This project is proposed as on-site, partial mitigation for impacts of Albeni Falls Dam.  Fall draw downs of the naturally created Lake Pend Oreille greatly reduced the amount of shoreline spawning habitat for kokanee, the primary forage of bull trout and rainbow trout.    Albeni Falls Dam also inundated about 26 miles of the Pend Oreille River and the lower two miles of the Clark Fork River.  Thus, both river and lake habitats have been changed by the operation of the dam.  The goal of this project is to recover the sport fisheries that were impacted by the federal hydropower system.

Until recently, fall draw downs that negatively influenced spawning habitat were the primary limiting factor for kokanee.  While lake level management is still critically important and a major player in this project, predation manifested itself as the primary limiting factor during the past decade.  This study has documented that predation on kokanee is a threat to the Lake Pend Oreille ecosystem.  Exceptionally high predation levels by lake trout and rainbow trout could extirpate kokanee from the lake if left unchecked.  Without kokanee, lake trout and bull trout would be in direct competition for a limited food supply.  In Flathead Lake, Montana and Priest Lake, Idaho, lake trout replaced bull trout as the dominant predator species once the kokanee forage base was gone.  To avoid a similar scenario in Lake Pend Oreille, we propose several tasks, including the direct removal of lake trout using trap nets and gill nets.  Hansen et al. (2006) estimated that lake trout are currently being exploited at a level that results in annual mortality in excess of 50%.  This is beyond the threshold where lake trout populations begin to decline.  Continued lake trout removal is needed to cause a substantial decline in lake trout abundance.  Rainbow trout are the second most abundant kokanee predator in the lake.  Management actions have been enacted to reduce rainbow trout abundance.  These actions include allowing unlimited angler harvest, allowing the use of four fishing rods, opening tributary streams to fishing, and paying anglers a $15 per fish bounty.   The Avista Corporation is cost-sharing on efforts to reduce kokanee predation by funding a bounty program for lake and rainbow trout harvested by anglers and by funding a large portion of the lake trout netting efforts. The current study includes work aimed at evaluating the effectiveness of predator reduction efforts.  This includes evaluating the responses of predator populations and the kokanee population.  In 2007, kokanee survival was at a record low and the population was on the verge of collapse.  Since then kokanee survival has improved substantially, which indicates that predator removal efforts to reduce the influence of predation on kokanee are working.  If these higher survival rates can be sustained, predation will no longer  limit kokanee population growth.  This will allow lake level management to be fully tested, without the confounding of high predation that has occurred in recent years.

Field work in this proposal is largely to be conducted by the Idaho Department of Fish and Game.  However, several subcontracts are proposed for portions of the work.  The Washington Department of Fisheries will examine kokanee otoliths to determine whether they are of wild or hatchery origin.  Operation of gill nets and trap nets to remove lake trout will be conducted by Hickey Bros. Research, LLC.  A graduate project conducted by the University of Idaho will evaluate mysis shrimp and zooplankton dynamics and the influence they have on kokanee survival.  Additionally, the University of Idaho will conduct a graduate study to evaluate kokanee egg survival to emergence at different lake elevations and in various habitat conditions.  This work will supplement existing egg-to-fry survival estimates.  

Tasks in this Statement of Work fall under four major objectives:

Objective 1-  Kokanee restoration, "To restore kokanee abundance in Lake Pend Oreille so that it is capable of sustaining a harvest of 300,000 kokanee on an annual basis, by 2015."  Several work elements address this objective.  One work element is to assist the USFWS with long-term lake level management planning.  Fluctuating the winter water level has been shown to increase spawning habitat for kokanee and increase their egg-to-fry survival by 2.5 times.  We will continue to provide input into the process of choosing winter lake levels throughout the duration of this project.  Also, a graduate project has been initiated to examine kokanee egg survival under different substrate and water depth conditions.  We also will monitor shoreline spawning habitat to see if lake level management is producing the desired habitat.  Predator control, which more recently emerged as a limiting factor for kokanee, is being implemented to help restore kokanee.    As part of a cooperative effort, Avista Power Company is funding a $15/fish bounty program on rainbow and lake trout to help reduce predator numbers.  This supplements the lake trout removal efforts described by the work element of "Lake trout removal by gill nets and trap nets," which is also funded jointly by BPA and Avista.   During the project, the kokanee population will be examined to determine if predator control efforts are successful.  

Objective 2 - Bull trout / Cutthroat trout Preservation,  "To reduce the lake trout population to a level where lake trout are no longer threatening the kokanee population.”   The work element of "Lake trout removal by gill nets and trap nets" is to reduce the number of lake trout, which are known to be a competitor of bull trout and a predator on cutthroat trout.  In addition to threatening the long-term persistence of bull trout and cutthroat trout, lake trout pose a predation threat to kokanee that threatens to collapse the stock.  

Objective 3-  Restore Bull Trout,  "To restore bull trout so that they can meet USFWS recovery criteria and provide a fishery with a harvest of 1,000 fish annually in Lake Pend Oreille by 2030".  This is relates to objective two.  Efforts to reduce predators will benefit bull trout by reducing competition with lake trout and increasing the abundance of kokanee, which are the primary food supply for bull trout.  

Objective 4-  Improve survival of kokanee,  "Improve survival of kokanee in Lake Pend Oreille so that the population can sustain an annual harvest of 375,000 individuals (the original mitigation objective for the hatchery).  This relates to objective one.  In addition to reducing predator abundance, a work element is included to evaluate nutrient dynamics and their relation to kokanee survival.  This represents a major step towards determining whether nutrient addition can be used as a strategy for improving kokanee survival.