scholarly journals Beavers, Castor canadensis, Feeding on Salmon Carcasses: Opportunistic Use of a Seasonally Superabundant Food Source

2005 ◽  
Vol 119 (4) ◽  
pp. 591 ◽  
Author(s):  
Jeffrey S. Gleason ◽  
Ryan A. Hoffman ◽  
James M. Wendland
Keyword(s):  
Chinook Salmon ◽  
Food Source ◽  
Oncorhynchus Tshawytscha ◽  
Foraging Ecology ◽  
Castor Canadensis ◽  
The Other ◽  
Streams And Rivers ◽  
Southcentral Alaska ◽  
Common Strategy ◽  
Salmon Carcasses

We report observations of Beavers (Castor canadensis) foraging and feeding on discarded Chinook Salmon (Oncorhynchus tshawytscha) carcasses within the confines of the Susitna River drainage in southcentral Alaska on three separate occasions between 1999 and 2004. In all three instances, Beavers were observed actively seeking out freshly discarded carcasses or transporting “fresh” salmon carcasses in their mouths. In one instance, Beavers were seen using their dextrous forefeet to “handle” chunks of salmon while hunched over carcasses and in this case we actually witnessed Beavers “chewing” and ingestion was assumed. In the other two instances, Beavers were observed swimming with salmon carcasses in their mouths. Though unique within the framework of Beaver foraging ecology, we suggest this behavior may be a fairly common strategy employed by Beavers in Alaskan streams and rivers to take advantage of a seasonally superabundant source of protein.

Comparison of Spawning Areas and Times for Two Runs of Chinook Salmon (Oncorhynchus tshawytscha) in the Kenai River, Alaska

1985 ◽  
Vol 42 (4) ◽  
pp. 693-700 ◽  
Author(s):  
Carl V. Burger ◽  
Richard L. Wilmot ◽  
David B. Wangaard
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Main Stem ◽  
Upstream Migration ◽  
Cook Inlet ◽  
Large Lakes ◽  
Spawning Areas ◽  
Winter Temperatures ◽  
Southcentral Alaska ◽  
Radio Transmitters

From 1979 to 1982,188 chinook salmon (Oncorhynchus tshawytscha) were tagged with radio transmitters to locate spawning areas in the glacial Kenai River, southcentral Alaska. Results confirmed that an early run entered the river in May and June and spawned in tributaries, and a late run entered the river from late June through August and spawned in the main stem. Spawning peaked during August in tributaries influenced by lakes, but during July in other tributaries. Lakes may have increased fall and winter temperatures of downstream waters, enabling successful reproduction for later spawning fish within these tributaries. This hypothesis assumes that hatching and emergence can be completed in a shorter time in lake-influenced waters. The time of upstream migration and spawning (mid- to late August) of the late run is unique among chinook stocks in Cook Inlet. This behavior may have developed only because two large lakes (Kenai and Skilak) directly influence the main-stem Kenai River. If run timing is genetically controlled, and if the various components of the two runs are isolated stocks that have adapted to predictable stream temperatures, there are implications for stock transplantation programs and for any activities of man that alter stream temperatures.

Differential effect of formalin preservation on yolk and tissue of young chinook salmon (Oncorhynchus tshawytscha Walbaum)

1981 ◽  
Vol 59 (8) ◽  
pp. 1608-1611 ◽  
Author(s):  
T. A. Heming ◽  
R. P. Preston
Keyword(s):  
Weight Gain ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
The Other ◽  
Weight Changes ◽  
Tissue Weight ◽  
Perivitelline Fluid ◽  
Egg Composition ◽  
Formalin Preservation ◽  
Neutral Formalin

Preservation in 5% neutral formalin for periods up to 50 days differentially increased the yolk and tissue weight of young chinook salmon (Oncorhynchus tshawytscha). Yolk gained relatively more weight than tissue. As a result, intact alevins showed a net weight gain during preservation, the magnitude of which was related to the amounts of yolk and tissue present at preservation. No single correction factor was generally applicable to compensate for weight changes in preserved alevins. On the other hand, preservation had little effect on weight of intact chinook eggs, regardless of egg composition. Presumably, increases in yolk and tissue weights of preserved eggs were masked by loss of perivitelline fluid.

Effect of ACTH and Salmon Gonadotropin on Interrenal and Thyroid Activity of Gonadectomized Adult Sockeye Salmon (Oncorhynchus nerka)

1974 ◽  
Vol 31 (7) ◽  
pp. 1211-1214 ◽  
Author(s):  
Edward M. Donaldson ◽  
J. R. McBride
Keyword(s):  
Plasma Concentration ◽  
Chinook Salmon ◽  
Sockeye Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Oncorhynchus Nerka ◽  
The Other ◽  
Thyroid Activity ◽  
Other Hand

Injection of a chinook salmon (Oncorhynchus tshawytscha) gonadotropin preparation into gonadectomized sockeye salmon (Oncorhynchus nerka) did not result in any increase in the plasma concentration of cortisol or cortisone, nor did it stimulate the activity of the interrenal tissue. On the other hand, injection of mammalian ACTH (Acthar) did result in an increase in the plasma concentration of cortisol and cortisone, and stimulated the interrenal tissue. The salmon gonadotropin preparation, however, elicited an increase in thyroid activity. The results suggest that in the salmon, ovulation is not caused by gonadotropin induced interrenal corticosteroidogenesis.

Chinook salmon outmigration survival in wet and dry years in California’s Sacramento River

2015 ◽  
Vol 72 (11) ◽  
pp. 1749-1759 ◽  
Author(s):  
Cyril J. Michel ◽  
Arnold J. Ammann ◽  
Steven T. Lindley ◽  
Philip T. Sandstrom ◽  
Eric D. Chapman ◽  
...  
Keyword(s):  
Survival Rate ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Management Strategies ◽  
Coastal Ocean ◽  
High Flow ◽  
Sacramento River ◽  
The Other ◽  
Low Flow ◽  
Receiver Array

Outmigration survival of acoustic-tagged, hatchery-origin, late-fall-run Chinook salmon (Oncorhynchus tshawytscha) smolts from the Sacramento River was estimated for 5 years (2007–2011) using a receiver array spanning the entire outmigration corridor, from the upper river, through the estuary, and into the coastal ocean. The first 4 years of releases occurred during below-average river flows, while the fifth year (2011) occurred during above-average flows. In 2011, overall outmigration survival was two to five times higher than survival in the other 4 years. Regional survival estimates indicate that most of the improved survival seen in 2011 occurred in the riverine reaches of the outmigration corridor, while survival in the brackish portions of the estuary did not significantly differ among the 5 years. For the 4 low-flow years combined, survival rate in the river was lower in the less anthropogenically modified upper reaches; however, across all regions, survival rate was lowest in the brackish portion of the estuary. Even in the high-flow year, outmigration survival was substantially lower than yearling Chinook salmon populations in other large rivers. Potential drivers of these patterns are discussed, including channelization, water flow, and predation. Finally, management strategies are suggested to best exploit survival advantages described in this study.

The development of chinook (Oncorhynchus tshawytscha) and chum salmon (Onchorhynchus keta) embryos and alevins under varying temperature regimes

1987 ◽  
Vol 65 (11) ◽  
pp. 2672-2681 ◽  
Author(s):  
C. B. Murray ◽  
T. D. Beacham
Keyword(s):  
Chinook Salmon ◽  
Chum Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Survival Rates ◽  
The Other ◽  
Temperature Regimes ◽  
Late Transfer ◽  
Eye Pigmentation ◽  
Early Transfer ◽  
Incubation Temperatures

Chinook (Oncorhynchus tshawytscha) and chum salmon (O. keta) embryos were initially incubated at 4, 8, or 12 °C and then maintained at the same temperature or systematically transferred at completion of epiboly (early transfer) or complete eye pigmentation (late transfer) to each of the other incubation temperatures. For both species initial incubation at 8 or 12 °C resulted in higher embryo and alevin survival rates than initial incubation at 4 °C. Increasing or decreasing temperature regimes had little effect on embryo and alevin survival rates. Transfers after epiboly or completion of eye pigmentation had little influence on subsequent survival rates, except the early and late transfers of chinook salmon embryos from 4 to 12 °C, which resulted in an increase in alevin mortality. Hatching and emergence times varied inversely with temperature, and chum salmon generally hatched and emerged sooner than chinook salmon. Decreasing temperature regimes produced longer and heavier chinook salmon alevins and fry, but constant incubation at 8 °C or early or later transfers to 8 °C resulted in longer and heavier chum salmon alevins and fry. Temperature regimes that simulate those experienced by a species during natural incubation tend to enhance survival and alevin and fry size. Different trends in embryo and alevin developmental characters between species and among families within a species were assumed to reflect adaptations to variable natural incubation conditions.

Geographic Variation in the Occurrence of Red- and White-Fleshed Chinook Salmon (Oncorhynchus tshawytscha) in Western North America

1989 ◽  
Vol 46 (7) ◽  
pp. 1107-1113 ◽  
Author(s):  
Jeffrey J. Hard ◽  
Alex C. Wertheimer ◽  
William F. Johnson
Keyword(s):  
British Columbia ◽  
North America ◽  
Geographic Variation ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Early Life History ◽  
Western North America ◽  
Flesh Color ◽  
Southeast Alaska ◽  
Southcentral Alaska

Flesh color, as reported by fishery processors, was surveyed in coded-wire tagged chinook salmon (Oncorhynchus tshawytscha) sampled from the 1983–85 Southeast Alaska commercial troll fisheries. Flesh color data were collected from 11 373 fish originating from 95 locations in western North America between southcentral Alaska and central California. White-fleshed chinook salmon were most common in stocks from coastal British Columbia, Southeast Alaska, and the tributaries of the Fraser River, British Columbia. Heterogeneity between neighboring locations was also greatest in this region, the most recently glaciated area of western North America. Differences in flesh color proportions are consistent with the hypothesis that chinook from the Pacific refuge colonized rivers in British Columbia and Southeast Alaska after the recession of the last Pleistocene glaciation. Genetic drift of populations founded by small numbers of parents is one explanation of the pattern of occurrence of white-fleshed chinook salmon. An alternate explanation is that geographic variation in the occurrence of red- and white-fleshed chinook salmon reflects evolutionary adaptations of these fish during early life history to local freshwater environments.

Systematic hexamitid (Protozoa: Diplomonadida) Infection in seawater pen-reared Chinook salmon Oncorhynchus tshawytscha

1992 ◽  
Vol 14 ◽  
pp. 81-89 ◽  
Author(s):  
ML Kent ◽  
J Ellis ◽  
JW Fournie ◽  
SC Dawe ◽  
JW Bagshaw ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha

scholarly journals Managed Wetlands Can Benefit Juvenile Chinook Salmon in a Tidal Marsh

2021 ◽  
Author(s):  
Nicole M. Aha ◽  
Peter B. Moyle ◽  
Nann A. Fangue ◽  
Andrew L. Rypel ◽  
John R. Durand
Keyword(s):  
San Francisco ◽  
Growth Rates ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Nursery Habitat ◽  
San Francisco Estuary ◽  
Rice Fields ◽  
Fish Growth ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

AbstractLoss of estuarine and coastal habitats worldwide has reduced nursery habitat and function for diverse fishes, including juvenile Chinook salmon (Oncorhynchus tshawytscha). Underutilized off-channel habitats such as flooded rice fields and managed ponds present opportunities for improving rearing conditions and increasing habitat diversity along migratory corridors. While experiments in rice fields have shown enhanced growth rates of juvenile fishes, managed ponds are less studied. To evaluate the potential of these ponds as a nursery habitat, juvenile Chinook salmon (~ 2.8 g, 63 mm FL) were reared in cages in four contrasting locations within Suisun Marsh, a large wetland in the San Francisco Estuary. The locations included a natural tidal slough, a leveed tidal slough, and the inlet and outlet of a tidally muted managed pond established for waterfowl hunting. Fish growth rates differed significantly among locations, with the fastest growth occurring near the outlet in the managed pond. High zooplankton biomass at the managed pond outlet was the best correlate of salmon growth. Water temperatures in the managed pond were also cooler and less variable compared to sloughs, reducing thermal stress. The stress of low dissolved oxygen concentrations within the managed pond was likely mediated by high concentrations of zooplankton and favorable temperatures. Our findings suggest that muted tidal habitats in the San Francisco Estuary and elsewhere could be managed to promote growth and survival of juvenile salmon and other native fishes.

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