Differential susceptibility of Yukon River and Salish Sea stocks of Chinook salmon Oncorhynchus tshawytscha to ichthyophoniasis

2021 ◽  
Author(s):  
DG Elliott ◽  
CM Conway ◽  
CL McKibben ◽  
AH MacKenzie ◽  
LM Hart ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Differential Susceptibility ◽  
Salish Sea ◽  
Yukon River

Using thalweg profiling to assess and monitor juvenile salmon (Oncorhynchus spp.) habitat in small streams

2006 ◽  
Vol 63 (7) ◽  
pp. 1515-1525 ◽  
Author(s):  
Brent Mossop ◽  
Michael J Bradford
Keyword(s):  
Chinook Salmon ◽  
Stream Flow ◽  
Gold Mining ◽  
Oncorhynchus Tshawytscha ◽  
Fish Habitat ◽  
Juvenile Chinook Salmon ◽  
Yukon River ◽  
Small Streams ◽  
Longitudinal Profiles ◽  
Small Tributary

Thalweg profiles are longitudinal profiles of the streambed elevation measured along the deepest portion of the stream. This technique has recently been advocated as a tool to assess and monitor fish habitat in streams because metrics calculated from thalweg profiles can provide useful information on habitat quality, and measurements are both repeatable and independent of stream flow. Relations between thalweg metrics and land use have also been documented. However, a relation between fish abundance and thalweg metrics has not been established. To develop this relation, we surveyed thalweg profiles and sampled juvenile Chinook salmon (Oncorhynchus tshawytscha) density in 14 reaches of small tributary streams of the upper Yukon River. Chinook salmon density was correlated with three thalweg metrics. Two of these metrics — length in residual pool and mean maximum residual pool depth — provided useful measures of pool extent and quality and useful information on Chinook salmon habitat. Thalweg metrics differed between these undisturbed streams and reaches in streams affected by placer gold mining. These results suggest that thalweg profiling provides a useful tool to assess and monitor fish habitat in small streams.

Declining spring usage of core habitat by endangered fish-eating killer whales reflects decreased availability of their primary prey

2018 ◽  
Vol 24 (2) ◽  
pp. 189 ◽  
Author(s):  
Monika W. Shields ◽  
Jimmie Lindell ◽  
Julie Woodruff
Keyword(s):  
British Columbia ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Prey Availability ◽  
The United States ◽  
Killer Whales ◽  
Salish Sea ◽  
Critical Habitat ◽  
Endangered Fish ◽  
The North

The salmon-eating Southern Resident killer whales (Orcinus orca) of the north-eastern Pacific Ocean are listed as endangered both in the United States and Canada. Their critical habitat has been defined as the region of the inland waters of Washington State and British Columbia known as the Salish Sea, where they have traditionally spent much of their time from spring through fall. Using reports from experienced observers to sightings networks, we tracked the daily presence of the Southern Residents in these waters from 1 April to 30 June from 1994 through 2016. We found that the escapement estimates of spring Chinook salmon (Oncorhynchus tshawytscha) on the Fraser River in British Columbia were a significant predictor of the cumulative presence/absence of the whales throughout the spring season. There was also a difference in both whale presence and salmon abundance before and after 2005, suggesting that the crash in Chinook salmon numbers has fallen below threshold where it is worthwhile for the whales to spend as much time in the Salish Sea. The use of the Salish Sea by the Southern Residents has declined in the spring months as they are either foraging for Chinook salmon elsewhere or are shifting to another prey species. In order to continue providing necessary protections to this endangered species, critical habitat designations must be re-evaluated as this population of killer whales shifts its range in response to prey availability.

Low productivity of Chinook salmon strongly correlates with high summer stream discharge in two Alaskan rivers in the Yukon drainage

2015 ◽  
Vol 72 (8) ◽  
pp. 1125-1137 ◽  
Author(s):  
Jason R. Neuswanger ◽  
Mark S. Wipfli ◽  
Matthew J. Evenson ◽  
Nicholas F. Hughes ◽  
Amanda E. Rosenberger
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Population Declines ◽  
Environmental Predictors ◽  
High Discharge ◽  
Stream Discharge ◽  
Yukon River ◽  
Stock Recruitment ◽  
Sources Of Variation ◽  
Major Floods

Yukon River Chinook salmon (Oncorhynchus tshawytscha) populations are declining for unknown reasons, creating hardship for thousands of stakeholders in subsistence and commercial fisheries. An informed response to this crisis requires understanding the major sources of variation in Chinook salmon productivity. However, simple stock–recruitment models leave much of the variation in this system’s productivity unexplained. We tested adding environmental predictors to stock–recruitment models for two Yukon drainage spawning streams in interior Alaska — the Chena and Salcha rivers. Low productivity was strongly associated with high stream discharge during the summer of freshwater residency for young-of-the-year Chinook salmon. This association was more consistent with the hypothesis that sustained high discharge negatively affects foraging conditions than with acute mortality during floods. Productivity may have also been reduced in years when incubating eggs experienced major floods or cold summers and falls. These freshwater effects — especially density dependence and high discharge — helped explain population declines in both rivers. They are plausible as contributors to the decline of Chinook salmon throughout the Yukon River drainage.

Mitochondrial DNA Variation in Chinook (Oncorhynchus tshawytscha) and Chum Salmon (O. keta) Detected by Restriction Enzyme Analysis of Polymerase Chain Reaction (PCR) Products

1993 ◽  
Vol 50 (4) ◽  
pp. 708-715 ◽  
Author(s):  
Matthew A. Cronin ◽  
William J. Spearman ◽  
Richard L. Wilmot ◽  
John C. Patton ◽  
John W. Bickham
Keyword(s):  
Polymerase Chain Reaction ◽  
Mitochondrial Dna ◽  
Chinook Salmon ◽  
Chum Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Vancouver Island ◽  
Chain Reaction ◽  
Dna Variation ◽  
Yukon River ◽  
Polymerase Chain

We analyzed intraspecific mitochondrial DNA variation in chinook salmon (Oncorhynchus tshawytscha) from drainages in the Yukon River (Alaska and Yukon Territory), the Kenai River (Alaska), and Oregon and California rivers; and chum salmon (O. keta) from the Yukon River and Vancouver Island, and Washington rivers. For each species, three different portions of the mtDNA molecule were amplified separately using the polymerase chain reaction and then digested with at least 19 restriction enzymes. Intraspecific sequence divergences between haplotypes were less than 0.01 base substitution per nucleotide. Nine chum salmon haplotypes were identified. Yukon River chum salmon stocks displayed more haplotypes (eight) than the stocks of Vancouver Island and Washington (two). The most common chum salmon haplotype occurred in all areas. Seven chinook salmon haplotypes were identified. Four haplotypes occurred in the Yukon and Kenai rivers and four occurred in Oregon/California, with only one haplotype shared between the regions. Sample sizes were too small to quantify the degree of stock separation among drainages, but the patterns of variation that we observed suggest utility of the technique in genetic stock identification.

Catalog of Chinook Salmon Spawning Areas in Yukon River Basin in Canada and United States

2017 ◽  
Vol 8 (2) ◽  
pp. 558-586 ◽  
Author(s):  
Randy J. Brown ◽  
Al von Finster ◽  
Robert J. Henszey ◽  
John H. Eiler
Keyword(s):  
United States ◽  
River Basin ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
The United States ◽  
Maximum Effect ◽  
Yukon River ◽  
Spawning Areas ◽  
Yukon River Basin ◽  
Major Producer

Abstract Chinook Salmon Oncorhynchus tshawytscha return to the Yukon River in northwestern North America each summer, migrating to spawning destinations from the lower river to more than 3,000 km upstream. These returns support numerous fisheries throughout the basin. Despite a long history of fisheries research and management, there is no comprehensive account of Chinook Salmon spawning areas in the basin. To address this issue, we cataloged, summarized, and mapped the known spawning areas of Yukon River Chinook Salmon by using a variety of sources including published articles, gray literature, and information archived in agency databases. Most of our sources were published within the past 30 y, but some refer to observations that were recorded as long ago as the late 1800s. We classified spawning areas as major or minor producers with three indicators of abundance: 1) quantitative estimates of escapement (major producer if ≥500 fish, minor producer if <500 fish), 2) radiotelemetry-based proportions of annual production (major producer if ≥1% of the run, minor producer if <1% of the run), and 3) aerial survey index counts (major producer if ≥165 fish observed, minor producer if <165 fish observed). We documented 183 spawning areas in the Yukon River basin, 79 in the United States, and 104 in Canada. Most spawning areas were in tributary streams, but some were in main-stem reaches as well. We classified 32 spawning areas as major producers and 151 as minor producers. The Chinook Salmon spawning areas cataloged here provide a baseline that makes it possible to strategically direct abundance, biological sampling, and genetics projects for maximum effect and to assess both spatial and temporal changes within the basin.

Ecology of juvenile chinook salmon in a small non-natal stream of the Yukon River drainage and the role of ice conditions on their distribution and survival

2001 ◽  
Vol 79 (11) ◽  
pp. 2043-2054 ◽  
Author(s):  
Michael J Bradford ◽  
Jeff A Grout ◽  
Sue Moodie
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Thick Layer ◽  
Average Density ◽  
Yukon River ◽  
Small Streams ◽  
Mean Size ◽  
Ice Conditions ◽  
Stream Type

We investigated the ecology of juvenile stream-type chinook salmon (Oncorhynchus tshawytscha) in Croucher Creek, a small non-natal tributary of the upper Yukon River, in 1998 and 1999. Underyearling (age 0+) salmon enter Croucher Creek from the Yukon River in June, and by midsummer reached an average density of >0.5/m2. Fish were most commonly found in small pools. Their mean size increased until the end of August, but growth virtually ceased after that, when water temperatures fell. Juveniles remained in the stream through winter, and their distribution and survival were strongly influenced by aufeis, a thick layer of ice that develops from the freezing of groundwater. Over-winter survival was not dependent on fish size. Those fish that survived the winter grew rapidly and doubled in body mass in the spring. About 900 yearling fish emigrated from Croucher Creek in late June and early July at a mean length of 89 mm and mass of 7.2 g. Most of the migrants overwintered in a 700 m long reach of the creek that was downstream from groundwater sources and did not experience severe icing conditions. We suggest that small streams may be important habitats for juvenile salmon in the Yukon drainage, especially if there is a year-round source of groundwater flow that creates conditions suitable for overwintering.

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