., 1999 through 2004), it was estimated that on average approximately 83% of the total integrated mortality for nontransported, tagged wild spring and summer Chinook, and 78% for steelhead (omitting the 2001 release year), occurred during the ocean life stage (i.e., from Bonneville to Bonneville). This suggests that additional monitoring and research efforts should include the ocean and estuary environment. Annual estimates of the dam-specific T/I for Lower Granite Dam were available for the 2003 and 2004 release years for both wild Chinook salmon and wild steelhead. The estimated T/I for Lower Granite was significantly> 1.0 for Chinook in 2004 (P 0.0001) and for steelhead in both 2003 (P
Book Synopsis Development of an Index to Bird Predation of Juvenile Salmonids Within the Yakima River, 2001 Annual Report by :
Download or read book Development of an Index to Bird Predation of Juvenile Salmonids Within the Yakima River, 2001 Annual Report written by and published by . This book was released on 2002 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Avian predation of fish is suspected to contribute to the loss of out-migrating juvenile salmonids in the Yakima Basin, potentially constraining natural and artificial production. In 1997 and 1998, the Yakima/ Klickitat Fisheries Project (YKFP)--whose goal is increasing natural production within the Yakima River--initiated investigations to assess the feasibility of developing an index to avian predation of juvenile salmon within the river. This research confirmed that Ring-billed Gulls and Common Mergansers were the primary avian predators of juvenile salmon (Phinney et al. 1998), and that under certain conditions could significantly impact migrating smolt populations. Beginning in 1999, the Washington Cooperative Fish and Wildlife Research Unit (WACFWRU) was asked by the YKFP to continue development of avian consumption indices. Monitoring methods developed by Phinney et al. (1998) were adopted (with modifications) and monitoring of impacts to juvenile salmon along river reaches and at areas of high predator/prey concentrations (colloquially referred to as ''hotspots'') has continued each year through 2001. In 2001, piscivorous birds were counted from river banks at hotspots and from a raft or drift boat along river reaches. Consumption by gulls at hotspots was based on direct observations of foraging success and modeled abundance; consumption by all other piscivorous birds was estimated using published dietary requirements and modeled abundance. Seasonal patterns of avian piscivore abundance were identified, diurnal patterns of gull abundance at hotspots were identified, and predation indices were calculated for hotspots and river reaches (for both spring and summer). Changes in survey methods in 2001 included the addition of surveys in the ''Canyon'' reach during spring and altering the method of directly measuring gull feeding rates at hotspots. Primary avian predators in 2001 were ''gulls'' (California and Ring-billed) at hotspots and Common Mergansers within upper river reaches. Consumption on the lower reaches was distributed among a number of species, with slightly more then half of all fish consumption being attributed to American White Pelicans. Estimated consumption by gulls at both hotspots combined (8 Apr-30 Jun) was 169,883 fish. Assuming a worst case scenario (all fish taken were smolts) this represented approximately 4.9% of all smolts estimated passing or being released from the Prosser Dam area during the 2001 smolt migration season. Total gull abundances and estimates of consumption between the two hotspot sites were opposite that seen in 2000. Foraging gulls at Horn Rapids Dam were regressed against flow for the 3 years and found to be significant (alpha = 0.1, P=0.081, r2 = .2589). A similar 3-year regression vs fish passage through the Chandler Juvenile Fish Facility, however, did not show a significant relationship (alpha = 0.1, P = 0.396, r2 = .3708). Total estimated take by Common Mergansers across all strata surveyed was 14,777 kg between 8 Apr and 31 Aug, 2001. Approximately 66 percent of that consumption was within the upper river reaches (Stratum 1) where there is a known breeding population of mergansers. Graphical comparisons of merganser abundances over the three years (1999-2001) in the upper reaches of the Yakima River suggest an increase in 2001 from the previous 2 years in both the spring and summer survey periods, but overlapping confidence intervals prevent assumptions regarding upward or downward trends in abundance.
Book Synopsis Evaluate the Impacts of Avian Predation on Salmonid Smolts from the Columbia and Snake Rivers - 2007 Final Season Summary by :
Download or read book Evaluate the Impacts of Avian Predation on Salmonid Smolts from the Columbia and Snake Rivers - 2007 Final Season Summary written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Evaluate the Impacts of Avian Predation on Salmonid Smolts from the Columbia and Snake Rivers, 2008 Final Season Summary by :
Download or read book Evaluate the Impacts of Avian Predation on Salmonid Smolts from the Columbia and Snake Rivers, 2008 Final Season Summary written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of an Index to Bird Predation of Juvenile Salmonids Within the Yakima River, 2000 Annual Report by :
Download or read book Development of an Index to Bird Predation of Juvenile Salmonids Within the Yakima River, 2000 Annual Report written by and published by . This book was released on 2002 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt: Avian predation of fish is suspected to contribute to the loss of juvenile spring chinook salmon in the Yakima Basin, potentially constraining natural production. In 1997 and 1998, the Yakama/Klickitat Fisheries Project (YKFP) and the Washington Department of Fish and Wildlife (WDFW)--whose goal is to increase natural production historically present within the Yakima River--initiated investigations to assess the feasibility of developing an index to avian predation of juvenile salmon within the river. This research--conducted by Dr. Steve Mathews and David Phinney of the University of Washington--confirmed that Ring-billed Gulls and Common Mergansers were the primary avian predators of juvenile salmon, and that under certain conditions could impact migrating smolt populations. Beginning in 1999, the Washington Cooperative Fish and Wildlife Research Unit (WACFWRU) was asked by the YKFP and the WDFW to continue development of avian consumption indices. Monitoring methods developed by Phinney et al. (1998) were adopted (with modifications) and monitoring of impacts to juvenile salmon along river reaches and at areas of high predator/prey concentrations (colloquially referred to as ''hotspots'') continued through 2000. In 2000, piscivorous birds were counted from river banks at hotspots and from a raft or drift boat along river reaches. Consumption by gulls at Hotspots was based on direct observations of foraging success and modeled abundance; consumption by all other piscivorous birds was estimated using published dietary requirements and modeled abundance. Further development of the avian consumption index model provided an estimation of smolt consumption for the 2000 survey season. Seasonal patterns of avian piscivore abundance were identified, diurnal patterns of gull abundance at hotspots were identified, predation indices were calculated for hotspots and spring and summer river reaches, and the efficacy of aerial surveys for estimating bird abundance within river reaches was evaluated. The only change in survey methods in 2000 was the shortening (in river miles) of surveys on the North Fork of the Teanaway River and the shifting of start and stop dates for river drifts and hotspot surveys. Primary avian predators in 2000 were ''gulls'' (California and Ring-billed) at hotspots and Common Mergansers within upper river reaches. Estimated consumption by gulls at both hotspots combined (10 April-30 June) was 163,475 fish. Assuming a worst case scenario (all fish taken were smolts) this represented 6.0% of all smolts estimated passing or being released from the Chandler Dam area during the 2000 smolt migration season. Total estimated take by Common Mergansers across all strata surveyed was 7,654 kg between 10 Apr and 30 Aug, 2000. Seventy-three percent of that consumption was within the upper river reaches (Stratum 1) where there is a known breeding population of mergansers.
Book Synopsis Bioenergetics-based Predator-prey Relationships Between Piscivorous Birds and Juvenile Salmonids in the Columbia River Estuary by : Donald E. Lyons
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.
Book Synopsis Impacts of Avian Predation on Salmonid Smolts from the Columbia and Snake Rivers by : Daniel D. Roby
Download or read book Impacts of Avian Predation on Salmonid Smolts from the Columbia and Snake Rivers written by Daniel D. Roby and published by . This book was released on 2011 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of an Index to Bird Predation of Juvenile Salmonids Within the Yakima River, 1999 Annual Report by :
Download or read book Development of an Index to Bird Predation of Juvenile Salmonids Within the Yakima River, 1999 Annual Report written by and published by . This book was released on 2001 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Avian predation of fish is suspected to contribute to the loss of juvenile spring chinook salmon in the Yakima Basin, potentially constraining natural production. In 1997 and 1998, the Yakama/Klickitat Fisheries Project (YKFP) and the Washington Department of Fish and Wildlife (WDFW)--whose goal is to increase natural production historically present within the Yakima River--initiated investigations to assess the feasibility of developing an index to avian predation of juvenile salmon within the river. This research--conducted by Dr. Steve Mathews and David Phinney of the University of Washington--confirmed that Ring-billed Gulls and Common Mergansers were the primary avian predators of juvenile salmon, and that under certain conditions could significantly impact migrating smolt populations. Beginning in 1999, the Washington Cooperative Fish and Wildlife Research Unit was asked by the YKFP and the WDFW to continue development of avian consumption indices. Monitoring methods developed by Mathews and Phinney were adopted (with modifications) and monitoring of impacts to juvenile salmon along river reaches and at areas of high predator/prey concentrations (colloquially referred to as ''hotspots'') continued. New efforts initiated in 1999 included piscivorous bird surveys at smolt acclimation sites operated by the Yakama Nation, monitoring of the North Fork Teanaway River for changes in avian piscivore abundance associated with the installation of the Jack Creek acclimation facility, and aerial surveys seeking to identify avian piscivores along the length of the Yakima River. In 1999, piscivorous birds were counted from river banks at hotspots and from a raft or drift boat along river reaches. Consumption by gulls was based on direct observations of foraging success and modeled abundance; consumption by Common Mergansers (which forage underwater) was estimated using published dietary requirements and modeled abundance. A second-order polynomial equation was used to interpolate gull and Common Merganser abundance on days when surveys were not conducted. Seasonal patterns of avian piscivore abundance were identified, diurnal patterns of gull abundance at hotspots were identified, predation indices were calculated for hotspots and summer river reaches, and the efficacy of aerial surveys for estimating bird abundance within river reaches was evaluated. Primary avian predators were California and Ring-billed Gulls at hotspots and Common Mergansers within upper river reaches. Estimated take (presumed to be salmonids) by gulls at hotspots (22 April-30 May) was 4,084 fish at the Chandler Bypass Outfall and 12,636 fish at Horn Rapids Dam. Combined take was 2.65% of the salmonids passing over Chandler Dam or 0.89 % of all smolts estimated passing or being released from the Chandler Dam area during the 1999 smolt migration season. Estimated take by Common Mergansers within upper river reaches in summer was 4,092 kg between 7 May and 18 August 1999.
Book Synopsis Avian Predation on Juvenile Salmonids in the Lower Columbia River Research Project by : United States. Bonneville Power Administration
Download or read book Avian Predation on Juvenile Salmonids in the Lower Columbia River Research Project written by United States. Bonneville Power Administration and published by . This book was released on 2001 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
