A Rapid Assessment Method to Estimate the Distribution of Juvenile Chinook Salmon (Oncorhynchus Tshawytscha) in an Interior Alaska River Basin PDF Download
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Author: Allison N. Matter Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 132
Book Description
Identification and protection of water bodies used by anadromous species in Alaska are critical in light of increasing threats to fish populations, yet challenging given budgetary and logistical limitations. Non-invasive, rapid assessment sampling techniques may reduce costs and effort while increasing species detection efficiencies. I used an intrinsic potential (IP) habitat model to identify high quality Chinook Salmon Oncorhynchus tshawytscha rearing habitats and select sites to sample throughout the Chena River basin for juvenile occupancy using environmental DNA (eDNA) and distribution within tributaries using snorkel surveys. Water samples were collected from 75 tributary sites in 2014 and 2015. The presence of Chinook Salmon DNA in water samples was assessed using a quantitative polymerase chain reaction (qPCR) assay targeting that species. Snorkel surveys were conducted and physical habitat was measured for a subset of tributaries examined with the eDNA approach. Juvenile salmon were counted within 50 m reaches starting at the tributary confluence and continuing upstream until no juvenile salmon were observed. The IP model predicted over 900 stream km in the basin to support high quality (IP ≥ 0.75) rearing habitat. Occupancy estimation based on eDNA samples indicated that 80.2% (± 4.3 SE) of previously unsampled sites classified as high IP and 56.4% of previously unsampled sites classified as low IP were occupied. The probability of detection of Chinook Salmon DNA from three replicate water samples was high (0.76 ± 1.9 SE) but varied with drainage area. A power analysis indicated power to detect proportional changes in occupancy based on parameter values estimated from eDNA occupancy models. Results of snorkel surveys showed that the upper extent of juvenile Chinook Salmon within tributaries was from 200 to 1,350 m upstream of tributary confluences. Occurrence estimates based on eDNA and snorkel surveys generally agreed, but care should be taken to ensure that little temporal gap exists between samples as juvenile salmon use of tributary habitats is likely often intermittent. Overall, the combination of IP habitat modeling, occupancy estimation based on eDNA, and snorkel surveys provided a useful, rapid-assessment method to predict and subsequently quantify the distribution of juvenile salmon in previously unsampled tributary habitats. These methods will provide tools for managers to rapidly and efficiently map critical rearing habitats and prioritize sampling efforts to expand the known distribution of juvenile salmon in interior Alaska streams.
Author: Allison N. Matter Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 132
Book Description
Identification and protection of water bodies used by anadromous species in Alaska are critical in light of increasing threats to fish populations, yet challenging given budgetary and logistical limitations. Non-invasive, rapid assessment sampling techniques may reduce costs and effort while increasing species detection efficiencies. I used an intrinsic potential (IP) habitat model to identify high quality Chinook Salmon Oncorhynchus tshawytscha rearing habitats and select sites to sample throughout the Chena River basin for juvenile occupancy using environmental DNA (eDNA) and distribution within tributaries using snorkel surveys. Water samples were collected from 75 tributary sites in 2014 and 2015. The presence of Chinook Salmon DNA in water samples was assessed using a quantitative polymerase chain reaction (qPCR) assay targeting that species. Snorkel surveys were conducted and physical habitat was measured for a subset of tributaries examined with the eDNA approach. Juvenile salmon were counted within 50 m reaches starting at the tributary confluence and continuing upstream until no juvenile salmon were observed. The IP model predicted over 900 stream km in the basin to support high quality (IP ≥ 0.75) rearing habitat. Occupancy estimation based on eDNA samples indicated that 80.2% (± 4.3 SE) of previously unsampled sites classified as high IP and 56.4% of previously unsampled sites classified as low IP were occupied. The probability of detection of Chinook Salmon DNA from three replicate water samples was high (0.76 ± 1.9 SE) but varied with drainage area. A power analysis indicated power to detect proportional changes in occupancy based on parameter values estimated from eDNA occupancy models. Results of snorkel surveys showed that the upper extent of juvenile Chinook Salmon within tributaries was from 200 to 1,350 m upstream of tributary confluences. Occurrence estimates based on eDNA and snorkel surveys generally agreed, but care should be taken to ensure that little temporal gap exists between samples as juvenile salmon use of tributary habitats is likely often intermittent. Overall, the combination of IP habitat modeling, occupancy estimation based on eDNA, and snorkel surveys provided a useful, rapid-assessment method to predict and subsequently quantify the distribution of juvenile salmon in previously unsampled tributary habitats. These methods will provide tools for managers to rapidly and efficiently map critical rearing habitats and prioritize sampling efforts to expand the known distribution of juvenile salmon in interior Alaska streams.
Author: Jason Neuswanger Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 362
Book Description
Chinook salmon (Oncorhynchus tshawytscha) are critical to subsistence and commerce in the Yukon River basin, but several recent years of low abundance have forced devastating fishery closures and raised urgent questions about causes of the decline. The Chena River subpopulation in interior Alaska has experienced a decline similar to that of the broader population. To evaluate possible factors affecting Chena River Chinook salmon productivity, I analyzed both population data and the behavior of individual fish during the summer they spend as fry drift feeding in the river. Using a stereo pair of high definition video cameras, I recorded the fine-scale behavior of schools of juvenile Chinook salmon associated with woody debris along the margins of the Chena River. I developed a software program called VidSync that recorded 3-D measurements with sub-millimeter accuracy and provided a streamlined workflow for the measurement of several thousand 3-D points of behavioral data (Chapter 1). Juvenile Chinook salmon spent 91% of their foraging attempts investigating and rejecting debris rather than capturing prey, which affects their energy intake rate and makes foraging attempt rate an unreliable indicator of foraging success (Chapter 2). Even though Chinook salmon were schooling, some were highly territorial within their 3-D school configurations, and many others maintained exclusive space-use behaviors consistent with the population regulatory effects of territoriality observed in other salmonids (Chapter 3). Finally, a twenty-year population time series from the Chena River and neighboring Salcha River contained evidence for negative density dependence and a strong negative effect of sustained high summer stream discharge on productivity (Chapter 4). The observed territoriality may explain the population's density dependence, and the effect of debris on foraging efficiency represents one of many potential mechanisms behind the negative effect of high stream discharge. In combination, these findings contribute to a statistically and mechanistically plausible explanation for the recent decline in Chena River Chinook salmon. If they are, in fact, major causes of the decline (other causes cannot be ruled out), then we can be tentatively hopeful that the population may be experiencing a natural lull in abundance from which a recovery is possible.
Author: Nathan Frost Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 0
Book Description
This plan describes the coded-wire-tagging of juvenile Chinook salmon Oncorhynchus tshawytscha on the Unuk River for the 2021 and 2022 brood years, which covers the coded-wire-tagging of parr in fall of 2022 and 2023 and smolt in spring of 2023 and 2024, and sampling returning adults for age, sex, length, and coded wire tags in escapement from the 2024 through 2029 return years. This study provides estimates of smolt and parr abundance, overwinter (freshwater) survival, mean lengths of juveniles, and harvest information of Chinook salmon originating from the Unuk River in Southeast Alaska. A separate project will be conducted on the Unuk River that employs aerial and foot survey peak counts to estimate large (≥ 660 mm mid eye to fork of tail length) adult Chinook salmon returning to the river in 2022 and 2023. The primary goals of this and the companion study are to estimate inriver run size, total run size, marine harvest and exploitation rates, harvest distribution, smolt and parr abundance, marine survival (smolt to adult) and overwinter survival (parr to smolt). The Alaska Department of Fish and Game uses this information to make local and regional management decisions and to evaluate the Unuk River Chinook salmon escapement goal, and the Pacific Salmon Commission uses the data for coastwide management and stock assessment through the Chinook Technical Committee.
Author: John Heinrich Eiler Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 296
Book Description
[Cont.] Although not surprising considering the extensive variation in migration rates observed among individual fish, this finding does suggest that these pulses do not represent cohesive aggregates of fish moving upriver. Unlike the well established methods used to estimate other life history characteristics, the development of quantitative methods for analyzing and modeling fish movements has lagged noticeably behind, due in part to the complexity associated with movement data and (prior to the advent of telemetry) the difficulty of collecting this type of information on free-ranging individuals. Two fundamentally different analytical approaches, hierarchical linear regression models and multivariate ordination, were used during this study to evaluate factors thought to influence the upriver movements of the fish. In spite of the inherent differences, both methods provided strikingly similar results, indicating that the study findings were not dependent on the approach used, and suggesting that the results were plausible based on the information available and the weight of evidence. Both analytical methods had advantages, and provided complementary information. With hierarchical linear models, it was possible to simultaneously evaluate a wide range of explanatory variables (in our case, both biological and environmental), which provided standardized comparisons and simplified the interpretation of the results. Since both fixed and random effects were incorporated in the models, it was possible to account for sources of variation when insufficient information was available to identify the underlining factors - an important consideration since few field studies provide comprehensive data. With multivariate ordination, separate analyzes were needed to examine the relationships between the migration rates and the biotic and physical variables. In addition to being cumbersome, this limitation made it more difficult to compare the relative influence of the different factors and interactions between factors. However, ordination was very useful as an exploratory tool. Although compartmentalized by stock, across fish comparisons were simple and relatively straightforward. Because the explanatory variables were evaluated separately in relation to the ordination score assigned to the fish, it was possible to examine and compare highly correlated variables. Ordination was also able to identify overall patterns within the data and assess the relative importance. While this can be accomplished within the framework of linear regression using mixture models to determine whether multiple distributions exist within the data, the process is much simpler with ordination. The migratory patterns of the fish were influenced by a wide range of factors, with evidentiary support for complex, multi-faceted relationships. Physical features of the basin demonstrated stronger explanatory power, accounting for over 70% of the observed variation in migration rate compared to 18% for the biological characteristics of the fish. Parameter estimates associated with the steepness of the migratory route and remaining distance the fish had to travel to reach their natal rivers were most strongly correlated with migration rate, with consistent relationships observed across stocks. Migration rates were also noticeably slower in extensively braided reaches of the basin. The weaker relationships between migration rate and biotic factors may reflect stabilizing selection on long-distance migrants. Smaller fish exhibited minimally faster swimming speeds on average than larger individuals. This relationship was stronger in highly braided reaches. Run timing was positively related to migration rate for most stocks. Surprisingly, upper basin stocks traveling farther upriver displayed progressively negative relationships, suggesting that late-run fish were moving slower. Ancillary information suggests that this decline may relate to deteriorating fish condition later in the season.
Author: Laura Gutierrez Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 126
Book Description
Terrestrial prey subsidies can be a key food source for stream fish, but their importance and environmental controls on their abundance have not been widely documented in high latitude ecosystems. This study investigated terrestrial invertebrate prey availability and predation by age-0+ juvenile chinook salmon (Oncorhynchus tshawytscha), overlap between terrestrial infall and drift to diet, and the relationship between diet to stream temperature and discharge in the Chena River, Interior Alaska. Terrestrial infall, drift, and juvenile chinook diet varied widely through the summers (May-September) of 2008 and 2009. Drift was comprised of 33% terrestrial and 67% aquatic invertebrate mass, while juvenile chinook diet contained 19% terrestrial, 80% aquatic, and 1% unidentifiable invertebrate mass. The proportion of terrestrial invertebrate mass consumed increased through summer and, at times, made up to 39% of total diet. Low similarity of invertebrates in diet and infall, and diet and drift suggested that fish were, in part, prey-selective, selecting hymenopterans and chironomid midges (Diptera). In both years, prey mass consumed and discharge varied inversely, but no correlation was found between proportion of terrestrial invertebrates consumed and discharge. However, the two sampling dates with the highest proportion of terrestrial invertebrates consumed occurred shortly after a 60-year flood, indicating that terrestrial invertebrates may be important during rain and associated high water. This study found that, although terrestrial infall and drift are highly variable, terrestrial invertebrates are an important prey resource for rearing chinook salmon in this high latitude riverine system, especially later in the summer.
Author: Kathrine G. Howard Publisher: ISBN: Category : Chinook salmon Languages : en Pages : 85
Book Description
Long-term monitoring of juvenile Chinook salmon Oncorhynchus tshawytscha is needed to identify recruitment and mortality processes, to understand early marine biology and ecology, and develop tools useful for fisheries management. A sampling program for Yukon River salmon was established in the northern Bering Sea in 2003 but annual sampling has been tenuous due to funding limitations. This project was designed to maintain the sampling program for Yukon River stocks, develop a genetic baseline to identify Yukon River stocks, and evaluate a lower cost survey alternative using a smaller vessel and trawl configuration. Results indicated that the genetic baseline can identify four groups of populations from Western Alaska, the two vessel/trawl configurations provided similar estimates of juvenile Chinook salmon abundance (within 20%); however, sea state limitations of the small vessel required an earlier survey timing (August rather than September). The change in survey timing contributed to differences in the spatial distribution and length of salmon caught during the 2 surveys. Surveys identified above average juvenile Chinook salmon abundance during 2014-2016 and above average juvenile abundance per spawner in 2014 and 2015. Both indicate an improvement to the recent poor production of Yukon River Chinook salmon, because juvenile abundance in the northern Bering Sea is known to be a leading indicator of adult returns for this stock. Sampling 2 different time periods provided additional insight into the early marine growth rates of juvenile Yukon River Chinook and other salmon species. Average Chinook salmon growth rate was 1.55 mm per day from marine entry to August, and 1.06 mm per day from August through September. This project represents a critical step to enable the long-term monitoring of juvenile Chinook salmon in Western Alaska and continued pursuit of factors that determine productivity and cohort strength of Yukon River Chinook salmon.
Author: Allison N. Matter
Author: Allison N. Matter
Author: Jason Neuswanger
Author: Gabriel S. Hansen
Author: Richard G. Rowland
Author: Nathan Frost
Author: Robbin L. Hunka
Author: Robert F. Raleigh
Author: John Heinrich Eiler
Author: Laura Gutierrez
Author: Kathrine G. Howard