This is a well-written proposal with evidence of learning from past studies and development of a decision tree to guide the work. This is apparently a last ditch effort to provide a kokanee fishery in Banks Lake. The ISRP appreciates how the sponsors have eliminated several candidate factors as major bottlenecks to kokanee recovery. Based on research to date, the sponsors have concluded that competition for food with the very abundant lake whitefish population and reduction of predation from other introduced game fishes, especially walleye, constitute the two most important limiting factors at the present time. Qualification: Desired outcomes of the whitefish removal and walleye angling regulation change elements should be specified before project implementation. With regard to the whitefish removal element: 1. Identify the target whitefish population density after removal and describe how this density was determined. 2. Justify that this target whitefish population abundance is achievable given the limitations of the staff and equipment, assuming the project is funded. 3. Specify how bycatch of non-target species will be monitored. 4. Determine if the cost of the whitefish reduction program can be partially offset by utilizing removed whitefish as food or some other beneficial use. 5. Document the size of whitefish now and whether that has changed over time. Identify whether whitefish are not taken by anglers due to their size or due to what specific other factors. With regard to the walleye angling regulation change: 1. Even though regulation changes will be subject to administrative review and approval, specify what regulation changes are being contemplated. 2. Provide evidence that the type of regulation changes being considered will be sufficient to reduce predation on kokanee sufficient to allow desired recovery. 3. Specify the metric for recovery of kokanee and

1. Purpose: Significance to Regional Programs, Technical Background, and Objectives

This unique and beautiful landscape, highly utilized as a recreational area, was formed from the glacial Lake Missoula flood and construction of the Coulee Dam, and innovative engineering foresight to pump water up into a reservoir for storage and irrigation purposes below Dry Falls. A subsequent kokanee fishery collapsed after the 1970s. The purpose of the project is to restore the kokanee fishery in Banks Lake, which is in serious decline and has been depressed since the introduction of non-native smallmouth bass and walleye several decades ago. Past research has shown that the principle constraints on kokanee are predation by these introduced species (mainly walleye) and competition with non-native lake whitefish – a coregonid that was likely introduced to the area in the late 1800s. Kokanee themselves are not technically native to Banks Lake, having entered the lake from Lake Roosevelt when irrigation pumps diverted water to the Columbia Basin Irrigation Project after construction of Grand Coulee Dam.

The proposal adequately describes the significance of the project to regional programs. However, additional explanation would have been appreciated of why so much effort is being dedicated to kokanee restoration when Banks Lake has clearly undergone significant shifts in fish community composition (in addition to the species mentioned above, the lake now contains introduced centrarchids and ictalurids). Apparently there must be considerable pressure to restore a salmonid fishery to Banks Lake and WDFW feels kokanee is the most favorable candidate species, but the obstacles to be overcome in this highly altered ecosystem are formidable. Additional explanation of why kokanee were selected as the focal species would have been helpful, apart from the observation that the lake once supported a thriving kokanee fishery.

There are two strategies under consideration: (1) test alternative hatchery rearing and release approaches, and (2) reduce populations of fish species that compete with kokanee (walleye and lake whitefish). Monitoring will continue for whitefish population abundance, water quality, and zooplankton density. What remains somewhat obscure or inadequately described are the changes in the early 1980s that led to collapse.

As stated, this represents "the last attempt to restore kokanee to Banks Lake." A well-written and referenced presentation proposes a modeled and mechanistic process to improve survival and abundance of kokanee to the creel introduced as fry. Target reference points for abundance were provided (20 to 30 age 2/3 kokanee/hectare), but derivation was obscure, and creel targets are also needed. Models that were or will be applied to the analyses include Fish Bioenergetics 3.0 (Henson et al. 1997) and Fisheries Analysis and Modeling Simulator (Taylor 2011).

Simulation models will be utilized to consider regulation scenarios on introduced walleye (from pumping) and effects of whitefish capture and removal. In addition, fry release experiments will be conducted, comparing shoreline, night, and limnetic releases, with evaluation of adults and creel to 2015. Details on the statistical tests and procedures to be followed were scant. Some important references on Banks Lake could not be located (e.g., McCulloch et al. 2011).

2. History: Accomplishments, Results, and Adaptive Management (ISRP Review of Results)

The history of the project was explained in reasonable detail. Project sponsors presented a logical progression of evidence that examined possible bottlenecks to kokanee abundance including water quality, harvest rates, entrainment during the irrigation season, variable lake level effects on spawning success, and hatchery kokanee release strategies. While all of these factors have had some impact, the weight of evidence supports the hypothesis that predation (primarily by walleye) and competition for zooplankton with lake whitefish are the two factors most likely to be limiting kokanee recovery. WDFW staff did a good job of following the evidence to reach this conclusion.

The best example of adaptive management has been a shift in hatchery releases from spring fry releases to fall fry releases and spring net pen yearling releases. Studies of the survival of otolith-marked fish in these three release groups clearly indicated that spring fry releases had very low survival, and therefore the latter two release strategies are now being implemented.

One important factor that has admittedly not yet been clarified is the actual abundance of walleye in Banks Lake. Based on gill net captures from other large lakes in the region, walleye in Banks Lake are not particularly abundant, yet they are thought to consume up to 90% of the released kokanee fry. As project sponsors point out, developing an improved method of estimating walleye abundance is critical to the project, especially if harvest regulations are changed.

The sponsors have collected data for 10 years and determined: (1) predation by walleye is the primary factor (annually take 90% of fry released based upon modeling scenarios), (2) forage base (zooplankton) is limiting in spring and summer due to lake whitefish competition, (3) entrainment is low, (4) temperature and DO is suitable most of year, and (5) harvest of kokanee is very low. A Walleye Population Index was initiated in 2002 (based on standard technique developed in Ontario) to determine status and to track the population over time. Regarding adaptive management, the above conclusions have resulted in a plan to reduce the lake whitefish population that competes for the zooplankton prey via mechanical means, and to reduce abundance of walleye, a top end predator, by regulation change. Present annual harvest of walleyes at Banks Lake is 16,200. Regulation changes, specifically harvest increases at nearby Moses Lake, resulted in lower walleye annual populations. The sponsors recognize that predator eradication is virtually impossible in large systems, but cite work (Zimmerman and Ward 1999) saying that reduction to levels where impacts are insignificant can be accomplished. However, the Zimmerman and Ward (1999) study involves northern pikeminnow effects on migrating smolts, not resident predators in a lake.

ISRP Retrospective Evaluation of Results

The goal of restoring the kokanee fishery has not been met but monitoring of Banks Lake limnology and biology has been completed successfully. What is required now is a more comprehensive analysis using ecosystem models to facilitate the decision process and document the feasibility of kokanee restoration given the current suite of conditions.

A thorough knowledge and review of local limnology and the related issues of competition and predation were evident, including the review results of lake monitoring to date. These data were presented in a series of traditional figures. Fish bioenergetics models will be included in the future analyses. What may be more helpful are a suite of simulation models that consider the limnology, hydro system operations, fish recruitment for all species and their interactions, harvest, using EcoSim and EcoPath. Such comprehensive modeling could include a structured decision management (SDM) process and a stakeholder-based workshop approach to consider the proposed and many more scenarios, for example nutrient addition. Indeed, the more comprehensive ecosystem model approach may be more instructive to managers on the feasibility of the overall plan of kokanee restoration, if such modeling is at all possible given the suite of introduced and invasive species and consequent interactions.

Angler preference surveys were not mentioned but could be accommodated by SDM, along with climate change impacts. The latter was considered briefly as likely leading to further decline in kokanee habitat availability. This impact needs to be explored further via modeling.

Examples where more comprehensive EcoSim models have been recently applied to reservoir fisheries are included in the list below. The ISRP encourages the development of a comprehensive resident fish ecosystem model for application in this and several other reservoirs in the Columbia Basin.

Walleye population estimates seemed unavailable or unobtainable, but further exploration and modeling may assist in that quest. The ISRP has previously stated “serious misgivings about the project’s emphasis on creating a kokanee fishery…” due to walleye presence. As a key variable in the kokanee abundance and survival issue, methods of monitoring walleye abundance are needed, particularly if an impact of regulation change is to be effectively monitored. The estimated abundance of whitefish (0.5M) suggests consideration of a small commercial fishery may be worthwhile. This too should be part of the simulations.

See http://www.ecopath.org/

Osidele O.O., Beck M.B. 2004. Food web modeling for investigating ecosystem behaviour in large reservoirs of the south-eastern United States: Lessons from Lake Lanier, Georgia. (2004) Ecological Modeling, 173 (2-3), pp. 129-158. http://www.sciencedirect.com/science/article/pii/S0304380003003831

Thebault J.M., Salencon M.-J. 1993. Simulation model of a mesotrophic reservoir (Lac de Pareloup, France): biological model.(1993) Ecological Modeling, 65 (1-2), pp. 1-30. http://www.sciencedirect.com/science/article/pii/030438009390124B

Laurel Saito, Brett M. Johnson, John Bartholow and R. Blair Hanna. 2000. Assessing Ecosystem Effects of Reservoir Operations Using Food Web–Energy Transfer and Water Quality Models Ecosystems Volume 4, Number 2, 105-125. www.springerlink.com/content/3d871lfmwpv27x7j/

Angelini Ronaldo, Agostinho Angelo Antonio, Gomes Luiz Carlos. Modeling energy flow in a large Neotropical reservoir: a tool to evaluate fishing and stability. Neotrop. Ichthyol. [serial on the Internet]. 2006 June [cited 2012 Jan 09] ; 4(2): 253-260. Available from: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252006000200011&lng=en. Http://dx.doi.org/10.1590/S1679-62252006000200011.

Gamito S., Erzini K. 2005. Trophic food web and ecosystem attributes of a water reservoir of the Ria Formosa (south Portugal). (2005) Ecological Modeling, 181 (4), pp. 509-520. http://www.sciencedirect.com/science/article/pii/S0304380004003849

Taylor, M.W. 1981. A Generalized Inland Fishery Simulator for Management Biologists. North American Journal of Fisheries Management Vol. 1, Iss. 1, 1981

Hanson, P. C., T. B. Johnson, D. E. Schindler, and J. F. Kitchell. 1997. Fish bioenergetics 3.0 software and manual. Sea Grant Institute, Center for Limnology, University of Wisconsin-Madison.

3. Project Relationships, Emerging Limiting Factors, and Tailored Questions for Type of Work (hatchery, RME, tagging)

The proposal provides an adequate explanation of its relationships to other projects in the Crab Creek system, and also with the relevant Lake Roosevelt fisheries projects that are related to the work on Banks Lake.

It was encouraging to see that the project is considering the effects of toxins and climate change on the lake ecosystem. Both of these factors could have significant effects on kokanee recovery over time.

This project is 100% RME, and the questions are appropriate for the type of work being proposed. Project relationships were clearly defined in relation to resident fish recovery and mitigation efforts and the Subbasin Plan.

4. Deliverables, Work Elements, Metrics, and Methods

Sufficient details were presented for the majority of the seven deliverables presented and the work elements. Descriptions of methods were uploaded to MonitoringMethods.org, and the project sponsors did an especially good job in this regard.

Additional information is needed on how the success of the two major initiatives proposed here will be assessed. For the lake whitefish removal effort, how will success be defined: by lowering the whitefish abundance to a level that is believed to allow for reduced competition for food resources or by simply documenting an increase in survival and growth of rearing kokanee and assuming improvements have resulted from lake whitefish removal? For the walleye angling regulation change, what parameters are under consideration and what is the anticipated change in the Banks Lake walleye population that is anticipated to result from the changes? Assuming that near elimination of walleye is not an objective, what is the target number and age distribution of walleye that is believed to be sufficient to reduce the predator cap on kokanee? Given that there does not seem to be an accurate method of measuring walleye abundance in Banks Lake, how will it be possible to determine when success is achieved, especially when lake whitefish removal is occurring simultaneously?

4a. Specific comments on protocols and methods described in MonitoringMethods.org

As stated above, the project sponsors did an excellent job of providing details on their monitoring protocols. Monitoring protocols and methods are appropriate, but additional more comprehensive ecosystem models are required. It seems it will be extremely difficult to maintain a trophy walleye fishery, and at the same time increase the kokanee population to a viable harvestable population. It may be necessary that the harvest of walleye be modified to reduce the predation significantly, and then the lake whitefish must be collected in adequate numbers to reduce the competition with kokanee. This may require continued annual effort in reduction of walleye and whitefish, and monitoring. Further exploration of reductions required is needed.

Modified by Dal Marsters on 4/17/2012 2:39:54 PM.

The non-fundable element is the proposal to create a spawning channel for kokanee (withdrawn by sponsor in their response). The ISRP has serious misgivings about the project's emphasis on creating a kokanee fishery by other means, as well, because significant populations of non-native, top-predator fishes exist in the lake. However, kokanee stocking could justifiably proceed under appropriate monitoring and evaluation, and in view of the sponsor's revised proposal to manage angling to reduce the lake's walleye population.

The project involves the problem-prone situation of an artificially created and artificially manipulated water body that contains an artificial assemblage of fishes, including species not native to the region. The lake functions in some unnatural ways to which the fish are not adapted, and some members of the fish assemblage are not adapted to interact well with each other. The sponsors' task of trying to manage this system to suit a diversity of angling interests is difficult indeed.

The project's stated purpose is fishery mitigation for the loss of anadromous salmon. The proposal's main focus is on creating a kokanee fishery, secondarily rainbow trout, walleye, and bass. Its more specific goals involve increasing natural-origin kokanee (thus reducing fishery reliance on hatchery-origin kokanee), while maintaining "quality fisheries" for walleye, bass, and burbot. Toward this, and based on the project's previous studies, the sponsors proposed two lines of work: (1) to continue studying water quality, food limitation, angling exploitation, predation by exotic fishes, and the effectiveness of hatchery kokanee releases (adaptive management implied) and (2) to increase the lake's kokanee production by enhancing spawning habitat and improving access at Northrup Creek and adjacent shorelines.

The ISRP considered the idea of trying to boost kokanee production by creating an artificial spawning channel unsound, partly because a concentrated source of kokanee fry could attract walleye to the entry area, and thus much of the new production would just feed predators. In response, the sponsors withdrew that part of the proposal.

Moreover, the ISRP considered the original proposal's overall emphasis on kokanee scientifically unsound and thus not fundable because the sponsor maintains major fisheries for walleye and bass in the lake, and these are top predator species capable of preying on kokanee. The proposal indicated that the project's studies to date found predation by walleye to be a limiting factor for kokanee in the lake. The narrative stated: "Predation has been identified as the predominate factor affecting survival of kokanee in Banks Lake. Annual kokanee losses to walleye predation are 13-17% . . . a conservative estimate since acute predation occurs during stocking events." Also, the proposal stated that smallmouth bass are about three times more abundant than walleye but did not mention their effects on kokanee.

The ISRP suggested that the effort to manage for a significant kokanee fishery in the lake halt, pending literature evidence from elsewhere that suggests kokanee can thrive in the face of predation by walleye and bass, species with which kokanee did not co-evolve. The ISRP suggested also that the sponsors should clearly eliminate alternative hypotheses for low numbers of kokanee before accepting the alternative that shortage of spawning habitat is the problem. The ISRP recognized that a strategy of eliminating walleye and bass from the lake probably would be impractical from a management standpoint and undesirable for many of the lake's present anglers.

The ISRP rated the proposal as not fundable and explained that it did not request a response because the proposal presented enough information to determine, based on science, that the management strategy described had a very low probability of success. In other words, the project did not meet criteria for benefit to fish and wildlife.

The sponsors submitted a reasonably thorough response that showed thoughtful consideration of the issues. They dropped the idea of a kokanee spawning channel, but maintained that continued emphasis and study of kokanee stocking should continue. They argued, somewhat in contradiction to statements in the original proposal, that predation on kokanee by walleye is not great enough to impair the development of a viable kokanee population and fishery. They held that bass predation must be insignificant. They offered other evidence (mainly gray literature and personal communications) to support those positions, pointed to recent improvement in kokanee catch (probably due to changed stocking procedures), and said they could liberalize angling regulations so as to reduce the walleye population. Regarding bass predation, they contend that bass occupy shallow areas that do not overlap significantly with salmonid habitat of the same lake, that bass would not eat many salmonids, and that kokanee exist in other Washington lakes that contain bass.

On the other hand, the ISRP is aware of evidence that bass eat many rainbow trout in some California lakes. Furthermore, the sponsors have not yet truly measured predation by walleye and bass in Banks Lake. A related problem is that the sponsors can express the fish populations only in terms of relative size (percentage of total species composition) and do not know their numerical abundances. This is understandable in a large body of water that is difficult to sample for abundance estimates.

The ISRP recommended that the sponsors search literature for evidence that kokanee are compatible with walleye and bass. In an intensive search for this, the sponsors found little: the only reports on waters containing all three species together came from Lakes Roosevelt and Rufus Woods, where harvest and escapement goals for hatchery kokanee have not been achieved. The sponsors feel those situations do not apply to Banks Lake. The response stated: "We can find no literature to support [the ISRP] conclusion that these species [kokanee, walleye, smallmouth bass] are not compatible . . ." This isn't surprising, for kokanee, a Pacific drainage species, did not coevolve with those Atlantic drainage species. There is, however, reason to expect low success in trying to maintain a kokanee fishery in the face of walleye and bass populations because kokanee are unlikely to be well adapted for coexistence with those predators.

The ISRP still has serious concern about the advisability of trying to manage for kokanee in a walleye and bass lake but believes the project could be funded in part to continue testing that effort.