Download or read book Linking Freshwater Growth to Size dependent Marine Survival of Sockeye Salmon written by Marta Elizabeth Ree and published by . This book was released on 2019 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the mediating role of body size in determining fitness, the ‘bigger is better’ hypothesis still pervades evolutionary ecology despite evidence that natural selection on phenotypic traits varies in time and space. For Pacific salmon (genus Oncorhynchus), the size at which juveniles migrate to sea (i.e., smolts) has been linked to survival during the early marine period, where larger smolts typically survive at a higher rate than their smaller counterparts. However, the relationship of smolt size and survival becomes more ambiguous when considering confounding factors of age, ocean entry timing, and environmental variability. Despite equivocal results, smolt size appears to be a key trait and therefore changes in freshwater conditions may have consequences for population productivity. Furthermore, due to differences in site-specific habitats, trophic dynamics, and population traits the response of specific populations to these changes is likely to be context specific. The objective of this thesis was to 1) quantify the direction and magnitude of natural selection on smolt size for three age classes of sockeye salmon in a small watershed on Kodiak Island, AK and 2) explore stock-specific effects of temperature and conspecific density on smolt size over a multi-decade time-series to understand historic and possible future trends. To address our first objective, we calculated standardized selection differentials by comparing observed size distributions of out-migrating juvenile salmon to back-calculated smolt length from the scales of surviving, returning adults. Results reveal the magnitude of selection on size was very strong and consistent among years. However, the direction of selection on size consistently varied among age classes. The absolute magnitude of selection was negatively correlated to apparent marine survival and positively correlated to late mean ocean entry timing. To address our second objective, we back-calculated smolt size from returning adult scales to reconstruct a time-series of smolt length of two stocks within a small Alaska watershed on Kodiak Island. Using a dynamic linear model framework, we detected evidence that for one stock, temperature was important in explaining smolt length, and density effects influenced both stocks utilizing the same lakes. Furthermore, forecasts of smolt length showed highly variable responses under scenarios of increasing temperature and high and low densities. Collectively, these results demonstrate that interactions between processes of climate, density, and natural selection are highly context-specific in terms of both inter- and intra- population variability.
Download or read book Ecological Drivers of Variation in Juvenile Sockeye Salmon Marine Migrations written by Cameron Freshwater and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Animal migrations are often associated with high mortality due to increased energy expenditure, reduced foraging opportunities, and increased predation risk. Migratory traits such as body size, phenology, or use of stopover habitats may moderate individual risk to mortality mechanisms and influence patterns of survival. However, variability in migratory traits is rarely quantified in detail because tracking many individuals over large areas is logistically challenging. In this dissertation, I used otoliths to examine migratory variability among and within sockeye salmon (Oncorhynchus nerka) populations, a species that has recently experienced declines associated with poor survival during juvenile marine migrations. Broadly, I examined the individual and environmental drivers of migratory patterns, as well as how variation across ecological scales (individuals, populations, and years) contributed to migratory diversity. First, I conducted a laboratory study to validate the use of otolith microstructure techniques in sockeye salmon post-smolts. Next, I assessed how a suite of ecological processes could interact to create a latitudinal gradient in sockeye salmon body size. By reconstructing individual growth and migration histories I determined that variation in size was correlated with ocean entry size and phenology, rather than differential marine growth or size-selective mortality. I then used estimates of migratory rate from otoliths to demonstrate that juvenile sockeye salmon exhibited distinct migratory phenotypes associated with ocean entry traits. Larger individuals migrated rapidly offshore, while smaller fish reared for several weeks in nearshore regions. Furthermore, a subset of the smallest individuals entered the ocean late in the year, migrated particularly slowly, and may have overwintered on the continental shelf. These linkages between ocean entry and migratory traits suggest juvenile sockeye salmon exhibit substantial migratory plasticity associated with carry-over effects from freshwater residence; however juvenile salmon may also respond strongly to variable conditions in marine habitats. In my fifth chapter, I compared marine growth and migration phenology in years with low and high competitor densities. After accounting for freshwater density-dependent effects, growth rates were similar in both years, but mean migration rates were nearly 50% faster in the high-density year. Migratory behavior may be used to buffer individuals from the effect of competitive interactions. In my final chapter, I sampled 16 Fraser River sockeye salmon populations to explore variation in the timing and duration of early marine migrations. Although populations differed in downstream migration timing, as well as their duration of residence within nearshore habitats, there was substantial variation within each population and between sampling years. These findings suggest individual characteristics and stochastic processes interact with population-specific strategies to shape migratory phenologies in this metapopulation. Management actions should account for and preserve migratory diversity at multiple ecological scales to maintain resilient salmon populations into the future.
Download or read book Marine Survival of Coho Salmon Oncorhynchus Kisutch from Small Coastal Watersheds in Northern California written by Sean M. Cochran and published by . This book was released on 2015 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: California coho salmon Oncorhynchus kisutch populations are at low abundance and factors governing recruitment variability remain unclear. Changes in freshwater habitat that increase juvenile growth and size of salmon outmigrating to sea (smolts) may improve ocean survival. The best data to evaluate this among wild coho salmon populations in California come from life-cycle monitoring (LCM) stations. This study investigated whether marine survival is size-dependent (larger individuals within a cohort have higher marine survival) and whether sites and years with higher growth have higher marine survival across five LCM locations. I tested for size-dependent survival using two techniques: comparing the size of outmigrating smolts and back-calculated smolt sizes from scales of adult fish that survived to return; and using information from fish that were tagged as smolts and survived to return as adults. Analyses comparing smolt sizes back-calculated from adult scales and observed lengths from smolt traps indicated that within-year size-dependent mortality at sea occurred among many outmigrant cohorts, while analyses using smolt lengths of recaptured adult fish tagged as juveniles did not indicate any within-cohort size-selective mortality at sea. Potential explanations for the conflicting results include errors in scale back-calculation; smolts growing in habitats below smolt traps prior to ocean entrance; and fish with alternative juvenile life histories that were unaccounted for in outmigrant sampling surviving and contributing to the adult populations. In regressions across sites and years, marine survival was positively associated with early marine growth measured from the scales of surviving adult salmon and in some instances marine survival was also positively associated with mean fork length of outmigrating smolts. Although size may be an important determinant of ocean survival, this study shows that comparison of back-calculated smolts sizes from scales of adult fish and observed lengths of smolts at an upstream trapping location are unreliable approaches for testing size-selective mortality. This study also provides support for expanding studies at LCM stations to determine how juvenile coho salmon use habitat downstream of migrant trapping locations.
Download or read book Physiological Ecology of Pacific Salmon written by Cornelis Groot and published by UBC Press. This book was released on 2010-10-01 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: Every year, countless juvenile Pacific salmon leave streams and rivers on their migration to feeding grounds in the North Pacific Ocean and the Bering Sea. After periods ranging from a few months to several years, adult salmon enter rivers along the coasts of Asia and North America to spawn and complete their life cycle. Within this general outline, various life history patterns, both among and within species, involve diverse ways of exploiting freshwater, estuarine, and marine habitats. There are seven species of Pacific salmon. Five (coho, chinook chum, pink, and sockeye) occur in both North America and Asia. Their complex life histories and spectacular migrations have long fascinated biologists and amateurs alike. Physiological Ecology of Pacific Salmon provides comprehensive reviews by leading researchers of the physiological adaptations that allow Pacific Salmon to sustain themselves in the diverse environments in which they live. It begins with an analysis of energy expenditure and continues with reviews of locomotion, growth, feeding, and nutrition. Subsequent chapters deal with osmotic adjustments enabling the passage between fresh and salt water, nitrogen excretion and regulation of acid-base balance, circulation and gas transfer, and finally, responses to stress. This thorough and authoritative volume will be a valuable reference for students and researchers of biology and fisheries science as they seek to understand the environmental requirements for the perpetuation of these unique and valuable species.
Download or read book Managing the Columbia River written by National Research Council (U.S.). Committee on Water Resources Management, Instream Flows, and Salmon Survival in the Columbia River Basin and published by National Academy Press. This book was released on 2004 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Book News, Inc., Portland, OR (booknews.com).
Download or read book Atlantic Salmon Ecology written by Øystein Aas and published by John Wiley & Sons. This book was released on 2011-07-05 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Atlantic salmon is one of the most prized and exploited species worldwide, being at the centre of a massive sports fishing industry and increasingly as the major farmed species in many countries worldwide. Atlantic Salmon Ecology is a landmark publication, both scientifically important and visually attractive. Comprehensively covering all major aspects of the relationship of the Atlantic salmon with its environment, chapters include details of migration and dispersal, reproduction, habitat requirements, feeding, growth rates, competition, predation, parasitsm, population dynamics, effects of landscape use, hydro power development, climate change, and exploitation. The book closes with a summary and look at possible future research directions. Backed by the Norwegian Research Council and with editors and contributors widely known and respected, Atlantic Salmon Ecology is an essential purchase for all those working with this species, including fisheries scientists and managers, fish biologists, ecologists, physiologists, environmental biologists and aquatic scientists, fish and wildlife department personnel and regulatory bodies. Libraries in all universities and research establishments where these subjects are studied and taught should have copies of this important publication. Comprehensive and up-to-date coverage of Atlantic Salmon Atlantic Salmon is one of the world's most commercially important species Backed by the Norwegian Research Council Experienced editor and internationally respected contributors
Download or read book Linking Estuary Rearing Habitats to Migration Traits Behaviour and Survival of Juvenile Coho Salmon Oncorhynchus Kisutch written by Alexandra Sawyer and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estuaries are nursery habitats for juvenile Pacific salmon, yet quantifying estuary contributions to behaviour, adaptations, and fitness across the salmon life-cycle remains a challenge. Using data from 64 coho salmon populations ranging from California to Alaska, I first examined how juvenile migration traits covary with estuary and freshwater habitat characteristics. Populations from lower latitudes, and with access to more enclosed and complex estuaries, exhibited earlier and more protracted migrations. Second, I used a mark-recapture study to examine estuary residence, growth, and subsequent marine survival by juveniles from the Koeye River in British Columbia. Relative to larger individuals, small juveniles resided longer and grew more in the estuary before marine entry. Marine survival increased with juvenile body size and estuary growth improved survival prospects by 44-46%. This research reveals that juvenile salmon are locally adapted to estuary habitats, and that condition-dependent stopover can mitigate freshwater carryover effects and boost marine survival.
Download or read book Linking Density dependent Survival and Growth of Juvenile Atlantic Salmon to Their Predators and Prey written by Darren M. Ward and published by . This book was released on 2007 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Juvenile, stream-dwelling salmon are a model system for studies of density dependence. However, while salmon exhibit diverse mechanisms and patterns of density dependence, the factors that drive variation in density dependence are not clear. I used the unique experimental setting of an ongoing population restoration effort to identify key factors that limit survival and growth of juvenile Atlantic salmon (Salmo salar), then tested how these factors interact with density dependence. Using a large-scale salmon population density manipulation in natural streams, I showed that slimy sculpin (Cottus cognatus), a common predator of salmon, limited salmon survival and reversed the direction of density dependence. Sculpin dramatically suppressed salmon survival at low salmon population density, but had little effect on survival at high salmon density. Such predator-mediated inverse density dependence can eliminate low-density populations even if predators have little effect when prey are abundant. Individual growth of juvenile salmon was also density dependent. Fish stocked at low density grew faster than those stocked at high density, and mean growth increased even more when high mortality further reduced population density. Increased growth may help compensate for decreased population abundance. However, variation in prey availability across streams, not population density, explained most of the variation in individual growth. Thus, the demographic effects of density-dependent growth depend on stream productivity. I also used the salmon restoration program as a controlled setting to investigate another applied problem: accumulation of toxic mercury in fish. Conducting ecological research within the applied context of an intensively managed population provides unique opportunities for direct application of the results as well as insight into the fundamental factors that drive population dynamics.
Download or read book Effect of Density dependent Marine Growth on the Economically Optimal Lake Enrichment Strategy for British Columbia Sockeye Salmon Oncorhynchus Nerka microform written by Guthrie, Ian C. (Ian Campbell) and published by National Library of Canada. This book was released on 1985 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Influence of Three North Pacific Ocean Regime Shifts on the Early Marine Growth and Survival of Sockeye Salmon Oncorhynchus Nerka from Karluk Lake Alaska written by Ellen Martinson and published by . This book was released on 2004 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Juvenile Bristol Bay Sockeye Salmon Ecology written by Edward Vincent Farley (Jr.) and published by . This book was released on 2008 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Predicting annual returns of Bristol Bay sockeye salmon (Oncorhynchus nerka) has been difficult due to large, unexplained variations in return strength. Ocean conditions, particularly during the first few months after salmon leave freshwater, are believed to have a strong influence on their early marine growth and survival. Limited historical and present research suggests that sea temperature can affect juvenile Bristol Bay distribution. During years with cool spring sea temperatures, juvenile sockeye salmon are distributed nearshore along the Alaska Peninsula, whereas they are found further offshore during years with warm spring sea temperatures. Juvenile sockeye salmon are larger, in better condition, and have higher marine stage survival after the first year at sea when they are distributed further offshore than when they are distributed nearshore along the Alaska Peninsula. Juvenile sockeye salmon stomach contents also shift from primarily Pacific sand lance (Ammodytes hexapterus) and euphausiids to age 0 walleye pollock (Theragra chalcogramma) when their distribution changes from nearshore to further offshore. Annual averages of juvenile sockeye salmon growth rate potential (GRP) were generally lower among years and regions with cool spring sea temperatures. In addition, juvenile sockeye salmon GRP was generally higher in offshore regions than nearshore regions of the eastern Bering Sea shelf. A sensitivity analysis indicated that juvenile sockeye salmon GRP was more sensitive to changes in observed (August to September) sea surface temperatures during years when prey densities were lower. The results of the dissertation suggest that variability in early marine survival is primarily due to bottom-up control of the trophic structure of the eastern Bering Sea ecosystem"--Leaf iii.
Download or read book Canadian Journal of Fisheries and Aquatic Sciences written by and published by . This book was released on 2014-05 with total page 666 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atlantic Salmon in Maine written by National Research Council and published by National Academies Press. This book was released on 2004-09-07 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Because of the pervasive and substantial decline of Atlantic salmon populations in Maine over the past 150 years, and because they are close to extinction, a comprehensive statewide action should be taken now to ensure their survival. The populations of Atlantic salmon have declined drastically, from an estimated half million adult salmon returning to U.S. rivers each year in the early 1800s to perhaps as few as 1,000 in 2001. The report recommends implementing a formalized decision-making approach to establish priorities, evaluate options and coordinate plans for conserving and restoring the salmon.
Download or read book Connecting Physiological Condition with Salinity Preference Behaviour to Infer Estuary Habitat Choice in Sockeye Salmon Smolts Oncorhynchus Nerka written by Daniella LoScerbo and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The time period in which juvenile salmon remain in an estuary varies greatly among and within populations, with some individuals passing through estuaries in a matter of hours, while others remain in the estuary for several months. This individual variation in estuary use suggests that there may be underlying differences in individual salmon condition that temporally mitigate the selection of habitat, such as smolt size (fork length, mass, condition factor), stored energy (lipids and proteins), and osmoregulatory function (gill N+-K+-ATPase activity, NKA). I investigated the role of physical and physiological condition on the selection of estuarine and ocean habitat by sockeye salmon (Oncorhynchus nerka) smolts intercepted at the initiation of their downstream migration from Chilko Lake, Fraser River, B.C.. Since juvenile salmon energetic costs increase with rising salinity, I expected that smolts of lower physiological condition (i.e. low condition factor, poor energetic status and low NKA) would prefer to remain in the freshwater environment of the estuary, while smolts of higher physiological condition would prefer saline waters in the estuary and potentially indicate more rapid ocean entry. Behavioural salinity preference experiments were conducted on unfed smolts (n = 263) held in freshwater at three time intervals during their downstream migration period, representing the expected timing for lake exit, estuary entry, and ocean entry, at 0, 1, and 3 weeks respectively. Smolt condition factor (K), energetic stores and NKA predicted salinity preference behaviour in the estuary and ocean outmigration stages, but not at lake exit. Our results suggest that smolt physiological condition upon reaching the estuary may influence migratory behaviour and habitat selection, providing novel evidence on the temporally dependent interplay of physiology, behaviour and migration in wild juvenile Pacific salmon. As juvenile migratory behaviour is linked to physiological condition, and physiological condition is determined by productivity and competition within the rearing habitat, the importance of estuaries likely varies across years and within a population cohort; thus estuaries may be of heightened importance for wild juvenile salmon in years of poor freshwater growth conditions. These findings support the growing body of evidence on the importance of conserving both rearing habitat for juvenile growth potential and estuarine habitat for smolt refugia before ocean entry.
Download or read book Effect of Smolt Size and Marine Growth Rates on Adult Sockeye Salmon Oncorhynchus Nerka Returns and Possible Implications for the Cost written by Ryall, Paul J. (Paul James) and published by National Library of Canada. This book was released on 1985 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stock Enhancement and Sea Ranching written by Kenneth M. Leber and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: The collapse of many of the World’s fisheries continues to be of major concern and the enhancement of fish stocks through techniques such as ranching is of huge importance and interest across the globe. This important book, which contains fully peer reviewed and carefully edited papers from the 2nd International Symposium in Stock Enhancement and Sea Ranching is broadly divided into sections covering the following areas: The present situation of stock enhancement Seed quality and techniques for effective stocking Health management of hatchery stocks Methods for evaluating stocking effectiveness Population management in stock enhancement and sea ranching Management of stocked populations Ecological interactions with wild stocks Genetic management of hatchery and wild stocks Socio-economics of stock enhancement Case studies Stock Enhancement and Sea Ranching has been written and edited by some of the world’s foremost authorities in fisheries science and related areas and is essential reading for all fisheries scientists throughout the World. Fish biologists, marine and aquatic scientists, environmental biologists, ecologists, conservationists, aquaculture personnel and oceanographers will all find much of use and interest within this book. All libraries within universities and research establishments where these subjects are studied and taught should have copies of this book on their shelves.
Download or read book Introduction to Hierarchical Bayesian Modeling for Ecological Data written by Eric Parent and published by CRC Press. This book was released on 2012-08-21 with total page 429 pages. Available in PDF, EPUB and Kindle. Book excerpt: Making statistical modeling and inference more accessible to ecologists and related scientists, Introduction to Hierarchical Bayesian Modeling for Ecological Data gives readers a flexible and effective framework to learn about complex ecological processes from various sources of data. It also helps readers get started on building their own statistical models. The text begins with simple models that progressively become more complex and realistic through explanatory covariates and intermediate hidden states variables. When fitting the models to data, the authors gradually present the concepts and techniques of the Bayesian paradigm from a practical point of view using real case studies. They emphasize how hierarchical Bayesian modeling supports multidimensional models involving complex interactions between parameters and latent variables. Data sets, exercises, and R and WinBUGS codes are available on the authors’ website. This book shows how Bayesian statistical modeling provides an intuitive way to organize data, test ideas, investigate competing hypotheses, and assess degrees of confidence of predictions. It also illustrates how conditional reasoning can dismantle a complex reality into more understandable pieces. As conditional reasoning is intimately linked with Bayesian thinking, considering hierarchical models within the Bayesian setting offers a unified and coherent framework for modeling, estimation, and prediction.
