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.

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.

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.

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.

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.

scholarly journals Response of the Sea Louse Lepeophtheirus salmonis Infestation Levels on Juvenile Wild Pink, Oncorhynchus gorbuscha, and Chum, O. keta, Salmon to Arrival of Parasitized Wild Adult Pink Salmon

2006 ◽  
Vol 120 (2) ◽  
pp. 199
Author(s):  
Alexandra Morton ◽  
Rob Williams
Keyword(s):  
Chum Salmon ◽  
Pacific Salmon ◽  
Pink Salmon ◽  
Primary Source ◽  
Sea Lice ◽  
Oncorhynchus Gorbuscha ◽  
Oncorhynchus Keta ◽  
Lepeophtheirus Salmonis ◽  
Louse Infestation ◽  
Age Cohorts

Recent recurring infestations of Sea Lice, Lepeophtheirus salmonis, on juvenile Pacific salmon (Oncorhynchus spp.) and subsequent annual declines of these stocks have made it imperative to identify the source of Sea Lice. While several studies now identify farm salmon populations as sources of Sea Louse larvae, it is unclear to what extent wild salmonid hosts also contribute Sea Lice. We measured Sea Louse numbers on adult Pink Salmon (Oncorhynchus gorbuscha) migrating inshore. We also measured Sea Louse numbers on wild juvenile Pink and Chum salmon (Oncorhynchus keta) migrating to sea before the adults returned, and as the two age cohorts mingled. Adult Pink Salmon carried an average of 9.89 (SE 0.90) gravid lice per fish, and thus were capable of infecting the adjacent juveniles. Salinity and temperature remained favourable to Sea Louse reproduction throughout the study. However, all accepted measures of Sea Louse infestation failed to show significant increase on the juvenile salmon, either in overall abundance of Sea Lice or of the initial infective-stage juvenile lice, while the adult wild salmon were present in the study area. This study suggests that even during periods of peak interaction, wild adult salmon are not the primary source of the recent and unprecedented infestations of Sea Lice on juvenile Pacific Pink and Chum salmon in the inshore waters of British Columbia.

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.

The Behaviour of Migrating Pink and Chum Salmon Fry

1956 ◽  
Vol 13 (3) ◽  
pp. 309-325 ◽  
Author(s):  
William S. Hoar
Keyword(s):  
Light Intensity ◽  
Chum Salmon ◽  
Pink Salmon ◽  
Bright Light ◽  
Circular Channel ◽  
Water Currents ◽  
Salmon Fry ◽  
First Time

Pink salmon fry which have never schooled are negatively phototactic, prefer a cover of stones and do not emerge into bright light. Those which have schooled show a strong cover reaction when exposed to a rapid increase in light intensity but do not seek cover unless the change is abrupt. In general they remain in bright light after they have schooled. This change in behaviour occurs rapidly (15 minutes or less) when the fry school for the first time. Chum salmon fry establish a definite direction of swimming in the quiet water of a circular channel or basin. The established direction is stable and not permanently disturbed by light or darkness, by water currents, by strong avoiding reactions, by changing the location or by excluding direct skylight. The direction may be initially established in relation to water currents.

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 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.

Estimation of Functional Responses of Predators on Juvenile Salmon

1978 ◽  
Vol 35 (6) ◽  
pp. 797-808 ◽  
Author(s):  
Randall M. Peterman ◽  
Marino Gatto
Keyword(s):  
Functional Response ◽  
Chum Salmon ◽  
Pink Salmon ◽  
Experimental Studies ◽  
Functional Responses ◽  
Response Curves ◽  
Response Component ◽  
Predation Mortality ◽  
Salmon Fry ◽  
Salmon Population

Several studies have shown that predators can eat large portions (up to 85%) of emerging salmon (Oncorhynchus spp.) fry populations. To understand salmon population dynamics and the effect of salmon enhancement projects, it is necessary to determine how present predation mortality varies with prey density. To predict the shape of this relation outside the range of past observations, we must examine the basic components of the predation process, the functional and numerical responses. A review of past, sparse data on the functional response component shows that predators of salmon fry and smolts were mostly not being saturated (i.e. maximum attack rates were not being achieved) at high prey densities. A method to estimate functional responses from certain types of existing field data is derived and applied to Hooknose Creek pink salmon (O. gorbuscha) and chum salmon (O. keta) information. Results from 7 out of 9 yr corroborate earlier observations that predators are normally operating on the low end of their functional response curves and are therefore capable of causing high mortality on larger prey populations. Also, competition among predators is demonstrated to be significant, resulting in changes in slopes of functional responses. More experimental studies of functional responses are needed, and such research should be carried out in conjunction with perturbations in salmon fry abundance which will result from enhancement projects. Key words: salmon fry, predation, freshwater survival, enhancement, functional response, predator competition

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