| can intense predation by bears exert a depensatory effect on recruitment in a pacific salmon population? | it has long been recognized that, as populations increase in density, ecological processes affecting growth and survival reduce per capita recruitment in the next generation. in contrast to the evidence for such "compensatory" density dependence, the alternative "depensatory" process (reduced per capita recruitment at low density) has proven more difficult to demonstrate in the field. to test for such depensation, we measured the spawner-recruit relationship over five decades for a sockeye salmo ... | 2014 | 25154755 |
| size selectivity of predation by brown bears depends on the density of their sockeye salmon prey. | can variation in prey density drive changes in the intensity or direction of selective predation in natural systems? despite ample evidence of density-dependent selection, the influence of prey density on predatory selection patterns has seldom been investigated empirically. we used 20 years of field data on brown bears (ursus arctos) foraging on sockeye salmon (oncorhynchus nerka) in alaska, to test the hypothesis that salmon density affects the strength of size-selective predation. measurement ... | 2013 | 23594549 |
| sockeye salmon immunoglobulin vh usage and pathogen loads differ between spawning sites. | the immunological imprinting hypothesis proposes that juvenile anadromous fish respond to the pathogen fingerprint specific to their natal site by producing protective long lived plasma cells (llpcs) that constitutively produce antibodies against those pathogens. hence, fish returning to their natal streams have immunological protection from pathogens at that specific location. here, we tested the hypothesis through analysis of antibody composition and usage in sockeye salmon populations in alas ... | 2017 | 28847679 |
| self-sustaining populations, population sinks or aggregates of strays: chum (oncorhynchus keta) and chinook salmon (oncorhynchus tshawytscha) in the wood river system, alaska. | small populations can provide insights into ecological and evolutionary aspects of species distributions over space and time. in the wood river system in alaska, usa, small aggregates of chinook (oncorhynchus tshawytscha) and chum salmon (o. keta) spawn in an area dominated by sockeye salmon (o. nerka). our objective was to determine whether these chinook and chum salmon are reproductively isolated, self-sustaining populations, population sinks that produce returning adults but receive immigrati ... | 2011 | 22026559 |
| residues of pbdes in northeastern pacific marine fish: evidence for spatial and temporal trends. | in the flesh (skinless fillet) of chinook, chum, coho, pink, and sockeye salmon (oncorhynchus tshawytscha, o. keta, o. kisutch, o. gorbuscha, and o. nerka, respectively), sablefish (anoplopoma fimbria) and walleye pollock (theragra chalcogramma) from several sites in the northeast pacific sampled between 2002 and 2008, tetra- and pentabrominated diphenyl ethers (bdes) (bde 47, 49, 99, and 100) dominated the congener distribution. chinook and sablefish contained the highest concentrations, follow ... | 2011 | 21360729 |
| the utilization of a pacific salmon oncorhynchus nerka subsidy by three populations of charr salvelinus spp. | the l(f) -at-age trajectories differentiated two populations of dolly varden charr salvelinus malma and a population of arctic charr salvelinus alpinus from the eastern end of iliamna lake, alaska. salvelinus malma from the pedro bay ponds were the smallest for a given age, followed by salvelinus alpinus from the lake, and s. malma from the iliamna river were much larger. the utilization of a large sockeye salmon oncorhynchus nerka subsidy by the three salvelinus spp. populations was then invest ... | 2010 | 20840627 |
| population diversity and the portfolio effect in an exploited species. | one of the most pervasive themes in ecology is that biological diversity stabilizes ecosystem processes and the services they provide to society, a concept that has become a common argument for biodiversity conservation. species-rich communities are thought to produce more temporally stable ecosystem services because of the complementary or independent dynamics among species that perform similar ecosystem functions. such variance dampening within communities is referred to as a portfolio effect ... | 2010 | 20520713 |
| infection by the cestode parasite schistocephalus sp. and effects on diet, body condition and survival of sculpins cottus aleuticus and cottus cognatus. | sampling in iliamna lake, alaska, u.s.a. revealed that a greater proportion of coastrange sculpins cottus aleuticus were infected by the cestode schistocephalus solidus than slimy sculpins cottus cognatus (52 v. 23%), and infected c. aleuticus contained more cestodes than did c. cognatus (2·1 v. 1·3 per fish). consumption of sockeye salmon oncorhynchus nerka eggs (the primary diet item) was lower in fishes with cestodes, and a model based on cestode prevalence and age composition estimated highe ... | 2015 | 25809184 |
| historical analysis of salmon-derived polychlorinated biphenyls (pcbs) in lake sediments. | several recent studies have highlighted the importance of salmon as a means to deliver biomagnifying contaminants to nursery lakes. there is a lack of studies, however, which demonstrate empirically how this source has varied through time. this is of great significance because past salmon-derived contaminant loading was potentially greater than it is today. by analyzing radiometrically dated sediment cores collected from ten lakes in alaska and british columbia (b.c.), we relate historical numbe ... | 2009 | 19162299 |
| fine-scale differentiation between sockeye salmon ecotypes and the effect of phenotype on straying. | a long-standing goal of evolutionary biology is to understand the factors that drive population divergence, local adaptation and speciation. in particular, the effect of selection against dispersers on gene flow and local adaptation has attracted interest, although empirical data on phenotypic characters of dispersers are scarce. here, we used genetic and phenotypic data from beach and creek ecotypes of sockeye salmon (oncorhynchus nerka) in little togiak lake, alaska, to examine the relationshi ... | 2008 | 18594560 |
| ten years of varying lake level and selection on size-at-maturity in sockeye salmon. | despite the ubiquity of studies quantifying the strength and form of selection in nature, rarely is the ecological context for contemporary selection understood. here we report a case where lake level is a selective factor acting on sockeye salmon body size-at-maturity because low lake levels cause large salmon to strand and die rather than reach the breeding grounds. as a result of a semelparous life history, death for salmon at this stage results in a lifetime fitness of zero. we combined info ... | 2007 | 18027764 |
| biotic control of stream fluxes: spawning salmon drive nutrient and matter export. | organisms can control movements of nutrients and matter by physically modifying habitat. we examined how an ecosystem engineer, sockeye salmon (oncorhynchus nerka), influences seasonal fluxes of sediments, nitrogen (n), and phosphorus (p) in streams of southwestern alaska. the purpose of this study was to investigate whether salmon act as net importers or net exporters of matter and nutrients from streams and how these roles change as a function of salmon population density. we measured discharg ... | 2007 | 17536413 |
| directional selection by fisheries and the timing of sockeye salmon (oncorhynchus nerka) migrations. | the timing of migration from feeding to breeding areas is a critical link between the growth and survival of adult animals, their reproduction, and the fitness of their progeny. commercial fisheries often catch a large fraction of the migrants (e.g., salmon), and exploitation rates can vary systematically over the fishing season. we examined daily records of sockeye salmon (oncorhynchus nerka) in the egegik and ugashik management districts in bristol bay, alaska (usa), for evidence of such tempo ... | 2007 | 17494392 |
| concentrations and fluxes of salmon-derived polychlorinated biphenyls (pcbs) in lake sediments. | fourteen sediment cores were collected from 10 lakes spanning a large gradient of sockeye salmon returns (0-40 000 spawners km(-2)) in alaska and british columbia in 1995-98 and 2002/03. the cores were analyzed for 210pb to determine sedimentation rates and focusing factors. polychlorinated biphenyl (pcbs) concentrations in the surface sediments (0-2 cm) were highly correlated with the number of sockeye salmon returns to each nursery lake. for 2002/03, the correlation between pcb concentration a ... | 2005 | 16201625 |
| bioaccumulation and transport of contaminants: migrating sockeye salmon as vectors of mercury. | biological transport by migratory animals is increasingly recognized as important to the long-range dispersal of toxic contaminants. mercury (hg) contamination is a widespread environmental concern with serious health implications for humans and wildlife. due to their unique life history, anadromous salmon may act as important vectors for this contaminant, transferring hg between marine and freshwater ecosystems. previous analyses have considered contaminant transport by salmon to be unidirectio ... | 2009 | 19943655 |
| disturbance of freshwater habitats by anadromous salmon in alaska. | high densities of habitat modifiers can dramatically alter the structure of ecosystems. whereas spawning sockeye salmon ( oncorhynchus nerka) dig nests that cover over 2 m(2) and are at least 20 cm deep, and can spawn at high densities, relatively little attention has been devoted to investigating the impacts of this disturbance. we hypothesized that this temporally and spatially predictable bioturbation has large impacts on the coastal aquatic habitats used by sockeye. we experimentally investi ... | 2004 | 14997375 |
| levels of polychlorinated biphenyls (pcbs) and three organochlorine pesticides in fish from the aleutian islands of alaska. | persistent organic pollutants (pops), including polychlorinated biphenyls (pcbs) and chlorinated pesticides, have been shown to have many adverse human health effects. these contaminants therefore may pose a risk to alaska natives that follow a traditional diet high in marine mammals and fish, in which pops bioaccumulate. | 2010 | 20811633 |
| biocomplexity and fisheries sustainability. | a classic example of a sustainable fishery is that targeting sockeye salmon in bristol bay, alaska, where record catches have occurred during the last 20 years. the stock complex is an amalgamation of several hundred discrete spawning populations. structured within lake systems, individual populations display diverse life history characteristics and local adaptations to the variation in spawning and rearing habitats. this biocomplexity has enabled the aggregate of populations to sustain its prod ... | 2003 | 12743372 |
| fisheries productivity in the northeastern pacific ocean over the past 2,200 years. | historical catch records suggest that climatic variability has had basin-wide effects on the northern pacific and its fish populations, such as salmon, sardines and anchovies. however, these records are too short to define the nature and frequency of patterns. we reconstructed approximately 2,200-year records of sockeye salmon abundance from sediment cores obtained from salmon nursery lakes on kodiak island, alaska. large shifts in abundance, which far exceed the decadal-scale variability record ... | 2002 | 11961553 |
| ecology. pacific salmon run hot and cold. | using a novel technique, described on page 795, paleoceanographers have been able to chart the abundance of sockeye salmon in the bristol bay and kodiak island regions of alaska over the past 300 years--by far the most complete record yet. through time, they found, sockeye populations have alternately soared and slipped, following natural climate variations--well before commercial fishers began throwing nets over the sides of boats. | 2000 | 11184190 |
| impacts of climatic change and fishing on pacific salmon abundance over the past 300 years. | the effects of climate variability on pacific salmon abundance are uncertain because historical records are short and are complicated by commercial harvesting and habitat alteration. we use lake sediment records of delta15n and biological indicators to reconstruct sockeye salmon abundance in the bristol bay and kodiak island regions of alaska over the past 300 years. marked shifts in populations occurred over decades during this period, and some pronounced changes appear to be related to climati ... | 2000 | 11052941 |
| predator avoidance during reproduction: diel movements by spawning sockeye salmon between stream and lake habitats. | daily movements of mobile organisms between habitats in response to changing trade-offs between predation risk and foraging gains are well established; however, less in known about whether similar tactics are used during reproduction, a time period when many organisms are particularly vulnerable to predators. we investigated the reproductive behaviour of adult sockeye salmon (oncorhynchus nerka) and the activity of their principal predator, brown bears (ursus arctos), on streams in south-western ... | 2014 | 24702169 |
| single nucleotide polymorphisms unravel hierarchical divergence and signatures of selection among alaskan sockeye salmon (oncorhynchus nerka) populations. | disentangling the roles of geography and ecology driving population divergence and distinguishing adaptive from neutral evolution at the molecular level have been common goals among evolutionary and conservation biologists. using single nucleotide polymorphism (snp) multilocus genotypes for 31 sockeye salmon (oncorhynchus nerka) populations from the kvichak river, alaska, we assessed the relative roles of geography (discrete boundaries or continuous distance) and ecology (spawning habitat and ti ... | 2011 | 21332997 |
| founding events influence genetic population structure of sockeye salmon (oncorhynchus nerka) in lake clark, alaska. | bottlenecks can have lasting effects on genetic population structure that obscure patterns of contemporary gene flow and drift. sockeye salmon are vulnerable to bottleneck effects because they are a highly structured species with excellent colonizing abilities and often occupy geologically young habitats. we describe genetic divergence among and genetic variation within spawning populations of sockeye salmon throughout the lake clark area of alaska. fin tissue was collected from sockeye salmon r ... | 2004 | 14717887 |
| assignment of sockeye salmon (oncorhynchus nerka) to spawning sites using dna markers. | randomly amplified polymorphic dna (rapd) markers were used to assign individual adult sockeye salmon to their spawning sites using a genotype assignment test. six primers were selected for use by screening bulked dna samples for markers missing in fish from one or more of 5 sites in british columbia or alaska. of 73 markers scored, 54 showed variation between or within sites among the sampled fish. thirty-seven of the variable markers were not detected in any fish from one or more sites; 18 var ... | 2005 | 15976939 |
| using grizzly bears to assess harvest-ecosystem tradeoffs in salmon fisheries. | implementation of ecosystem-based fisheries management (ebfm) requires a clear conceptual and quantitative framework for assessing how different harvest options can modify benefits to ecosystem and human beneficiaries. we address this social-ecological need for pacific salmon fisheries, which are economically valuable but intercept much of the annual pulse of nutrient subsidies that salmon provide to terrestrial and aquatic food webs. we used grizzly bears, vectors of salmon nutrients and animal ... | 2012 | 22505845 |