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.

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.

Behavioral Ecology of Chum Salmon Fry (Oncorhynchus keta) in a Small Estuary

1974 ◽  
Vol 31 (1) ◽  
pp. 83-92 ◽  
Author(s):  
J. C. Mason
Keyword(s):  
Fresh Water ◽  
Behavioral Ecology ◽  
Chum Salmon ◽  
Oncorhynchus Keta ◽  
Natural Systems ◽  
Active Selection ◽  
Resource Managers ◽  
Salmon Fry ◽  
Seaward Migration ◽  
And Behavior

Chum salmon fry (Oncorhynchus keta) in the estuary of a small coastal stream exploited fresh water, estuarine, and marine food chains and, by so doing, were exposed to marked, daily fluctuations in salinity that demanded active selection of fresh water on ebbing tides day and night. The resulting delay in seaward migration and associated behavioral observations are inadequately reflected in published accounts of the life history and behavior of chum fry in natural systems and laboratory situations, and the downstream displacement theory. The biological basis for delayed seaward migration of chum fry merits the attention of fishery researchers and resource managers alike.

Reactions of Juvenile Pacific Salmon to Light

1957 ◽  
Vol 14 (6) ◽  
pp. 815-830 ◽  
Author(s):  
W. S. Hoar ◽  
M. H. A. Keenleyside ◽  
R. G. Goodall
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Low Light ◽  
Salmon Fry ◽  
Experimental Apparatus ◽  
Schooling Behaviour ◽  
Marked Preference ◽  
Juvenile Pacific Salmon ◽  
Changing Light

When given a choice between light and dark areas, schools of chum or pink salmon fry remain in the light, sockeye fry prefer the dark and coho fry show no marked preference for either. Newly emerged sockeye fry are the most strongly photonegative, remaining mostly under stones. Older sockeye fry move more into the light. Sockeye and coho smolts stay in the dark more than sockeye and coho underyearlings. Territorial and "escape" behaviour by fish in the experimental apparatus may obscure these reactions to light. Soon after emerging from the gravel, pink fry swim near the surface under low light intensity and retreat to deeper water in brighter light. Older pink fry seem indifferent to changing light. Recently emerged chum salmon fry do not respond in this way to changing illumination, although older fry tend to swim closer to the surface. This difference between pink and chum salmon fry may be related to differences in schooling behaviour and alarm responses of the two species.

The Behaviour of Chum, Pink and Coho Salmon in Relation to their Seaward Migration

1951 ◽  
Vol 8b (4) ◽  
pp. 241-263 ◽  
Author(s):  
William S. Hoar
Keyword(s):  
Fresh Water ◽  
Coho Salmon ◽  
Pink Salmon ◽  
Water Levels ◽  
Salmon Fry ◽  
Seaward Migration ◽  
Active Swimming ◽  
Increased Activity ◽  
Downstream Movement ◽  
Marked Tendency

In fresh water, chum and pink salmon fry form schools or mills, are constantly active both day and night, show positive rheotaxis and move into fast water. This activity takes them into the swiftest currents. At night loss of visual and contact stimuli reduces the intensity of the rheotactic response and results in downstream movement. An active swimming downstream occurs only with unusually high temperatures. Coho salmon fry occupy and defend territory, maintain definite positions in relation to particular objects in their environment, show a less marked tendency to move into fast water and are quiet at night. They are thus displaced downstream to a much lesser degree. Coho smolts, in contrast to the fry, demonstrate a lowered threshold for stimulation both day and night, a tendency to aggregate and a lessening in territory behaviour. During the day smolts group in deeper water or under cover. At night they rise to the surface and manifest increased activity which, in swift water, will result in displacement seaward. Pronounced changes in temperature modify these reactions. Sudden elevation of water levels hastens the downstream displacement.

Notes on the Seaward Migration of Pink and Chum Salmon Fry

1955 ◽  
Vol 12 (3) ◽  
pp. 369-374 ◽  
Author(s):  
Ferris Neave
Keyword(s):  
Vertical Distribution ◽  
Chum Salmon ◽  
Pink Salmon ◽  
Strong Light ◽  
Salmon Fry ◽  
Seaward Migration ◽  
Schooling Behaviour ◽  
And Migration ◽  
A Current ◽  
Downstream Movement

The seaward migration of pink and chum salmon fry takes place at night. Strong light is avoided. In pink salmon negative rheotaxis (swimming with a current) is strongly developed and migration is not primarily effected by random swimming and passive displacement. Downstream movement is mainly at or close to the surface. In slack water vertical distribution is more uniform. In the shortest streams examined, each night's migrants appeared to reach the sea before daybreak. In a longer stream, fry were seen to bury themselves at the onset of daylight. After being held in fresh water for an undetermined period, fry show positive rheotaxis and schooling behaviour and no longer avoid light. Behaviour of fry after reaching the sea also differs from that shown during actual migration. Changes in behaviour may coincide with commencement of feeding.

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 Resources and fishery of Pacific salmon in Magadan region in the beginning of the 21st century

Trudy VNIRO ◽  
2020 ◽  
Vol 179 ◽  
pp. 90-102
Author(s):  
M. N. Gorokhov ◽  
V. V. Volobuev ◽  
I. S. Golovanov
Keyword(s):  
Chum Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Spawning Grounds ◽  
Magadan Region ◽  
Spawning Areas ◽  
Optimal Values ◽  
In The Beginning ◽  
Salmon Fishery

There are two main areas of pacific salmon fishing in the Magadan region: Shelikhova Gulf and Tauiskaya Bay. The main fishing species is pink salmon in the region. Its share of total salmon catch by odd-year returns reaches 85 %. Data on the dynamics of escapement to the spawning grounds of pink salmon of the Shelikhova Gulf and Tauiskaya Bay are presented. The displacement of the level of spawning returns of pink salmon into the Shelihova Gulf with the simultaneous reduction of its returns to the Tauiskaya Bay is shown. Data on the dynamics of the fishing indicators of pink salmon for the two main fishing areas are provided. The Tauiskaya Bay as the main pink salmon fishery area loses its importance is shown. Graphical data on the escapement of producers pink salmon to the spawning grounds are presented and the optimal values of spawning escapements are estimated. Chum salmon is the second largest and most fishing species. Information on the dynamics of the number of returns, catch and escapement to the spawning grounds of chum salmon is given. The indicators of escapement to the spawning areas and their compliance with the optimal passes of salmon producers are analyzed. The issues of the dynamics of returns number, catch and the escapement to the spawning grounds of coho salmon producers are considered. The level of the escapement to the spawning areas is shown and the ratio of actual to optimal values of passes is estimated. The role of coho salmon as an object of industrial fishing and amateur fishing is shown. The extent of fishing press on individual groups of salmon populations is discussed. It is concluded that it is necessary to remove the main salmon fishery from the Tauiskaya Bay to the Shelikhova Gulf.

Toxicity and Avoidance Tests with Prudhoe Bay Oil and Pink Salmon Fry

1973 ◽  
Vol 1973 (1) ◽  
pp. 667-670 ◽  
Author(s):  
Stanley D. Rice
Keyword(s):  
Fresh Water ◽  
Oil Pollution ◽  
Pink Salmon ◽  
Marine Resources ◽  
Migration Behavior ◽  
Salmon Fry ◽  
Avoidance Tests ◽  
Oil Toxicity ◽  
National Marine Fisheries Service ◽  
Prudhoe Bay

ABSTRACT With the potential of oil pollution harming Alaska's marine resources, experiments were conducted at the National Marine Fisheries Service, Auke Bay Fisheries Laboratory to determine the concentrations of Prudhoe Bay crude oil that are acutely toxic to pink salmon fry in fresh water and seawater and also the concentrations of this oil that the fry would avoid. Observed 96-hour TLM values were 88 mg of oil/liter of water in fresh water and 213 mg/liter in seawater in June and 110 mg/liter in seawater in August. Among fry held in seawater, older fry were more susceptible to oil toxicity than younger fry and older fry were also more sensitive in their detection and avoidance of oil; older fry in seawater avoided oil concentrations as low as 1.6 mg of oil/liter of water. The avoidance of oil by salmon fry was quite apparent and suggests that there is potential for oil pollution to change their migration behavior.

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.

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