scholarly journals Homing in Pacific salmon: mechanisms and ecological basis

1996 ◽  
Vol 199 (1) ◽  
pp. 83-91 ◽  
Author(s):  
A Dittman ◽  
T Quinn
Keyword(s):  
Pacific Salmon ◽  
Juvenile Salmon ◽  
Olfactory Recognition ◽  
Seaward Migration ◽  
Natal Habitat ◽  
Ecological Basis ◽  
Feeding Grounds

Pacific salmon (Oncorhynchus spp.) are famous for their homing migrations from oceanic feeding grounds to their natal river to spawn. During these migrations, salmon travel through diverse habitats (e.g. oceans, lakes, rivers), each offering distinct orientation clues and, perhaps, requiring distinct sensory capabilities for navigation. Despite these challenges, homing is generally precise and this philopatry has resulted in reproductively isolated spawning populations with specialized adaptations for their natal habitat. This paper reviews the mechanisms underlying all aspects of salmon homing but emphasizes the final, freshwater phase governed by olfactory recognition of homestream water. Prior to their seaward migration, juvenile salmon learn (imprint on) odors associated with their natal site and later, as adults, use these odor memories for homing. Our understanding of this imprinting process is derived primarily from studies using artificial odorants and hatchery-reared salmon. Recent findings suggest, however, that such studies may underestimate the complexity of the imprinting process in nature.

scholarly journals Evidence for Freshwater Residualism in Coho Salmon, Oncorhynchus kisutch, From a Watershed on the North Coast of British Columbia

2017 ◽  
Vol 130 (4) ◽  
pp. 336 ◽  
Author(s):  
Eric A Parkinson ◽  
Chris J Perrin ◽  
Daniel Ramos-Espinoza ◽  
Eric B Taylor
Keyword(s):  
British Columbia ◽  
Fresh Water ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Kisutch ◽  
Water Levels ◽  
North Coast ◽  
The North ◽  
Seaward Migration ◽  
Mature Fish

The Coho Salmon, Oncorhynchus kisutch, is one of seven species of Pacific salmon and trout native to northeastern Pacific Ocean watersheds. The species is typically anadromous; adults reproduce in fresh water where juveniles reside for 1–2 years before seaward migration after which the majority of growth occurs in the ocean before maturation at 2–4 years old when adults return to fresh water to spawn. Here, we report maturation of Coho Salmon in two freshwater lakes on the north coast of British Columbia apparently without their being to sea. A total of 15 mature fish (11 males and four females) were collected in two lakes across two years. The mature fish were all at least 29 cm in total length and ranged in age from three to five years old. The occurrence of Coho Salmon that have matured in fresh water without first going to sea is exceedingly rare in their natural range, especially for females. Such mature Coho Salmon may represent residual and distinct breeding populations from those in adjacent streams. Alternatively, they may result from the ephemeral restriction in the opportunity to migrate seaward owing to low water levels in the spring when Coho Salmon typically migrate to sea after 1–2 years in fresh water. Regardless of their origin, the ability to mature in fresh water without seaward migration may represent important adaptive life history plasticity in response to variable environments.

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.

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

2007 ◽  
Keyword(s):  
Fish Assemblages ◽  
Pacific Salmon ◽  
California Current ◽  
Minor Component ◽  
Species Group ◽  
Juvenile Salmon ◽  
Species Assemblages ◽  
Coastal Species ◽  
Night And Day ◽  
Associated Species

Abstract.—We compared epipelagic fish assemblages associated with juvenile (ocean-age 0) Pacific salmon <em>Oncorhynchus </em>spp. from neritic waters of the California Current and Alaska Current regions in the spring–summer and summer–fall periods of 2000–2004. Catches originated from rope trawl surveys conducted between latitudes 37°N and 60°N and spanned more than 1,100 km in the coastal and inshore habitats of each region. Catch data were used from the epipelagic sampling of waters from near surface to depths of about 18 m, primarily over the continental shelf. Catch composition, frequency of occurrence, and density were evaluated between regions and habitats for day sampling. Diel (night and day) catch comparisons were also made at a few localities in each region. In day catches from both regions, a total of 1.69 million fish and squid representing 52 fish families and 118 fish species were sampled from 2,390 trawl hauls. Ninety-seven percent of the daytime catch was composed of 11 fish families and squid in coastal and inshore habitats of each region: clupeids dominated catches in the California Current (72% and 76% of catch, respectively), and salmonids dominated catches in the Alaska Current (46% and 62% of catch, respectively). Juveniles comprised 81–99% of salmon sampled in both coastal and inshore habitats of each region. Frequencies of occurrence were highest for juvenile salmon in both regions, but average densities were highest for Pacific herring <em>Clupea pallasii </em>and Pacific sardine <em>Sardinops sagax </em>in the California Current region. Cluster analyses revealed distinct geographic breakpoints in coastal species assemblages off central Vancouver Island and in inshore species assemblages in southeastern Alaska. Species were found to cluster into six groups from coastal localities and four groups from inshore localities. Indicator species analysis and nonmetric multidimensional scaling revealed that most species of juvenile salmonids were located in northern localities. Although juvenile salmon had the most uniform distribution of any species group, their densities relative to associated species were dramatically lower in the California Current, suggesting a higher degree of interactions between juvenile salmon and other species in this region. Diel comparisons in both regions indicated substantially higher catches at night, particularly of clupeids, osmerids, and gadids. Salmonids were a relatively minor component of the night catch in both regions due to dramatic diel shifts in community structure. Additional study of diel interactions of juvenile salmon and associated species is needed to quantify habitat utilization dynamics in marine ecosystems.

Salinity Preference, Thyroid Activity and the Seaward Migration of Four Species of Pacific Salmon (Oncorhynchus)

1960 ◽  
Vol 17 (3) ◽  
pp. 295-322 ◽  
Author(s):  
Bertha Baggerman
Keyword(s):  
Fresh Water ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Salt Water ◽  
Iodine Content ◽  
Day Length ◽  
Thyroid Activity ◽  
Seaward Migration ◽  
Salinity Preference ◽  
External Stimuli

In juvenile Pacific salmon the changes in salinity preference associated with seaward migration and thyroid activity were studied and used as criteria for the induction of the physiological condition required for migration (migration-disposition).Four species of Oncorhynchus (chum, pink, coho and sockeye) changed preference from fresh to salt water at the onset of seaward migration and maintained this preference throughout the migration season. At the end of this migration period coho and sockeye salmon changed preference from salt to fresh water if retained in fresh water, indicating a re-adaptation to this medium in which they may survive for several years. Chum and pink fry did not show this change in preference and usually died when retained in fresh water. They were apparently unable to re-adapt to this environment.The increasing day length in spring controls the time at which the change in preference from fresh to salt water takes place, and is thus involved in timing the induction of migration-disposition.The photoperiod seems to affect particularly the pituitary-thyroid system. Thyroid activity increases shortly before the onset of migration, remains high during the migration season, and decreases towards its end. The level of thyroid hormone in the blood influences salinity tolerance and preference and, thus, the induction of migration-disposition. Metamorphosis, osmotic "stress" and iodine content of the water may have some additional effect on thyroid activity, but are not the only factors responsible for thyroid hyperactivity during migration.Animals in which migration-disposition has been induced are thought to have become susceptible to appropriate external stimuli "releasing" migration.

scholarly journals Associations among Fish Length, Dam Passage History, and Survival to Adulthood in Two At-Risk Species of Pacific Salmon

2019 ◽  
Author(s):  
James R. Faulkner ◽  
Blane L. Bellerud ◽  
Daniel L. Widener ◽  
Richard W. Zabel
Keyword(s):  
At Risk ◽  
River Basin ◽  
Pacific Salmon ◽  
Juvenile Fish ◽  
Fish Length ◽  
Hydroelectric Dams ◽  
Successful Management ◽  
Fish Size ◽  
Seaward Migration ◽  
Pass Through

AbstractThreatened or endangered salmon and steelhead originating in the Snake River basin must pass through a series of eight major hydroelectric dams during their seaward migration. Understanding the effects of specific dam passage routes on lifetime survival for these stocks is essential for successful management. Juvenile fish may pass these dams via three primary routes: 1) spillways; 2) turbines; or 3) juvenile bypass systems, which divert fish away from turbines and route them downstream. Bypass systems may expose fish to trauma, increased stress, or disease. However, numerous studies have indicated that direct survival through bypass systems is comparable to and often higher than that through spillways. Some researchers have suggested that route of dam passage affects mortality in the estuary or ocean, but this is complicated by studies finding fish size affects route of passage. We tested whether passage through bypass systems was associated with probability of adult return after accounting for fish length and other covariates for two species of concern. We also investigated the association between fish length and probability of bypass at dams, and how this relationship could lead to spurious conclusions regarding effects of bypass systems on survival if length was ignored. We found that: 1) larger fish had lower bypass probabilities at 6 of 7 dams; 2) larger fish had higher probability of surviving to adulthood; 3) bypass history had little association with adult return after accounting for length; and 4) simulations indicated spurious effects of bypass on survival may arise when no true bypass effect exists, especially in models without length. Our results suggest that after fish leave the hydropower system, bypass passage history has little effect on mortality. Our findings underscore the importance of accounting for fish size in studies of dam passage or survival.

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.

Models of the effects of marine-derived nutrients on salmon (Oncorhynchus spp.) population dynamics

2010 ◽  
Vol 67 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Milo D. Adkison
Keyword(s):  
Population Dynamics ◽  
Mathematical Models ◽  
Fresh Water ◽  
Growth Rates ◽  
Pacific Salmon ◽  
Food Resources ◽  
Juvenile Salmon ◽  
Management Implications ◽  
Freshwater Habitats ◽  
Stock Recruitment

Pacific salmon ( Oncorhynchus spp.) populations transfer large quantities of nutrients from their marine to their freshwater habitats. These nutrients have been shown to affect salmon populations in fresh water, including increasing basal food resources and elevating juvenile salmon growth rates and condition. The broader effects on recruitment and commercial harvests, however, are not clear. I developed and explored mathematical models of the effects of these nutrients on stock–recruitment relationships and used these models to investigate management implications. Populations strongly dependent on nutrients had lower sustained yields than those not dependent on nutrients. When nutrients strongly affected the stock–recruitment relationship, relatively low harvest rates and high escapement levels were necessary to maintain the population’s productivity. However, in some scenarios, the highest yields were obtained from small, nutrient-depleted populations. In other scenarios, the nutrient dependence had few management implications.

scholarly journals On conducting management-relevant mechanistic science for upriver migrating adult Pacific salmon

2020 ◽  
pp. 35-56
Author(s):  
Steven J. Cooke ◽  
Graham D. Raby ◽  
Nolan N. Bett ◽  
Amy K. Teffer ◽  
Nicholas J. Burnett ◽  
...  
Keyword(s):  
Pacific Salmon ◽  
Warm Water ◽  
Relevant Research ◽  
Conservation Physiology ◽  
Thermal Thresholds ◽  
Coastal Rivers ◽  
Fisheries Interactions ◽  
Feeding Grounds ◽  
Spawning Sites

Pacific salmon undertake iconic homeward migrations where they move from ocean feeding grounds to coastal rivers where they return to natal spawning sites. However, this migration is physiologically challenging as fish have to navigate past predators, nets, hooks, and dams while dealing with variable flows, warm water temperatures, and pathogens. These challenges often interact in synergistic ways that can sometimes lead to migration failure. The conservation physiology toolbox has led to new understanding of how salmon deal with different challenges with a goal of generating management-relevant science. Given the sensitivity of Pacific salmon to warm temperatures, much research has focused on identifying thermal thresholds. In addition, physiology has informed the development of methods for recovering fish that are exhausted from fisheries interactions and for enhancing passage success at fishways. These successes have arisen in part due to the extent to which we partnered with fisheries managers and other stakeholders to ensure that we were conducting relevant research.

Juvenile salmon in estuaries: comparisons between North American Atlantic and Pacific salmon populations

2014 ◽  
Vol 24 (3) ◽  
pp. 713-736 ◽  
Author(s):  
Laurie A. Weitkamp ◽  
Graham Goulette ◽  
James Hawkes ◽  
Michael O’Malley ◽  
Christine Lipsky
Keyword(s):  
North American ◽  
Pacific Salmon ◽  
Juvenile Salmon

Biofilm nutrient limitation, metabolism, and standing crop responses to experimental application of salmon carcass analog in Idaho streams

2014 ◽  
Vol 71 (12) ◽  
pp. 1796-1804 ◽  
Author(s):  
Jonathan D. Ebel ◽  
Amy M. Marcarelli ◽  
Andre E. Kohler
Keyword(s):  
Nutrient Limitation ◽  
Pacific Northwest ◽  
Standing Crop ◽  
Pacific Salmon ◽  
Trophic Levels ◽  
Juvenile Salmon ◽  
Stream Metabolism ◽  
Growth And Survival ◽  
Nutrient Additions ◽  
Salmon Carcass

Dramatic declines of Pacific salmon (Oncorhynchus spp.) populations have decreased delivery of marine-derived material to Pacific Northwest streams where juvenile salmon reside. Managers use artificial nutrient additions to increase juvenile salmon growth and survival and typically assume nutrient-driven increases in biofilm production are an important pathway by which nutrients become available to higher trophic levels. To evaluate how biofilms respond to additions of salmon carcass analog, a pasteurized, processed form of nutrient mitigation materials, we quantified biofilm nutrient limitation, benthic and whole-stream metabolism, and biofilm standing crops before and following experimental additions in tributaries of the Salmon River, Idaho, USA. Biofilm nutrient limitation did not change and standing crop did not increase in response to analog additions at two different levels (low, 30 g·m−2; or high, 150 g·m−2) within 1 month of addition. In contrast, whole-stream and benthic primary productivity and respiration increased in a high-analog treated segment, but did not increase in a low-analog treated segment. Together, our results suggest that metabolism may be a more appropriate tool for assessing the ecosystem effects of nutrient additions than biofilm standing crop or nutrient limitation, which are constrained by a variety of abiotic and biotic factors like hydrology and grazing.

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