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Quantification of the Probable Effects of Alternative In-River Harvest Regulations on Recovery of Snake River Fall Chinook Salmon : Final Report March 1996.

Description: The goal of this study was to quantify the probable effects that alternative strategies for managing in-river harvest would have on recovery of Snake River fall chinook salmon. This report presents the analysis of existing data to quantify the way in which various in-river harvest strategies catch Snake River bright (SRB) fall chinook. Because there has been disagreement among experts regarding the magnitude of in-river harvest impacts on Snake River fall chinook, the authors compared the results from using the following three different methods to estimate in-river harvest rates: (1) use of run reconstruction through stock accounting of escapement and landings data to estimate harvest rate of SRB chinook in Zone 6 alone; (2) use of Coded Wire Tag (CWT) recoveries of fall chinook from Lyons Ferry Hatchery in a cohort analysis to estimate age and sex specific harvest rates for Zone 6 and for below Bonneville Dam; (3) comparison of harvest rates estimated for SRB chinook by the above methods to those estimated by the same methods for Upriver Bright (URB) fall chinook.
Date: March 1, 1996
Creator: Cramer, Steven P. & Vigg, Steven
Partner: UNT Libraries Government Documents Department

Evaluation of Delisting Criteria and Rebuilding Schedules for Snake River Spring/Summer Chinook, Fall Chinook and Sockeye Salmon : Recovery Issues for Threatened and Endangered Snake River Salmon : Technical Report 10 of 11.

Description: We develop a framework for distinguishing healthy and threatened populations, and we analyze specific criteria by which these terms can be measured for threatened populations of salmon in the Snake River. We review reports and analyze existing data on listed populations of salmon in the Snake River to establish a framework for two stages of the recovery process: (1) defining de-listing criteria, and (2) estimating the percentage increase in survival that will be necessary for recovery of the population within specified time frames, given the de-listing criteria that must be achieved. We develop and apply a simplified population model to estimate the percentage improvement in survival that will be necessary to achieve different rates of recovery. We considered five main concepts identifying de-listing criteria: (1) minimum population size, (2) rates of population change, (3) number of population subunits, (4) survival rates, and (5) driving variables. In considering minimum population size, we conclude that high variation in survival rates poses a substantially greater probability of causing extinction than does loss of genetic variation. Distinct population subunits exist and affect both the genetic variability of the population and the dynamics of population decline and growth. We distinguish between two types of population subunits, (1) genetic and (2) geographic, and we give examples of their effects on population recovery.
Date: June 1, 1993
Creator: Cramer, Steven P. & Neeley, Doug
Partner: UNT Libraries Government Documents Department

Spawning Success of Hatchery Spring Chinook Salmon Outplanted as Adults in the Clearwater River Basin, Idaho, 2001.

Description: The study described in this report evaluated spawning distribution, overlap with naturally-arriving spawners, and pre-spawning mortality of spring chinook salmon, Oncorhynchus tshawytscha, outplanted as adults in the Clearwater River Subbasin in 2001. Returns of spring chinook salmon to Snake River Basin hatcheries and acclimation facilities in 2001 exceeded needs for hatchery production goals in Idaho. Consequently, management agencies including the U.S. Fish and Wildlife Service (FWS), Idaho Department of Fish and Game (IDFG) and Nez Perce Tribe (NPT) agreed to outplant chinook salmon adults as an adaptive management strategy for using hatchery adults. Adult outplants were made in streams or stream sections that have been typically underseeded with spawners. This strategy anticipated that outplanted hatchery chinook salmon would spawn successfully near the areas where they were planted, and would increase natural production. Outplanting of adult spring chinook salmon from hatcheries is likely to be proposed in years when run sizes are similar to those of the 2001 run. Careful monitoring of results from this year's outplanting can be used to guide decisions and methods for future adult outplanting. Numbers of spring chinook salmon outplanted was based on hatchery run size, hatchery needs, and available spawning habitat. Hatcheries involved in outplanting in the Clearwater Basin included Dworshak National Fish Hatchery, Kooskia National Fish Hatchery, Clearwater Anadromous Fish Hatchery, and Rapid River Fish Hatchery. The NPT, IDFG, FWS, and the National Marine Fisheries Service (NMFS) agreed upon outplant locations and a range of numbers of spring chinook salmon to be outplanted (Table 1). Outplanting occurred mainly in the Selway River Subbasin, but additional outplants were made in tributaries to the South Fork Clearwater River and the Lochsa River (Table 1). Actual outplanting activities were carried out primarily by the NPT with supplemental outplanting done in the Lochsa basin by IDFG. Fish were ...
Date: April 16, 2002
Creator: Cramer, Steven P.; Ackerman, Nichlaus & Witty, Kenneth L.
Partner: UNT Libraries Government Documents Department