Download Free Survival And Behavior Of Juvenile Steelhead Trout Oncorhynchus Mykiss In Two Small Estuaries In Oregon Book in PDF and EPUB Free Download. You can read online Survival And Behavior Of Juvenile Steelhead Trout Oncorhynchus Mykiss In Two Small Estuaries In Oregon and write the review.

A number of steelhead (Oncorhynchus mykiss) populations are at risk throughout Oregon, including five populations that are federally listed as threatened or endangered. However, little is known about behavior and survival of these fish as they transition from freshwater to seawater. We investigated whether estuarine survival varies on a temporal scale within or between years, on a spatial scale between zones within the estuary, and between basins within the same distinct population segment. We implanted acoustic transmitters on 69 wild steelhead smolts in the Nehalem basin and 70 in the Alsea basin and compared run timing, migration rate, and estuarine residence times between basins. We also measured gill ATP-ase levels and parasite loads in each basin to evaluate the relationship between these indices and migration timing, life history strategy or age of smoltification. In general, only 40-50% of the wild steelhead smolts tagged at upstream smolt traps were detected entering the ocean, although survival was highly variable among years. The majority of "mortality" occurred in the lower estuary near the mouth. Wild steelhead smolts spent a median of 0.72 and 0.83 d in the estuary in the Nehalem and Alsea basin, respectively, in 2009. This research provides a baseline by which we can monitor temporal changes in the survival and behavior of juvenile salmon in the estuary. Such information is vital for monitoring the impact of estuarine restoration and reiterates the importance of the lower river and estuary environment for smolt survival.
The Behavior and Ecology of Pacific Salmon and Trout combines in-depth scientific information with outstanding photographs and original artwork to fully describe the fish species critical to the Pacific Rim. This completely revised and updated edition covers all aspects of the life cycle of these remarkable fish in the Pacific: homing migration from the open ocean through coastal waters and up rivers to their breeding grounds; courtship and reproduction; the lives of juvenile salmon and trout in rivers and lakes; migration to the sea; the structure of fish populations; and the importance of fish carcasses to the ecosystem. The book also includes information on salmon and trout transplanted outside their ranges. Fisheries expert Thomas P. Quinn writes with clarity and enthusiasm to interest a wide range of readers, including biologists, anglers, and naturalists. He provides the most current science available as well as perspectives on the past, present, and future of Pacific salmon and trout. In this edition: Over 100 beautiful color photographs of salmon and troutUpdated information on all aspects of the salmon and trout life cycleExpanded coverage of trout
Juvenile steelhead are known to associate with shiner groups, though they also compete for food. Steelhead form dominance hierarchies within cohorts and aggressively defend feeding territories against all other fish. This study focused on the differential effect of shiner competition on steelhead of different social standing. Survival of subordinate juvenile steelhead was significantly enhanced by the presence of redside shiner under laboratory conditions. A factorial experiment in 80 L tanks examined the relative effects of 0, 3, and 9 shiner at 15° and 20°C on the growth and survival of 3 juvenile steelhead per tank. No temperature effect was detected and there was no significant difference in steelhead growth though statistical power was low (n=5). The largest steelhead did not die in any treatment and no steelhead died in the presence of 9 shiner. In treatments where no shiner were present mortality in the smallest steelhead was 80% (p-value
For centuries, biologists have marvelled at how anadromous salmonids – fish that pass from rivers into oceans and back again – survive as they migrate between these two very different environments. Yet, relatively little is understood about what happens to salmonid species (including salmon, steelhead, char, and trout) in the estuaries where they make this transition from fresh to salt water. This book explains the critical role estuaries play in salmonid survival. Ecology of Salmonids in Estuaries around the World synthesizes information from a vast array of literature, to describe the specific adaptation of eighteen anadromous salmonids in four genera (Hucho, Oncorhynchus, Salmo, and Salvelinus) explain the ecological relationships between anadromous salmonids, the fish they coexist with, and their estuarine habitat discuss key fitness elements salmonids need for survival (including those relating to osmoregulation, growth and feeding mechanisms, and biotic interactions) provide guidance on how to conduct estuarine sampling and scientific aspects of management and recovery plans offer directions for future research. The critical reference is further enhanced by extensive supplementary appendices that are available online, including data tables, additional references on estuarine salmonids, and a primer on estuaries and salmonids for citizen scientists.
Estuarine environments provide an essential habitat to many aquatic animals and, in some settings, can be susceptible to drastic environmental transformations caused by deviations in connectivity with the ocean. In these intermittently closed estuaries (ICEs), the presence or absence of a barrier beach, naturally controlled by wave action and river flow, determines the mouth state (closed or open). Depending on the frequency and duration of closures and reopenings, ICEs can create a conundrum for inhabitants, especially diadromous fish that must transit between marine and freshwater habitats to reproduce. Changes in connectivity to the ocean not only obstructs migration between the ocean and the river but can also cause deadly conditions, especially for juvenile pacific salmonids (Oncorhynchus spp.) that have a narrow range of physiological tolerances for the abiotic variables susceptible to large fluctuations in ICEs. Despite these hurdles, ICEs constitute essential habitats for threatened populations of steelhead (Oncorhynchus mykiss). This dissertation utilizes a threatened population of juvenile steelhead in the Russian River estuary, northern California, USA as a case study to examine an array of relevant topics about the efficacy of a juvenile anadromous fish occupying an ICE. The intersection of a threatened fish with a plastic and complex life history within an understudied system provides many challenges as well as opportunities. In addition to a brief introduction (Chapter 1) and conclusion (Chapter 6), the main chapters of this dissertation (Chapters 2-5) will address knowledge gaps specific to juvenile steelhead in the Russian River estuary. The second chapter addressed uncertainties regarding what abiotic conditions juvenile steelhead are exposed to and how steelhead may avoid physiologically stressful conditions. Specifically, we answered the following questions: (1) "What are the WQ habitats used by juvenile steelhead during open and closed conditions in an ICE?" and (2) "What behavioural change is evidenced between open and closed conditions that might alter the juvenile steelhead's risk of exposure to stressful WQ?" To answer these questions, we combined thermal sensor encoded acoustic telemetry and coincidental WQ sampling. Chapter two determined that, under open conditions, juvenile steelhead experienced primarily brackish and saline water in the lower and middle reaches and warm freshwater in the upper reach, whereas under closed conditions, they moved greater distances and were found to be aggregating near cool water refugia not used during open mouth conditions. These findings shed light on the abiotic conditions juvenile steelhead are exposed to and emphasize the importance of tributary hydrogeomorphic processes and groundwater linkages in subwatersheds that are sources of cool water refugia in ICEs. The purpose of the third chapter was to evaluate the vertical response of juvenile steelhead to the physiochemical conditions (i.e., temperature, DO, salinity) in the Russian River estuary. This chapter further explored the acoustic telemetry and simultaneously collected WQ data from chapter two to test the following hypotheses: (i) juvenile steelhead will shift their position in the water column based on prevailing physiochemical conditions; (ii) the degree to which juvenile steelhead adjust their position in the water column will vary with fish size; and (iii) smaller juvenile steelhead will risk potentially stressful conditions to take advantage of prey sources. The results indicated the depth of fish varied in response to the present abiotic conditions and typically reflected the occupation of more energetically and physiologically beneficial habitats, with smaller fish being shallower in the water column when proximate salinities are higher. Results indicated management activities that promote open mouth conditions may create challenges for steelhead that are not acclimated to saline conditions but reveal foraging strategies used by juvenile steelhead that are not yet tolerant of higher salinities. Macroinvertebrates are fundamental to the food webs, yet their response to management activities that affect connectivity to the ocean is not well understood. The fourth chapter used systematic sampling of the benthic and epibenthic macroinvertebrates to assess factors that affect the diversity and abundance of key food web taxa. Similar to other ICEs, the macroinvertebrate assemblage of the Russian River estuary was primarily composed of taxa that can deal with the variability, either physiologically or behaviourally. Furthermore, the prominent food web taxa were abundant during both open and closed mouth conditions and were found in large aggregations in habitat only inundated during closed mouth conditions. These increased densities in the closure-inundated habitat may reflect more expansive aggregations of key food web taxa that would lead to more efficient foraging for juvenile steelhead. Although the growth rates of juvenile steelhead in ICEs have been reported near the highest in literature, leading to increased marine survival, the specific factors contributing to this growth have not been specifically evaluated. The fifth chapter incorporated observed growth rates, a diet analysis, and thermal history of juvenile steelhead into a bioenergetics model to explore factors that most influence the growth potential of juvenile steelhead. In this chapter, I confirmed that growth rates of juvenile steelhead in the Russian River estuary rival the highest in literature and are attributed to ample foraging opportunities and the ability of juvenile steelhead to thermo-regulate behaviourally in the heterogeneous abiotic environment. Higher energetic costs due to higher temperatures in the upper reach were possibly buffered by the consumption of more energy dense prey. These results indicated that growth is likely not limiting the recovery of threatened steelhead in the Russian River estuary. With many populations of salmonids imperiled near their southern range, efforts for recovery could benefit from protecting habitats in ICEs and considering the impacts of management activities to the water quality conditions.
Snorkel dive estimates and an inventory of stream habitat of the juvenile steelhead (Oncorhynchus mykiss) population in the Steamboat Creek basin were made in the summers of 1987 and 1988. Emigration was monitored by fish trapping from spring through fall of 1988. Distribution, abundance, and habitat utilization of juvenile steelhead were affected by stream size and temperature. The majority (65%) of age>1 fish were in two mainstem channels, whereas numbers of age 0 fish were more evenly distributed throughout the basin. Age>1 fish significantly (PO.005) increased their use of riffles with depth, and avoided shallow riffles. Where riffles were apparently too shallow, age1 steelhead utilized pool habitat to a greater extent. Age>1 steelhead greatly avoided glides in all sizes of channels. Age 0 steelhead appeared to be less restricted in their choice of habitat than age>1 fish. Age 0 fish, presumably by virtue of a smaller body size, showed only slightly increased use of riffles with depth. Both age 0 and>1 steelhead increased their use of riffles in streams with higher temperature regimes. Densities of age>1 fish in channels with large boulder substrate increased significantly (p=O.02) with mean riffle depth, probably as a function of more wetted area being useable in streams with deep riffles, and more feeding microhabitats being afforded by rough channels. Densities of age 0 fish did not appear to be affected by the range of stream sizes studied, or by channel roughness, but were low in all channels with high stream temperatures. Compared to other steelhead producing streams, Steamboat Creek had low summer rearing densities, small smolts, and an exceptionally high proportion of fish emigrating as parr (considered to be at least one year away from development of smolt characteristics). Roughly 120,000 age 0 steelhead, 60,000 parr, and 4,100 steelhead smolts were estimated to have emigrated from the basin. Most parr emigrated in the spring when stream flows were high, whereas the majority of age 0 fish emigrated during summer base flow recession. I suggest that parr emigration from Steamboat Creek may be a life history adaptation that takes advantage of rearing conditions downstream in the North Umpqua River.
Wild Steelhead Trout, Oncorhynchus mykiss, in the Puget Sound are currently in decline, and very little is known about the early life history of these threatened fish. This study evaluated consequences of early life growth in terms of survival to smolt or adult stages. The objectives of this study were to determine whether significant size-selective mortality (SSM) in Steelhead could be detected between freshwater stages and returning adults; and if so, how the magnitude of size selectivity varied among reaches categorized by three different precipitation zones (snow, mixed rain-snow, or rain). Wild Steelhead in the Skagit River basin were sampled as juveniles, smolts, and adults, and scales were measured to compare back-calculated freshwater growth rates and size distributions of rearing juveniles with individuals that survived from an earlier life stage to the smolt and adult stages. Linear regression of scale radius (SR) and fork length indicated that SR was a reasonable predictor of fork length during freshwater residency. Back-calculated size-at-annulus estimates indicated that fish sampled as adults grew significantly faster to age 1, 2, and 3 annuli compared to fish sampled as juveniles, and faster to the age 2 and 3 annuli compared to fish sampled as smolts. Within precipitation zones, fish sampled as juveniles were consistently smaller at each freshwater annulus compared to those same freshwater annuli on fish sampled as adults. An increased disparity in size-at-annuli 2 and 3 between fish sampled as juveniles, smolts, and adults suggests that fast growth during the period at which Steelhead smoltify is vitally important to survival to adulthood. These findings provide evidence that survival among life stages is an important dynamic in wild Steelhead, and can be attributed, in part, to size attained at earlier life stages. Efforts for recovery of threatened Puget Sound Steelhead could benefit by considering growth- and size-selective mortality in freshwater environments, and identifying factors that limit early life growth at a finer scale of habitat, for example among sub-basins or precipitation zones.