Fraser River Sockeye Salmon Oncorhynchus Research Articles

Has Steller Sea Lion Predation Impacted Survival of Fraser River Sockeye Salmon?

The commercially, recreationally, and culturally important Fraser River Sockeye Salmon Oncorhynchus nerka has experienced a productivity decline over the past 3 decades, which—along with greater temporal variation in annual abundance (i.e., cyclic dominance)—may at least partly be due to Steller sea lion Eumetopias jubatus (SSL) predation on returning adult salmon. This assumes that SSLs residing around northern Vancouver Island (British Columbia, Canada) target Sockeye Salmon for just a few weeks during the peak of their run. It is a reasonable enough assumption to warrant immediate priority for field research on SSL behavior and diets during the migration period. We evaluated the plausibility of the assumption with a variety of approaches ranging from simple estimates of maximum SSL consumption to partitioning of observed marine mortality rates and analysis of SSL foraging behavior to show that SSLs could have caused the decline in productivity and abundance of Fraser River Sockeye Salmon.

Variable thermal experience and diel thermal patterns of homing sockeye salmon in coastal marine waters

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 496:109-124 (2014) - DOI: https://doi.org/10.3354/meps10551 Theme Section: Tracking fitness in marine vertebrates Variable thermal experience and diel thermal patterns of homing sockeye salmon in coastal marine waters S. M. Drenner1,*, S. G. Hinch1, E. G. Martins2, D. Robichaud3, T. D. Clark4, L. A. Thompson5, D. A. Patterson5, S. J. Cooke2, R. E. Thomson6,** 1Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada 2Fish Ecology and Conservation Physiology Laboratory, Institute of Environmental Science and Department of Biology, Carleton University, Ottawa, Ontario K1S 5B6, Canada3LGL Limited, 9768 Second Street, Sidney, British Columbia V8L 3Y8, Canada4Australian Institute of Marine Science, PMB 3, Townsville MC, Queensland 4810, Australia5Fisheries and Oceans Canada, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada6Fisheries and Oceans Canada, Canada Institute of Ocean Science, PO Box 6000, Sidney, British Columbia V8L 4B2, Canada *Corresponding author: smdrenner@gmail.com ABSTRACT: Temperature is recognized as a key factor influencing physiology, behaviour and survival of anadromous salmonids, yet little is known about their thermal experience, nor factors affecting it, during marine homeward migrations. In 2006 and 2010, approximately 1000 Fraser River sockeye salmon Oncorhynchus nerka were captured and tagged in coastal marine waters, ~215 km from the river mouth, during their spawning migration. Individual salmon were blood sampled, gastrically implanted with temperature loggers fixed to radio or acoustic tags, and released. We recovered 50 loggers from freshwater locales containing 14690 hourly temperature readings. Mixed-effects models were used to characterize marine thermal experience, and examine the association of thermal experience with initial physiological status as well as oceanographic and meteorological conditions. Sockeye salmon thermal experience was highly variable (8.4°C to 20.5°C), and we detected opposite diel patterns between study years that could be associated with moon phase, behavioural thermoregulation, olfactory/celestial navigation or predator avoidance. We were unable to find any relationships between thermal experience and environmental conditions or fish physiological state. Nonetheless, we found that the greatest variability in thermal experience was attributed to within-individual variation, suggesting that environmental and physiological variables need to be examined at different temporal and spatial scales, and/or additional environmental and physiological variables need to be assessed. Overall, the factors associated with the thermal experience of homing sockeye salmon in coastal marine environments are more complex than previously thought, and multiple year studies are needed before generalizing behavioural patterns observed from single year studies. KEY WORDS: Temperature · Sockeye salmon · Migration · Behaviour · Physiology · Oceanography · Thermal logger · Telemetry Full text in pdf format Supplementary material **Amended author list. See Corrigendum PreviousNextCite this article as: Drenner SM, Hinch SG, Martins EG, Robichaud D and others (2014) Variable thermal experience and diel thermal patterns of homing sockeye salmon in coastal marine waters. Mar Ecol Prog Ser 496:109-124. https://doi.org/10.3354/meps10551 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 496. Online publication date: January 27, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Prey Selectivity of Fraser River Sockeye Salmon during Early Marine Migration in British Columbia

AbstractMortality of salmon during early marine life has long been thought to be a critical factor in limiting overall abundance. One of the key hypotheses proposed to explain the long‐term productivity decline of Canada's iconic Fraser River Sockeye Salmon Oncorhynchus nerka, is deficient habitat conditions experienced during early marine life. Our study is a first step towards testing this hypothesis, with an aim of understanding food availability and prey choice of juvenile salmon early in their coastal migration. We investigated zooplankton density, diet composition, and foraging selectivity of juvenile Fraser Sockeye Salmon during the 2009 and 2010 migrations and determined whether the timing of their migration was related to feeding success. Sockeye Salmon diets showed high prey diversity and a preference for euphausiid, amphipod, decapod, terrestrial insect, fish, egg, and cumacean prey. Calanoid copepods, the most abundant available prey, were not strongly selected in either year. Zooplankton densities were highest in the tidally mixed Discovery Passage–Johnstone Strait area. The fish appeared to have an adequate prey resource pool during their early marine migration, and in the 2 years of our study we observed similar feeding success throughout the migration period. Importantly, we found no evidence of food limitations that might indicate that juveniles suffered food deprivation. Further research is needed to test the generality of these findings, including the potential impacts of warming ocean temperatures on the timing and availability of prey during migration.

Low cardiac and aerobic scope in a coastal population of sockeye salmon Oncorhynchus nerka with a short upriver migration

This study showed that a coastal population (Harrison) of Fraser River sockeye salmon Oncorhynchus nerka had a lower aerobic and cardiac scope compared with interior populations with more challenging upriver spawning migrations, providing additional support to the idea that Fraser River O. nerka populations have adapted physiologically to their local migratory environment.

Provenance matters: thermal reaction norms for embryo survival among sockeye salmon Oncorhynchus nerka populations

Differences in thermal tolerance during embryonic development in Fraser River sockeye salmon Oncorhynchus nerka were examined among nine populations in a controlled common-garden incubation experiment. Forcing embryonic development at an extreme temperature (relative to current values) of 16° C, representing a future climate change scenario, significantly reduced survival compared to the more ecologically moderate temperature of 10° C (55% v. 93%). Survival at 14° C was intermediate between the other two temperatures (85%). More importantly, this survival response varied by provenance within and between temperature treatments. Thermal reaction norms showed an interacting response of genotype and environment (temperature), suggesting that populations of O. nerka may have adapted differentially to elevated temperatures during incubation and early development. Moreover, populations that historically experience warmer incubation temperatures at early development displayed a higher tolerance for warm temperatures. In contrast, thermal tolerance does not appear to transcend life stages as adult migration temperatures were not related to embryo thermal tolerance. The intra-population variation implies potential for thermal tolerance at the species level. The differential inter-population variation in thermal tolerance that was observed suggests, however, limited adaptive potential to thermal shifts for some populations. This infers that the intergenerational effects of increasing water temperatures may affect populations differentially, and that such thermally mediated adaptive selection may drive population, and therefore species, persistence.

Quantitative methods for analysing cumulative effects on fish migration success: a review

It is often recognized, but seldom addressed, that a quantitative assessment of the cumulative effects, both additive and non-additive, of multiple stressors on fish survival would provide a more realistic representation of the factors that influence fish migration. This review presents a compilation of analytical methods applied to a well-studied fish migration, a more general review of quantitative multivariable methods, and a synthesis on how to apply new analytical techniques in fish migration studies. A compilation of adult migration papers from Fraser River sockeye salmon Oncorhynchus nerka revealed a limited number of multivariable methods being applied and the sub-optimal reliance on univariable methods for multivariable problems. The literature review of fisheries science, general biology and medicine identified a large number of alternative methods for dealing with cumulative effects, with a limited number of techniques being used in fish migration studies. An evaluation of the different methods revealed that certain classes of multivariable analyses will probably prove useful in future assessments of cumulative effects on fish migration. This overview and evaluation of quantitative methods gathered from the disparate fields should serve as a primer for anyone seeking to quantify cumulative effects on fish migration survival.

Modeling the Influence of Environmental Factors on Spawning Migration Mortality for Sockeye Salmon Fisheries Management in the Fraser River, British Columbia

AbstractThe impact of freshwater environmental factors on spawning migration mortality was modeled to provide a predictive tool for fisheries management of four run timing groups of Fraser River sockeye salmon Oncorhynchus nerka: early Stuart (Stuart Lake), early summer, summer, and late. We tested the significance of different measures of water temperature, discharge, fish abundance, and entry timing for forecasting discrepancies between lower‐river and upriver escapement estimates using multiple regressions of principal component scores. Descriptive discrepancy models (i.e., “management adjustment” models) identified using Akaike's information criterion were consistent with the known biology of each group. For example, temperature and discharge thresholds were selected for early Stuart run discrepancy models, reflecting the extremes in both variables experienced by these early migrants. Predictive discrepancy models were also generated for each run timing group by using the limited number of environmental variables that are available in‐season to fisheries managers. Even predictive discrepancy models using simple environmental metrics of average river temperature, flow, and river entry timing provide a valuable tool for forecasting relative indices of spawning migration mortality. This study provides an example of how environmentally based predictive tools can be used to inform fisheries management decisions and improve the probability of achieving spawning escapement targets.

Energy expenditures during spawning by chum salmon Oncorhynchus keta (Walbaum) in British Columbia

Physiological telemetry and proximate tissue analyses were used to assess energy expended by chum salmon Oncorhynchus keta on various behaviours during spawning in Kanaka Creek, British Columbia, Canada, and results were compared with published data on Fraser River sockeye salmon Oncorhynchus nerka, the only other species for which both types of measurements have been taken. Chum salmon arrived at the spawning grounds with body energy densities of 4·84 MJ kg−1 in males and 4·62 MJ kg−1 in females, lower than most sockeye salmon populations, and died with energy densities of c. 4 MJ kg−1, similar to that observed in sockeye salmon and other salmonids. Moisture levels generally increased in body tissues over the spawning life, particularly in female gonads, and lipid levels decreased. Declines in protein observed over the spawning life of other Pacific salmon Oncorhynchus sp. were less evident in Kanaka Creek chum salmon. Holding behaviour constituted the dominant component of the activity schedule and energy budget of both sexes. After holding, the most expensive behaviours were nest digging in females and aggressive displays in males. Dominant males expended the most energy on behaviours each day, as indexed by oxygen consumption (3600 mgO2 kg−1), while satellite males expended nearly as much (3504 mgO2 kg−1) but females expended considerably less (2327 mgO2 kg−1). Kanaka chum salmon engaged more frequently in energetically expensive reproductive behaviours than Stuart River sockeye salmon.

Migration Timing and River Survival of Late‐Run Fraser River Sockeye Salmon Estimated Using Radiotelemetry Techniques

AbstractIn recent years, large numbers of late‐run Fraser River sockeye salmon Oncorhynchus nerka have died in freshwater areas before they spawned. We used radiotelemetry techniques to determine river entry timing, migration rates, and survival for the summer and late runs of sockeye salmon in 2002 and 2003. Fishery removals and river detections accounted for 62% of the 873 fish tagged and released in marine areas in 2002. Some late‐run fish migrated from release sites to the Mission hydroacoustic site in 8–10 d and migrated upstream with the summer run. Most late‐run fish remained in the Strait of Georgia for 15–33 d and entered the river after the summer run. Tracking data indicated that individual sockeye salmon maintained essentially the same chronological order as they migrated up the Fraser and Thompson rivers. Summer‐run stocks traveled faster between Mission and the Thompson Junction (33–39 km/d) than late‐run fish (17–21 km/d). After accounting for fishery removals, the river survival rate for summer‐run fish was 92%, and differences between the three release timing groups were not significant. In contrast, the first migration group of late‐run fish that passed Mission had significantly lower survival (13%) than all other timing groups. The survival rate for the second and third river entry groups combined (74%) was significantly lower than that of the fourth group (92%). Period‐specific survival rates were used to define a relationship between river entry timing and survival and to identify additional factors influencing river entry timing for late‐run fish. These relationships may be useful in predicting river survival rates for late‐run stocks in future years.

Stock Identification of Fraser River Sockeye Salmon Using Microsatellites and Major Histocompatibility Complex Variation

The utility of DNA-based variation for stock identification was evaluated for Fraser River sockeye salmon Oncorhynchus nerka. For this evaluation, the variation at 14 microsatellite loci and one major histocompatibility complex (MHC) locus was determined from approximately 13,000 fish from 47 populations in the drainage. Genetic differentiation among the populations was observed, the overall FST value for the 14 microsatellite loci surveyed being 0.054 and that for the MHC locus being 0.215. The variation among regions and populations within regions was approximately 20 times as great as that of the annual variation within populations for the microsatellite loci and 28 times as great for the MHC locus. The power of a microsatellite locus for population-specific identification in simulated mixture samples was positively correlated with the number of observed alleles at the locus. Analysis of simulated mixtures indicated that the mean percentage error of estimated stock compositions was less than 1% per population, with a standard deviation of approximately 3% for a mixture sample size of 150 fish. Estimated stock compositions of a known sample of radio-tagged sockeye salmon indicated that the mean percentage error was 1% per population and 1% per run-time group. The use of DNA variation to estimate stock compositions in the management of the 2002 Fraser River sockeye salmon fisheries indicated the early arrival of the late run in the Fraser River. Stock identification based on DNA-level variation will probably become the preferred method in Pacific salmon applications in the near future.

Energetics and morphology of sockeye salmon: effects of upriver migratory distance and elevation

Depending on population, wild Fraser River sockeye salmon Oncorhynchus nerka travel distances of <100 km to >1100 km and ascend elevations ranging from near sea‐level to 1200 m to reach spawning areas. Populations embarking on distant, high elevation migrations (i.e. Early Stuart, Chilko and Horsefly populations) began their upriver spawning migrations with higher densities of somatic energy (c. 9·2 to 9·8 MJ kg−1) and fewer eggs (c. 3200 to 3800) than populations making shorter, low elevation migrations (i.e. Weaver and Adams; c. 7·1 to 8·3 MJ kg−1 gross somatic energy and c. 4300 to 4700 eggs). Populations making difficult upriver migrations also had morphologies that were smaller and more fusiform than populations making less difficult migrations, traits that may facilitate somatic energy conservation by reducing transport costs. Indeed, fish travelling long distances expended less somatic energy per unit of migratory difficulty than those travelling shorter distances (2·8 to 3·8 kJ v. 10–1400 kJ). Consistent with evolutionary theory, difficult migrations appear to select for energy efficiency but ultimately fish making more difficult migrations produce fewer eggs, even when differences in body length have been accounted for. Despite large among‐population differences in somatic energy at the start of upriver migration, all populations completed migration and spawning, and subsequently died, with c. 4 MJ kg−1 of energy remaining, a level which may reflect a threshold to sustain life.

The effect of exercise and captivity on energy partitioning, reproductive maturation and fertilization success in adult sockeye salmon

Releasing a population of adult Fraser River sockeye salmon Oncorhynchus nerka from an energetically more expensive non‐feeding natural migration (1089 km, natal groups) and allowing them to sexually mature in either a moderate flow (captive exercise group) or a no flow (captive non‐exercise group) environment resulted in significant differences in body energy densities (MJ kg−1) among groups (ranked: initial natural migrator > non‐exercise > exercise > natal arrivals). Similarly, per cent body lipids were significantly lower in exercise females compared with non‐exercise females, experimentally confirming the central role lipid catabolism has in powering swimming. Although restricting exercise did result in greater body energy reserves at spawning, this did not result in a reallocation of energy to reproduction, as fecundity, egg size and gonad composition were unchanged among the groups. Furthermore, non‐exercise females had delayed maturity, lower egg deposition rates, and were more likely to die prior to egg ovulation than exercise females and natal spawners. Eggs from captive exercise adult females were more likely to survive to the eyed stage than eggs from captive non‐exercise females, but both captive groups had significantly lower egg fertilization success than natal spawners suggesting that confinement stress played a role in some of results presented. There were no significant differences in plasma levels of glucose, lactate, cortisol and reproductive hormones among the groups, but correlations among acute and chronic indicators of stress were significant among individuals. These results indicate that exercise during the late stages of maturation, as might occur normally, may be required for optimizing reproductive maturation and maximizing reproductive success.