Non-native salmonids are impacting native salmonid populations throughout the Pend Oreille Subbasin. Competition, hybridization, and predation by non-native fish have been identified as primary factors in the decline of some native bull trout and cutthroat trout populations. Therefore, the goal of this project is to implement actions to suppress or eradicate non-native fish in areas where native populations are declining or have been extirpated and then reintroduce native fish species. These projects have been identified as critical to recovering native bull trout and westslope cutthroat trout (WCT).

Westslope cutthroat trout have recently been extirpated in upper Cee Cee Ah Creek due to displacement by brook trout. Prior to implementing non-native fish removal and WCT translocation in upper Cee Cee Ah Creek, an extensive public outreach program was initiated.  In 2007, much of the effort for this project was made towards public education and involvement in using piscicides for native fish recovery.  To date, public acceptance of using piscicides as a management tool has been accomplished.  In 2008 , 2009, and 2010,  Cee Cee Ah Creek was treated with rotenone and non-native brook trout were successfully  eradicated. Re-invasion of the treatment area is impossible due to the Cee Cee Ah Falls.  In 2011, efforts to reintroduce WCT commenced:100 mature WCT were collected from East Fork Smalle Creek, a neighboring tributary, and translocated directly into reclaimed reaches of Cee Cee Ah Creek.  Those translocated fish should spawn in the spring of 2012.  In 2012, eggs and sperm from 50 pairs of WCT from East Fork Smalle Creek will be collected; eggs will be fertilized and transported directly to Cee Cee Ah Creek.  Half of the eggs will be incubated in egg tubes buried in the stream bottom and the other half will be incubated using stream-side RSIs.  

The Tribe recently was awarded funding to conduct watershed assessments using NetMap (www.netmaptools.org), a coupled watershed database and analysis system to create spatially specific analyses of watershed processes and patterns pertinent to habitat restoration. NetMap is comprised of a community-based set of watershed databases and analysis tools designed to support diverse natural resource management including restoration, conservation, forestry, monitoring and wildfire planning.  The project manager and personell from Earth Systems Institute (ESI) wil develop a piscicide tool in NetMap to predict the best locations for reducing populations of non native trout species and for enhancing recovery of native fishes. ESI will develop a piscicide tool in NetMap to predict the channel reaches in the study area where piscicide treatments are appropriate for the recovery of native fish species. Parameters may include: i) natural and artificial barriers, ii) cutthroat habitat suitability (using HIP modeling, another task in the project); iii) present cutthroat trout presence or absence, iv) distance to appropriate donor population, v) live stock grazing, vi) vegetative condition of riparian zone (including present wood abundance), and vii) private ownership downstream (percent of area). Other potential parameters include domestic surface water rights and angler use.

The Tribe, through various funding sources, has completed a conceptual design for restoration of Goose Creek, a tributary to UWB (see project 1995-001-00 for details).  Except for 2 small (>0.5 mile in length) headwater stream segments, brook trout are the only salmonid present in Goose Creek.  In 2011, a fish passage barrier was constructed at the downstream end of the restoration reach.  Once the stream channel is restored, piscicide treatments for Goose Creek will be implemented.

The Idaho Department of Fish and Game has been working at suppressing lake trout in Upper Priest Lake through extensive gill netting.  Since 1997, over 10,000 lake trout have been removed from the lake; however, the population continues to rebound, through in-lake recruitment and immigration of mature, ripe lake trout from Priest Lake in the fall. Permanent suppression of lake trout in Upper Priest Lake will also require successful suppression in Priest Lake.  The intent of lake trout suppression in Upper Priest Lake and the thorofare is to prevent a population explosion in the upper lake prior to initiating suppression efforts in Priest Lake.

In 2009, IDFG contracted Harbor Fisheries (with funding from USFWS) to install and operate trap nets and gillnets in the Thorofare in the fall on an experimental basis.  The intent of the project was to identify whether or not nets could be used to effectively curb immigration through the Thorofare in the fall.  Initially, the trap nets proved to be ineffective.  Lake trout were able to avoid the trap nets, despite using leads that completely spanned the Thorofare channel.  One challenge faced by any project aimed at controlling lake trout immigration is the need to maintain boat passage.  In 2009, the crew submerged a portion of the trap net leads and a portion of each gillnet and used markers to guide boats.  

Several modifications were made to the trap nets, and toward the end of the project, the nets were effective in capturing a portion of the upstream migrants.  The contractors were confident that additional modifications, including larger throats, heavier lead lines on the leads, and staggering leads to create a boat channel would further improve trap efficiency.  In 2010 the modifications were made and the trap nets captured 182 lake trout while gill nets set upstream of the trapnets to monitor effectiveness captured 59 lake trout.  In 2011, the thorofare trap nets were fished an additional two weeks and, combined with increased net efficiency, 355 lake trout were captured.

In 2012, this project will provide cost-share funding for the IDFG project and enable them to continue with lake trout removals in the Thorofare by installing and operating the modified trap nets and gillnets from mid September through mid November in an effort to refine the immigration control efforts.

Northern pike (NP), illegally introduced in the Clark Fork River, Montana have immigrated to the Box Canyon Reservoir (BCR) where they are causing drastic declines in native species and gamefish being managed by the Kalispel Tribe Natural Resources Department (KNRD) , Washington Department of Fish and Wildlife (WDFW) and Idaho Department of Fish and Game (IDFG). The NP population grew exponentially from <400 in 2006 to >5,500 in 2010 between Newport (Pioneer Park) and Riverbend. Reservoir-wide, we estimate the population to be over 10,000 individuals today. Northern pike threaten to undermine current and future recovery efforts for bull trout and westslope cutthroat trout, as well as other native salmonids, minnows, suckers and introduced gamefish in the watershed. Northern pike pose significant risks to the anadromous fisheries of the Columbia River and Endangered Species Act (ESA) recovery efforts if left to emigrate further downstream.  The KNRD and WDFW plan to implement a suite of measures, including mechanical suppression of the population, beginning in 2012.

The BCR population is currently expanding exponentially and have expanded their range in the reservoir, as well as been documented in small numbers in Boundary Reservoir, upper Columbia River in Canada, and Lake Roosevelt. Although angler effort has increased 20-fold in the last decades, angler exploitation alone cannot likely control or reduce the abundance of NP at the level of effort and harvest observed in 2010. Anglers presently release a large portion (>50%) of the NP they catch and harvest exploitation is less than 25% (Connor et al. in prep.). Modeling with the Fisheries Analysis and Simulation Tool (FAST) indicated that under current conditions greater than 55% of the population would have to be removed annually to begin reducing their abundance (WDFW unpublished).

Northern pike pose immediate threats to the survival of bull trout and westslope cutthroat trout entrained at Albeni Falls Dam (AFD). KNRD, U.S. Army Corps of Engineers (USACE), Bonneville Power Administration (BPA), Eastern Washington University (EWU), and Pacific Northwest National Laboratory (PNNL) have been studying the feasibility of fish passage at AFD and have been temporarily providing passage for bull trout with the use of electrofishing and angling. Movement, habitat use, behavior, and survival of bull trout and westslope cutthroat trout has been monitored in the watershed with biotelemetry since 2007. Bull trout and westslope cutthroat trout collected near the tailrace of AFD are all thought to originate from upstream source populations, based on size, color, behavior, and genetics. For example 100% of the bull trout collected at the tailrace area of AFD have been genetically assigned to upstream tributaries. Of those that were transported upstream and entered tributaries, 100% entered either their primary or secondary genetic assignment. Thirty-six percent of those originated from severely depressed Lake Pend Oreille tributaries including Morris Creek, Lightening Creek, East Fork Lightening Creek, and Rattle Creek. We are only just beginning to understand the magnitude of entrainment at AFD and plan to genetically catalog westslope cutthroat trout collected below AFD beginning 2013 to identify source populations. Entrainment of westslope cutthroat trout tagged at the mouth of Priest River exceeded 30% in 2011 (Connor and Olson in prep).

Northern pike threatens bull trout and westslope cutthroat trout survival due to high degree of habitat overlap, especially during summer when reservoir temperatures surpass 18 °C and native salmonids seek thermal refuge. Documented cold water refuge include a spring-fed culvert near AFD, Charr Springs, Indian Creek, Kent Creek, and tributary mouths farther downstream (e.g. Cedar Creek). A bull trout has been observed holding at Charr Springs in an area less than 1 m2 after navigating >100 m through dense macrophytes (Paluch et al 2011). Adult NP in BCR are capable of consuming all but the largest adult bull trout that we have encountered (Bean et al. 2011), and have been collected in close proximity spatially and temporally (i.e. same electrofishing pass). Efforts to increase the relative abundance of native salmonids in the lower Pend Oreille through mainstem fish passage projects, tributary restoration, and conservation aquaculture may be seriously compromised by the establishment and expansion of NP in the watershed. Furthermore, NP also threaten Lake Pend Oreille native salmonid populations as well.

Mechanical suppression of northern is a well established management tool and efforts are currently or have recently been implemented in the Missouri River drainage, MT (MFWP 2011), Susitna River drainage, AK (Ivey et al. 2011), Colorado River drainage, UT, WY, CO (Monroe  and Hedrick 2008; Finney and Haynes 2008), and AZ reservoirs (Kuzmenko et al. 2010).  A variety of methods have been employed for suppression including electrofishing, fyke netting, and gill nets. Gill netting methods that focus effort on sloughs and backwaters during spring when pike are congregated for spawning have been developed and implemented in Alaska’s Alexander Creek, a tributary to the Susitna River that once supported popular chinook and coho salmon fisheries decimated by illegally stocked NP. Ivey et al. (2011) demonstrated that large numbers of mature NP could be efficiently removed with this strategy.

To assess the feasibility of such a strategy in BCR, KNRD and WDFW initiated a pilot removal project in 2011 under the range of environmental conditions, water elevation and surface area, and access limitations commonly experienced. We assessed CPUE, spawn timing and duration, maturity, sex ratio, fecundity, diet, age and growth from two representative slough locations from ice-off through June when flood level flow (120Kcfs) reduced access and CPUE dropped sharply. With minimal effort (4 nets/week; 48 total nets), we removed 647 NP (1.16 tons). Spawning began in late March and peaked the 4th week of April. Over 90% of mature females collected after May 1 were post-spawn. CPUE was consistent between locations and peaked in April and May at reservoir elevations of 2035-2040 ft (Figure 6).  Shallow depth sets (<2 m) produced nearly 3 times the catch of deep sets (>4 m). The size distribution has not changed appreciably, with 90% of the catch less than 700 mm. Males averaging 611 mm accounted for 60% of the catch. Bycatch included 11 fish species, 394 individuals, with brown bullhead, tench, yellow perch and peamouth accounting for 84% of bycatch. Four brown trout were the only salmonids collected (Connor et al. in prep). We concluded that intensively netting NP in sloughs and backwaters from ice off through the spring freshet could drastically reduce the abundance of NP in BCR.

Our objective is to reduce the abundance of NP in BCR from the current mean CPUE of 13.2 NP/night to <1.73 NP/night between Pioneer Park and Riverbend and <0.5 NP/night north of Riverbend in annual Spring Pike Index Netting (SPIN) survey.
The Joint Stock Assessment Project (BPA Project No. 1997-004-00) and WDFW will monitor the effectiveness of mechanical removal and other measures by annually monitoring the NP population with  SPIN survey and periodically monitoring the fish community with standardized warmwater fish surveys (Bonar et al. 2000) to detect trends in abundance and population characteristics as a response to removal efforts.