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Author : Gregg Mauser
Publisher :
ISBN 13 :
Total Pages : 48 pages
Book Rating : 4.3/5 (121 download)
Download or read book Dworshak Dam Impact Assessment and Fishery Investigation written by Gregg Mauser and published by . This book was released on 1989 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 24 pages
Book Rating : 4.:/5 (727 download)
Download or read book Dworshak Dam Impact Assessment and Fishery Investigation, 1989 Annual Report written by and published by . This book was released on 1990 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Bonneville Power Administration (BPA) funded two 4-year research projects to develop recommendations for improving the sport fishery on Dworshak Reservoir. Research began during 1987 as a cooperative effort between the Idaho Department of Fish and Game (IDFG) and the Nez Perce Tribe of Idaho. The Nez Perce Tribe examined smallmouth bass and rainbow trout fisheries. The IDFG evaluated kokanee population dynamics and documented changes in reservoir productivity. 12 refs., 12 figs.
Author :
Publisher :
ISBN 13 :
Total Pages : 92 pages
Book Rating : 4.:/5 (727 download)
Download or read book Dworshak Dam Impact Assessment and Fishery Investigation and Trout, Bass and Forage Species written by and published by . This book was released on 1992 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Nez Perce Tribe (NPT) and the Idaho Department of Fish and Game (IDFG) entered into separate intergovernmental agreements with the Bonneville Power Administration in a cooperative four-year effort to study impacts of Dworshak Dam operation on resident fisheries. The NPT Department of Fisheries Management focused on rainbow trout, smallmouth bass and forage fish. The IDFG's segment of the project was to document kokanee population dynamics, relate it to the changing nutrient status of the reservoir, evaluate kokanee losses through Dworshak Dam, and make kokanee management recommendations. This final report includes findings for 1990 and 1991 and relates these data to information previously presented in annual reports for 1987, 1988 and 1989.
Author : Melo Maiolie
Publisher :
ISBN 13 :
Total Pages : 68 pages
Book Rating : 4.3/5 (121 download)
Download or read book Dworshak Dam Impacts Assessment & Fishery Investigations written by Melo Maiolie and published by . This book was released on 1993 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Melo Maiolie
Publisher :
ISBN 13 :
Total Pages : 34 pages
Book Rating : 4.:/5 (465 download)
Download or read book Dworshak Dam Impacts Assessment and Fisheries Investigations Project written by Melo Maiolie and published by . This book was released on 1995 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Eric J. Stark
Publisher :
ISBN 13 :
Total Pages : 93 pages
Book Rating : 4.:/5 (18 download)
Download or read book Dworshak Dam Impacts Assessment and Fisheries Investigation written by Eric J. Stark and published by . This book was released on 2006 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes research to test underwater strobe lights to determine their effectiveness at repelling kokanee away from the turbine intakes of Dworshak Dam.
Author :
Publisher :
ISBN 13 :
Total Pages : 42 pages
Book Rating : 4.:/5 (727 download)
Download or read book Dworshak Dam Impact (Impacts) Assessment and Fishery Investigation written by and published by . This book was released on 1989 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: Kokanee abundance, estimated from July trawl data, was 1.2 million fish in 1988, including 553,000 fry, 501,000 yearlings and 156,000 subadults. Spawning trend data indicated escapement was up threefold compared to 1987, despite a sport harvest of 207,000 kokanee averaging 258 mm caught at a rate of 1.5 fish per hour. An estimated 40,000 kokanee were counted during the September peak of spawning in five tributaries of the reservoir. Size of adult fish was below average at 293 mm. Zooplankton densities averaged 10.3 organisms/L in 1988 and ranged from 0.3 organisms/L during April at the Little North Fork station to 26.2 organisms/L in November at the Elk Creek station. Densities were similar to values obtained prior to the development of the primary kokanee fishery; however, cladocerans made up only 34.9% of the zooplankton sampled. Daphnia and Cyclops were the most important food items; Daphnia became the prime food organism as its seasonal abundance increased. Concentrations of ortho-phosphate and nitrate, lower than in the 1970s, indicated Dworshak may have become more oligotrophic. 13 refs., 24 figs., 4 tabs.
Author : Melo Maiolie
Publisher :
ISBN 13 :
Total Pages : 39 pages
Book Rating : 4.:/5 (465 download)
Download or read book Dworshak Dam Impacts Assessment and Fishery Investigation written by Melo Maiolie and published by . This book was released on 1988 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 46 pages
Book Rating : 4.:/5 (727 download)
Download or read book Dworshak Dam Impacts Assessment and Fishery Investigation written by and published by . This book was released on 1988 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: A total of 7,071 kokanee spawners were counted during the peak of the spawning run in five tributaries to Dworshak Reservoir during 1987. Both size and numbers of fish were fairly average. During years when numbers of fish were large, total length of age 3+ kokanee was as low as 25 cm. Conversely, small numbers of kokanee resulted in an average length of 37 cm. Zooplankton densities during November of 1987 averaged 17.92 organisms/L, but decreased to 3.96 organism/L during December. These densities are similar to values obtained during 1972, although the percentage of cladocerans in the samples may have declined. Kokanee preferred Daphnia over 1 mm in length. Concentrations of orthophosphate and nitrate appear to have declined since the reservoir filled. Kokanee catch rates for boat anglers changed from 1.4 fish/h during November to 2.7 fish/h during December to 0.0 fish/h during January. This declining trend may have been temperature related. Harvest for these 3 months was an estimated 1,612 kokanee. 10 refs., 13 figs., 4 tabs.
Author : Steve Elam
Publisher :
ISBN 13 :
Total Pages : 39 pages
Book Rating : 4.:/5 (524 download)
Download or read book Dworshak Dam Impacts Assessment and Fisheries Investigation written by Steve Elam and published by . This book was released on 1996 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Melo Maiolie
Publisher :
ISBN 13 :
Total Pages : 12 pages
Book Rating : 4.:/5 (563 download)
Download or read book Kokanee Entrainment Losses at Dworshak Reservoir written by Melo Maiolie and published by . This book was released on 1998 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 18 pages
Book Rating : 4.:/5 (727 download)
Download or read book Dworshak Dam Impacts Assessment and Fisheries Investigation Project written by and published by . This book was released on 1998 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: We used split-beam hydroacoustics to monitor kokanee Oncorhynchus nerka kennerlyi abundance in Dworshak Reservoir from 1995 to 1996 in order to quantify the impacts of water releases from Dworshak Dam. The kokanee population was at a record high level of 1.9 million age-1 and age-2 fish (350 fish/ha) during June 1995. Large discharges of water during July and August of 1995 did not result in major losses of kokanee. Mid-winter flooding in February. March, and April of 1996: however, caused entrainment losses of 90% of all kokanee in the reservoir. The population declined to 140,000 kokanee. High flows during spring runoff used another 50% of the kokanee to be lost, further reducing the population to 71,000 fish (13 fish/ha). Entrainment losses were partially explainable by the distribution of kokanee in the reservoir. During winter, all age-classes of kokanee congregated near the dam making them susceptible to high releases of water. Kokanee appeared to be less susceptible to entrainment during summer and early fall because most kokanee were in other parts of the reservoir: adults were in the upper reservoir staging to spawn, fry were in the upper reservoir having emerged from tributary streams, and juvenile kokanee were spread throughout the reservoir.
Author :
Publisher :
ISBN 13 :
Total Pages : 39 pages
Book Rating : 4.:/5 (683 download)
Download or read book Dworshak Dam Impacts Assessment and Fisheries Investigations Project, 1993 Annual Report written by and published by . This book was released on 1995 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: We monitored the kokanee Oncorhynchus nerka kennerlyi population in Dworshak Reservoir, Idaho, by mid-water trawling and counting spawners in representative streams. Our estimates of age 1 kokanee abundance in 1993 were the highest on record; 556,000 fish. These fish resulted from last years record year class of age 0 kokanee. Age 2 kokanee were also abundant, achieving their second highest level on record. Dworshak Dam discharged less water between July 1, 1992 and June 30, 1993 than any of our recent years of study (the lowest since 1986-1987). Based on a past relationship with an r2=0.62, we expected age 2 kokanee abundance to be very high with this low level of discharge. We estimated mature kokanee abundance by trawling, which correlated well (r2=.89) to standardized spawner counts. This gives us the means to convert the older spawner count data into age 2 kokanee estimates. It is also a validation of spawner counts in tributary streams as an accurate method to obtain an index of adult kokanee abundance.
Author :
Publisher :
ISBN 13 :
Total Pages : 34 pages
Book Rating : 4.:/5 (91 download)
Download or read book Dworshak Dam Impacts Assessment and Fisheries Investigations Project written by and published by . This book was released on 1995 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: We monitored the kokanee Oncorhynchus nerka kennerlyi population in Dworshak Reservoir, Idaho, by mid-water trawling and counting spawners in representative streams. Our estimates of age 1 kokanee abundance in 1993 were the highest on record; 556,000 fish. These fish resulted from last years record year class of age 0 kokanee. Age 2 kokanee were also abundant, achieving their second highest level on record. Dworshak Dam discharged less water between July 1, 1992 and June 30, 1993 than any of our recent years of study (the lowest since 1986-1987). Based on a past relationship with an r2=0.62, we expected age 2 kokanee abundance to be very high with this low level of discharge. We estimated mature kokanee abundance by trawling, which correlated well (r2=.89) to standardized spawner counts. This gives us the means to convert the older spawner count data into age 2 kokanee estimates. It is also a validation of spawner counts in tributary streams as an accurate method to obtain an index of adult kokanee abundance.
Author :
Publisher :
ISBN 13 :
Total Pages : 66 pages
Book Rating : 4.:/5 (685 download)
Download or read book Dworshak Dam Impacts Assessment and Fisheries Investigation, 1991-1992 Progress Report written by and published by . This book was released on 1993 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lake Pend Oreille, 38,000 hectares, is Idaho's largest natural lake. Fisheries for kokanee Onchorynchus nerka, rainbow trout Onchorynchus mykiss, and bull trout Salvelinus confluentus have gone through major declines over the last 40 years. To date, the decline in kokanee abundance has not been fully explained. Water level management may be the single largest contributing factor to this decline. Two aspects of water level management appear critical. Dropping water level once kokanee spawning has occurred wall correlated with poor fishery harvest five years later (r = -0.71) (alpha = 0.005). Secondly, dropping the water level more than 2 m immediately before spawning leaves wave-washed gravel high on the bank and forces kokanee to spawn in low quality substrates, which again reduces survival. Changes in water level management coincided with the sharp declines in the kokanee fishery during the 1960s. Although the water level has been stabilized once spawning has occurred, the deep drawdowns resulting in poor spawning substrates continues to cause problems for the kokanee population. Recognizing the importance of these two factors gives hope that changes in water management can reverse the 30-year trend of declining kokanee populations before they are lost from the system. The authors recommend an experimental test of higher winter lake elevation for several years to document potential changes in kokanee abundance.
Author :
Publisher :
ISBN 13 :
Total Pages : 43 pages
Book Rating : 4.:/5 (684 download)
Download or read book Dworshak Dam Impacts Assessment and Fisheries Investigation written by and published by . This book was released on 1996 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors measured the day and night depth distribution of kokanee Oncorhynchus nerka kennerlyi directly upstream of Dworshak Dam from October 1993 to December 1994 using split-beam hydroacoustics. At night most kokanee (70%) were distributed in a diffuse layer about 10 m thick. The depth of the layer varied with the season and ranged from 30 to 40 m deep during winter and from 15 to 25 m deep during summer. Nighttime depth of the kokanee layer during summer roughly corresponded to a zone where water temperatures ranged from 7 C to 12 C. Daytime kokanee distribution was much different with kokanee located in dense schools. Most kokanee (70%) were found in a 5--15 m thick layer during summer. Daytime depth distribution was also shallowest during fall and deepest during winter. Dworshak Dam has structures which can be used for selective water withdrawal and can function in depth ranges that will avoid the kokanee layer. Temperature constraints limit the use of selective withdrawal during the spring, summer, and fall, but in the winter, water is nearly isothermal and the full range of selector gate depths may be utilized. From October 1993 to February 1994, selector gates were positioned to withdraw water from above the kokanee layer. The discharge pattern also changed with more water being released during May and July, and less water being released during fall and winter. A combination of these two changes is thought to have increased kokanee densities to a record high of 69 adults/ha.
Author : Melo Maiolie
Publisher :
ISBN 13 :
Total Pages : 21 pages
Book Rating : 4.:/5 (446 download)
Download or read book Strobe Light Testing and Kokanee Population Monitoring written by Melo Maiolie and published by . This book was released on 1999 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
