EBookClubs

Read Books & Download eBooks Full Online

EBookClubs

Read Books & Download eBooks Full Online

Book Predation of Sockeye Salmon Fry by Cottids and Other Predatory Fishes in the Cedar River and Southern Lake Washington 1997

Download or read book Predation of Sockeye Salmon Fry by Cottids and Other Predatory Fishes in the Cedar River and Southern Lake Washington 1997 written by Roger Tabor and published by . This book was released on 1998 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Cedar River Section 205 Flood Damage Reduction Study Renton King County

Download or read book Cedar River Section 205 Flood Damage Reduction Study Renton King County written by and published by . This book was released on 1997 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Predation on Sockeye Salmon Fry by Piscivorous Fishes in Southern Lake Washington 1996 Western Washington Office Aquatic Resources Division Olympia Washington June 1997

Download or read book Predation on Sockeye Salmon Fry by Piscivorous Fishes in Southern Lake Washington 1996 Western Washington Office Aquatic Resources Division Olympia Washington June 1997 written by and published by . This book was released on 1997* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Bibliography of Agriculture

Download or read book Bibliography of Agriculture written by and published by . This book was released on 1996 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Cedar River Sockeye Salmon Fry Production Evaluation

Download or read book Cedar River Sockeye Salmon Fry Production Evaluation written by and published by . This book was released on 2002 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Quantifying the Impact of Two Native Predators on Juvenile Sockeye Salmon Survival in Lake Washington

Download or read book Quantifying the Impact of Two Native Predators on Juvenile Sockeye Salmon Survival in Lake Washington written by Casey Porter Clark and published by . This book was released on 2017 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the mechanisms regulating population fluctuations, such as births, reproduction, and deaths, remains a persistent question in ecology. Mortality can be incurred at any point during the lifecycle, but mortality rates can be high for juvenile animals in particular. One source of this early life history mortality is via predation. Accurately measuring predation rates requires intensive studies, and is further complicated by variability in habitats and changes in the extent of spatial and temporal overlap between predators and prey. In this study, we examined abundance, spatial distributions and diets of two piscivorous fishes and their predation impact on juvenile salmonids in a well-studied large western lake, Lake Washington. We addressed the following questions: (i) What is the abundance of cutthroat trout and northern pikeminnow in Lake Washington? (ii) At what rates do these predators consume juvenile salmon throughout the year, and how many total juvenile salmon are consumed given the predator population size? Understanding which factors influence predation and the extent of this predatory impact requires temporally and spatially explicit data on the interaction between predators and prey, including both juvenile sockeye salmon and the main alternative prey fish species. To observe these interactions, we used several overlapping sampling types across trophic levels. We used a Chapman-modified population estimation procedure to estimate a cutthroat trout population size of 22,791 ≥300 mm FL and the same procedure to estimate a northern pikeminnow population size of 13,582 ≥300 mm FL. We also used a relative catch method to estimate a northern pikeminnow population size of 112,816 ≥300 mm FL. The magnitude of predation on juvenile salmon and other prey fishes varied considerably among months and between cutthroat trout and northern pikeminnow, between small and large size classes of each predator species, and between years. In 2015, predation mortality of lake entry 2015 (sub-yearling) sockeye salmon was 20% of fry production in that year, and predation losses of lake entry 2014 (yearling) sockeye were 56% of pre-smolt production. In 2016, mortality of lake entry 2016 (sub-yearling) sockeye was 44% of fry production, and predation losses of lake entry 2014 sockeye were 473% of pre-smolt production of that year. Our work shows that the current predation rate is high enough and these predator populations are of sufficient size that predation is a significant source of mortality for juvenile sockeye and Chinook salmon in this system. This work highlights a scenario of combined physical and biological factors that influence mortality in juvenile fish, and can potentially inform the potential for predation mortality in other lake systems.

Book 1999 Cedar River Sockeye Salmon Fry Production Evaluation

Download or read book 1999 Cedar River Sockeye Salmon Fry Production Evaluation written by Dave Seiler and published by . This book was released on 2001 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Effects of Habitat and Predator prey Interactions on Stocked Sockeye Fry in Tatsamenie Lake

Download or read book Effects of Habitat and Predator prey Interactions on Stocked Sockeye Fry in Tatsamenie Lake written by Renate R. Riffe and published by . This book was released on 2006 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tatsamenie Lake has been stocked with marked sockeye salmon fry since 1991, as part of a program initiated by the Pacific Salmon Commission to increase annual returns of sockeye salmon (Oncorhynchus nerka) to the Taku River system by 100,000 fish annually. However, the average annual commercial catch of stocked Tatsamenie sockeye salmon between 1995 and 2000 has been only about 2,000 fish. This study was conducted in 2001 and 2002 to ascertain whether predators were targeting stocked sockeye fry in the lake, and which species, if any, were responsible. Other questions investigated included whether age-0 stocked sockeye fry were migrating prematurely from the lake, and whether differences in water chemistry between Tatsamenie Lake and the incubating hatchery were depressing stocked-fry survival rates.

Book Investigations Into the Feeding Habits of Piscivorous Fishes in Coeur D Alene Lake Idaho

Download or read book Investigations Into the Feeding Habits of Piscivorous Fishes in Coeur D Alene Lake Idaho written by Jennifer L. Scott and published by . This book was released on 2002 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The Coeur d'Alene Tribe of lndians have proposed a westslope cutthroat trout, Oncorhynchus clarki lewisi, production facility to enhance adfluvial populations within the Coeur d'Alene Lake System. Westslope cutthroat trout are a species of special concern in Idaho. One of the limiting factors to be examined prior to implementing the trout hatchery was the potential for predatory fish to eat cutthroat trout after they migrated into Coeur d'Alene Lake. The annual feeding habits of the five major piscivorous fishes were examined from Coeur d'Alene Lake, the lateral lakes of the Coeur d'Alene River and lower sections ofthe St. Joe River, Idaho to determine the importance of the westslope cutthroat trout in their diets. Fish were collected by boat electrofishing, horizontal gillnets, vertical gillnets, and angling. Stomach contents were extracted from the stomach and preserved in 10% formalin. Fish remains in predator diets were keyed using diagnostic bones. Diagnostic bone length to total body length regressions were used to back calculate the original size of the prey fish. Of 493 stomachs examined, nine westslope cutthroat trout could be positively identified in the stomach contents. Six were in northern pike (Esox lucius) stomachs, two were from chinook salmon (O. tshawytscha), and one from a smallmouth bass (Micropterus dolomieui). Cutthroat trout were not found in any northern pikeminnow (Ptychocheilus oregonensis) or largemouth bass (M. salmoides) stomach samples. The average size of cutthroat trout consumed by these piscivores was 215 mm in total length, which correlates with the average size of a four year old in this system. The cutthroat trout consumed by predators in this study were likely first year spawners or making their first adfluvial migration into the lake from natal tributaries. In many chinook salmon and northern pikeminnow stomachs, salmonids were present, but could not be keyed to species due to extensive digestion and/or lack of diagnostic bones. Northern pike seemed to pose the biggest threat to migrating cutthroat trout. Northern pike are typically found in shallow water, as were cutthroat trout in this study. Westslope cutthroat trout were identified in 23% of northern pike stomachs analyzed (n=26). Chinook salmon and northern pikeminnow typically consume fish in pelagic waters; cutthroat trout were positively identified in 5% of chinook stomachs (n=43) examined and none were found in northern pikeminnow stomachs (n=227)"--Document.

Book Ecology of Atlantic Salmon and Brown Trout

Download or read book Ecology of Atlantic Salmon and Brown Trout written by Bror Jonsson and published by Springer Science & Business Media. This book was released on 2011-05-03 with total page 720 pages. Available in PDF, EPUB and Kindle. Book excerpt: Destruction of habitat is the major cause for loss of biodiversity including variation in life history and habitat ecology. Each species and population adapts to its environment, adaptations visible in morphology, ecology, behaviour, physiology and genetics. Here, the authors present the population ecology of Atlantic salmon and brown trout and how it is influenced by the environment in terms of growth, migration, spawning and recruitment. Salmonids appeared as freshwater fish some 50 million years ago. Atlantic salmon and brown trout evolved in the Atlantic basin, Atlantic salmon in North America and Europe, brown trout in Europe, Northern Africa and Western Asia. The species live in small streams as well as large rivers, lakes, estuaries, coastal seas and oceans, with brown trout better adapted to small streams and less well adapted to feeding in the ocean than Atlantic salmon. Smolt and adult sizes and longevity are constrained by habitat conditions of populations spawning in small streams. Feeding, wintering and spawning opportunities influence migratory versus resident lifestyles, while the growth rate influences egg size and number, age at maturity, reproductive success and longevity. Further, early experiences influence later performance. For instance, juvenile behaviour influences adult homing, competition for spawning habitat, partner finding and predator avoidance. The abundance of wild Atlantic salmon populations has declined in recent years; climate change and escaped farmed salmon are major threats. The climate influences through changes in temperature and flow, while escaped farmed salmon do so through ecological competition, interbreeding and the spreading of contagious diseases. The authors pinpoint essential problems and offer suggestions as to how they can be reduced. In this context, population enhancement, habitat restoration and management are also discussed. The text closes with a presentation of what the authors view as major scientific challenges in ecological research on these species.