Effect of Thermal Stress on Predator Avoidance in Sockeye Salmon

1972 ◽  
Vol 29 (5) ◽  
pp. 601-603 ◽  
Author(s):  
J. R. Sylvester
Keyword(s):  
Thermal Stress ◽  
Predator Avoidance ◽  
Sockeye Salmon ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Acclimation Temperature ◽  
Natural Conditions ◽  
Predator Prey ◽  
Salmon Fry ◽  
Predation Rates

Under laboratory conditions, predation rates of yearling coho salmon (Oncorhynchus kisutch) on sockeye salmon fry (Oncorhynchus nerka) increased with increasing acclimation temperature. Elevated temperature doses significantly decreased survival of sockeye salmon fry. The results suggest that under natural conditions, sudden increases in water temperature could alter predator–prey interactions of some fish by increasing predation mortalities.

Threespine stickleback aggregations create a potential predation refuge for sockeye salmon fry

1992 ◽  
Vol 70 (5) ◽  
pp. 1052-1056 ◽  
Author(s):  
Gregory T. Ruggerone
Keyword(s):  
Sockeye Salmon ◽  
Gasterosteus Aculeatus ◽  
Coho Salmon ◽  
Prey Size ◽  
Threespine Stickleback ◽  
Salmon Fry ◽  
Threespine Sticklebacks ◽  
Series Of Experiments ◽  
Predation Rates ◽  
Predation Refuge

Coho salmon (Oncorhynchus kisutch) frequently consume sockeye salmon (Oncorhynchus nerka) fry in Chignik Lake, Alaska, but have never been observed to consume threespine sticklebacks (Gasterosteus aculeatus), which are often closely associated with sockeye fry. Because coho salmon are visual predators and appear to avoid sticklebacks, a series of experiments was conducted in net pens to determine whether juvenile sockeye associated with threespine sticklebacks experienced less prédation than sockeye without sticklebacks and whether prey size affected prédation rates. Significantly fewer sockeye fry by coho were consumed in the pen containing 60 sticklebacks [Formula: see text] than in the 30-stickleback (4.7 fry/day) and 0-stickleback (4.4 fry/day) pens. An identical experiment with large, yearling sockeye (rather than sticklebacks) did not reveal a significant effect (p = 0.28), although there was a tendency for fewer large fry to be consumed when yearlings were abundant. A third experiment demonstrated predation rates on fry that were 45% lower in the presence of sticklebacks (1.2 fry/day) than in the presence of yearling sockeye (2.2 fry/day). Large sockeye fry (37–44 mm) consumed by coho declined steadily from about 36 to 29 to 22% of the total number of fry eaten as the number of sticklebacks or yearling sockeye increased from 0 to 30 to 60, respectively. These data suggest that the presence of threespine sticklebacks may reduce predation by coho on juvenile sockeye, especially those sockeye similar in size to sticklebacks.

Toxicity of Various Formulations of 2,4-D to Salmonids in Southeast Alaska

1974 ◽  
Vol 31 (4) ◽  
pp. 480-485 ◽  
Author(s):  
William R. Meehan ◽  
Logan A. Norris ◽  
Howard S. Sears
Keyword(s):  
Sockeye Salmon ◽  
Coho Salmon ◽  
Pink Salmon ◽  
Butyl Ester ◽  
Southeast Alaska ◽  
Dolly Varden Char ◽  
Salmon Fry ◽  
Percent Mortality ◽  
The Mean ◽  
Made In

To determine acute toxicity to juvenile (1) pink, chum, coho, and sockeye salmon, (2) Dolly Varden char, and (3) rainbow trout, 2,4-D acid, butyl and isooctyl esters were tested in southeast Alaska. A comparable test was made in Oregon using coho salmon fingerlings. The mean percent mortality after 96 h and the highest concentration of herbicide that did not produce any mortality were determined for each formulation tested.At less than 50 ppm 2,4-D acid produced no mortality except in pink salmon fry. The butyl ester was most toxic causing nearly complete mortality in all species at concentrations > 1.0 ppm and the isooctyl ester least toxic of the ester formulations. Alaskan and Oregon coho fingerlings were similar in their responses to 2,4-D acid, butyl and isooctyl esters. The toxicities of three different formulations of isooctyl ester, a PGBE ester, and butyl ester to Alaskan coho fingerlings were also determined. There were few or no differences in toxicity among isooctyl ester formulations. The butyl and PGBE esters were similar in toxicity.

Emigration and Production of Hatchery Coho Salmon (Oncorhynchus kisutch) Stocked in Streams Draining an Old-growth and a Clear-cut Watershed

1987 ◽  
Vol 44 (8) ◽  
pp. 1397-1407 ◽  
Author(s):  
Robert E. Bilby ◽  
Peter A. Bisson
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Old Growth ◽  
Trophic Conditions ◽  
Temperature Changes ◽  
Gross Photosynthesis ◽  
Clear Cut ◽  
Salmon Fry ◽  
Streamflow Change ◽  
Downstream Movement

Downstream movement of coho salmon fry (Oncorhynchus kisutch) stocked in old-growth and clear-cut watersheds occurred in three phases: (1) a brief period of heavy emigration immediately after stocking, (2) relatively little movement throughout most of the summer, and (3) intermittent heavy emigration during early autumn freshets. Coho emigrated whenever a streamflow change ≥ 3%∙d−1 occurred, but movement nearly ceased at flows above a certain level. Temperature changes were less important than discharge in triggering movement. When high densities were stocked, emigrant fry were smaller than residents. When low densities were stocked, emigration after the initial pulse of downstream movement was generally lower and there were no size differences between emigrants and residents. Production in the clear-cut was greater than in the old-growth watershed. Proportionately fewer fish emigrated from the old-growth stream, but when population densities were high, mortality in the old-growth exceeded the clear-cut. Greater emigration from the clear-cut site was possibly related to a scarcity of pools. Although the old-growth stream possessed better rearing habitat, less food may have been available, as suggested by gross photosynthesis rates 50% lower than in the clear-cut stream. Coho production therefore appeared to be most strongly influenced by trophic conditions, while volitional residency was most strongly influenced by habitat quality.

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.

Seasonal Changes in Habitat Use by Juvenile Coho Salmon (Oncorhynchus kisutch) in Oregon Coastal Streams

1992 ◽  
Vol 49 (4) ◽  
pp. 783-789 ◽  
Author(s):  
Thomas E. Nickelson ◽  
Jeffrey D. Rodgers ◽  
Steven L. Johnson ◽  
Mario F. Solazzi
Keyword(s):  
Habitat Use ◽  
Seasonal Changes ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Beaver Pond ◽  
Winter Habitat ◽  
Oregon Coast ◽  
Beaver Ponds ◽  
Salmon Fry ◽  
Coastal Streams

Habitat use by juvenile coho salmon (Oncorhynchus kisutch) during spring, summer, and winter was examined in Oregon coastal streams. Coho salmon fry were most abundant in backwater pools during spring. During summer, juvenile coho salmon were more abundant in pools of all types than they were in glides or riffles. During winter, juvenile coho salmon were most abundant in alcoves and beaver ponds. Because of the apparent strong preference for alcove and beaver pond habitat during winter and the rarity of that habitat in coastal streams, we concluded that if spawning escapement is adequate, the production of wild coho salmon smolts in most coho salmon spawning streams on the Oregon Coast is probably limited by the availability of adequate winter habitat.

Absence of Acute Effects on Threespine Sticklebacks (Gasterosteus aculeatus) and Coho Salmon (Oncorhynchus kisutch) Exposed to Resuspended Harbor Sediment Contaminants

1973 ◽  
Vol 30 (8) ◽  
pp. 1240-1242 ◽  
Author(s):  
Richard S. LeGore ◽  
David M. DesVoigne
Keyword(s):  
Gasterosteus Aculeatus ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Dry Weight ◽  
Oil And Grease ◽  
Volatile Solids ◽  
Salmon Fry ◽  
Threespine Sticklebacks ◽  
Sediment Contaminants ◽  
Wet Weight

Threespine sticklebacks (Gasterosteus aculeatus) and coho salmon fry (Oncorhynchus kisutch) were challenged in static 96-hr bioassays with suspensions of sediment from the Duwamish Waterway, Seattle, Wash. Doses of up to 5% wet weight (28.8 g/liter dry weight basis) were used. No observable effect on the fish of contaminants released from the sediment was elicited, although high levels of these contaminants, such as volatile solids, COD, organic nitrogen, oil and grease, zinc, and lead, were present.

Logging Impacts and Some Mechanisms that Determine the Size of Spring and Summer Populations of Coho Salmon Fry (Oncorhynchus kisutch) in Carnation Creek, British Columbia

1984 ◽  
Vol 41 (7) ◽  
pp. 1097-1105 ◽  
Author(s):  
J. C. Scrivener ◽  
B. C. Andersen
Keyword(s):  
Growth Rate ◽  
British Columbia ◽  
Growth Rates ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Growing Season ◽  
Channel Morphology ◽  
Creek Watershed ◽  
Salmon Fry ◽  
Logging Impacts

Natural patterns in emergence times, seaward movements, instream distributions, densities, and growth of coho salmon fry (Oncorhynchus kisutch) between March and September are contrasted with patterns observed during and after logging in the Carnation Creek watershed. After streamside logging in 1976–77, fry emerged up to 6 wk earlier and moved seaward more quickly than during years before logging. These observations are attributed to higher water temperatures during the winter and to emergence during a period of more frequent freshets. Increased fry movement from the stream could result in habitat being underutilized. In sections affected by intense streamside logging, the deposition of "fine" logging debris led to increased fry densities during the summers of 1977 and 1978. After major freshets in November 1978, which removed this fine debris and affected channel morphology in these sections, fry densities declined below those observed prior to logging. Growth rate of fry was inversely correlated with density in all stream sections. Growth rates, after correction for density, tended to be greater in all sections after the adjacent streamside was logged. Larger fry and more variable numbers of fry remained in the stream in September after logging than before logging. Their increased size is attributed to the longer growing season afforded by earlier emergence. This complex of interacting factors determines the number and size of fry in autumn and it can influence the production of smolts the following spring.

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