Trophic responses of juvenile Pacific salmon to warm and cool periods within inside marine waters of Southeast Alaska

Habitat utilization was determined in summer 1986 by sampling 54 sites of nine habitat types: main channels, backwaters, braids, channel edges, and sloughs in the river; and beaver ponds, terrace tributaries, tributary mouths, and upland sloughs on the valley floor. Physical characteristics were measured at all sites, and all habitats except main channels (current too swift for rearing salmon) were seined to determine fish density. Sockeye (Oncorhynchus nerka) averaged 23 fish/100 m2, nearly twice the density of coho (O. kisutch) and four times that of chinook (O. tshawytscha), 14 and 6 fish/100 m2, respectively. Sockeye were age 0, 27–84 mm fork length (FL), and most abundant in upland sloughs, beaver ponds, and tributary mouths. Coho were ages 0 and 1, 33–132 mm FL, and most abundant in beaver ponds and upland sloughs. Chinook were age 0, 40–93 mm FL, and more abundant than the other species in habitats with faster currents (1–20 cm/s), particularly channel edges. Each species was absent from about one-quarter of the seining sites of each habitat type. Thus, the lower Taku River provides important summer habitat for juvenile salmon, but many suitable areas were unoccupied, possibly because of their distance from spawning areas and poor access for colonizing fish.

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Assessing estuaries as stopover habitats for juvenile Pacific salmon

Marine Ecology Progress Series ◽

10.3354/meps11933 ◽

2016 ◽

Vol 559 ◽

pp. 201-215 ◽

Cited By ~ 27

Author(s):

JW Moore ◽

J Gordon ◽

C Carr-Harris ◽

AS Gottesfeld ◽

SM Wilson ◽

...

Keyword(s):

Pacific Salmon ◽

Juvenile Pacific Salmon

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Diet composition of Steller sea lions (Eumetopias jubatus) in Frederick Sound, southeast Alaska: a comparison of quantification methods using scats to describe temporal and spatial variabilities

Canadian Journal of Zoology ◽

10.1139/cjz-2014-0292 ◽

2015 ◽

Vol 93 (5) ◽

pp. 361-376 ◽

Cited By ~ 7

Author(s):

D.J. Tollit ◽

M.A. Wong ◽

A.W. Trites

Keyword(s):

Pacific Salmon ◽

Biomass Energy ◽

Eumetopias Jubatus ◽

Steller Sea Lions ◽

Southeast Alaska ◽

Merluccius Productus ◽

Sea Lions ◽

Sampling Protocols ◽

Dietary Indices

We compared eight dietary indices used to describe the diet of Steller sea lions (Eumetopias jubatus (Schreber, 1776)) from 2001 to 2004 in Frederick Sound, southeast Alaska. Remains (n = 9666 items) from 59+ species categories were identified from 1684 fecal samples (scats) from 14 collection periods. The most frequently occurring prey were walleye pollock (Theragra chalcogramma (Pallas, 1814) = Gadus chalcogrammus Pallas, 1814; 95%), Pacific herring (Clupea pallasii Valenciennes in Cuvier and Valenciennes, 1847; 30%), Pacific hake (Merluccius productus (Ayres, 1855); 29%), and arrowtooth flounder (Atheresthes stomias (Jordan and Gilbert, 1880) = Reinhardtius stomias (Jordan and Gilbert, 1880); 21%). These species, along with Pacific salmon (genus Oncorhynchus Suckley, 1861) and skate (genus Raja L., 1758), accounted for 80%–90% of the reconstructed biomass and energy contribution, with pollock contributing 37%–60%. Overall, 80% of fish were 14–42 cm long and mainly pelagic, though 40% of scats contained benthic-associated prey. Steller sea lions switched from adult pollock to strong cohorts of juvenile pollock, and took advantage of spawning concentrations of salmon in autumn and herring in late spring and summer, as well as a climate-driven increase in hake availability. Observed temporal and site differences in diet confirm the need for robust long-term scat sampling protocols. All major indices similarly tracked key temporal changes, despite differences in occurrence and biomass-energy-based diet estimates linked to prey size and energy-density effects and the application of correction factors.

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Improvement of Juvenile Pacific Salmon Production in a Regional Ecosystem after the 1998 Climatic Regime Shift

Transactions of the American Fisheries Society ◽

10.1577/t03-170.1 ◽

2004 ◽

Vol 133 (5) ◽

pp. 1163-1175 ◽

Cited By ~ 20

Author(s):

R. J. Beamish ◽

R. M. Sweeting ◽

C. M. Neville

Keyword(s):

Regime Shift ◽

Pacific Salmon ◽

Climatic Regime ◽

Juvenile Pacific Salmon ◽

Salmon Production

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

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

10.47886/9781888569957.ch7 ◽

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 Oncorhynchus 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 O. tshawytscha, coho salmon O. kisutch, chum salmon O. keta, sockeye salmon O. nerka, and pink salmon O. gorbuscha) 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.

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