Salinity Preference: an Orientation Mechanism in Salmon Migration

1964 ◽  
Vol 21 (5) ◽  
pp. 995-1018 ◽  
Author(s):  
John E. McInerney
Keyword(s):  
Fresh Water ◽  
Pacific Salmon ◽  
Temporal Changes ◽  
Open Ocean ◽  
Salinity Gradients ◽  
Seaward Migration ◽  
Salinity Preference ◽  
Juvenile Pacific Salmon ◽  
Orientation Mechanism ◽  
Seawater Concentration

An examination of the modal salinity preferences of five Pacific salmon species showed the following pattern of temporal changes. The sequence began with a preference for fresh water, then changed gradually, in the direction of increasing seawater concentration. The terminal pattern indicated a preference for water of open ocean concentration. This temporal progression of salinity preference changes was shown to parallel closely the salinity gradients typical of river outflows through which young salmon pass on their way to the ocean. On the basis of this evidence the following orientation mechanism was proposed: that juvenile Pacific salmon are able to use estuarial salinity gradients as one of the directive cues in their seaward migration.

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 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.

scholarly journals Gametogenesis of the Pacific salmon. 3. Comparative analysis of the state of gonads in juvenile Pacific salmon due to fertility formation

2019 ◽  
Vol 323 (4) ◽  
pp. 429-441
Author(s):  
O.V. Zelennikov
Keyword(s):  
Comparative Analysis ◽  
Mitotic Activity ◽  
Fresh Water ◽  
Fish Species ◽  
Germ Cells ◽  
Pacific Salmon ◽  
Juvenile Fish ◽  
Pink Salmon ◽  
The Pacific ◽  
Juvenile Pacific Salmon

The ovarian condition was studied in juveniles of six species of the Pacific salmon of different ages, taken for research at four hatcheries, as well as captured in lakes and rivers in the Sakhalin Province and Kamchatka Territory. The formation of the older generation of germ cells, consisting of previellogenic oocytes, in females of the Pacific salmon ends at the age of 0+, in pink salmon, with a mass of about 0.2–0.3 g, in other species, with a mass of about 1–2 g. In all species, the replenishment of this generation ceases during the habitat of juvenile fish in fresh water. After the formation of the older generation of germ cells is completed and its number reaches a certain level characteristic of each fish species, two oogenesis processes, that are not externally related to each other, continue to be carried out in the ovaries. The first process is the growth of the older generation oocytes, which develop relatively synchronously, varying 1.5–2 times in diameter. The second process is the mitotic reproduction of the gonies, their entry into meiosis, and subsequent resorption at the stage of pachytene and early diplotene. The mitotic activity of the gonies is minimal in females of the pink salmon, and, in fact, it is not detected in the fish caught in the coast. In females of other species, a decrease in both mitotic activity and initiation of new meiotic cycles does not occur during the entire period of their habitat in fresh water.

THE EFFECT OF TSH AND ANTITHYROID SUBSTANCES ON SALINITY PREFERENCE AND THYROID ACTIVITY IN JUVENILE PACIFIC SALMON

1963 ◽  
Vol 41 (2) ◽  
pp. 307-319 ◽  
Author(s):  
Bertha Baggerman
Keyword(s):  
Thyroid Gland ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Secretory Activity ◽  
Conversion Ratio ◽  
Sodium Thiocyanate ◽  
Thyroid Activity ◽  
Salinity Preference ◽  
Juvenile Pacific Salmon

Underyearling coho salmon treated with TSH showed a change from fresh- to saltwater preference, which was correlated with an increase in thyroid activity (as measured by the amount of radioiodine taken up by the gland and the conversion ratio).Under-yearling pink salmon treated with thiourea showed a change from salt-to freshwater preference, which was accompanied by a decrease in thyroid activity. In this species treatment with thiouracil and sodium thiocyanate also induced a change from salt- to freshwater preference.It is concluded that the secretory activity of the thyroid gland is intimately involved in the induction of changes in salinity preference, which, in their turn, are closely associated with the onset and end of the migration season.

THE THYROID GLAND IN RELATION TO THE SEAWARD MIGRATION OF PACIFIC SALMON

1950 ◽  
Vol 28d (3) ◽  
pp. 126-136 ◽  
Author(s):  
William S. Hoar ◽  
G. Mary Bell
Keyword(s):  
Fresh Water ◽  
Chum Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
River Estuary ◽  
Salt Balance ◽  
Thyroid Activity ◽  
Salmon Fry ◽  
Thyroid Glands ◽  
Seaward Migration

Histological examination of the thyroid glands from chum salmon fry taken in the river, estuary, or sea shows the organ to be in a quiescent condition at the time of migration. If, however, this species is retained in fresh water for two or three months the gland becomes extremely hyperplastic. The pink salmon thyroid behaves in essentially the same way as that of the chum, but migrating pink fry taken at great distances from the sea have active glands. The thyroids of yearling coho and sockeye moving into the sea display heightened activity. Thyroid activity is apparently greater in coho migrants taken later in the season from the headwaters of rivers. In part, the heightened thyroid activity seen in these migrating Pacific salmon is probably a spring-time seasonal change. It seems, however, to be more particularly related to the increased metabolic work of osmotic regulation and salt balance in a fish physiologically prepared for life in the sea. In general, this study suggests that the increased thyroid activity seen in young migrating salmonoids is largely due to increased demands for thyroid hormone in the metabolism of a fish no longer completely adjusted physiologically to fresh water.

Assessing estuaries as stopover habitats for juvenile Pacific salmon

2016 ◽  
Vol 559 ◽  
pp. 201-215 ◽  
Author(s):  
JW Moore ◽  
J Gordon ◽  
C Carr-Harris ◽  
AS Gottesfeld ◽  
SM Wilson ◽  
...  
Keyword(s):  
Pacific Salmon ◽  
Juvenile Pacific Salmon

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

2004 ◽  
Vol 133 (5) ◽  
pp. 1163-1175 ◽  
Author(s):  
R. J. Beamish ◽  
R. M. Sweeting ◽  
C. M. Neville
Keyword(s):  
Regime Shift ◽  
Pacific Salmon ◽  
Climatic Regime ◽  
Juvenile Pacific Salmon ◽  
Salmon Production

scholarly journals The Economic Impacts of Humpback Whale Depredation on Hatchery-Released Juvenile Pacific Salmon in Southeast Alaska

2019 ◽  
Vol 11 (1) ◽  
pp. 62-75
Author(s):  
Ellen M. Chenoweth ◽  
Keith R. Criddle
Keyword(s):  
Pacific Salmon ◽  
Economic Impacts ◽  
Humpback Whale ◽  
Southeast Alaska ◽  
Juvenile Pacific Salmon

scholarly journals Response of the Snowy River Estuary to two environmental flows

2015 ◽  
Vol 127 (2) ◽  
pp. 28
Author(s):  
Errol J. McLean ◽  
Jon B. Hinwood
Keyword(s):  
Fresh Water ◽  
Peak Flow ◽  
Environmental Flows ◽  
River Estuary ◽  
Environmental Flow ◽  
River Channel ◽  
Salinity Gradients ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Major River

The Snowy River is a major river in south-eastern Australia, discharging to the Tasman Sea via a barrier estuary, with its entrance constricted by marine sands. Since the construction of the Snowy Mountains Scheme, river flows have not been sufficient to maintain the river channel. A program of environmental flow releases (EFR) is returning water to the river to restore the fluvial reaches and is now trialling flow regimes that may also benefit the estuarine reaches. This paper documents the response of the estuarine segments of the Snowy River to two EFRs; the release in 2010 was designed to scour the upper reaches of the Snowy River while the larger 2011 release was intended to extend the scouring downstream. For each release, the effects on the entrance morphology, tides and salinity through the flow peak and recovery are described. Each EFR caused minor increases in depth and very minor longshore movement of the entrance channel, although each EFR had been preceded by a larger fresh flow that would have scoured the channels. The small increase in fresh water inflow in the 2010 EFR pushed salinity contours seawards and steepened vertical salinity gradients. The larger inflow in the 2011 EFR purged the upper estuary of saltwater. After the peak flow, salinity recovery was rapid in the principal estuarine channels but took weeks where poorly connected wetlands could store fresh flood waters. Critical flows for scouring the entrance and purging salinity are estimated.

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.

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