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.

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.

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.

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.

Pacific Salmon: Ecology and Management of Western Alaska’s Populations

2009 ◽  
Keyword(s):  
Chinook Salmon ◽  
Chum Salmon ◽  
Coho Salmon ◽  
Life Stage ◽  
Early Summer ◽  
Juvenile Salmon ◽  
Ice Melt ◽  
Estuarine Ecology ◽  
Species Abundances ◽  
Salinity Water

<em>Abstract.</em>—In the late 1990s and early 2000s, large declines in numbers of chum salmon <em>Oncorhynchus keta </em>and Chinook salmon <em>O. tshawytscha </em>returning to the Arctic-Yukon-Kuskokwim (AYK) region (Alaska, USA) illuminated the need for an improved understanding of the variables controlling salmon abundance at all life stages. In addressing questions about salmon abundance, large gaps in our knowledge of basic salmon life history and the critical early marine life stage were revealed. In this paper, results from studies conducted on the estuarine ecology of juvenile salmon in western Alaska are summarized and compared, emphasizing timing and distribution during outmigration, environmental conditions, age and growth, feeding, and energy content of salmon smolts. In western Alaska, water temperature dramatically changes with season, ranging from 0°C after ice melt in late spring/early summer to 19°C in July. Juvenile salmon were found in AYK estuaries from early May until August or September, but to date no information is available on their residence duration or survival probability. Chum salmon were the most abundant juvenile salmon reported, ranging in percent catch from <0.1% to 4.7% and most research effort has focused on this species. Abundances of Chinook salmon, sockeye salmon <em>O. nerka</em>, and pink salmon <em>O. gorbuscha </em>varied among estuaries, while coho salmon <em>O. kisutch </em>juveniles were consistently rare, never amounting to more than 0.8% of the catch. Dietary composition of juvenile salmon was highly variable and a shift was commonly reported from epibenthic and neustonic prey in lower salinity water to pelagic prey in higher salinity water. Gaps in the knowledge of AYK salmon estuarine ecology are still evident. For example, data on outmigration patterns and residence timing and duration, rearing conditions and their effect on diet, growth, and survival are often completely lacking or available only for few selected years and sites. Filling gaps in knowledge concerning salmon use and survival in estuarine and near-shore habitats within the AYK region will aid in assessing the relative roles of all habitats (freshwater to marine) in controlling salmon abundance.

Review of the Rate of Growth and Mortality of Pacific Salmon in Salt Water, and Noncatch Mortality Caused by Fishing

1976 ◽  
Vol 33 (7) ◽  
pp. 1483-1524 ◽  
Author(s):  
W. E. Ricker
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Salt Water ◽  
Pink Salmon ◽  
Total Yield ◽  
Coastal Region ◽  
Natural Mortality ◽  
Time Of Year

Mortality (other than landed catch) caused by pelagic gillnetting is estimated to be equal to the catch, for salmon in their penultimate year of life, and equal to about a quarter of the catch for salmon in their final year of life. Mortality caused by trolling for coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) averages about one fish killed (mostly below legal size) for every two that are boated. The natural mortality rate for sockeye salmon (O. nerka) in their final year of life averages about 0.015 per mo and is somewhat more in earlier years of pelagic life; the greater part of natural mortality after the smolt stage occurs during the downstream migration and early months of "coastal" life. For coho and chinook the best natural mortality estimate for the last year of life is 0.013 per mo, and that for pink (O. gorbuscha) and chum (O. keta) is of the same order. Growth rates during the final growing season vary from 0.26 per mo for pink and coho salmon to 0.06 per mo for chinook in their 5th ocean yr. Gains from ceasing to take immature salmon on the high seas range up to 300% of the catch now being taken in that category, while for fish taken in their final year they range up to about 70%, depending on the time of year at which the fishing is done. Gains from transferring existing pelagic net fisheries to the coastal region would be 76% (North American sockeye) and 86% (Asian sockeye) of the weight of fish now caught pelagically. Gains in total yield of existing salmon fisheries (pelagic and coastal) are estimated as 78% for Asian pink salmon and 72% for Asian sockeye. The increase in weight of the total catch from discontinuing ocean trolling for Columbia River chinook salmon and increasing river fishing correspondingly is estimated tentatively as between 63 and 98%.

Thyroid Hormone Content of Eggs and Early Developmental Stages of Five Oncorhynchus Species

1989 ◽  
Vol 46 (12) ◽  
pp. 2140-2145 ◽  
Author(s):  
J. F. Leatherland ◽  
L. Lin ◽  
N. E. Down ◽  
E. M. Donaldson
Keyword(s):  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Chum Salmon ◽  
Developmental Stages ◽  
Coho Salmon ◽  
Pink Salmon ◽  
Detectable Range ◽  
Early Developmental Stages ◽  
Low Levels ◽  
Early Developmental

Measurements were made of thyroxine (T4) and triiodothyronine (T3) levels in the embryos and larvae of five species of the genus Oncorhynchus. Pink salmon (O. gorbuscha) embryos and larvae contained relatively low levels of both T4 and T3 throughout the early developmental stages. Sockeye salmon (O. nerka) had the highest levels of T4, with coho (O. kisutch), chum (O. keta), and chinook salmon (O. tshawytscha) having similar total T4 content. The chinook salmon embryos contained the highest T3 content of the five species studied, pink, sockeye, and chum salmon embryos had relatively low levels, and coho salmon embryos had intermediate levels of T3. In the pink salmon, there was little evidence of significant change in either T4 or T3 during development. In the other four species, the T4 content changed little between fertilization and hatch, but fell thereafter to stabilize at levels close to the lower detectable range of the assay used, except in the sockeye salmon larvae in which the values were considerably higher. The T3 content of chinook and coho salmon changed with development in a manner comparable with that observed for T4, but there was little evidence of a comparable posthatch decline in T3 levels in chum, sockeye, or pink salmon.

scholarly journals Pacific salmon abundance trends and climate change

2011 ◽  
Vol 68 (6) ◽  
pp. 1122-1130 ◽  
Author(s):  
James R. Irvine ◽  
Masa-aki Fukuwaka
Keyword(s):  
Climate Change ◽  
Pacific Ocean ◽  
North Pacific ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
North Pacific Ocean ◽  
Pink Salmon ◽  
The North ◽  
Abundance Trends

Abstract Irvine, J. R., and Fukuwaka, M. 2011. Pacific salmon abundance trends and climate change. – ICES Journal of Marine Science, 68: 1122–1130. Understanding reasons for historical patterns in salmon abundance could help anticipate future climate-related changes. Recent salmon abundance in the northern North Pacific Ocean, as indexed by commercial catches, has been among the highest on record, with no indication of decline; the 2009 catch was the highest to date. Although the North Pacific Ocean continues to produce large quantities of Pacific salmon, temporal abundance patterns vary among species and areas. Currently, pink and chum salmon are very abundant overall and Chinook and coho salmon are less abundant than they were previously, whereas sockeye salmon abundance varies among areas. Analyses confirm climate-related shifts in abundance, associated with reported ecosystem regime shifts in approximately 1947, 1977, and 1989. We found little evidence to support a major shift after 1989. From 1990, generally favourable climate-related marine conditions in the western North Pacific Ocean, as well as expanding hatchery operations and improving hatchery technologies, are increasing abundances of chum and pink salmon. In the eastern North Pacific Ocean, climate-related changes are apparently playing a role in increasing chum and pink salmon abundances and declining numbers of coho and Chinook salmon.

Challenges for Diadromous Fishes in a Dynamic Global Environment

2009 ◽  
Keyword(s):  
Chinook Salmon ◽  
Large Scale ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Commercial Catch ◽  
Atmospheric Processes ◽  
Energy Transfers ◽  
Salmon Production ◽  
The Impact

<em>Abstract</em>.-Pacific salmon <em>Oncorhynchus </em>spp. catches are at historic high levels. It is significant that one of the world's major fisheries for a group of species that dominates the surface waters of the subarctic Pacific is actually very healthy. Natural trends in climate are now recognized to cause large fluctuations in Pacific salmon production, as shown in historical records of catch and recent changes probably have been affected by greenhouse gas induced climate changes. Pink salmon <em>O. gorbuscha </em>and chum salmon <em>O. keta </em>production and catch has increased in the past 30 years and may continue in a similar trend for for the next few decades. Coho salmon <em>O. kisutch </em>and Chinook salmon <em>O. tshawytscha </em>catches have been declining for several decades, particularly at the southern end of their range, and they may continue to decline. In the 1970s, hatcheries were considered to be a method of adding to the wild production of coho and Chinook salmon because the ocean capacity to produce these species was assumed to be underutilized. Large-scale changes in Pacific salmon abundances are linked to changes in large-scale atmospheric processes. These large-scale atmospheric processes are also linked to planetary energy transfers, and there is a decadal scale pattern to these relationships. Pacific salmon production in general is higher in decades of intense Aleutian lows than in periods of weak Aleutian lows. Key to understanding the impact of climate change on Pacific salmon is understanding how the Aleutian low will change. Chinook and coho salmon are minor species in the total commercial catch, but important socially and economically in North America. A wise use of hatcheries may be needed to maintain abundances of these species in future decades.

Proliferative kidney disease and Sphaerospora oncorhynchi in wild-caught salmonids from the Puntledge River system, Vancouver Island, British Columbia

1995 ◽  
Vol 52 (S1) ◽  
pp. 13-17 ◽  
Author(s):  
M.L. Kent ◽  
M. Higgins ◽  
D.J. Whitaker ◽  
H. Yokoyama
Keyword(s):  
British Columbia ◽  
Kidney Disease ◽  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Natural Infection ◽  
Vancouver Island ◽  
Renal Tubules ◽  
Kokanee Salmon ◽  
Proliferative Kidney Disease ◽  
Sexually Mature

Proliferative kidney disease (PKD), caused by the PKX myxosporean, was observed in kokanee salmon (non-anadromous sockeye salmon) (Oncorhynchus nerka) and chinook salmon (O. tshawytscha) collected from the Puntledge River, Vancouver Island, British Columbia in July 1993. This is the first report of a natural infection of PKX in either captive or wild sockeye salmon. All 14 underyearling kokanee salmon and the one underyearling chinook salmon exhibited numerous PKX organisms and associated chronic inflammation in the renal interstitium. Thirty-eight percent of sexually mature kokanee salmon collected in the autumn of 1993 from Comox Lake (which drains into the Puntledge River) were infected with Sphaerospora oncorhynchi, Kent, Whitaker and Margolis, 1993 in the renal tubules, while immature cutthroat trout (O. clarki) and coho salmon (O. kisutch) from the same collection did not exhibit myxosporean spores in the kidney. The kidneys of threespine stickleback (Gasterosteus aculeatus) and prickly sculpin (Cottus asper) collected from the Puntledge River during the summer were all infected with a Myxobilatus sp., but no organisms suggestive of PKX or Sphaerospora were observed. This study further supports the hypothesis that PKX is a developmental stage of S. oncorhynchi, which may sporulate only in sexually mature salmonids.

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

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