Transmission of Myxobolus arcticus Pugachev and Khokhlov, 1979, a myxosporean parasite of Pacific salmon, via a triactinomyxon from the aquatic oligochaete Stylodrilus heringianus (Lumbriculidae)

1993 ◽  
Vol 71 (6) ◽  
pp. 1207-1211 ◽  
Author(s):  
M. L. Kent ◽  
D. J. Whitaker ◽  
L. Margolis
Keyword(s):  
Life Cycle ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Well Water ◽  
Experimental Fish ◽  
Salmon Fry ◽  
Myxosporean Parasite ◽  
Transmission Studies ◽  
The Brain

Laboratory transmission studies were conducted on Myxobolus arcticus, a myxosporean that infects the brain of Pacific salmon (Oncorhynchus spp.). Attempts at transmission from fish to fish with spores of M. arcticus from sockeye salmon (Oncorhynchus nerka), including experiments with spores aged for up to 9 months in sterilized mud, were unsuccessful. Transmission was achieved when hatchery-reared (in well water) sockeye salmon fry were exposed to the oligochaete Stylodrilus heringianus collected from a lake where M. arcticus infections are common in this fish. All experimental fish exhibited the infection when examined 3 –4 months after exposure. Of 23 sockeye salmon fry exposed to triactinomyxon spores collected from naturally infected S. heringianus, 21 were found to be infected with M. arcticus spores when examined after 3 months. Thus, the life cycle of M. arcticus involves transformation into a triactinomyxon stage in S. heringianus. Alternate development of myxosporeans in aquatic oligochaetes has been established or implicated for nine other species of myxosporeans belonging to three families, but this is the first report of alternate development in a lumbriculid worm.

CHANGES IN THE MULTIPLE HEMOGLOBIN PATTERNS OF SOME PACIFIC SALMON, GENUS ONCORHYNCHUS, DURING THE PARR–SMOLT TRANSFORMATION

1964 ◽  
Vol 42 (6) ◽  
pp. 697-703 ◽  
Author(s):  
W. E. Vanstone ◽  
Eve Roberts ◽  
H. Tsuyuki
Keyword(s):  
Life Cycle ◽  
Gel Electrophoresis ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Starch Gel Electrophoresis ◽  
Mature Adults ◽  
Salmon Fry ◽  
Starch Gel ◽  
Sexually Mature

By employing starch gel electrophoresis it has been found that coho salmon fry and smolts contain 10 anodal-migrating, and 12 cathodal-migrating, hemoglobin fractions. Prepuberal [Formula: see text]-year-old coho salmon caught at sea and sexually mature adults taken from fresh water contained the same anodal fractions and at approximately the same concentrations as were found in fry and smolts. However, the concentrations of the cathodal fractions had increased so that these were very nearly equal to those of the anodal fractions. Similar hemoglobin changes were found in both anadromous and land-locked sockeye salmon, but in this species seven anodal and six cathodal fractions were present at their "adult" concentrations in fry and smolts. Six other cathodal fractions which were absent entirely or present only in trace amounts in fry and smolts increased to their adult concentrations some time later in the life cycle of both varieties of sockeye. It is postulated that these changes reflect an ecological adaption to life in the ocean.

Effects of Androgens, Estrogens, and Cortisol on the Skin, Stomach, Liver, Pancreas, and Kidney in Gonadectomized Adult Sockeye Salmon (Oncorhynchus nerka)

1971 ◽  
Vol 28 (4) ◽  
pp. 485-490 ◽  
Author(s):  
J. R. McBride ◽  
A. P. van Overbeeke
Keyword(s):  
Islets Of Langerhans ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Skin Atrophy ◽  
Histological Changes ◽  
Male And Female ◽  
Liver And Kidney ◽  
Marked Atrophy

A study was made of the histological changes occurring in the skin, stomach, liver, pancreas and kidney of adult gonadectomized male and female sockeye salmon in response to hormone treatments. The males received 11-ketotestosterone, 17α-methyltestosterone or cortisol for 4 or 7 weeks, and the females received estradiol, estradiol cypionate, or cortisol for 8 weeks.In the males, androgen injection evoked a highly significant increase in the thickness of the epidermis, a marked atrophy of the stomach, and a degeneration in the liver and kidney. In the pancreas, the exocrine portion showed characteristics of cytolysis in the acini, whereas the islets of Langerhans were hypertrophied. These changes were generally more pronounced after 7 weeks than after 4 but, in the skin, no further increase in the thickening of the epidermis was noted after the 4th week of treatment. No differences between responses of these tissues to 11-ketotestosterone and 17α-methyltestosterosne were detected.Estrogen administration in the females evoked similar, albeit weaker, responses in the skin, stomach, pancreas, and kidney than those recorded in the androgen-treated males. The liver of the females exhibited the characteristics of a hyperactive organ, which probably reflects estrogen-induced vitellogenesis.The effects of cortisol were similar in both sexes: little, if any, change was noted in the skin; atrophy or degeneration was observed in the stomach, liver, kidney, and in the exocrine portion of the pancreas, and the islets of Langerhans were hypertrophied. The cortisol-induced alterations were not, however, as pronounced as those noted in either the androgen- or estrogen-treated fish.These changes are discussed in relation to the changes observed in normal sexually maturing and reproducing Pacific salmon.

Daily Growth Rings in the Otoliths of Juvenile Sockeye Salmon (Oncorhynchus nerka)

1980 ◽  
Vol 37 (10) ◽  
pp. 1495-1498 ◽  
Author(s):  
K. H. Wilson ◽  
P. A. Larkin
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Growth Rings ◽  
Daily Growth ◽  
Salmon Fry

Sockeye salmon fry were collected from the Fulton River spawning channel at Babine Lake, British Columbia, in May 1978. The fish were reared for 26 d in enclosures in the spawning channel and were sampled every 7 to 10 d. The sagittae were removed from 25 fish from each sample, and the growth rings in one otolith from each fish were counted. A regression of the number of rings on the number of days since capture showed that these rings are, on average, formed daily, beginning at the time of emergence. A number of possible technical and biological causes of variation in ring counts within and between samples are considered.Key words: otolith, sagittae, daily growth rings, sockeye salmon fry

Quantifying cutthroat trout (Oncorhynchus clarki) predation on sockeye salmon (Oncorhynchus nerka) fry using a bioenergetics approach

1998 ◽  
Vol 55 (5) ◽  
pp. 1285-1295 ◽  
Author(s):  
Margaret A Cartwright ◽  
David A Beauchamp ◽  
Mason D Bryant
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Cutthroat Trout ◽  
Oncorhynchus Clarki ◽  
Field Sampling ◽  
Total Consumption ◽  
Model Simulations ◽  
Salmon Fry ◽  
Survey Results ◽  
Hydroacoustic Survey

Although some sockeye salmon (Oncorhynchus nerka) enhancement programs achieve production goals in Alaskan lakes, others like the Margaret Lake project fall well below expected levels. We used bioenergetics model simulations, coupled with field sampling of predator diet and distribution, to quantify the intensity of cutthroat trout (Oncorhynchus clarki) predation on stocked sockeye salmon fry in Margaret Lake during 1993 and 1994. Model results indicated that, by September, cutthroat trout consumed an estimated 34-51 and 32-100% of the 200 000 and 100 000 sockeye salmon fry stocked in May 1993 and 1994, respectively. September hydroacoustic survey results estimated a 82-87% decline of fry in 1993 and 90-93% in 1994. Stomach fullness and evacuation estimates of total consumption were 59% of model estimates after the first fry release in 1994 and 120% of the model estimates after the second release. All approaches to estimating cutthroat trout predation on stocked fry suggested that piscivores played a substantial role in the decline of sockeye salmon fry in Margaret Lake. The ability to estimate consumption is valuable in isolating predator influence on food web dynamics, especially in manipulated systems.

A hierarchical model for salmon run reconstruction and application to the Bristol Bay sockeye salmon (Oncorhynchus nerka) fishery

2006 ◽  
Vol 63 (7) ◽  
pp. 1564-1577 ◽  
Author(s):  
Lucy Flynn ◽  
André E Punt ◽  
Ray Hilborn
Keyword(s):  
Hierarchical Structure ◽  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Model Development ◽  
Bristol Bay ◽  
Process Error ◽  
The Hierarchical Structure ◽  
River Test ◽  
Run Timing

The goal of spreading the annual catch of a Pacific salmon (Oncorhynchus spp.) run proportionally across all segments of the migration is rendered difficult or impossible because of the interannual variability in both run size and run timing. This problem is particularly acute in the case of the fishery for sockeye salmon (Oncorhynchus nerka) in Bristol Bay, Alaska, for which traditional run reconstruction models are not applicable because of the extreme temporal compression of the run. We develop a run reconstruction model appropriate for sockeye salmon in Bristol Bay by accounting for the hierarchical structure of the problem and by including process error. Our results indicate that the hierarchical structure is, in fact, not necessary, whereas the process error parameters are needed to fit the data. We suggest further model development without the hierarchical structure, including incorporating in-river test fishing data. The results of our method can be used to address questions regarding environmental or intrinsic drivers of run timing and the possibility of artificial selection on run timing.

Behaviour and Ecology of Sockeye Salmon Fry in the Babine River

1967 ◽  
Vol 24 (2) ◽  
pp. 375-428 ◽  
Author(s):  
P. McCart
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Diel Pattern ◽  
Low Velocity ◽  
Migrant Populations ◽  
Salmon Fry

In the Upper and Lower Babine rivers the fry of sockeye salmon (Oncorhynchus nerka) emerge and move downstream, predominately at night, before reaching low-velocity areas along the stream margins. After a period of days or weeks these fry migrate upstream, close inshore, during the day. The diel pattern of upstream movement appears to be bimodal. The seasonal periodicities of both downstream and upstream movement are related to water temperatures.Upstream migrants were larger than downstream migrants in the Upper Babine River but not in the Lower Babine River. Upper River upstream migrants were similar in length to Lower River upstream migrants during 1964 but not in 1965. In both years Upper River fry weighed proportionately more than Lower River fry, and in both rivers 1964 fry weighed proportionately less than 1965 fry. Some possible explanations of these observations are discussed.Early in the season, fry tend to disperse alongshore after entering the lake. Later they leave these inshore areas and become entirely pelagic.The principal foods of fry both in the river and in the lake were copepod and cladoceran plankters.Both fish and birds were found to be preying on sockeye salmon fry. Fry appear to be more vulnerable to predation in the river than in the lake.The upstream movement of fry in the Babine River does not appear to differ appreciably from upstream movements in other areas. A comparison of fry movements in the Babine River and the Fulton River, where fry move only downstream, suggests that the differences in behaviour are genetically rather than environmentally induced.It is suggested that, because of high mortalities in the prepelagic period, upstream-migrant populations will only develop where the environment of both the river and the rearing lake are especially favourable.

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.

Factors Affecting Rainbow Trout (Salmo gairdneri) Predation on Migrant Fry of Sockeye Salmon (Oncorhynchus nerka)

1976 ◽  
Vol 33 (1) ◽  
pp. 19-24 ◽  
Author(s):  
R. M. Ginetz ◽  
P. A. Larkin
Keyword(s):  
Rainbow Trout ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Development Stage ◽  
Salmo Gairdneri ◽  
Factors Affecting ◽  
Light Intensities ◽  
Salmon Fry ◽  
Lower Stream ◽  
Downstream Movement

Predation of rainbow trout (Salmo gairdneri) on migrant sockeye salmon (Oncorhynchus nerka) fry in experimental streams was higher on fry at an earlier development stage, in moonlight by contrast to cloudy night light intensities, at lesser turbidities, and at lower stream velocities. At dusk light intensities, from.05 to.30 ft-c, mortality from predation was inversely related to light intensity. The longer the period of exposure of fry to naturally declining light intensities prior to downstream movement, the lower was the loss to predators. Exposure of predators to high light intensities prior to the downstream movement of fry resulted in decreased fry mortality. Fry that had survived exposure to predators in an experimental stream 1 and 2 days previous were less vulnerable to predation than "naive" fry. Successive exposures further decreased the loss to predation. Fry enumerated at a counting fence suffered less predation than fry not enumerated. Experienced fry moved downstream more rapidly than naive fry.In laboratory aquaria, experienced fry formed compact schools prior to and in response to stimuli, while naive fry formed loose schools or did not school. Experienced fry were less active in responding to stimuli. Enumerated fry resembled experienced fry; nonenumerated fry resembled naive fry.Various techniques of enhancing sockeye salmon fry survival during downstream migration are suggested by these results.

Spawning success of males using alternative mating tactics in sockeye salmon, Oncorhynchus nerka

1997 ◽  
Vol 54 (8) ◽  
pp. 1785-1795 ◽  
Author(s):  
C J Foote ◽  
G S Brown ◽  
C C Wood
Keyword(s):  
Sockeye Salmon ◽  
Pacific Salmon ◽  
Oncorhynchus Nerka ◽  
Relative Size ◽  
Mating Strategies ◽  
Older Individuals ◽  
Alpha Male ◽  
Gonad Size ◽  
Sperm Volume ◽  
Spawning Success

Protein electrophoresis was used to determine the relative spawning success of jack sockeye salmon, Oncorhynchus nerka, males when they joined spawnings of larger, older individuals in experimental enclosures in the natal stream, Pierre Creek, Babine Lake, British Columbia. We attempted to relate the results to distance of the jack from female before spawning and relative size of the jack to the alpha male. Further, we measured the relationships between relative gonad size and available sperm volume to body size to determine if sperm competition could also play a role in determining the relative spawning success of males. Jack spawning success was variable (3-93%) and not significantly different from that of large males, even though they were further from the female before spawning, had smaller gonads, and had less available sperm. Jack males were adept at sneaking, usually commencing spawning within a split second of the alpha male and always on the opposite, free, side of the spawning female. The results are related to various theories on the evolution of alternative mating strategies and tactics in Pacific salmon.

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