Abundance, Size, Habitat Utilization, and Intrastream Movement of Juvenile Coho Salmon in a Small Southeast Alaskan Stream PDF Download
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Author: Roger Dean Harding
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 216
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Author: Roger Dean Harding
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 216
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Author: Mason D. Bryant
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 88
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We describe a protocol to monitor the effectiveness of the Tongass Land Management Plan (TLMP) management standards for maintaining fish habitat. The protocol uses juvenile coho salmon (Oncorhynchus kisutch) in small tributary streams in forested watersheds. We used a 3-year pilot study to develop detailed methods to estimate juvenile salmonid populations, measure habitat, and quantitatively determine trends in juvenile coho salmon abundance over 10 years. Coho salmon have been shown to be sensitive to habitat alterations, and we use coho salmon parr as the primary indicator in the protocol. A priori criteria for type I and type II error rates, effect size, and sample sizes for the protocol were derived with estimates of variance computed from the 3-year pilot study. The protocol is designed to detect trends in abundance of coho salmon parr, as well as coho salmon fry and Dolly Varden (Salvelinus malma), in small streams managed according to TLMP standards and guidelines and to compare these to trends in unmanaged (old-growth) watersheds. Trends are adjusted to account for statistically significant habitat covariates. This information provides an important element in monitoring land management practices in the Tongass National Forest. The methods we describe may have application to monitoring protocols elsewhere for fish populations and land management practices.
Author:
Publisher:
ISBN:
Category : Ecology
Languages : en
Pages : 360
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Author: Brianna Dailey Pierce
Publisher:
ISBN:
Category :
Languages : en
Pages : 97
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Estuaries are valuable nursery grounds for anadromous Pacific salmon supplying diverse habitats, quality foraging grounds, and a transition between freshwater and saltwater environments. By providing alternative rearing habitats, estuaries may also bolster the life history diversity expressed in a population, thereby increasing population-level stability. Conversely, the degradation and loss of estuarine habitats has been partially responsible for declines in wild salmon populations. In Alaska, most natural systems are largely intact with minimal anthropogenic alterations. However, the human population and associated land use is increasing. Alaska has the opportunity to learn from the mistakes made in the Pacific Northwest and identify and protect the critical rearing habitat of these culturally, economically, and ecologically valuable species. To do so, we need an understanding of how juvenile salmon use Alaskan estuaries. In this thesis, I describe the resource use, residence, and movement patterns of juvenile salmon in the Anchor River estuary in southcentral Alaska. Specifically, I (1) assess the resource partitioning between juvenile Coho and Chinook salmon, (2) determine which age classes use the estuary and for how long, (3) examine the tidal movement of juvenile salmon, and (4) utilize a social network analysis to explore the social structure of juvenile Coho Salmon. Coho and Chinook salmon primarily partitioned resources spatially and to a lesser extent temporally, whereas their prey resources overlapped considerably. Varying abundances of Chinook Salmon provided a natural experiment that I used to determine that Coho Salmon interactively partition habitat resources by primarily occupying tidal marsh channels when Chinook Salmon are present in the main channel. Although juvenile Coho Salmon were present throughout the sampling period (May-Oct), they were most abundant later in the season (Aug) and individuals of all three age classes reared in the estuary for over 100 d. Some Coho Salmon tagged in 2015 were still present in the estuary in 2016. Chinook Salmon were most abundant earlier in the season (Jun-July) and did not remain in the estuary past mid-August. The longest individual residence time for a Chinook Salmon was 42 d. Channel connectivity influenced the tidal movement patterns of Coho Salmon. I used passive integrated transponder (PIT) tags and in-channel antennas to assess fish movement in two marsh channels. In the marsh channel that remained fully connected to the main channel at low tide, fish movement was mostly independent of the tidal stage or channel depth. In the marsh channel that was only marginally connected to the main channel, fish detections were greatest when the tidal stage was high enough to raise the channel depth. However, contrary to my expectations, fish were detected throughout the tidal cycle and at all channel depths, indicating that they used the marginal connection to move between habitat patches even at low tide. Juvenile Coho Salmon social relationships varied through time. I constructed static and dynamic social networks from the time-stamped observations of fish detections to explore the social structure of juvenile Coho Salmon. Fish did not preferentially associate with similarly sized fish. Fish did not appear to maintain stable relationships, but instead exhibited fission-fusion dynamics where social relationships were continually formed and dissolved, indicating that the frequent co-occurrence of individuals is likely due to mutual site fidelity and not social preference. Although the Anchor River is relatively small, the salmon populations it supports are highly important to the culture, economy, and ecology of the region. The results of this thesis demonstrate that the diverse habitats of the estuary support multiple species and life history types for prolonged periods. By appropriately identifying and conserving critical juvenile salmon rearing habitat, we can help maintain healthy salmon populations into the future. This thesis includes an animated dynamic social network (Video S1) provided as supplementary material.
Author: Daniel L. Bottom
Publisher:
ISBN:
Category : Nature
Languages : en
Pages : 396
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Author: Kevin Michael Foley
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 286
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Understanding how headwater streams function as rearing habitats for juvenile coho salmon Oncorhynchus kisutch is essential for effective population management and conservation. To inform habitat restoration activities within the Matanuska-Susitna Valley, Alaska, I determined upstream distribution limits, validated abundance estimates, and established fish habitat relationships in two headwater stream tributaries of the Little Susitna River in 2010-11. Using a low-effort, spatially continuous sampling approach and linear mixed-effects models, I related local- and landscape-scale habitat associations to abundance estimates. All-aged coho salmon composed approximately 98% of all fish sampled and inhabited the entire stream length to their upstream limits. Age-1+ fish resided in 64% and 44% of the stream length for the two sampled streams. The mean upstream elevation limit for all-aged fish in these streams was 278m and 267m. For age- 1+ fish, the upstream elevation limit in the two streams was 275m and 238m. Percent slope at the distribution limit of all-aged fish was consistent across streams at 5%, whereas percent slope for age-1+ fish correspond to 4% and 6%. Elevation and percent slope consistently described upstream distribution limits among age classes. Therefore, we must consider these landscape features when prioritizing restoration projects in headwater streams.
Author: Jeffrey D. Rodgers
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 122
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The abundance of the 1982 brood of juvenile coho salmon (Oncorhynchus kisutch) was determined in August 1983, and January and April 1984 at 20 study sites spread throughout Knowles Creek, an Oregon coastal watershed. The timing of emigration of juvenile coho from the watershed was monitored from October 1983 through June 1984. Condition factor, fork length, and gill (Na+K)-ATPase activity were measured in migrants, a captive group of Knowles Creek juvenile coho held in the laboratory, and nonmigrant fish periodically sampled from the stream. Skin guanine levels were also measured in migrant and nonmigrant groups. Juvenile coho abundance in January was significantly correlated with abundance in August. Wood volume and amount of undercut streambank were the pair of physical variables that best explained variation in the number of fish per square meter or per cubic meter in January. Two debris torrent ponds in the middle of the watershed contained large amounts of woody debris and were the most heavily used overwintering habitats for juvenile coho in the Knowles Creek. Few juvenile coho overwintered in the lower half of watershed, an area lacking woody debris. Peaks in outmigration occurred in November and May. Approximately 24% of the total number of migrants emigrated in November. Fish that reared in two of three third-order areas in summer, together with fish from the lower (fifth-order) half of the mainstem, were the first to leave the watershed. While lack of winter habitat may have been the cause of migration from the lower mainstem, low summer streamflows may have caused early migration from the low order sites. Gill (Na+K)-ATPase activity of migrants rose gradually from a low in January to a peak at the end of the study in June. Mean gill (Na+K)-ATPase activity of nonmigrants was only significantly lower than that of migrant fish during April. Gill (Na+K)-ATPase of captives was similar to that of nonmigrants until it peaked during the last two weeks in April, after which the activity fell below that of migrants or nonmigrants. Condition factor of nonmigrant fish was higher than either migrants or captives throughout the study. Migrant skin guanine levels rose sharply during the first two weeks in April and continued to rise until the end of the study in June. Approximately 8,300 juvenile coho, 44% of the estimated number of juvenile coho present in Knowles Creek in August, migrated from the watershed by the following June. An estimated 9% of the August population migrated as smolts after April 1.
Author: Adam D. Weybright
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 110
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Juvenile salmonids display highly variable spatial and temporal movement patterns that are influenced by density dependent (e.g., competition, predation) and density independent (e.g., genetics, stream discharge, physical habitat conditions) factors. The effects of these factors differ with fish life history stage, but will ultimately affect how salmonids utilize freshwater nursery habitats and influence their size at smolting. Although juvenile coho salmon (Oncorhynchus kisutch) (Walbaum 1792) movement patterns and their relationships with body mass have been previously examined, the temporal scale considered in most studies has been within individual seasonal periods. In this study, we monitored the movement of PIT tagged juvenile coho salmon throughout the period of freshwater residence in an entire southern Oregon coastal basin to identify the prevalent sedentary and mobile strategies these fish may adopt and to examine possible relationships between those strategies and fish body mass, growth and survival. Specific objectives include: 1) to describe juvenile coho salmon movement strategies and patterns during the freshwater residence period; 2) to determine the relative proportions of juvenile coho salmon that exhibit each movement strategy; 3) to establish whether juvenile coho salmon body mass and growth rates are related with a set of habitat variables recorded during this study; 4) to determine whether coho salmon body mass or growth rates are related to movement strategy; and 5) to evaluate whether winter survival of juvenile coho salmon is associated with movement strategy. Results revealed seasonally and spatially variable movement. More than half of coho salmon tracked throughout the period of freshwater residence exhibited movement behavior that differed between summer and winter seasons. Within seasonal periods, coho salmon in tidally affected reaches exhibited greater prevalence of mobile behavior relative to those in riverine reaches. Regression analysis indicated coho biomass density, habitat unit structural complexity and size at tagging were important in predicting summer growth of coho salmon. Juvenile coho salmon that were mobile during summer were either larger or no different in body mass in early summer relative to fish that exhibited sedentary behavior. Similarly, no consistent differences were observed between sedentary and mobile coho salmon in regards to summer growth. Coho salmon that were sedentary in summer and winter experienced higher apparent winter survival than mobile fish in each season, though the reach in which an individual resided at the start of winter appeared to also affect survival. Coho salmon residing in the tide gate reservoir reach and mainstem headwater reaches experienced greatest apparent winter survival. These results indicate that juvenile coho salmon movement within a stream basin is spatially and temporally variable and that mobility does not necessarily indicate inferior competitive ability. In a broader context, variable movement patterns reflect the capacity for plastic behavior in salmonids and this research demonstrates the importance of maintaining seasonally diverse freshwater and estuarine nursery habitats for juvenile fish.
Author: Michelle Catherine Nelson
Publisher:
ISBN:
Category :
Languages : en
Pages : 104
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The movement of nutrients across ecosystem boundaries can affect recipient ecosystems at individual, population, and community levels. This is particularly the case when more productive systems subsidize less productive ones, where subsidies can sustain and enhance populations in nutrient-poor recipient environments. One prominent example of this is the annual migration of salmon from the marine environment into low-productivity freshwater streams for spawning. This thesis uses data collected from 47 near-pristine streams on the central coast of British Columbia to study spawning chum (Oncorhynchus keta) and pink (O. gorbuscha) salmon and the ecological implications of their nutrient subsidy, focusing on stream-rearing juvenile coho salmon (O. kisutch). While considering a broad suite of habitat characteristics, the strongest predictors of juvenile coho size and abundance were spawning chum and pink salmon abundance. Streams with more spawning chum salmon had larger coho, while streams with more spawning pink salmon had higher coho populations. Further, the evidence suggested the negative association between juvenile coho and their intraguild predators/competitors, sculpin (Cottus aleuticus and C. asper), may be reduced as more spawning salmon nutrients became available. Altogether, this thesis shows strong impacts of marine-derived nutrient subsidies to freshwater ecosystems at multiple ecological scales. In general, it provides insights into the ecological mechanisms by which species interact with their environments, the potential for nutrient subsidies to affect recipient populations through changing food supply and predator-prey dynamics, and the role of multi-trophic interactions in subsidized trophic cascades. In specific, this research improves our understanding of the potential positive feedback between different species of salmon while incorporating the importance of multiple habitat characteristics. This has the potential to inform conservation and ecosystem-based management, particularly in light of the drastic decline in spawning salmon abundance in northern Pacific regions.
Author: Dalton J. Hance
Publisher:
ISBN:
Category : Coho salmon
Languages : en
Pages : 77
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From the summer dry season to the winter wet season. Such movement that connects summer and winter habitats may be particularly important for coho salmon, O. kisutch, because availability of overwintering habitat can limit freshwater survival for this species. Here, I describe basin-scale variability in the spatial pattern of fall movement for juvenile coho salmon between mainstem and tributary streams during the fall of 2002, 2003, 2004, and 2005. Juvenile coho salmon were tagged with a passive integrated transponder (PIT) and could be detected at five stationary detection sites, two located in perennial tributaries, two in intermittent tributaries, and one in the upper mainstem of the West Fork Smith River, Oregon. For each detection site, I compare the likelihood of detection during the fall by juvenile coho salmon from tagging locations over a multi-kilometer range of distances in each direction away from the tributary confluence. I developed logistic regression models with data from each detection site to estimate: 1) the relative likelihood of immigration into a tributary as compared to emigration out of the tributary, and 2) the relative likelihood of immigration into a tributary from the mainstem downstream of the tributary confluence as compared to immigration from the mainstem upstream of the confluence. For each pair of directions at each detection site, I also compare the change in the likelihood of detection with increasing distance for each direction. Overall, at the two upper-river detection sites, juvenile coho salmon were more likely to emigrate than to immigrate. At the remaining detection sites, juvenile coho salmon were no more likely to emigrate than immigrate. Of these detection sites, fish that immigrated into the mid-river perennial stream were more likely to come from the mainstem downstream of the confluence, whereas fish that immigrated into the two lower-river intermittent tributaries were more likely to come from the mainstem upstream of the confluence. Fall movement of juvenile coho salmon between tributary and mainstem habitat can occur over relatively long distances. This case study demonstrates variation among tributaries in the overall likelihood of emigration and immigration and in the source of immigrants from the mainstem, which may be related to spatial context that combines the physical characteristics and network position of tributary streams. The demonstrated variation in fall movement that connects summer and winter habitat within a stream network is a first step in exploring how complexity in movement interacts with the spatial arrangement and quality of seasonal habitats. More research on the causes of variation in the expression of fall movement will improve our understanding of how the spatial arrangement of habitat within a stream network influences the survival of juvenile coho salmon over the whole freshwater life cycle.
