The Effects of Structural Enhancement on Chinook Salmon (Oncorhynchus Tshawytscha) Spawning Habitat PDF Download

Author: Robyn Louise Bilski
Publisher:
ISBN:
Category :
Languages : en
Pages : 288

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 199

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This report describes research conducted by the Pacific Northwest National Laboratory for the Bonneville Power Administration (BPA) as part of the Fish and Wildlife Program directed by the Northwest Power and Conservation Council. The study evaluated the restoration potential of Snake River fall Chinook salmon spawning habitat within the impounded lower Snake River. The objective of the research was to determine if hydroelectric dam operations could be modified, within existing system constraints (e.g., minimum to normal pool levels; without partial removal of a dam structure), to increase the amount of available fall Chinook salmon spawning habitat in the lower Snake River. Empirical and modeled physical habitat data were used to compare potential fall Chinook salmon spawning habitat in the Snake River, under current and modified dam operations, with the analogous physical characteristics of an existing fall Chinook salmon spawning area in the Columbia River. The two Snake River study areas included the Ice Harbor Dam tailrace downstream to the Highway 12 bridge and the Lower Granite Dam tailrace downstream approximately 12 river kilometers. These areas represent tailwater habitat (i.e., riverine segments extending from a dam downstream to the backwater influence from the next dam downstream). We used a reference site, indicative of current fall Chinook salmon spawning areas in tailwater habitat, against which to compare the physical characteristics of each study site. The reference site for tailwater habitats was the section extending downstream from the Wanapum Dam tailrace on the Columbia River. Fall Chinook salmon spawning habitat use data, including water depth, velocity, substrate size and channelbed slope, from the Wanapum reference area were used to define spawning habitat suitability based on these variables. Fall Chinook salmon spawning habitat suitability of the Snake River study areas was estimated by applying the Wanapum reference reach habitat suitability criteria to measured and modeled habitat data from the Snake River study areas. Channel morphology data from the Wanapum reference reach and the Snake River study areas were evaluated to identify geomorphically suitable fall Chinook salmon spawning habitat. The results of this study indicate that a majority of the Ice Harbor and Lower Granite study areas contain suitable fall Chinook salmon spawning habitat under existing hydrosystem operations. However, a large majority of the currently available fall Chinook salmon spawning habitat in the Ice Harbor and Lower Granite study areas is of low quality. The potential for increasing, through modifications to hydrosystem operations (i.e., minimum pool elevation of the next downstream dam), the quantity or quality of fall Chinook salmon spawning habitat appears to be limited. Estimates of the amount of potential fall Chinook salmon spawning habitat in the Ice Harbor study area decreased as the McNary Dam forebay elevation was lowered from normal to minimum pool elevation. Estimates of the amount of potential fall Chinook salmon spawning habitat in the Lower Granite study area increased as the Little Goose Dam forebay elevation was lowered from normal to minimum pool elevation; however, 97% of the available habitat was categorized within the range of lowest quality. In both the Ice Harbor and Lower Granite study areas, water velocity appears to be more of a limiting factor than water depth for fall Chinook salmon spawning habitat, with both study areas dominated by low-magnitude water velocity. The geomorphic suitability of both study areas appears to be compromised for fall Chinook salmon spawning habitat, with the Ice Harbor study area lacking significant bedforms along the longitudinal thalweg profile and the Lower Granite study area lacking cross-sectional topographic diversity. To increase the quantity of available fall Chinook salmon spawning habitat in the Ice Harbor and Lower Granite study area, modifications to hydroelectric dam operations beyond those evaluated in this study likely would be necessary. Modifications may include operational and structural changes, such as lowering downstream dam forebay elevations to less than minimum pool. There is a large amount of uncertainty as to whether or not such modifications could increase the quantity of available fall Chinook salmon spawning habitat in the Ice Harbor and Lower Granite study area. The results from this study provide some certainty that the quantity and quality of fall Chinook salmon spawning habitat within the lower Snake River are not likely to be increased within the existing hydroelectric dam operations.

Author: Robert F. Raleigh
Publisher:
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Category : Chinook salmon
Languages : en
Pages : 80

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Author: Anne Elizabeth Senter
Publisher: ProQuest
ISBN: 9781109082791
Category :
Languages : en
Pages : 82

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To determine whether large wood (LW,>̲1 m length,>̲10 cm diameter) plays a role in Chinook salmon redd (i.e. egg nests) placements in a regulated, medium-sized, Mediterranean-climate river, characteristics of 542 large wood pieces, locations of 650 redds, and habitat unit delineations (riffle, run, glide, pool) were collected during a spawning season along a 7.7 km reach directly below Camanche Dam on the Mokelumne River (average width 31 m). Large wood was regularly distributed across the study reach with an average of 70 LW pieces km−1. Some LW clustering was evident at islands. Chinook spawners built 75% of observed redds at spawning habitat rehabilitation sites, and 85% of redds were within one average channel width of large wood. At the hydraulic scale of ~10−1 channel widths, redds were within a 10-m radius of large wood 36% of the time. These results suggest that spawners had the opportunity to utilize large wood as cover and refugia. In the lower 4.7 km where marginal habitat was prevalent, redds were within a 5-m radius of large wood 21% of the time and within a 2.5 m radius 10% of the time, indicating use of the hydraulic properties of instream large wood structures. Results from randomized tests indicate that large wood-redd interactions systematically occurred at a greater rate than by random chance alone in the lower 4.7 km, but not in the upper 3 km, which implies that large wood aids spawning in marginal habitats. Key Words: large wood, gravel rivers, Chinook salmon, ecohydraulics, fluvial geomorphology, river rehabilitation.

Author: Stephen Monismith
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Category : Salmon
Languages : en
Pages : 23

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Author: Joseph Eugene Merz
Publisher:
ISBN:
Category : Pacific salmon
Languages : en
Pages : 392

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Author: Elizabeth Matteri
Publisher:
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Category :
Languages : en
Pages : 25

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Streambed particle size is a key factor influencing Chinook salmon (Oncorhynchus tshawytscha) spawning site suitability. Both the construction and removal of dams alter the sediment in rivers, resulting in changes to suitable habitat for salmon. When in place, dams impede the movement of sediment, resulting in an accumulation of sediment above the dam and a degradation of the riverbed below the dam. The release of this accumulated sediment after dam removal can restore a more natural distribution of sediment size classes below the dam, potentially improving salmon spawning habitat. Dam removal for the purpose of river restoration and improving conditions for salmon has increased in recent decades. The purpose of this study is to assess the effects of the sediment released from two large dam removals on the Elwha River in Washington state on streambed particle size, and the resultant amount of suitable spawnable habitat for Chinook salmon. Pebble counts were conducted in 45 riffles in 2009, before dam removal, and in 21 riffles in 2015, after dam removal, in the mainstem of the Lower and Middle sections of the Elwha River. The fraction of movable particles by a spawning Chinook salmon in the riffle crests increased by 43% after dam removal, resulting in more suitable spawning habitat. After dam removal, there was greater variation in sediment size within riffle crests, whereas there were predominantly larger particles before dam removal. The positive changes in sediment measured in this project support the concept that dam removal is a meaningful strategy for salmon restoration.

Author:
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ISBN:
Category :
Languages : en
Pages : 186

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The Pacific Northwest National Laboratory conducted this study for the Bonneville Power Administration (BPA) with funding provided through the Northwest Power and Conservation Council(a) and the BPA Fish and Wildlife Program. The study was conducted in the Hanford Reach of the Columbia River. The goal of study was to determine the physical habitat factors necessary to define the redd capacity of fall Chinook salmon that spawn in large mainstem rivers like the Hanford Reach and Snake River. The study was originally commissioned in FY 1994 and then recommissioned in FY 2000 through the Fish and Wildlife Program rolling review of the Columbia River Basin projects. The work described in this report covers the period from 1994 through 2004; however, the majority of the information comes from the last four years of the study (2000 through 2004). Results from the work conducted from 1994 to 2000 were covered in an earlier report. More than any other stock of Pacific salmon, fall Chinook salmon (Oncorhynchus tshawytscha) have suffered severe impacts from the hydroelectric development in the Columbia River Basin. Fall Chinook salmon rely heavily on mainstem habitats for all phases of their life cycle, and mainstem hydroelectric dams have inundated or blocked areas that were historically used for spawning and rearing. The natural flow pattern that existed in the historic period has been altered by the dams, which in turn have affected the physical and biological template upon which fall Chinook salmon depend upon for successful reproduction. Operation of the dams to produce power to meet short-term needs in electricity (termed power peaking) produces unnatural fluctuations in flow over a 24-hour cycle. These flow fluctuations alter the physical habitat and disrupt the cues that salmon use to select spawning sites, as well as strand fish in near-shore habitat that becomes dewatered. The quality of spawning gravels has been affected by dam construction, flood protection, and agricultural and industrial development. In some cases, the riverbed is armored such that it is more difficult for spawners to move, while in other cases the intrusion of fine sediment into spawning gravels has reduced water flow to sensitive eggs and young fry. Recovery of fall Chinook salmon populations may involve habitat restoration through such actions as dam removal and reservoir drawdown. In addition, habitat protection will be accomplished through set-asides of existing high-quality habitat. A key component to evaluating these actions is quantifying the salmon spawning habitat potential of a given river reach so that realistic recovery goals for salmon abundance can be developed. Quantifying salmon spawning habitat potential requires an understanding of the spawning behavior of Chinook salmon, as well as an understanding of the physical habitat where these fish spawn. Increasingly, fish biologists are recognizing that assessing the physical habitat of riverine systems where salmon spawn goes beyond measuring microhabitat like water depth, velocity, and substrate size. Geomorphic features of the river measured over a range of spatial scales set up the physical template upon which the microhabitat develops, and successful assessments of spawning habitat potential incorporate these geomorphic features. We had three primary objectives for this study. The first objective was to determine the relationship between physical habitats at different spatial scales and fall Chinook salmon spawning locations. The second objective was to estimate the fall Chinook salmon redd capacity for the Reach. The third objective was to suggest a protocol for determining preferable spawning reaches of fall Chinook salmon. To ensure that we collected physical data within habitat that was representative of the full range of potential spawning habitat, the study area was stratified based on geomorphic features of the river using a two-dimensional river channel index that classified the river cross section into one of four shapes based on channel symmetry, depth, and width. We found that this river channel classification system was a good predictor at the scale of a river reach ((almost equal to)1 km) of where fall Chinook salmon would spawn. Using this two-dimensional river channel index, we selected study areas that were representative of the geomorphic classes. A total of nine study sites distributed throughout the middle 27 km of the Reach (study area) were investigated. Four of the study sites were located between river kilometer 575 and 580 in a section of the river where fall Chinook salmon have not spawned since aerial surveys were initiated in the 1940s; four sites were located in the spawning reach (river kilometer [rkm] 590 to 603); and one site was located upstream of the spawning reach (rkm 605).

Author:
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ISBN:
Category : Hydrology
Languages : en
Pages : 1198

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Author: Takayuki Hirai
Publisher:
ISBN:
Category : Chinook salmon
Languages : en
Pages : 254

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The research involved development of two ecological simulation models to explain the complex dimensionality of chinook salmon (Oncorhynchus tshawytscha) life history structure (represented by the age composition of the spawning stock) and management difficulties entailed in the complexity. Since different sizes of chinook salmon are thought to adapt differently to heterogeneous habitats, age composition of the spawning stock is determined by characteristics of the habitats of the substocks. Numerical properties of substocks result from the incorporation of individual spawners in different age classes and each substock performs differently because their age compositions are distinctive. A stock or population consists of substocks whose age compositions are concordant with their habitats. The productive capacity of a population will result from the incorporation of substocks. If habitat structures of streams are different, the age and size compositions and productive capacity of the populations may differ. Selective harvesting affects spawners in different ways, so that age compositions must be deformed differently by fishing pressure. Once the age composition deviates from the natural age composition, the productivity of the population will decrease. Population dynamics are strongly correlated with substock structure which is determined by habitat structure in a stream system. Hierarchical population structure make fisheries management difficult and requires not only quantitative but also qualitative analysis on the populations in relation to habitat classification.