Download or read book Effects of Marine derived Nutrients on Population Dynamics of Sockeye Salmon Oncorhynchus Nerka written by Tadayasu Uchiyama and published by . This book was released on 2006 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The effects of marine-derived nutrients (MDN) on the productivity of sockeye salmon (Oncorhynchus nerka) stocks in Alaska were examined through nitrogen stable isotope analysis of smolts and mathematical models of the sockeye stock-recruit relationship. Smolt 8 [delta]15N was used to infer the degree to which smolts depend on MDN for their growth. We attempted to identify the characteristics of sockeye nursery lakes and watersheds that affect the availability of MDN to juvenile sockeye using multiple regression. Stock-recruit models incorporating MDN effects were fit to sockeye escapement-return data to test if fluctuations in sockeye stock productivity could be explained by changes in MDN input into nursery lakes. The magnitude of escapement and water residence time were the most important factors affecting the MDN availability to juvenile salmon. Mixing state of lakes and the distance from the coast were also found to significantly affect the MDN availability. We found that regional environmental fluctuations had a large effect on stock productivities in stock-recruit modeling. However, we did not find strong evidence to support our hypothesis that increases in MDN input to nursery lakes will result in increased productivity of sockeye stocks. Stock-recruitment data may be poorly suited to detection of the influence of MDN"--Leaf iii.
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 The Diatoms written by John P. Smol and published by Cambridge University Press. This book was released on 2010-09-30 with total page 687 pages. Available in PDF, EPUB and Kindle. Book excerpt: This much revised and expanded edition provides a valuable and detailed summary of the many uses of diatoms in a wide range of applications in the environmental and earth sciences. Particular emphasis is placed on the use of diatoms in analysing ecological problems related to climate change, acidification, eutrophication, and other pollution issues. The chapters are divided into sections for easy reference, with separate sections covering indicators in different aquatic environments. A final section explores diatom use in other fields of study such as forensics, oil and gas exploration, nanotechnology, and archaeology. Sixteen new chapters have been added since the first edition, including introductory chapters on diatom biology and the numerical approaches used by diatomists. The extensive glossary has also been expanded and now includes over 1,000 detailed entries, which will help non-specialists to use the book effectively.
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 Canadian Journal of Fisheries and Aquatic Sciences written by and published by . This book was released on 2010 with total page 742 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ecosystem Effects on Harvested Populations Lower Trophic Level Dynamics in the Northeast Pacific and Its Implications on Sockeye Salmon oncorhynchus Nerka Survival written by and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Impacts of Spawning Sockeye Salmon Oncorhynchus Nerka on Benthic Macroinvertebrate Production in the White River Washington written by Conor T. Giorgi and published by . This book was released on 2014 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This research was conducted to determine the effects of salmon mediated marine-derived nutrient subsidies on benthic macroinvertebrate production. The Cascade Columbia Fisheries Enhancement Group (CCFEG) is evaluating whether stream nutrient enhancement might benefit struggling salmon populations in the Wenatchee River Watershed. To evaluate the potential benefit of enhancement, the Wenatchee Nutrient Assessment was conducted on Nason Creek, and the Chiwawa, White, Little Wenatchee and upper Wenatchee rivers. Historically these tributaries to the upper Wenatchee River experienced prolific runs of anadromous salmon, which provided a major nutrient subsidy during spawning events. As a result of decreased salmon populations, these rivers are deprived of that nutrient pulse. It has been suggested that, due to the reduced nutrient subsidy, the streams are not producing the food base necessary to support healthy numbers of rearing anadromous fish. Nutrient assessment is the first phase of a potential nutrient enhancement project, where the streams would be fertilized with salmon carcasses or carcass analogues to bolster lower trophic levels and promote juvenile salmonid production. In this study, I estimated benthic macroinvertebrate secondary production at two locations within the White River, a lower site within a distinct sockeye salmon spawning reach, and an upper site upstream of the spawning reach. Through regular sampling I determined the biomass produced by the macroinvertebrate assemblage and 10 individual taxa during one year. Assemblage annual production was higher at the upper site than at the lower site, 75,233 mg DM·m−2̈y−1 vs. 43,202 mg DM·m−2 ̈y−1, respectively. Although there appears to be a large disparity between the two sites, 95% confidence intervals generated using error propagation revealed no significant difference between sites. I also compared results from the White River to biomass and densities of macroinvertebrates sampled from Nason Creek and the Chiwawa, Little Wenatchee, and Wenatchee Rivers. These rivers were sampled three times, fall 2012, spring 2013, and fall 2013. Patterns for biomass and density were not consistent in and among rivers. In the White River, there was significantly higher biomass and abundance of invertebrates in the upstream reach compared to the spawning reach; there were no significant differences within the other rivers. The lower White River is the model salmon-bearing stream to which the other rivers were compared. The differences in biomass, density, and community composition between the upper and lower White River reaches suggest that spawning salmon alter macroinvertebrate communities through marine-derived nutrient subsidies and bioturbation. Further, the low densities and biomass of multivoltine taxa in the lower White River indicates that despite its substantial run of returning sockeye salmon, the river may still have a limited food base for rearing salmonids. However, the causes of this limitation are unclear, and studies of the interaction between bioturbation and MDN are recommended"--Leaves iv-v.
Download or read book Sockeye Salmon Oncorhynchus Nerka written by Canada. Department of Fisheries and Oceans and published by Fisheries and Oceans, Information and Publications Branch. This book was released on 1987 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: A three-day symposium was organized by the Department of Fisheries and Oceans and convened at Nanaimo, British Columbia in November 1985. Advice on subject matter and participation came from an external committee of senior scientists and administrators in contributing agencies in Canada, Japan, the United States, and the Union of Soviet Socialist Republics. The papers included in the proceedings deal with sockeye biology and stock management. Papers on sockeye biology are divided into those concerned primarily with life history strategies and enhancement and development. Papers dealing with management are divided into the tools of management and management of some principal stocks.
Download or read book Nutrient Linkages Between Freshwater and Marine Ecosystems written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Eighteenth Century written by and published by Primary Source Microfilm. This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ecosystem Effects on Harvested Populations written by Michael Baumann and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Gulf of Alaska Sockeye Salmon Oncorhynchus Nerka Abundance on Survival Body Size Growth Rate and Age at Maturity of British Columbia and Britol Bay Alaska Sockeye Populations written by Canada. Department of Fisheries and Oceans and published by . This book was released on 1984 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Response of Juvenile Coho and Chinook Salmon Stocks to Salmon Spawner Abundance written by Philip John Joy and published by . This book was released on 2019 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: Resource subsidies from spawning Pacific salmon (Oncorhynchus spp.) in the form of marine-derived nutrients (MDN) benefit juvenile salmonids while they rear in fresh water, but it remains unclear if the abundance of spawners in a watershed affects the productivity of salmon stocks that rear in those riverine systems. This dissertation aimed to provide a better understanding of these dynamics by evaluating whether the response of juvenile salmon to MDN is sufficient to enhance overall stock productivity. In Chapter 1, I examined correlative relationships in the abundance of Pink (O. gorbuscha) and Coho (O. kisutch) salmon and simulated spawner-recruit dynamics to determine if those correlations were produced by a Coho Salmon response to marine subsidies from Pink Salmon, a shared response to marine conditions, and/or autocorrelations in the returns of both species. Results demonstrated that observed correlative patterns most closely resembled simulated freshwater effects, providing evidence that marine subsidies from Pink Salmon influence Coho Salmon productivity. In Chapter 2, I examined the relationship between spawner abundance and MDN assimilation by juvenile Coho and Chinook (O. tshawytscha) salmon in the Unalakleet River watershed. Stable isotope analysis demonstrated that after salmon spawned, MDN assimilation by juvenile salmon in the fall was a function of adult Pink and Chinook salmon spawner abundance, regardless of the habitat occupied by rearing juveniles. However, by the following summer, high retention of MDN in complex habitat masked seasonality of MDN assimilation in sloughs and river sections with abundant lentic-lotic exchanges. As such, MDN assimilation in the summer (prior to arrival of spawners) bore only a faint relationship to spawner abundance and distribution from the previous year. In chapter 3 I examined the relationship between MDN assimilation (Chapter 2) and juvenile salmon growth, size, body condition, and abundance. Prior to salmon spawning, residual MDN from past years offered little advantage to juvenile salmon. However, after the arrival of spawning salmon, MDN enhanced juvenile salmon size, growth, and condition in fall and winter. The collective results from this dissertation thus provides compelling evidence that MDN from spawning Pink Salmon may enhance the productivity of Coho and Chinook salmon. Management agencies should explore modified spawner-recruit models that incorporate MDN relationships to determine if they more accurately describe population dynamics. Where they do, such models may be used to forecast salmon returns and possibly adjust escapement goals (the number of spawners desired on the spawing grounds) to improve maximum-sustained yields (MSY).
Download or read book Tracking Past Sockeye Salmon Oncorhyncus Nerka Population Dynamics in Alaska Using Paleolimnology written by Irene S. Gregory-Eaves and published by . This book was released on 2002 with total page 586 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessing the Production of Sockeye Salmon Oncorhynchus Nerka at Chilkat Lake Southeast Alaska Using Current Trophic Conditions and the Paleolimnologic Sediment Record written by David Barto and published by . This book was released on 2004 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Anadromous sockeye salmon are the only Pacific salmon that require an extensive rearing period in a lake environment. Recent studies suggest changes in lake nutrient inputs are directly related to the magnitude of annual spawning populations (escapement), and can be quantified by sediment stable isotope analysis of nitrogen 15N). Marine nitrogen supplied by returned salmon is enriched in 15N relative to the freshwater nitrogen, which is derived from atmospheric N2 (ð15N=0 0/00). Recent (1987-1996) limnological investigations of Chilkat Lake, Alaska, matched to brood year escapement estimates, indicate that sockeye marine-derived phosphorus and nitrogen contributed up to 87% and 20%, respectively, of the lake nutrient pool. Since salmon populations fluctuate annually, the resulting marine derived nutrient (MDN) inputs and ð15N also fluctuate. Sedimentary ð15N is positively correlated (r2=0.8605, p=0.0076, df=5) with observed escapement. Additionally, ð15N is positively related to lake paleoproductivity and inversely correlated with high concentrations of CaCO3 and glacial silt. The frequency and duration of these CaCO3 inputs are believed to be the result of climate related glacial meltwater intrusions from the Tsirku River. Thus, fluctuations in MDN can be shown to influence the overall sockeye salmon production at Chilkat Lake by controlling lake productivity"--Leaf iii.
Download or read book Factors Influencing the Early Marine Ecology of Juvenile Sockeye Salmon Oncorhynchus Nerka in Rivers Inlet British Columbia written by Seana Leigh Buchanan and published by . This book was released on 2006 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Rivers Inlet sockeye salmon (Oncorhynchus nerka) population was historically the third most numerous in British Columbia, with returns routinely exceeding one million adults. In recent years, the population has drastically declined, culminating in an utter failure of the adult spawning population in 1999, when returns were estimated at 3600 fish. Poor marine survival has been proposed as the primary cause of the decline. Existing evidence, including concurrent declines in sockeye salmon populations from nearby watersheds indicate the problem may lie in the early marine phase. We provide evidence suggesting that a crucial, population-limiting window may exist in the early marine phase, as the newly smolted juvenile sockeye salmon emerge into Rivers Inlet and nearby waters. Unless appropriate abiotic conditions exist in the lead-up to the juvenile migration, the brood year may suffer significant mortality. This, I propose, is a key contributor to reduced returns of Rivers Inlet sockeye salmon.
Download or read book Effects of Gulf of Alaska Sockeye Salmon Oncorhynchus Nerka Abundance on Survival Body Size Growth Rate and Age at Maturity of British Columbia and Bristol Bay Alaska Sockeye Populations written by Canada. Department of Fisheries and Oceans and published by Fisheries and Oceans, Canada. This book was released on 1984 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt:
