scholarly journals Population Trends for Chinook and Summer Chum Salmon in Two Yukon River Tributaries in Alaska

2020 ◽  
Author(s):  
Randy J. Brown ◽  
Catherine Bradley ◽  
Jeffery L. Melegari
Keyword(s):  
Chinook Salmon ◽  
Chum Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Demographic Data ◽  
Main Stem ◽  
Strongly Correlated ◽  
Yukon River ◽  
Over Time ◽  
Run Timing

Abstract An essential management objective of the Yukon Delta and Koyukuk National Wildlife Refuges in Alaska is to conserve fish and wildlife populations and habitats in their natural diversity. In keeping with this objective, the U.S. Fish and Wildlife Service installed weirs in two tributaries of the Yukon River, the East Fork Andreafsky and Gisasa rivers, in 1994 to collect information on salmon populations that used them. The weirs have been in operation for >23 y. Chinook Oncorhynchus tshawytscha and summer Chum Salmon O. keta were counted and sampled for various demographic data each year as they migrated through the weirs to upstream spawning areas. Here we examine this record of population data to describe and compare long-term variation in run abundance, run timing, length and age structure, sex composition, and production for these salmon populations. Fishery managers often look to multiple monitoring projects in-season seeking corroboration of observed run qualities; therefore, we also considered whether Yukon River main-stem indicators of abundance were correlated with these tributary escapements. Our analyses suggest long-term stability of these populations despite large annual variations in most metrics we examined. Annual escapements have varied by factors of 3–5 for Chinook Salmon and >23 for summer Chum Salmon, yet only the Chinook Salmon population in the Gisasa River appears to be declining. Main-stem abundance indicators were not correlated with Chinook Salmon escapements but were strongly correlated with summer Chum Salmon escapements. Run timing has varied annually by as much as a week earlier or later than average for all four populations with no trend over time. Mean age of the Chinook Salmon populations declined over time but remained stable for the summer Chum Salmon populations. Chinook Salmon populations in the East Fork Andreafsky and Gisasa rivers averaged 35% and 28% female, respectively. Both summer Chum Salmon populations averaged close to 50% female. Length at age has been stable or slightly declining for all four populations. Production over time was strongly correlated within species for populations in the two rivers, and averaged >1 recruit/spawner for all populations except Chinook Salmon from the Gisasa River. We discuss these findings in the context of major changes in the fishery and the environments these populations experience.

Temporal variation in synchrony among chinook salmon (Oncorhynchus tshawytscha) redd counts from a wilderness area in central Idaho

2003 ◽  
Vol 60 (7) ◽  
pp. 840-848 ◽  
Author(s):  
Daniel J Isaak ◽  
Russell F Thurow ◽  
Bruce E Rieman ◽  
Jason B Dunham
Keyword(s):  
Chinook Salmon ◽  
Large Scale ◽  
Oncorhynchus Tshawytscha ◽  
Structured Populations ◽  
Strongly Correlated ◽  
Wilderness Area ◽  
Large Scale Disturbance ◽  
Stochastic Events ◽  
Central Idaho

Metapopulation dynamics have emerged as a key consideration in conservation planning for salmonid fishes. Implicit to many models of spatially structured populations is a degree of synchrony, or correlation, among populations. We used a spatially and temporally extensive database of chinook salmon (Oncorhynchus tshawytscha) redd counts from a wilderness area in central Idaho to examine patterns in synchrony as these fish underwent a sixfold decrease in abundance. Our results suggested that populations became strongly synchronous as abundances decreased and that the range, or diversity of correlations, exhibited among populations also decreased. These changes indicate that the likelihood of simultaneous extirpations has increased, which could have long-term detrimental consequences for metapopulation persistence. Implications for management are that the resilience of many metapopulations to large-scale disturbance and anthropogenic suppression may not depend solely on attempts to maintain large and productive component populations, but also on efforts to desynchronize populations that have become strongly correlated. Such efforts could entail promoting the existence of a broad distribution and diversity of habitats that support a wide array of life-history forms and ensuring that some habitats are sufficiently spatially disjunct so that risks from catastrophic stochastic events are minimized.

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.

In a warming river, natural-origin Chinook salmon spawn later but hatchery-origin conspecifics do not

2021 ◽  
Vol 78 (1) ◽  
pp. 68-77
Author(s):  
Catherine S. Austin ◽  
Timothy E. Essington ◽  
Thomas P. Quinn
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
River System ◽  
Local Environment ◽  
Washington State ◽  
Human Intervention ◽  
Timing Of Reproduction ◽  
Natural Origin ◽  
Skagit River

Median timing of reproduction in salmonid populations is generally consistent among years, reflecting long-term patterns of natural selection from characteristics of the local environment. However, altered selection from factors related to climate change or human intervention might shift timing over generations, with implications for the population’s persistence. To study these processes, we modeled median timing of redd (nest) counts as an index of spawning timing by natural-origin Chinook salmon (Oncorhynchus tshawytscha) in the Skagit River system in Washington State, USA. Over the last 2–6 decades, natural-origin salmon have been spawning later by 0.03–0.52 days·year–1, while a naturally spawning group that is influenced by strays from a hatchery has been spawning earlier by 0.19 days·year–1. Trends in the spawning timing of hatchery-origin strays may reflect opposing selection from the hatchery, where egg take for propagation has become earlier by 0.58 days·year–1. As mean August river temperatures have risen over the period of record, hatchery timing trends may be moving in the opposite direction from the plastic or adaptive patterns expressed by natural-origin fish.

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.

scholarly journals Evaluation of Long-Term Mark-Recapture Data for Estimating Abundance of Juvenile Fall-Run Chinook Salmon on the Stanislaus River from 1996 to 2017

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Tyler Pilger ◽  
Matthew Peterson ◽  
Dana Lee ◽  
Andrea Fuller ◽  
Doug Demko
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Estimation Method ◽  
Central Valley ◽  
Mark Recapture ◽  
Important Species ◽  
Trap Efficiency ◽  
Monitoring Programs ◽  
Abundance Estimates

Conservation and management of culturally and economically important species rely on monitoring programs to provide accurate and robust estimates of population size. Rotary screw traps (RSTs) are often used to monitor populations of anadromous fish, including fall-run Chinook Salmon (Oncorhynchus tshawytscha) in California’s Central Valley. Abundance estimates from RST data depend on estimating a trap's efficiency via mark-recapture releases. Because efficiency estimates are highly variable and influenced by many factors, abundance estimates can be highly uncertain. An additional complication is the multiple accepted methods for how to apply a limited number of trap efficiency estimates, each from discrete time-periods, to a population’s downstream migration, which can span months. Yet, few studies have evaluated these different methods, particularly with long-term monitoring programs. We used 21 years of mark-recapture data and RST catch of juvenile fall-run Chinook Salmon on the Stanislaus River, California, to investigate factors associated with trap efficiency variability across years and mark-recapture releases. We compared annual abundance estimates across five methods that differed in treatment of trap efficiency (stratified versus modeled) and statistical approach (frequentist versus Bayesian) to assess the variability of estimates across methods, and to evaluate whether method affected trends in estimated abundance. Consistent with short-term studies, we observed negative associations between estimated trap efficiency and river discharge as well as fish size. Abundance estimates were robust across all methods, frequently having overlapping confidence intervals. Abundance trends, for the number of increases and decreases from year to year, did not differ across methods. Estimated juvenile abundances were significantly related to adult escapement counts, and the relationship did not depend on estimation method. Understanding the sources of uncertainty related to abundance estimates is necessary to ensure that high-quality estimates are used in life cycle and stock-recruitment modeling.

Contrasting patterns of productivity and survival rates for stream-type chinook salmon (Oncorhynchus tshawytscha) populations of the Snake and Columbia rivers

1999 ◽  
Vol 56 (6) ◽  
pp. 1031-1045 ◽  
Author(s):  
Howard A Schaller ◽  
Charles E Petrosky ◽  
Olaf P Langness
Keyword(s):  
Chinook Salmon ◽  
Physical Environment ◽  
Oncorhynchus Tshawytscha ◽  
Survival Rates ◽  
Temporal And Spatial Patterns ◽  
Hydropower System ◽  
Temporal And Spatial ◽  
Changes Over Time ◽  
Stream Type ◽  
Over Time

The effects of increasing hydropower development and operation appear extremely important in the decline and near extripation of stream-type chinook salmon (Oncorhynchus tshawytscha) stocks of the upper Columbia and Snake rivers. We evaluated temporal and spatial patterns of productivity and survival rates (for index stocks from the Snake, upper Columbia, and lower Columbia regions) to determine the cause of dramatic declines of the upriver stocks. This evaluation tested hypotheses about nonstationarity (changes over time in average productivity) in the Ricker recruitment function caused by changes in the physical environment. Individual stocks showed recent declines in indicators of productivity and survival rate; however, the comparisons indicate that upriver stocks showed greater declines coincident with the development and operation of the hydropower system. Evidence from the aggregate run indicates that declines over the last 50 years were quite abrupt and corresponded to construction and completion of the hydropower system.

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.

Life History of Juvenile Ocean-type Chinook Salmon (Oncorhynchus tshawytscha) in the Situk River, Alaska

1992 ◽  
Vol 49 (12) ◽  
pp. 2621-2629 ◽  
Author(s):  
S. W. Johnson ◽  
J. F. Thedinga ◽  
K. V. Koski
Keyword(s):  
Life History ◽  
Chinook Salmon ◽  
Habitat Preference ◽  
Oncorhynchus Tshawytscha ◽  
Fork Length ◽  
Main Stem ◽  
Seawater Tolerance ◽  
History Of ◽  
Two Phases ◽  
Stream Type

Distribution, abundance, habitat preference, migration and residence timing, seawater tolerance, and size were determined for juvenile ocean-type (age 0) chinook salmon (Oncorhynchus tshawytscha) in the Situk River, Alaska. Chinook primarily occupied main-stem habitats (channel edges in spring, pools and willow edges in summer). Peak chinook densities in the upper and lower main stem were 96 and 76 fish/100 m2, respectively. Chinook migrated downstream in two phases: a spring dispersal of emergent fry and a summer migration. Chinook marked in the upper river in late June and early July were recaptured 20 km downstream in the lower river in late July. Marked chinook resided in the lower river up to 34 d. Mean fork length of chinook in the lower river increased from 40 mm in May to 80 mm in early August. By late August, chinook had emigrated from the lower river at a size of approximately 80 mm. Fish this size were seawater tolerant and had the physical appearance of smolts. Ocean-type chinook in the Situk River are unique because in most Alaskan streams, chinook are stream-type (rear in freshwater at least 1 yr).

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