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.

Downstream migrations of juvenile Pacific salmon (Oncorhynchus spp.) in a glacial transboundary river

1997 ◽  
Vol 54 (12) ◽  
pp. 2837-2846 ◽  
Author(s):  
Michael L Murphy ◽  
K V Koski ◽  
J Mitchel Lorenz ◽  
John F Thedinga
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Transboundary Rivers ◽  
Delayed Entry ◽  
Transboundary River ◽  
Spawning Areas ◽  
Seventh Order ◽  
Juvenile Pacific Salmon

Migrations of juvenile Pacific salmon (Oncorhynchus spp.) in the glacial Taku River (seventh order) were studied to assess movement from upriver spawning areas (in British Columbia) into lower-river rearing areas (in Alaska). Differences between fyke-net catches in the river and seine catches in the river's estuary indicated that many downstream migrants remained in the lower river instead of migrating to sea. In particular, age-0 coho salmon (O. kisutch) and chinook salmon (O. tshawytscha) moved downriver from May to November but were not caught in the estuary. Age-0 sockeye salmon (O. nerka), coho presmolts, and other groups delayed entry into the estuary after moving downriver. We tagged groups of juvenile coho (ages 0-2) from the fyke net with coded-wire to determine when they left the river. One-third of all tags recovered from sport and commercial fisheries occurred 2-3 years later, showing that many coho remained in fresh water for 1-2 years after moving to the lower river. Lower-river areas of large glacial rivers like the Taku River can provide essential rearing habitat for juvenile salmon spawned upriver and are important to consider in integrated whole-river management of transboundary rivers.

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

2007 ◽  
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pink Salmon ◽  
Gulf Of Alaska ◽  
Vancouver Island ◽  
Early Summer ◽  
Juvenile Salmon ◽  
Central California ◽  
Bottom Depth

Abstract.—In this chapter, we describe the distributions and abundances of juvenile Chinook salmon <em>Oncorhynchus tshawytscha</em>, coho salmon <em>O. kisutch</em>, chum salmon <em>O. keta</em>, pink salmon <em>O. gorbuscha</em>, and sockeye salmon <em>O. nerka </em>in six regions along the west coast of North America from central California to the northern Gulf of Alaska during the early summer (June and July) and late summer–fall (August– November) of 2000, 2002, and 2004. We also describe fish abundance in relation to bottom depth and to the average temperature and salinity of the upper water column. Salmon were collected in rope trawls from the upper 15–20 m over the open coastal shelf. Catch per unit effort was standardized across the different regions. Subyearling Chinook salmon were found only from central California to British Columbia. Yearling Chinook salmon were widespread, but were most abundant between Oregon and Vancouver Island. Juvenile coho salmon were widespread from northern California to the northern Gulf of Alaska, whereas chum, sockeye, and pink salmon were only abundant from Vancouver Island north into the Gulf of Alaska. Generally, the juveniles of the different salmon species were most abundant at, or north of, the latitudes at which the adults spawn. Abundances were particularly high near major exit corridors for fish migrating from freshwater or protected marine waters onto the open shelf. Seasonal latitudinal shifts in abundance of the juvenile salmon were generally consistent with the counterclockwise migration model of Hartt and Dell (1986). Subyearling Chinook salmon were associated with the high salinity environment found off California and Oregon, whereas chum, sockeye, and pink salmon were associated with the lower salinity environment in the Gulf of Alaska. However, within regions, evidence for strong temperature or salinity preferences among the different species was lacking. Subyearling Chinook salmon were most abundant in shallow, nearshore water.

Protandry in Pacific salmon

2000 ◽  
Vol 57 (6) ◽  
pp. 1252-1257 ◽  
Author(s):  
Yolanda Morbey
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Statistical Procedure ◽  
Timing Data ◽  
Mating Opportunities ◽  
Gender Specific ◽  
Specific Timing

Protandry, the earlier arrival of males to the spawning grounds than females, has been reported in several studies of Pacific salmon (Oncorhynchus spp.). However, the reasons for protandry in salmon are poorly understood and little is known about how protandry varies among and within populations. In this study, protandry was quantified in a total of 105 years using gender-specific timing data from seven populations (one for pink salmon (O. gorbuscha), three for coho salmon (O. kisutch), two for sockeye salmon (O. nerka), and one for chinook salmon (O. tshawytscha)). Using a novel statistical procedure, protandry was found to be significant in 90% of the years and in all populations. Protandry may be part of the males' strategy to maximize mating opportunities and may facilitate mate choice by females.

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.

Changes in the Average Size and Average Age of Pacific Salmon

1981 ◽  
Vol 38 (12) ◽  
pp. 1636-1656 ◽  
Author(s):  
W. E. Ricker
Keyword(s):  
Growth Rate ◽  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Gill Nets ◽  
Growing Seasons ◽  
Mean Size ◽  
Average Size

Of the five species of Pacific salmon in British Columbia, chinook salmon (Oncorhynchus tshawytscha) and coho salmon (O. kisutch) are harvested during their growing seasons, while pink salmon (O. gorbuscha), chum salmon (O. keta), and sockeye salmon (O. nerka) are taken only after practically all of their growth is completed. The size of the fish caught, of all species, has decreased, but to different degrees and over different time periods, and for the most part this results from a size decrease in the population. These decreases do not exhibit significant correlations with available ocean temperature or salinity series, except that for sockeye lower temperature is associated with larger size. Chinook salmon have decreased greatly in both size and age since the 1920s, most importantly because nonmaturing individuals are taken by the troll fishery; hence individuals that mature at older ages are harvested more intensively, which decreases the percentage of older ones available both directly and cumulatively because the spawners include an excess of younger fish. Other species have decreased in size principally since 1950, when the change to payment by the pound rather than by the piece made it profitable for the gill-netters to harvest more of the larger fish. Cohos and pinks exhibit the greatest decreases, these being almost entirely a cumulative genetic effect caused by commercial trolls and gill nets removing fish of larger than average size. However, cohos reared in the Strait of Georgia have not decreased in size, possibly because sport trolling has different selection characteristics or because of the increase in the hatchery-reared component of the catch. The mean size of chum and sockeye salmon caught has changed much less than that of the other species. Chums have the additional peculiarity that gill nets tend to take smaller individuals than seines do and that their mean age has increased, at least between 1957 and 1972. That overall mean size has nevertheless decreased somewhat may be related to the fact that younger-maturing individuals grow much faster than older-maturing ones; hence excess removal of the smaller younger fish tends to depress growth rate. Among sockeye the decrease in size has apparently been retarded by an increase in growth rate related to the gradual cooling of the ocean since 1940. However, selection has had two important effects: an increase in the percentage of age-3 "jacks" in some stocks, these being little harvested, and an increase in the difference in size between sockeye having three and four ocean growing seasons, respectively.Key words: Pacific salmon, age changes, size changes, fishery, environment, selection, heritability

Homing behavior and vertical movements of four species of Pacific salmon (Oncorhynchus spp.) in the central Bering Sea

1995 ◽  
Vol 52 (3) ◽  
pp. 532-540 ◽  
Author(s):  
Miki Ogura ◽  
Yukimasa Ishida
Keyword(s):  
Chinook Salmon ◽  
Bering Sea ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Depth Sensing ◽  
Compass Orientation ◽  
Homing Behavior ◽  
Vertical Movements ◽  
Strong Surface

Four sockeye salmon (Oncorhynchus nerka), two chum salmon (O. keta), three pink salmon (O. gorbuscha), and four Chinook salmon (O. tshawytscha) with depth-sensing ultrasonic transmitters were tracked in the central Bering Sea to examine migration in the open sea. Ground speeds of maturing sockeye, chum, and pink salmon were at 0.54–0.66 m/s (0.88–1.17 fork lengths/s). Chinook salmon, probably immature fish, moved more slowly (0.34 m/s). Maturing individuals moved in particular directions and maintained their ground speeds and directions during day and night. The results also suggested that salmon had a compass orientation ability functioning without celestial information. Sockeye, chum, and pink salmon showed strong surface preferences but chinook salmon swam deeper (30–35 m) than did the other species.

Effect of incubation temperature on the development of five species of Pacific salmon (Oncorhynchus) embryos and alevins

1988 ◽  
Vol 66 (1) ◽  
pp. 266-273 ◽  
Author(s):  
C. B. Murray ◽  
J. D. McPhail
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Incubation Temperature ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Oncorhynchus Gorbuscha ◽  
Embryo Survival ◽  
Salmon Fry ◽  
Incubation Temperatures

Embryo and alevin survival, time to hatching and emergence, and alevin and fry size of five species of Pacific salmon (Oncorhynchus) were observed at five incubation temperatures (2, 5, 8, 11, and 14 °C). No pink (Oncorhynchus gorbuscha) or chum (O. keta) salmon embryos survived to hatching at 2 °C. Coho (O. kisutch) and sockeye (O. nerka) salmon had higher embryo survival at 2 °C than chinook (O. tschawytscha) salmon. At 14 °C, chum, pink, and chinook salmon had higher embryo survival than coho or sockeye salmon. In all species, peaks of embryo mortality occurred at specific developmental stages (completion of epiboly, eye pigmentation, and hatching). Alevin survival to emergence was high for all species, except for coho and pink salmon at 14 °C. Hatching and emergence time varied inversely with incubation temperature, but coho salmon hatched and emerged sooner at all temperatures than the other species. Coho and sockeye salmon alevins were larger at 2 °C, pink, chum, and chinook salmon alevins were larger at 5 and 8 °C. Coho salmon fry were larger at 2 °C, chinook and chum salmon fry were larger at 5 °C, and sockeye and pink salmon fry were larger at 8 °C. High incubation temperatures reduced fry size in all species. Each species of Pacific salmon appears to be adapted to different spawning times and temperatures, and thus indirectly to specific incubation temperatures, to ensure maximum survival and size and to maintain emergence at the most favorable time each year.

Dispersion of common merganser (Mergus merganser) breeding pairs in relation to the availability of juvenile Pacific salmon in Vancouver Island streams

1986 ◽  
Vol 64 (3) ◽  
pp. 756-765 ◽  
Author(s):  
C. C. Wood
Keyword(s):  
Pacific Salmon ◽  
Prey Availability ◽  
Vancouver Island ◽  
Egg Laying ◽  
Breeding Pair ◽  
Juvenile Salmon ◽  
Mergus Merganser ◽  
Juvenile Pacific Salmon ◽  
Stream Size ◽  
Common Merganser

Common merganser (Mergus merganser) breeding pairs and broods were censused on eight coastal streams on Vancouver Island to evaluate the relative importance of the number of potential breeding pairs, stream size, and the availability of juvenile Pacific salmon in limiting merganser breeding density. The number of potential breeding pairs did not limit nesting density on at least one stream where juvenile salmon populations were enhanced by a hatchery and spawning channel. At distances > 1 km above tidal influence, breeding pairs were evenly dispersed along the streams during the peak egg-laying and incubation period at maximum densities of 0.4–1.4 pairs/km. Maximum breeding pair counts were higher and more variable among streams on the lower kilometer of freshwater (1–9 pairs) and on tidal waters near the stream outlets (4–9 pairs). Stream size accounted for only a part of the variation in breeding pair counts. The estimated number of broods produced on each stream was highly correlated (r = 0.95) with both drainage area and juvenile salmon production, including production from hatcheries. Possible mechanisms relating the dispersion of breeding pairs to the availability of juvenile salmon are discussed. A "food assessment" hypothesis, whereby breeding pairs choose a nesting stream on the basis of prey availability during the nesting season, could not be rejected on the basis of predictions about hatching dates and duckling survival. This hypothesis has serious implications for mortality of wild salmonids in hatchery-enhanced streams.

The Behaviour of Juvenile Pacific Salmon, with Particular Reference to the Sockeye (Oncorhynchus nerka)

1954 ◽  
Vol 11 (1) ◽  
pp. 69-97 ◽  
Author(s):  
William S. Hoar
Keyword(s):  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Shallow Waters ◽  
Moderate Activity ◽  
Strong Response ◽  
Marked Preference ◽  
Juvenile Pacific Salmon ◽  
Experimental Findings ◽  
Persistent Response

Behaviour patterns of juvenile sockeye salmon in fresh water are compared with those of chum and coho salmon. Both sockeye and chum fry are schooling fish, responding positively to currents and avoiding shallow waters. Of the two species, chums, however, form more active schools, travel more rapidly, have a less marked cover reaction and prefer stronger light and shallower water. Sockeye smolts, in contrast to coho smolts, are more active, show little thigmotactic and territorial behaviour and a more persistent response to current. The experimental findings are discussed in relation to the migratory behaviour of these fish. It is suggested that sockeye fry, emerging from cover as the light intensity falls are displaced downstream after dark. Moderate activity and a marked preference for deep water are mechanisms postulated for continued residence of sockeye fry in lakes. Further it is suggested that the smolt exodus is due to heightened general activity, both day and night, associated with strong response to current. This brings sockeye smolts into the outflow from the lake where they hold position during the day but are displaced down the river after dark. Coho smolts, responding less vigorously to currents and maintaining a measure of contact with specific objects in their environment, move seaward more slowly than sockeye.

Levels of Constituents of Glycoproteins in the Sera of Pacific Salmon

1971 ◽  
Vol 28 (8) ◽  
pp. 1173-1179 ◽  
Author(s):  
M. D. Qureshi ◽  
R. V. Hledin ◽  
P. A. Anastassiadis ◽  
W. E. Vanstone
Keyword(s):  
Sialic Acid ◽  
Protein Content ◽  
Chinook Salmon ◽  
Bovine Serum ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Limited Extent ◽  
Carbohydrate Complex

The levels of hexosamine, sialic acid, fucose, and protein in serum of sockeye salmon (Oncorhynchus nerka) and, to a limited extent, in sera of coho salmon (O. kisutch) and chinook salmon (O. tshawytscha) at two reproductive stages, were determined. Hexosamine, sialic acid, fucose, hexose, seromucoid, and protein content of sexually maturing (early) and mature (spawning) sockeye salmon were studied and a comparison was attempted with the corresponding composition of bovine serum. Content of the above serum constituents was lower in spawning than in maturing populations. Protein content was much less, hexosamine a little less, and sialic acid higher, in the sera of sockeye salmon than in bovine serum. The protein–carbohydrate complex of serum appeared to contain more hexosamine and much more sialic acid than the protein–carbohydrate complex of bovine serum. Furthermore, the sialic acid-to-hexosamine ratio was much higher in sera of salmon than in bovine serum. Some other sex and reproductive stage differences were detected and reported.

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