Identification of Spawning Areas and the Influence of Environmental Variation on Freshwater Migration Timing and In-river Movements of Adult Coho Salmon in the Buskin River, Alaska PDF Download
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Author: Michelle Eileen Stratton Publisher: ISBN: Category : Coho salmon Languages : en Pages : 170
Book Description
The timing of freshwater entry by anadromous salmonids varies markedly among species and populations within species and is frequently used as an indicator of local adaptation to sitespecific patterns of selection. Although complex stock structure is most often associated with large watersheds that have extensive habitat diversity, even small drainages can produce multiple co-occurring stocks that differ in migratory timing. In addition, migration timing can be influenced by within-year environmental conditions experienced by migrating individuals en route to spawning sites, staging near the river mouth in the ocean, or within the river itself. Each stage of migration through both freshwater and saltwater could be altered based on climatic drivers and how each individual fish reacts to these stressors. The objective of this thesis was to assess the potential for stock structure in Coho Salmon within a small coastal watershed on Kodiak Island, Alaska by 1) identifying important differences in spawning and holding locations associated with run timing, length, and stream life between main stem and tributary spawners, 2) quantifying the influence of large-, intermediate-, and local-scale climate variables on freshwater entrance timing and in-river movements. To address the first objective, fish were tracked to their spawning locations using acoustic telemetry in three spawning seasons (2015-2017). I detected no statistically or biologically meaningful differences in body size (length, mm) or migration timing into the river between main stem and tributary spawning fish. Unexpectedly, I found that a large portion of fish (80%) utilize the lake during their in-river migration suggesting the lake may represent critical staging habitat for adult Coho Salmon prior to spawning. I also identified holding habitat throughout the river that both spawning groups consistently used across years that also appears to be important to premature migrating Coho Salmon. In Chapter Two, I analyzed 33 years of freshwater entrance timing data and utilized radio tags to track in-river movement to quantify the influence of precipitation and temperature on total distance moved and probability of moving. Despite marked variation among years, I found no evidence of a temporal trend in entrance timing based on escapement counts, which contrasts with other recent examples throughout Alaska reporting changes in run timing. The strongest influence on timing of freshwater entry was ocean sea surface temperature, where cold temperatures delayed entry up to 11 days. Within-river movements were positively related to precipitation and temperature, confirming local traditional knowledge in this system, and consistent with life history patterns of Coho Salmon. The primary messages of this thesis are that i) any within-watershed stock structure is unlikely to be differentially affected by harvest or management given overlapping run timing, body size, and use of main stem holding areas; future population genetics analyses would be an obvious and illuminating next step to assess the extent to which main stem and tributary spawners are reproductively isolated groups; ii) both main stem and tributary spawners use Buskin Lake as holding habitat prior to spawning, and thus assumptions that fish that enter the upper watershed are destined to spawn in headwater tributaries are invalid, which in turn limits the utility of enumerating adult passage into the lake for escapement-based management, iii) adult freshwater entrance timing is highly variable but not changing systematically through time, though the extent to which the variation in timing reflects environmental response vs. uncertainty in the counts at the weir is unknown, and iv) low precipitation and warm temperatures suppress movement and result in protracted use of main stem and lake habitats for holding, which may put some individuals at risk to angler harvest or, in extreme events, potentially low dissolved oxygen environments. Spatial management that restricts fishing in locations of known primary holding habitats may be an option to reduce probability of mortality and stress in years of low adult abundance.
Author: Michelle Eileen Stratton Publisher: ISBN: Category : Coho salmon Languages : en Pages : 170
Book Description
The timing of freshwater entry by anadromous salmonids varies markedly among species and populations within species and is frequently used as an indicator of local adaptation to sitespecific patterns of selection. Although complex stock structure is most often associated with large watersheds that have extensive habitat diversity, even small drainages can produce multiple co-occurring stocks that differ in migratory timing. In addition, migration timing can be influenced by within-year environmental conditions experienced by migrating individuals en route to spawning sites, staging near the river mouth in the ocean, or within the river itself. Each stage of migration through both freshwater and saltwater could be altered based on climatic drivers and how each individual fish reacts to these stressors. The objective of this thesis was to assess the potential for stock structure in Coho Salmon within a small coastal watershed on Kodiak Island, Alaska by 1) identifying important differences in spawning and holding locations associated with run timing, length, and stream life between main stem and tributary spawners, 2) quantifying the influence of large-, intermediate-, and local-scale climate variables on freshwater entrance timing and in-river movements. To address the first objective, fish were tracked to their spawning locations using acoustic telemetry in three spawning seasons (2015-2017). I detected no statistically or biologically meaningful differences in body size (length, mm) or migration timing into the river between main stem and tributary spawning fish. Unexpectedly, I found that a large portion of fish (80%) utilize the lake during their in-river migration suggesting the lake may represent critical staging habitat for adult Coho Salmon prior to spawning. I also identified holding habitat throughout the river that both spawning groups consistently used across years that also appears to be important to premature migrating Coho Salmon. In Chapter Two, I analyzed 33 years of freshwater entrance timing data and utilized radio tags to track in-river movement to quantify the influence of precipitation and temperature on total distance moved and probability of moving. Despite marked variation among years, I found no evidence of a temporal trend in entrance timing based on escapement counts, which contrasts with other recent examples throughout Alaska reporting changes in run timing. The strongest influence on timing of freshwater entry was ocean sea surface temperature, where cold temperatures delayed entry up to 11 days. Within-river movements were positively related to precipitation and temperature, confirming local traditional knowledge in this system, and consistent with life history patterns of Coho Salmon. The primary messages of this thesis are that i) any within-watershed stock structure is unlikely to be differentially affected by harvest or management given overlapping run timing, body size, and use of main stem holding areas; future population genetics analyses would be an obvious and illuminating next step to assess the extent to which main stem and tributary spawners are reproductively isolated groups; ii) both main stem and tributary spawners use Buskin Lake as holding habitat prior to spawning, and thus assumptions that fish that enter the upper watershed are destined to spawn in headwater tributaries are invalid, which in turn limits the utility of enumerating adult passage into the lake for escapement-based management, iii) adult freshwater entrance timing is highly variable but not changing systematically through time, though the extent to which the variation in timing reflects environmental response vs. uncertainty in the counts at the weir is unknown, and iv) low precipitation and warm temperatures suppress movement and result in protracted use of main stem and lake habitats for holding, which may put some individuals at risk to angler harvest or, in extreme events, potentially low dissolved oxygen environments. Spatial management that restricts fishing in locations of known primary holding habitats may be an option to reduce probability of mortality and stress in years of low adult abundance.
Author: Rachel LovellFord Publisher: ISBN: Category : Coho salmon Languages : en Pages : 146
Book Description
Coho salmon (Oncorhynchus kisutch) migration and spawning are unique components of the salmon life cycle because they require synchrony of behavior with other individuals as well as with acceptable fluvial conditions. As with other organisms that exhibit group mating behavior, it is likely that environmental cues trigger coho salmon movement to spawning grounds. These cues may also provide usable habitat for migration and spawning. River discharge, temperature, and length of day have long been assumed to be the environmental cues which trigger migration and spawning of coho salmon as coho return within the same season each year to spawn. Hatchery studies have also shown that the timing of reproductive behavior is heritable. If this heritability is determined by the fluvial conditions of the spawning grounds, then a predictable relationship should exist between reproductive behavior and the hydrologic and thermal regimes. Surprisingly, no defensible correlations between discharge thresholds and spawning or migrating activity have been identified for naturally reproducing coho salmon. Thermal, velocity, and depth limitations have been identified for coho salmon, but these values have not been examined in combination or within the context of a hydrologic and thermal regime. This study compares interannual patterns in the timing of coho mid-river migration in the North Umqua (180 km up river from the estuary) and the initiation of spawn timing in the Smith River basins (Oregon) with river discharge and water temperature data to ascertain whether these behaviors are driven by fluvial conditions. Additionally, we used this data to identify the window over which most migration and spawning takes place in our test systems. On the North Umpqua, coho salmon mid-river migration initiated (first 5% of migrants) after summer peak temperatures and following a threshold average daily temperature of 18° C, but before fall storm events occurred. In most years, approximately 75% of the migrating coho salmon have moved past the Winchester Dam before fall storms initiated and when discharge remained less than the 11 year average for the month of November, more similar to summer than winter flow levels. Additionally, characteristic lengths and numbers of peaks within the distribution of annual migrations were attributable to the generational cohort that the migration belonged to despite the similarity in population size across all years. These patterns in the distribution of generational cohorts suggest an inherited timing response as well as highlight cohorts which may contain diminished sub-populations. The initiation of coho salmon spawning appears limited both by a thermal threshold of 12° C in all basins, as well as by a minimal discharge threshold, which is unique to each stream. Continued spawning activity occurs as discharge remains elevated from fall levels. It is also notable that there was no statistical difference in the date of the initiation of spawning within each basin in a given year or across years at a given site. Together, these studies highlight the important role that the coho salmon genome plays in reproductive timing as well as the ways that fluvial thresholds limit reproductive behavior in time. Coho have survived because of their genome has been resilient when faced with environmental change. Future work should consider variability in fluvial conditions relative to coho salmon phenotypic plasticity over time. Coho salmon phenotypic plasticity will determine whether the rate of change of the hydrologic and thermal regimes important to coho salmon survival outpaces the coho's ability to adapt. This study contributed to this future work by establishing baseline relationships between the behavior of a threatened species and measurable environmental thresholds.
Author: Publisher: ISBN: Category : Coho salmon Languages : en Pages : 124
Book Description
Coho salmon (Oncorhynchus kisutch) rely on unique habitats during the winter season, which may dictate how much individuals may growth and when migration from freshwater rearing habitat to the ocean occurs. Here I analyze movement timing and growth patterns for coho salmon through a field-based study and a literature review. For the field portion, I examined hatchery-stocked juvenile coho salmon across four stream basins in the Russian River watershed, California to determine the relative importance of climate, landscape, and fish size metrics in predicting movement and growth patterns over a winter rearing and spring smolt outmigration time period (December 2014-June 2015). I observed three unique movement strategies: winter parr movement, spring smolt movement, and inter-tributary movement. Movement was predicted in relation to daily temperature and precipitation, followed by in-stream and upslope basin conditions in random forest modeling. Specifically, fish that moved later were associated with basins that contained higher productivity and low-gradient floodplain habitats, while fish that moved earlier came from streams that lacked invertebrate prey and had limited low-gradient rearing habitat. Fish size and timing of movement were the primary predictors of growth, with relatively larger fish in the spring growing faster than fish that were relatively smaller prior to winter. These relationships suggest that hatchery-release fish are still highly influenced by environmental conditions once released, especially in terms of initial seasonal movement, and that watershed conditions should be considered when utilizing hatchery-rearing programs to supplement wild fish populations. In North America, coho salmon populations are distributed from Alaska through California, and may exhibit unique movement and growth patterns in relationship to population-scale vulnerability (Endangered Species Act listing), basin area, and availability and types of rearing habitat. For the second part of my thesis, I conducted a literature review to assess what factors are commonly considered in predicting movement and growth patterns for these fish, as well as the types (season and life stage) and number of movement strategies reported. Eighteen studies were summarized, of which sixteen identified unique movement strategies, ranging from one to four. Despite a wide range of basin areas and latitudes, winter parr and spring smolt movements were commonly observed, with authors primarily relating these behaviors to in-stream habitat and fish size metrics. Additionally, growth was linked positively and primarily with off-channel winter rearing, which may outweigh the importance of fish size in predicting growth when high quality rearing habitats are available during the winter season. Recognizing movement timing diversity and its drivers can help recover threatened coho salmon populations. More widely distributed populations may have unique phenotypic expressions based on localized genetic and environmental interactions, increasing diversity and overall stability across the population, a concept known as the portfolio effect. Understanding fish-habitat relationships can aid recovery efforts by providing a framework of climatic and watershed conditions that support unique behaviors, even in already severely limited populations.
Author: Betsy W. McCracken Publisher: ISBN: Category : Coho salmon Languages : en Pages : 212
Book Description
Coho Salmon Oncorhynchus kisutch are the most widely distributed Pacific salmon species across Alaska. The lack of knowledge surrounding the habitat requirements of this species results in challenges for conservation and management due to natural and anthropogenic pressures. Tributaries of the Susitna River drainage in Alaska support many small and distinct Coho Salmon populations. Heterogeneity of in-stream spawning habitat is an ecological concept known to promote resiliency of salmonid populations. The goal of this study was to investigate the best habitat predictors of spawning site selection and the scale by which spawning habitat should be evaluated for management insights. Scale is particularly important when measuring, assessing, and predicting potential impacts to species from development activities because habitat research at the stream rather than the reach scale can overestimate the amount of available spawning habitat. I investigated a suite of field-measured stream habitat variables paired with empirical Coho Salmon spawning survey data in five tributaries during 2013 and 2014. Physical data was defined as biotic and abiotic surroundings of an organism or population that have an influence on survival, development, and evolution. Mixed-effects modeling results indicated that Coho Salmon spawning-site selection was positively related to gravel substrate and the presence of groundwater flux, and that spawning Coho Salmon avoided cobble substrate. Physical data were analyzed at both the stream and reach scales, and mixed-effects modeling results further concluded that variation in spawning activity at the reach scale (variance = 1.34, SD = 1.16) accounted for more variability and was more predictive than at the stream scale(variance = 0.04, SD = 0.19). This is important because fish habitat-associations identified at the reach scale were not identified at the stream scale. These results highlight the need for multi-scale habitat data collections and analyses to identify the most meaningful fish-habitat associations.
Author: Frederick A. Goetz Publisher: ISBN: Category : Languages : en Pages : 187
Book Description
The overall period of marine residence was similar among fish from different river basins and life stages; larger bull trout entered marine waters in late winter-early spring, juveniles in late spring, and most fish migrated back into rivers by late spring-early summer as temperatures were increasing. However, the timing of return migration was similar among rivers despite differences in their thermal regimes. Some fish entered and exited the rivers in the fall but few overwintered in marine areas. Most fish occupied estuary and nearshore areas near natal rivers but some moved over 100 km from the river mouth. These timing patterns and use of marine habitats contrast strongly with those of other salmonids in Puget Sound, revealing the diversity in migratory behavior under the broad category of anadromy, and emphasizing the importance of estuarine and nearshore habitats for the conservation of bull trout, listed as Threatened under the U. S. Endangered Species Act. Behavioral thermoregulation by adult Chinook salmon (Oncorhynchus tshawytscha) and comparison to sockeye salmon (O. nerka) in estuary and freshwater habitats prior to spawning The movements and thermal experience of Pacific salmon during their homeward migration through marine waters and into freshwater systems pose challenges for their physiology, especially in river basins altered by human structures and activities, and under regimes of increasingly high temperatures. This study determined the thermal regimes experienced by maturing Chinook salmon, Oncorhynchus tshawytscha, entering the Lake Washington basin via a navigational locks and canal, and migrating through the lake to spawning grounds or hatcheries. We then compared these patterns, determined from a combination of acoustic tracking and temperature loggers attached to the fish, with comparable data on sockeye salmon collected in an independent study in overlapping years. Chinook salmon exhibited complex patterns, occupying cool water refuges in stratified marine and freshwater areas: 1) in Puget Sound (28-30 ppt, 12-15 oC), 2) in deeper water in the salt wedge (upper estuary) above the locks (12-15 ppt, 18-21 oC), and 3) intermittently in deeper fresh water in Lake Washington (9-21 oC). Most Chinook salmon (> 75%) left the estuary after tagging and spent a short period (mean 4.6 d) in Puget Sound). Upon return to the upper estuary Chinook salmon either held in a small, cool area in the salt wedge (mean 11.1 d) or went back to Puget Sound twice to hold in tidally influenced saltwater. Sockeye salmon exhibited a fairly simple migration pattern, holding for a short period in warm water (median 18.4 oC) in the upper estuary and canal (mean 3.6 d), then migrating to the lake and residing in cold-water areas (mean 10.3 oC) at depths of 40 m (mean 88.3 d). Sockeye and Chinook salmon travelled through a 10.8 km canal to Lake Washington in relatively short periods, 2 d and 0.5 d (mean) respectively, but Chinook salmon experienced higher temperatures (20-22.5 oC) because they migrated later in summer. In Lake Washington Chinook salmon exhibited vertical migrations above and below the thermocline and used the lake as a thermal refuge to a lesser extent than did sockeye salmon, which remained below the thermocline almost exclusively until they ascended rivers to spawn. Individual fish utilized different migration paths and so had distinct thermal experiences but survived to reach breeding sites. The ability to exploit multiple refuges in this highly modified migratory corridor may be essential for the persistence of these species and especially the Chinook salmon. In the face of climate change, understanding how fish use available thermal refuges may help identify management alternatives to retain or increase these areas in the future.
Author: Douglas Clifford James Braun Publisher: ISBN: Category : Fish populations Languages : en Pages : 240
Book Description
Processes linking the environment and life histories are central to our understanding of population dynamics. This thesis combines life history theory and environmental variation to explain recruitment dynamics among populations in Fraser River sockeye salmon (Oncorhynchus nerka). I first explore relationships between spawning stream characteristics and spawning densities and show that streams with more cover have higher spawning densities. Next, I use a 21-year time series for three of these populations to explore hypotheses about how maternal life history traits and migration conditions, experienced during upstream migrations to their spawning grounds, influence reproductive investment. Maternal body size is strongly linked to total reproductive investment and both egg mass and fecundity; however, migration difficulty only influences egg mass and not fecundity. Using the same dataset, I show that egg mass and incubation temperatures influence juvenile fitness-related traits including length, mass and emergence timing. The main finding from these analyses, that warmer incubation temperatures result in lighter juveniles that emerge earlier, led to hypotheses about how incubation temperature might select for egg size among populations. I tested these hypotheses by comparing 16 populations and confirmed the prediction that in streams with warmer water, fish would produce heavier eggs. I then asked if these same maternal traits and environmental conditions would relate to adult recruitment dynamics. Populations spawning in streams with deeper water had higher maximum population growth rates and less variable recruitment. In addition, populations in streams with larger gravel exhibited stronger density-dependence. Finally, I develop a novel framework for evaluating how habitat data, combined with the cost of collecting such information, can be used in developing cost-effective surveys. I demonstrate this general framework with a simple example using the relationships between stream characteristics and sockeye densities, considering the costs and effectiveness of stream variables. Overall, this demonstration of the joint role of maternal traits and environmental conditions in recruitment dynamics supports the potential use of such variables as indicators of population dynamics in the absence of long-term demographic data. Furthermore, it supports the development of cost-effective surveys, which is important as human impacts on populations increase, and as monitoring resources decline.
Author: Michelle Eileen Stratton
Author: Michelle Eileen Stratton
Author: Rachel LovellFord
Author: Jonathan J. Goin
Author: 
Author: Betsy W. McCracken
Author: Cedric X. Cooney
Author: Kim Dennis Hyatt
Author: Leon D.. Shaul
Author: Frederick A. Goetz
Author: Douglas Clifford James Braun