Download or read book Ecology of Stream dwelling Fishes in Response to Inter annual Variation in the Abundance of Spawning Sockeye Salmon written by Kale T. Bentley and published by . This book was released on 2014 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Each year, millions of salmon enter the final stage of their life-cycle and migrate back towards their natal watersheds to reproduce. After accumulating >95% of their adult body mass in marine environments, salmon spawning migrations generate massive fluxes of nutrients and energy to inland food webs that can exceed background levels of in situ productivity, and these resources are utilized by a wide range of taxa (Naiman et al. 2002, Gende et al. 2002, Schindler et al. 2003). However, one-half to three-fourths of all returning salmon are harvested by commercial fisheries in coastal oceans prior to reproducing, as salmon fisheries in Alaska are currently managed to maximize the long-term sustainable yield of salmon (Baker et al. 2009). Although this practice is widely touted as a fisheries management success story (Hilborn 2006), people are beginning to ask, what effect does removing the biomass of salmon prior to spawning have on freshwater and terrestrial ecosystems. Thus, there has been a call to shift the paradigm of fisheries management from one that focuses solely on maximizing the yield of single target species to a more holistic approach that accounts for other ecosystem processes (Pikitch et al. 2004, Crowder et al. 2008, Piccolo et al. 2009). In order to develop an ecosystem-based management approach, salmon managers need to be able to assess the trade-offs of different management scenarios that affect how many salmon are harvested versus released to the watershed (known as "escapement") to spawn and benefit inland ecosystems. Currently, assessing these trade-offs is difficult; while there is a well-established theory of how to optimize commercial catch based on stock-recruit relationships (Ricker 1954, Hilborn and Walters 1992, Quinn and Deriso 1999), we lack a quantitative understanding of how the number of salmon returning to spawn influences freshwater and terrestrial ecosystems. The focus of my thesis was to evaluate of the ecological response of Arctic grayling (Thymallus arcticus) and rainbow trout (Oncorhynchus mykiss), two species of resident fish that rely heavily on consumption of salmon resource subsidies (Scheuerell et al. 2007, Moore et al. 2008), to variation in the abundance of adult sockeye salmon (Oncorhynchus nerka) in the Wood River watershed, Bristol Bay, Alaska. The first chapter of my thesis assessed the ability of a body condition index to serve as a proxy for estimating individual instantaneous growth rates as obtaining direct measurements of growth can be time consuming, costly, and logistically impractical. We found that relative body condition of grayling and rainbow trout, as measured by the residuals around a length-mass regression, was strongly correlated with direct measures of individual instantaneous growth from recaptured tagged fish. Using the derived relationship between body condition and growth, we developed a model to estimate growth rates of individual fish based on their observed body condition. Chapter two evaluated the foraging and growth responses of grayling and rainbow trout in two streams that vary in in situ productivity to changes in the abundances of spawning sockeye salmon. Over 11 years, and across a greater than 10-fold variation in density of spawning sockeye salmon, both species of resident fish exhibited a relatively similar, but mechanistically different, saturating growth response to increasing salmon density. This growth response was driven by both an increase in consumption of salmon eggs and also a decrease in dietary overlap between the two species. However, the relative change in growth from low to high salmon densities was different between streams and depended on in situ stream productivity. In low salmon density years the growth of resident consumers fell 46-68% relative to high years in the low productivity stream, but only by 26-34% in the high productivity stream. Growth rates of both consumer species saturated in years when densities of sockeye salmon exceeded about 0.3 - 0.4 m2 on the spawning grounds. Chapter three evaluated the movement patterns of Arctic grayling and rainbow trout within and among streams, which offer patchily distributed foraging opportunities during the summer months. Across both years, approximately 50% of individual grayling and rainbow trout exhibited kilometer-scale movements among two or more streams across the river network within a single summer. Movements were concentrated in June and July, and subsided by early August, coincident with the arrival of spawning sockeye salmon (O. nerka). These inter-stream movements may represent prospecting behavior as individuals seek out the most profitable foraging opportunities. Thus, resident fishes in the Wood River system appear to use the broad network of habitat available to them across the riverscape, rather than depend on individual tributaries for achieving growth. Together the results of this thesis improve our understanding of how inland ecosystem respond to changes in salmon abundance. These results will be of use for resource managers interested in directly evaluating the socio-economic trade-offs of allocating salmon resources among user groups. The results of this work also highlight the importance of maintaining connectivity to enable movements of resident fish across river basins, the ecological consequences of which remain poorly understood.

Download or read book Advances in the Ecology of Stream Dwelling Salmonids written by Javier Lobon-Cervia and published by Springer Nature. This book was released on with total page 733 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Variability and Asynchrony in Salmon Returns written by Brooke M. Davis and published by . This book was released on 2015 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pacific salmon are well-known for their unique life-history characteristics, complex population structures, and the wide range of ecosystem services they provide. Variability in life-history characteristics across and within species, along with their tendency to return to their natal sites, leads to phenotypically distinct populations that create portfolios of populations within watersheds. Pacific salmon are important for supporting valuable fisheries and for supporting key ecosystem processes in the marine and freshwater environment. Alaskan sockeye salmon populations display overall population stability despite large commercial harvests, a characteristic that has been attributed to their intact population complexity. Those fish that are not captured by the commercial fishery support key ecosystem processes in freshwater environments. This yearly, pulsed, resource subsidy provides a reliable source of food and nutrients to the watersheds where sockeye salmon spawn and die. These complex populations may pose challenges for management due to difficulties separating the contributions of individual populations or habitats to the overall population complex (or portfolio). In Chapter 1 we used abundance data for sockeye salmon (Oncorhynchus nerka) spawning in a set of eight streams in the Wood River watershed, southwest Alaska, to demonstrate how natural patterns of variability affect the ability of fixed assessment windows to characterize the contribution of an individual spawning population to the entire portfolio. Additionally, simulated data are used to explore how different levels of synchrony and autocorrelation affect the ability of monitoring schemes to estimate the contributions of individual populations to a portfolio. We find that the ability of fixed assessment windows to characterize a population's contribution to a portfolio is distinctly limited; asynchronous or independent dynamics among populations in a portfolio, and the presence of autocorrelation that creates slow changes in productivity, weaken the ability to characterize a stream's potential contribution to a portfolio. These results suggest that the structure of complex portfolios, and the presence of directional changes in productivity within individual populations, need to be taken into account when carrying out environmental risk assessments that aim to measure the contribution of an individual population or piece of habitat to dynamics observed at broader spatial and temporal scales. The reliable yearly pulse of marine-derived nutrients, in the form of spawning salmon, provides inland freshwater habitats with food and nutrients in the form of live fish, their gametes, and their carcasses. The highest quality food is provided by live fish and their eggs, which are important food sources for resident fish, bears, and birds, are only available for a short period. While the effects of this specific resource pulse are widely appreciated, little attention has been paid to the role that timing plays in conferring benefits to consumers, and previous research has mainly focused on biomass as the main control on the magnitude of effects. In Chapter 2 we used multiple in-stream counts of adult sockeye salmon abundance within the spawning season, and tagging data to estimate in-stream life span, to estimate how the amount of time that consumers have access to live salmon as a food resource is related to the adult spawner density in an individual stream. Our results demonstrate that duration of salmon availability as a food source is non-linearly related to escapement; across 3 orders of magnitude of spawner abundance, salmon were available to predators from about 2 weeks to about 5 weeks. This saturating relationship indicates that higher escapement values may not translate to proportionally higher benefits for consumers when these benefits are available during a fleeting window of opportunity. This result demonstrates that ecosystem based fisheries management (EBFM) of anadromous salmon should assume that benefits inferred to consumers are inherently time-mediated, and the numerical benefits of increased salmon density will not be straight-forward to estimate. Conservation strategies to maintain a range of spawn timing across watersheds may be the most successful for maintaining the importance of salmon subsidies in watersheds.

Download or read book Predation on Sockeye Salmon Fry by Piscivorous Fishes in the Lower Cedar River and Southern Lake Washington written by Roger Tabor and published by . This book was released on 1996 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Biology of Fish Growth written by A. H. Weatherley and published by London ; Toronto : Academic Press. This book was released on 1987 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of fish growth; Nutrition; Metabolism and growth; Protein, lipid and caloric contents; Tissues and growth; Influence of hormones; Determination of age and growth; Growth, competition, and the niche concept; Increase and self-regulation of fish populations; Feeding relations, correlated functional morphology, growth and size; Production dynamics of fish; Fish culture; Applications and the future.

Download or read book Stream Fish Community Dynamics written by William J. Matthews and published by JHU Press. This book was released on 2017-05 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most comprehensive synthesis of stream fish community research ever produced. Winner of the CHOICE Outstanding Academic Title of the Choice ACRL Ecologists have long struggled to understand community dynamics. In this groundbreaking book, leading fish ecologists William Matthews and Edie Marsh-Matthews apply long-term studies of stream fish communities to several enduring questions. This critical synthesis reaches to the heart of ecological theory, testing concepts against the four decades of data the authors have collected from numerous warm-water stream fish communities in the central and eastern United States. Stream Fish Community Dynamics draws together the work of a single research team to provide fresh analyses of the short- and long-term dynamics of numerous streams, each with multiple sampling sites. Conducting repeated surveys of fish communities at temporal scales from months to decades, the authors' research findings will fascinate anyone searching for a deeper understanding of community ecology. The study sites covered by this book range from small headwater creeks to large prairie rivers in Oklahoma and from Ozark and Ouachita mountain streams in Arkansas to the upland Roanoke River in Virginia. The book includes • A comparison of all global and local communities with respect to community composition at the species and family level, emergent community properties, and the relationship between those emergent properties and the environments of the study sites • Analyses of traits of individual species that are important to their distribution or success in harsh environments • A review of evidence for the importance of interactions—including competition and predation—in community dynamics of stream fishes • An assessment of disturbance effects in fish community dynamics • New analysis of the short- and long-term dynamics of variation in stream fish communities, illustrating the applicability and importance of the "loose equilibrium concept" • New analyses and comparisons of spatiotemporal variation in community dynamics and beta diversity partitioning • An overview of the effects of fish in ecosystems in the central and eastern United States The book ends with a summary chapter that places the authors' findings in broader contexts and describes how the "loose equilibrium concept"—which may be the most appropriate default assumption for dynamics of stream fishes in the changing climate of the future—applies to many kinds of stream fish communities.

Download or read book Ecological Distribution of Spawning Sockeye Salmon in Three Lateral Streams Brooks Lake Alaska written by David Townsend Hoopes and published by . This book was released on 1962 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Response of Freshwater Fish Communities to Spawning Sockeye Salmon Oncorhynchus Nerka written by Daniel E. Eastman and published by . This book was released on 1996 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The migration patterns, food habits and the overall body condition of resident fish populations were characterized with particular reference to spawning activity of sockeye salmon (Oncorhynchus nerka) in the Wood River lake system, AK. Juvenile and adult char (Salvelinus sp.) and rainbow trout (Oncorhynchus mykiss) moved into three of the four small study streams as salmon began to spawn, consumed large quantities of salmon eggs and other salmon-derived food items, and in most cases grew significantly (in weight) throughout the summer. Tag-recapture results indicated that rainbow trout, char and Arctic grayling (Thymallus arcticus) were moving substantially within the streams and that trout and grayling were migrating between streams (2.7-3.9 km) within the lake. Prior to salmon spawning, stomachs contained only small aquatic and terrestrial insects and, most fish were visibly emaciated. In Pick Creek salmon-derived food items dominated (>90% by weight) the diets of most fish for more than a month, with some individuals' stomachs containing more than 1,000 salmon eggs. During this time period, most species in the four streams were significantly heavier due to a combination of increased food consumption and growth. There were also costs associated with feeding in these small streams, as was evidenced by the high frequency of wounds inflicted upon resident fish by aggressive, spawning salmon. Grayling preyed primarily upon aquatic insects and did not exhibit significant growth throughout the salmon spawning season. Salmon-derived resources promote summer growth in those species which capitalize on their seasonal availability and may enhance survival in Arctic regions where the summer growth period is short and winter is severe"--Author's abstract.

Download or read book Variation in the Early Life History of Sockeye Salmon Oncorhynchus Nerka written by Caryn A. Abrey and published by . This book was released on 2005 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ecology Abstracts written by and published by . This book was released on 1999 with total page 778 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coverage: 1982- current; updated: monthly. This database covers current ecology research across a wide range of disciplines, reflecting recent advances in light of growing evidence regarding global environmental change and destruction. Major ares of subject coverage include: Algae/lichens, Animals, Annelids, Aquatic ecosystems, Arachnids, Arid zones, Birds, Brackish water, Bryophytes/pteridophytes, Coastal ecosystems, Conifers, Conservation, Control, Crustaceans, Ecosyst em studies, Fungi, Grasses, Grasslands, High altitude environments, Human ecology, Insects, Legumes, Mammals, Management, Microorganisms, Molluscs, Nematodes, Paleo-ecology, Plants, Pollution studies, Reptiles, River basins, Soil, TAiga/tundra, Terrestrial ecosystems, Vertebrates, Wetlands, Woodlands.

Download or read book Salmonid Spawning Habitat in Rivers written by David A. Sear and published by . This book was released on 2008 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Proceedings of the Symposium 'Physical Factors Affecting Salmon Spawning and Egg Survival to Emergence: Integrating Science and Remediation Management' Held in Quebec City, Quebec, Canada, August 13-14, 2003."

Download or read book Abundance of the Sockeye Salmon Escapement in the Alsek River Drainage 2004 written by and published by . This book was released on 2005 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determinants of Sockeye Salmon Abundance in the Columbia River 1880 s 1982 written by James W. Mullan and published by . This book was released on 1986 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Role of Life History and the Environment in Population Dynamics of Sockeye Salmon Oncorhynchus Nerka written by Douglas Clifford James Braun and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Processes linking the environment and life histories are central to our understanding of population dynamics. This thesis combines life history theory and environmental variation to explain recruitment dynamics among populations in Fraser River sockeye salmon (Oncorhynchus nerka). I first explore relationships between spawning stream characteristics and spawning densities and show that streams with more cover have higher spawning densities. Next, I use a 21-year time series for three of these populations to explore hypotheses about how maternal life history traits and migration conditions, experienced during upstream migrations to their spawning grounds, influence reproductive investment. Maternal body size is strongly linked to total reproductive investment and both egg mass and fecundity; however, migration difficulty only influences egg mass and not fecundity. Using the same dataset, I show that egg mass and incubation temperatures influence juvenile fitness-related traits including length, mass and emergence timing. The main finding from these analyses, that warmer incubation temperatures result in lighter juveniles that emerge earlier, led to hypotheses about how incubation temperature might select for egg size among populations. I tested these hypotheses by comparing 16 populations and confirmed the prediction that in streams with warmer water, fish would produce heavier eggs. I then asked if these same maternal traits and environmental conditions would relate to adult recruitment dynamics. Populations spawning in streams with deeper water had higher maximum population growth rates and less variable recruitment. In addition, populations in streams with larger gravel exhibited stronger density-dependence. Finally, I develop a novel framework for evaluating how habitat data, combined with the cost of collecting such information, can be used in developing cost-effective surveys. I demonstrate this general framework with a simple example using the relationships between stream characteristics and sockeye densities, considering the costs and effectiveness of stream variables. Overall, this demonstration of the joint role of maternal traits and environmental conditions in recruitment dynamics supports the potential use of such variables as indicators of population dynamics in the absence of long-term demographic data. Furthermore, it supports the development of cost-effective surveys, which is important as human impacts on populations increase, and as monitoring resources decline.

Download or read book Local Adaptation Dispersal and Gene Flow in a Metapopulation of Sockeye Salmon written by Daniel Alexander Peterson and published by . This book was released on 2012 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gene flow within a metapopulation depends on the reproductive success of dispersers after immigration, but few empirical studies have measured the reproductive contributions of dispersers from distinct natal populations. The local adaptation frequently observed within metapopulations of anadromous salmonids could exert strong selection against immigrants with phenotypes adapted to ecologically distinct habitats. Used was genetic parentage analysis to directly measure the reproductive success of dispersers from multiple natal habitats relative to philopatric individuals within a group of geographically proximate but ecologically and genetically distinct subpopulations of stream- and beach-spawning sockeye salmon (Oncorhynchus nerka). Results indicate that dispersers between stream-spawning populations and philopatric individuals experienced similar reproductive success, while immigrants from the beach habitat to the streams produced fewer returning adult offspring than either philopatric individuals or stream-to-stream dispersers. The difference in reproductive contribution between beach-to-stream dispersers and the other two dispersal categories was estimated to be one returning adult offspring per individual. Thus, the difference in reproductive success of dispersers between habitat types represents a strong barrier to gene flow between these sockeye salmon ecotypes. Experimental and observational studies of the homing and spawning behavior of hatchery-raised salmon have indicated that their search for high-quality spawning habitat can overcome their homing tendency. Nevertheless, the extent to which dispersal between populations is motivated by habitat selection versus navigational errors during the homing process is not well understood, especially in wild populations. Examined were whether dispersing individuals exhibited more exploratory behavior than philopatric individuals within a metapopulation of wild sockeye salmon, which would suggest that dispersal may be influenced by comparisons between potential spawning areas. The daily locations of all adult salmon spawning in two proximate streams were tracked and determined the dispersal status for each individual by comparing its chosen spawning stream with that of its parents (as determined by genetic parentage reconstruction). Dispersers were often observed in their natal stream (8-11% of individuals) or at its mouth (29-58% of individuals) before spawning in the other stream, whereas philopatric individuals were rarely observed in their non-natal stream (0-2% of individuals) or at its mouth (1-7% of individuals). These results suggest either that the mechanism of dispersal encourages exploration or that individuals that explore are more likely to disperse. In either case, dispersers are exposed to multiple spawning habitats, potentially allowing annual variation in local environmental or demographic conditions to influence the patterns of gene flow within a metapopulation.

Download or read book Community and Evolutionary Ecology of North American Stream Fishes written by William John Matthews and published by . This book was released on 1987-01-01 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ecological Effects of Spawning Salmon on Several Southcentral Alaskan Streams written by Robert Joseph Piorkowski and published by . This book was released on 1995 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: