scholarly journals Heavy sea louse infection is associated with decreased stomach fullness in wild juvenile sockeye salmon

2018 ◽  
Vol 75 (10) ◽  
pp. 1587-1595 ◽  
Author(s):  
Sean C. Godwin ◽  
Martin Krkošek ◽  
John D. Reynolds ◽  
Luke A. Rogers ◽  
Lawrence M. Dill
Keyword(s):  
Sockeye Salmon ◽  
Sublethal Effects ◽  
Infected Fish ◽  
Mixed Effects ◽  
Juvenile Salmon ◽  
Lepeophtheirus Salmonis ◽  
Fraser River ◽  
Stomach Fullness ◽  
Foraging Success ◽  
Marine Migration

Foraging success can be mediated by parasites, but this is poorly understood for marine fish whose aggregations and patchy prey fields create conditions for intense intraspecific competition. We evaluated whether sea louse infection is associated with decreased stomach fullness of wild juvenile sockeye salmon (Oncorhynchus nerka) in Johnstone Strait, British Columbia, during their marine migration from the Fraser River. Caligus clemensi comprised 98.6% of the pre-adult and adult lice and 86.5% of the copepodites (freshly attached juvenile lice); the rest were Lepeophtheirus salmonis. We found that infection status was an important predictor of relative stomach fullness for juvenile sockeye (wet stomach content mass divided by body mass), as indicated by mixed-effects model selection, and that highly infected fish had 17% ± 8% lower relative stomach fullness than did lightly infected fish. This louse-associated reduction in relative stomach fullness occurs as the juvenile sockeye migrate through a food-limited environment and, presumably, elevated competition. Given that early marine growth for juvenile salmon is often a predictor of survival, our results highlight the importance of understanding sublethal effects of parasites on salmonids and possibly other fish species.

Sea lice, sockeye salmon, and foraging competition: lousy fish are lousy competitors

2015 ◽  
Vol 72 (7) ◽  
pp. 1113-1120 ◽  
Author(s):  
Sean C. Godwin ◽  
Lawrence M. Dill ◽  
John D. Reynolds ◽  
Martin Krkošek
Keyword(s):  
Indirect Effects ◽  
Sockeye Salmon ◽  
Competitive Ability ◽  
Early Life History ◽  
Infected Fish ◽  
Sea Lice ◽  
Lepeophtheirus Salmonis ◽  
Fraser River ◽  
Ecological Processes ◽  
Parasite Exposure

Pathogens threaten wildlife globally, but these impacts are not restricted to direct mortality from disease. For fish, which experience periods of extremely high mortality during their early life history, infections may primarily influence population dynamics and conservation through indirect effects on ecological processes such as competition and predation. We conducted a competitive foraging experiment using outmigrating juvenile Fraser River sockeye salmon (Oncorhynchus nerka) to determine whether fish with high abundances of parasitic sea lice (Caligus clemensi and Lepeophtheirus salmonis) have reduced competitive abilities when foraging. Highly infected sockeye were 20% less successful at consuming food, on average, than lightly infected fish. Competitive ability also increased with fish body size. Our results provide the first evidence that parasite exposure may have negative indirect effects on the fitness of juvenile sockeye salmon and suggest that indirect effects of pathogens may be of key importance for the conservation of marine fish.

The Ecology of Juvenile Salmon in the Northeast Pacific Ocean: Regional Comparisons

2007 ◽  
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Gulf Of Alaska ◽  
Juvenile Salmon ◽  
Stomach Fullness ◽  
Feeding Intensity ◽  
Percentage Weight ◽  
Juvenile Pacific Salmon ◽  
Survival Patterns

Abstract.—Upon entering marine waters, juvenile Pacific salmon <em>Oncorhynchus </em>spp. depend on feeding at high and sustained levels to achieve growth necessary for survival. In the last decade, several concurrent studies have been examining the food habits and feeding intensity of juvenile Pacific salmon in the shelf regions from California to the northern Gulf of Alaska. In this paper, we compared results from feeding studies for all five species of juvenile salmon (Chinook salmon <em>O. tshawytscha</em>, coho salmon <em>O. kisutch</em>, chum salmon <em>O. keta, </em>sockeye salmon <em>O. nerka</em>, and pink salmon <em>O. gorbuscha</em>) between 2000 and 2002, years when these regions were sampled extensively. Within these years, we temporally stratified our samples to include early (May–July) and late (August–October) periods of ocean migration. Coho and Chinook salmon diets were most similar due to a high consumption of fish prey, whereas pink, chum, and sockeye salmon diets were more variable with no consistently dominant prey taxa. Salmon diets varied more spatially (by oceanographic and regional factors) than temporally (by season or year) in terms of percentage weight or volume of major prey categories. We also examined regional variations in feeding intensity based on stomach fullness (expressed as percent body weight) and percent of empty or overly full stomachs. Stomach fullness tended to be greater off Alaska than off the west coast of the United States, but the data were highly variable. Results from these comparisons provide a large-scale picture of juvenile salmon feeding in coastal waters throughout much of their range, allowing for comparison with available prey resources, growth, and survival patterns associated with the different regions.

Metabolic rates and swimming performance of adult Fraser River sockeye salmon (Oncorhynchus nerka) after a controlled infection with Parvicapsula minibicornis

2005 ◽  
Vol 62 (9) ◽  
pp. 2124-2133 ◽  
Author(s):  
G N Wagner ◽  
S G Hinch ◽  
L J Kuchel ◽  
A Lotto ◽  
S RM Jones ◽  
...  
Keyword(s):  
Sockeye Salmon ◽  
Swimming Performance ◽  
Oncorhynchus Nerka ◽  
Kidney Tissue ◽  
Severe Infection ◽  
Polymerase Chain Reaction Analysis ◽  
Infected Fish ◽  
Fraser River ◽  
Metabolic Rates ◽  
Holding Period

Adult sockeye salmon (Oncorhynchus nerka) acquire infections with the myxosporean kidney parasite Parvicapsula minibicornis during their spawning migration in the Fraser River, British Columbia. Controlled infections with this parasite in wild sockeye salmon had no significant impact on plasma ionic status, metabolic rates, and initial maximum prolonged swimming performance (Ucrit) for fish ranked as either strongly, weakly, or noninfected by polymerase chain reaction analysis of kidney tissue. However, strongly infected fish had significantly lower second Ucrit and recovery ratio (8%) values, indicating decreased ability to recover from exercise. As the present study shows that the severity of infection is affected by time and temperature, the accumulated thermal units (ATU) of exposure in this study were compared with those experienced by naturally migrating sockeye salmon. A parallel telemetry study revealed that early-timed sockeye experienced significantly more ATU (741.4 ± 29.4 °C) than normally migrating salmon (436.0 ± 20.0 °C) prior to spawning because of a significantly longer holding period in the lake system. The present data are discussed in the context of a threshold of >450 °C ATU for severe infection that would first manifest in early-timed fish in the upper reaches of the Fraser River and certainly on the spawning grounds.

scholarly journals Transcriptome patterns and blood physiology associated with homing success of sockeye salmon during their final stage of marine migration

2018 ◽  
Vol 75 (9) ◽  
pp. 1511-1524 ◽  
Author(s):  
S. Matthew Drenner ◽  
Scott G. Hinch ◽  
Nathan B. Furey ◽  
Timothy D. Clark ◽  
Shaorong Li ◽  
...  
Keyword(s):  
Gene Expression ◽  
Stress Responses ◽  
Sockeye Salmon ◽  
Protein Biosynthesis ◽  
Infected Fish ◽  
Pcr Analysis ◽  
Biological Processes ◽  
Marine Migration ◽  
Polymerase Chain ◽  
Marine Survival

To better understand the mechanisms that lead to marine mortality of homing adult sockeye salmon (Oncorhynchus nerka), gill and blood biopsies were used in combination with biotelemetry to demonstrate how survival to freshwater entry is related to gene expression and physiological indices of stress. Microarray analysis of gene expression indicated multiple biological processes, including immune and stress responses, protein biosynthesis, and metabolism. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) analysis indicated fish with upregulation of genes related to stress and infection had higher marine survival compared with fish without this genomic signature. We proposed that higher marine survival of potentially stressed and immune compromised fish can be explained by stressed and infected fish being highly motivated to enter fresh water, leading to enhanced marine survival. However, once in a river, stressed and immune compromised fish could suffer higher mortality because of premature river entry. Overall, this study supports the idea that infection and stress are important biological processes influencing behaviour and fate of sockeye salmon during homing migrations.

Freshwater and marine migration and survival of endangered Cultus Lake sockeye salmon (Oncorhynchus nerka) smolts using POST, a large-scale acoustic telemetry array

2009 ◽  
Vol 66 (5) ◽  
pp. 736-750 ◽  
Author(s):  
David W. Welch ◽  
Michael C. Melnychuk ◽  
Erin R. Rechisky ◽  
Aswea D. Porter ◽  
Melinda C. Jacobs ◽  
...  
Keyword(s):  
Sockeye Salmon ◽  
Large Scale ◽  
Oncorhynchus Nerka ◽  
Exit Time ◽  
Survival Rates ◽  
Release Site ◽  
Fraser River ◽  
Continental Scale ◽  
Marine Migration ◽  
Post Array

Freshwater and early marine migration and survival of endangered Cultus Lake sockeye ( Oncorhynchus nerka ) salmon were studied using the Pacific Ocean Shelf Tracking (POST) array. Smolts were acoustically tagged in 2004–2007, and their migration was recorded within the lower Fraser River and coastal southern British Columbia waters. Most smolts showed rapid directional movement (swimming speeds of ~15–30 km·day–1). Average exit time from the Fraser River was 4.0–5.6 days after release, and average residence time within the Strait of Georgia was 25.6–34.1 days. Most individuals migrated northward, generally close to the mainland coast. Survival rates, assessed using standard mark–recapture methods, were generally high during the downstream migration (50%–70%), except in 2005 when survival was <20%, possibly because of a late release. Marine survival rates were stable among years, between 10%–30% at a subarray sited 500 km away from the release site. Movement rates were similar to those of previously published work, but the POST array provided direct measurements of movement and estimates of survival and demonstrated the feasibility of establishing continental-scale acoustic arrays for management and conservation of marine species.

Occurrence of the eyefluke, Diplostomum (Diplostomum) baeri bucculentum Dubois et Rausch, 1948, in salmonid fishes of northern British Columbia

1985 ◽  
Vol 63 (2) ◽  
pp. 396-399 ◽  
Author(s):  
Hilda Lei Ching
Keyword(s):  
Rainbow Trout ◽  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Lake Trout ◽  
Infected Fish ◽  
Salmo Gairdneri ◽  
Coregonus Clupeaformis ◽  
Lake Whitefish ◽  
Dolly Varden Salvelinus Malma ◽  
Prosopium Williamsoni

As a result of experimental infections in chicks, diplostomula found in the retina of chinook salmon from the Nechako River were identified as Diplostomum (Diplostomum) baeri bucculentum. Eyeflukes in other salmonids were considered to be the same species based on similar measurements and site in the eyes. These eyeflukes varied in prevalence and mean intensity in seven salmonid species surveyed in nine localities in 1979–1981. The following fish were sampled: rainbow trout (Salmo gairdneri), 505; mountain whitefish (Prosopium williamsoni), 334; lake whitefish (Coregonus clupeaformis), 32; Dolly Varden (Salvelinus malma), 66; lake trout (S. namaycush), 13; kokanee or sockeye salmon (Oncorhynchus nerka), 323; and chinook salmon (O. tshawytscha), 164. Eyeflukes had prevalences ranging from 84 to 100% in six lakes, 64% in the river, 53% in one reservoir site, and a prevalence of 15% in the other reservoir site. Mountain and lake whitefishes had high mean intensities while kokanee had low mean intensities. Correlation of increased intensity with increased fish size was significant for 6 of 27 samples. Four samples of lake whitefish, mountain whitefish, rainbow trout, and chinook salmon showed significant asymmetry when numbers of diplostomula were compared between eyes. More of the heavily infected fish showed asymmetry than did the lightly infected fish.

Biochemical Studies on Sockeye Salmon During Spawning Migration: XI. The Free Histidine Content of the Tissues

1960 ◽  
Vol 17 (3) ◽  
pp. 347-351 ◽  
Author(s):  
J. D. Wood ◽  
D. W. Duncan ◽  
M. Jackson
Keyword(s):  
Amino Acid ◽  
Sockeye Salmon ◽  
Alimentary Tract ◽  
Oncorhynchus Nerka ◽  
The Other ◽  
Spawning Migration ◽  
Fraser River ◽  
Initial Value ◽  
Spawning Grounds ◽  
Biochemical Studies

During the first 250 miles (400 km) of spawning migration of Fraser River sockeye salmon (Oncorhynchus nerka) the free histidine content of the muscle, alimentary tract, and head+skin+bones+tail decreased to a small fraction of the initial value. A further decrease occurred in the levels of this amino acid in the alimentary tract during the subsequent 415-mile (657-km) migration to the spawning grounds, no change being observed with the other tissues. Comparatively small changes in free histidine were found with heart, spleen, liver, kidney and gonads during migration.

A widespread decrease in productivity of sockeye salmon (Oncorhynchus nerka) populations in western North America

2012 ◽  
Vol 69 (8) ◽  
pp. 1255-1260 ◽  
Author(s):  
Randall M. Peterman ◽  
Brigitte Dorner
Keyword(s):  
Sockeye Salmon ◽  
Spatial Scales ◽  
Oncorhynchus Nerka ◽  
Geographic Area ◽  
Fraser River ◽  
Western North America ◽  
Southeast Alaska ◽  
The Past ◽  
Large Geographic Area ◽  
Marine Areas

We used data on 64 stocks of sockeye salmon ( Oncorhynchus nerka ) from British Columbia (B.C.), Washington, and Alaska to determine whether recent decreases in abundance and productivity observed for Fraser River, B.C., sockeye have occurred more widely. We found that decreasing time trends in productivity have occurred across a large geographic area ranging from Washington, B.C., southeast Alaska, and up through the Yakutat peninsula, Alaska, but not in central and western Alaska. Furthermore, a pattern of predominantly shared trends across southern stocks and opposite trends between them and stocks from western Alaska was present in the past (1950–1985), but correlations have intensified since then. The spatial extent of declining productivity of sockeye salmon has important implications for management as well as research into potential causes of the declines. Further research should focus on mechanisms that operate at large, multiregional spatial scales, and (or) in marine areas where numerous correlated sockeye stocks overlap.

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