The proposal should have provided a better summary of the response of kokanee to the initial addition of nutrients to the lake and have more strongly anticipated the expected future response. The following comments are given as feedback so future analysis might be strengthened.

To understand how the kokanee population responds to nutrient addition, it would seem to be necessary to track each cohort (brood year) separately over its lifespan. Data should have been broken out into growth and abundance by age, and before and after maturation, as that gives a better indication of whether there is a strong year class and how well the fish are growing. Although the sponsors indicated that they would age fish and some objectives addressed specific numbers of fish of a given age, it would have been better if they had set a target density, that is number, of fish of a given growth rate or size.There are many problems with assessing kokanee populations because of their short life and semelparity. Density plays a large role in not only pre-maturation growth rate but maturation schedule, post-maturation-decision growth rate, total survival of fish to an age, and thus on year-class strength. The proposal would have benefited from a clearer description of exactly how the sponsors would monitor kokanee response to better clarify if abundance and growth are actually responses or just observations independent of the nutrient addition. The sponsors simply showed that kokanee biomass went up after the years of nutrient addition, without carefully documenting the exact age-specific response or causal links that may be potentially identifiable in their shorter term plankton responses.

The proposal does not indicate how many age-groups of kokanee are present in Dworshak Reservoir, but from papers by Rieman and others it appears to be three. Table 1 of the response gives data for a variety of age-groups and appears to suggest the age-2 fish might be the oldest the project dealt with. This point needs clarification.

Reviewers were expecting to see creel census data presented in the response, but the response indicates no creel surveys were done because of lack of funds. This is an important oversight, but the sponsors note that some creel census will be incorporated into future efforts.

The sponsors repeated that, “The benefits of N supplementation are cumulative, with benefits reaching higher trophic levels in successive years.” This statement is poorly documented. If many of the phytoplankton responses are rapid and zooplankton consume phytoplankton, then why is it assumed that it takes 4-5 years for a kokanee response? How good are the scientific data from Stockner and the work of others leading to this conclusion and why was it not referenced? Understanding the reality of this lag time seems crucial to their claimed observed kokanee response in the past and crucial to the proposed 5-year time frame in this proposal. Without that understanding, the observed year class of kokanee may have been due to more random and unknown year class events/variations that kokanee are well known to exhibit.

In the response, new information was given on kokanee size and numbers from fall seining of prespawning adults collected at index tributaries of the North Fork Clearwater River. These data, presented with minimal detail, appear to contradict previous conclusions based on trawl and acoustic surveys. Figure 4 shows that the number of adult kokanee gathering to spawn increased sharply in 2010, but that average length was the same as before nutrient addition. This is the opposite of what was observed in summer trawl/acoustic sampling when fish density remained about the same, but biomass increased after nutrient addition as compared to pre-nutrient addition. Also, having this "record number" of spawners indicates a high density of age-0 kokanee might be expected for 2011, which is not a desired outcome, and apparently did not occur.

The ISRP has concerns about the interpretation of Objective 3 and the part of Deliverable 3 that involves this seining of index spawning streams and measurement of spawner length, weight, and fecundity of female spawners. The inference here is that spawner carcasses will increase the productivity of these streams and thus benefit resident fishes. The sponsors make the valid point that nutrient addition to lakes has been shown in other studies to increase kokanee growth and biomass. The sponsors, however, plan to measure neither stream productivity nor the response of lower trophic levels and resident stream fishes. For these reasons, the ISRP does not believe that simply measuring spawner abundance in the index streams and inferring a positive response is scientifically warranted. Without basic measures of stream and lower trophic level biomass productivity, it will be difficult to demonstrate any relationship between the reservoir nutrient enrichment actions with increases in stream food web productivity. If the project moves in that direction, comparisons with adjacent reference streams that are not accessible by Dworshak kokanee spawners would seem an important evaluation element.

In Part - The enclosure experiments are not adequately justified. The enclosure (mesocosm) experiments were questioned in the initial ISRP review. Reviewers then felt this work might be of scientific value if it was well justified and shown to be an integral part of the overall effort. The response, however, did not provide an adequate justification for this component of the project. There were no hypotheses and no clear indication of what the measured responses would be, and how those responses could be directly related to kokanee growth and year class strength. This essential information should have been provided in the proposal or response, not just by referencing a U.S. Army Corps of Engineers study at Heppner, Oregon. The sponsor's response defended the intent of the mesocosm study, and one justification for the enclosure experiments is that it will help assuage public concerns. The sponsors also argue that the enclosure experiments will allow them to better regulate nutrient addition to the reservoir and provide a better understanding of the trophic dynamics of the system, although effects on kokanee growth will only be able to be inferred from these experiments. Another advantage of the enclosure experiments is that they could allow determination of the effects of nutrient additions under conditions of less environmental variability than in the reservoir, and could strengthen the inference, based on the response of lower trophic levels, that nutrient addition to the reservoir is having a positive effect on kokanee. The ISRP does not find those arguments to be sufficiently compelling to scientifically justify the resources that would be consumed by this task.

A lawsuit stopped lake fertilization in 2011, the fourth year of a five-year test, which although a setback for the project was beneficial in terms of monitoring and evaluation. With a cessation of fertilizer input, the sponsors saw a rapid response with blue green algae returning to pre-nutrient enhancement levels. In a nitrogen-limited system, blue green algae can fix nitrogen, and thus outcompete other species that need nitrogen. However, with adequate nitrogen levels, other algal species and their zooplankters predominate over blue green algae, and support a plankton-based kokanee fishery. 

The proposed food web monitoring is critical to evaluating success or failure of the proposed project and addressing both scientific and political concerns. Nevertheless, the ISRP wonders if the monitoring could be reduced in scale and budget and still meet the political and scientific needs for the project? For example, the enclosure experiment could be deleted, as it seems unnecessary and expensive. 

The sponsors did food web work, which should be encouraged, but do not identify the criteria they are going to use for evaluating success nor do they commit to much detail on their fishery goals, in spite of some recent positive results. For example, what kokanee population response is needed to indicate success? The sponsors need a more rigorous presentation of their analysis methods and of existing data to date, including how annual variation in kokanee abundance can be sorted out from treatment response. 

The proposal needs to be more sharply focused on a testable hypothesis. The sponsors argue that fertilization must be repeated, for an additional five years, because four years of data are apparently inconclusive (yet almost no detail regarding results is given to review). A critical question is whether four years of study shows significant enhancement of kokanee. When the population biomass "doubled" at the end of four seasons, were the IDFG management goals for kokanee met? Is it not possible that four years of fertilization were indeed adequate to evaluate a fishery response?

Alternatively, would simply monitoring the kokanee population in summer 2012 answer the question? Further, what really is the question – what kokanee population response is needed to indicate success? The sponsors need to discuss their results (especially kokanee) in light of what has been found in other water bodies. Is the Dworshak work really pioneering?

A response is requested on the following issues: 

1. Provide justification that the duration of the second phase of the study (five years) is long enough to yield conclusive results, given the inevitability of natural variation in kokanee abundance, catch, and spawner counts, and the likelihood that a response of kokanee to the treatment will only be observed in the last one or two years of the study. In their response the sponsors should consider providing a more comprehensive analysis of variability in kokanee abundance and spawner counts prior to the first treatment. In addition it would be helpful if the sponsors provided information on the response of lake biota following cessation of the first set of treatments in 2010.
2. Provide data indicating that pre-treatment kokanee population abundance, angler catch, and fish size did not meet IDFG’s management objectives for the reservoir, and how the objectives were derived.
3. Provide better justification for how the enclosure experiments will directly contribute to understanding kokanee response to nutrient additions in the reservoir. Granted these experiments will shed light on limnological responses over a range of nitrogen concentrations and perhaps assuage public concerns, but what else will they do? For example, will these experiments provide information on trends in lake chemistry, phytoplankton, and zooplankton that cannot be reliably obtained from reservoir samples? Will the experiments provide greater understanding of mechanisms underlying biotic responses to nutrient addition? Will the experiments provide information on kokanee response that is not already known from the fisheries literature? Finally, could the enclosure experiment be reduced in scope or eliminated without compromising the project’s biological goals? 

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

The proposal identifies three stated objectives: to enhance reservoir productivity, to enhance the kokanee population and to improve nutrient cycling in the river upstream from the reservoir.

The proposed work is to determine if the addition of nitrogen fertilizer to Dworshak Reservoir will enhance the kokanee population and improve the reservoir and upstream fishery. The U.S. Fish and Wildlife Service established a goal of stocking 100,000 lbs of trout annually in Dworshak as mitigation for the loss of resident fisheries (Ecovista et al. 2003, pg 327). However, this goal has only been met three times in the history of the project (IDWR 2000) and recently stocking has been approximately 20,000 pounds annually. Fisheries for non-native kokanee and smallmouth bass have since supplanted trout as the primary fisheries in the reservoir. However, these fisheries continue to be severely limited by reservoir operations. There are no present efforts to mitigate for the loss of historically abundant anadromous fish and marine derived nutrients to the fish and wildlife populations of the North Fork Clearwater ecosystem.

The sponsors present some evidence that the productivity of Dworshak Reservoir has declined, possibly due to operation of the dam, natural aging of the lake, and loss of marine-derived nutrients due to extinction of the salmon run in the North Fork Clearwater River. A five-year pilot nutrient enrichment project was funded in 2007 by BPA. After four years of nutrient addition and data collection the project was suspended in 2010 due to a permitting issue. A positive response in kokanee abundance was seen only in the fourth or last year of the study prior to its cessation. The sponsors are proposing another five year study to more conclusively determine whether nutrient additions to the reservoir will improve kokanee abundance, angler catch, and number of spawners. 

The work is consistent with the Fish and Wildlife Program and the North Fork Clearwater Subbasin Plan where one goal is “assessing where nutrient additions or reductions would be beneficial to focal species.” 

The proposed work would be better justified if the sponsors provided data indicating that pre-treatment kokanee population abundance, angler catch, and fish size did not meet IDFG’s management objectives for the reservoir, and how the objectives were derived. The project introduction states that it "seeks to improve resident fisheries in Dworshak Reservoir through the careful addition of a nitrogen-based fertilizer to the reservoir. In particular, the kokanee population should benefit from improved reservoir productivity and provide a better fishery for anglers. Further, fish and wildlife species in the North Fork Clearwater Subbasin will benefit from nutrients that kokanee transport to spawning tributaries where marine derived nutrients were historically abundant." However, it appears to reviewers that a more accurate description of the current goal is, or should be, to assess if fertilization is sufficiently cost-effective to adopt as regular, annual management.

Objective 3, “Improve nutrient cycling to the North Fork Clearwater River and its tributaries,” is based on the supposition that decomposition of the carcasses of larger runs of kokanee will increase nutrient levels in spawning streams and so benefit stream biota such as bull trout. They also surmise that kokanee fry will provide a food source for bull trout. While possible, this assumption seems at this point to be largely conjecture because no direct evidence was presented that the spawning streams were nutrient limited or that bull trout growth and survival were food limited. Furthermore, the sponsors do not propose to measure nutrient concentrations in the tributaries or determine if any changes in stream biota, including bull trout growth and abundance, have occurred following nutrient addition to the reservoir. Without this information Objective 3 cannot be accomplished. Consequently, either the sponsors should provide an adequate plan to accomplish this objective or the objective should be deleted from the proposed work at this time. 

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

In the spring of 2007, the U.S. Army Corps of Engineers (USACE) began applying liquid fertilizer weekly to the reservoir while IDFG monitored the response of the reservoir and kokanee population. Results from the first four years of nutrient supplementation indicated an immediate increase in densities of picoplankton, followed by a reduction in N₂ fixing cyanobacteria concurrent with an increase in the proportion of edible phytoplankton taxa, and an increase in the density and biomass of Daphnia, the preferred forage of kokanee (Scofield et al. 2011). By the fourth year of the project, kokanee were larger than they were in a pre-supplementation year with similar fish densities, and kokanee biomass was twice as high as it had been in recent years for which the sponsors were able to estimate biomass (Wilson et al. in prep). In addition, spawner counts in index streams were the highest on record (Wilson et al. in prep). How much confidence can be placed on the "biomass being twice as high" statistic? Is that likely to be a real, meaningful increase when considering the extent of normal interannual variability? 

A positive response by kokanee was seen only in the last, or fourth, year of the first set of treatments. The sponsors expect the lake to return to pre-treatment conditions following cessation of the first round of nutrient supplementation in 2010. If this occurs and a kokanee response is observed only in the fourth or fifth year of the second set of treatments, as it was in the first set, it could be difficult to determine, with only one or two years of data, whether the response was due to the treatment or to natural variability in lake chemistry, phytoplankton, zooplankton abundance, and kokanee abundance. Given this variability, there is no certainty that a clear, scientifically valid, kokanee response will be evident in a five-year time frame. It seems that a study of much longer duration would be needed to account for natural variability and to provide conclusive results.

ISRP Retrospective Evaluation of Results

The lack of detail given in the proposal on results to date, especially regarding kokanee, made the proposal more difficult to review adequately. The sponsors need to provide more results and discussion than a table and two figures. Data and discussion about creel results including fish size, and catch rates, would have been informative.

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

The sponsors will work in collaboration with the USACE’s Dworshak Resident Fish Mitigation Project. The proposed work also is relevant to two BPA funded projects: the Lake Pend Oreille Fishery Recovery Project (199404700) and IDFG’s nutrient restoration project on the Kootenai River that is part of the Kootenai River Resident Fish Mitigation Project (198806500). Relationships with USACE are described, with the USACE covering the cost of the fertilizer and its application, $181K annually, as before.

4. Deliverables, Work Elements, Metrics, and Methods

Most Deliverables are accomplishable and relate directly to the stated Objectives. Standard limnological methods will be used to collect data on lake chemistry, phytoplankton, and zooplankton. Data on the kokanee population will be collected using protocols developed by IDFG. These methods appear sound.

There are six deliverables, including badly-needed public outreach.

Deliverable 1: Monitor limnological conditions of the reservoir – Some monitoring is clearly appropriate but needs to be described in more detail and better justified. Monitoring accounts for nearly half of the annual budget for the proposal. 

The ISRP has commented in its retrospective reports and other reports on the importance of monitoring to evaluate responses to actions; however, the ISRP has also noted that monitoring needs to be targeted so it can answer the needed questions but not consume a disproportionate portion of the project’s budget. We wonder if a scaled down monitoring plan for the food web could adequately provide the project’s M&E needs and increase cost-effectiveness for the project. 

Deliverable 2 is the experimental enclosure experiments. Although interesting, the need for enclosure experiments (Deliverable 2) is uncertain. The central question this proposal addresses is whether the kokanee population will respond positively to nutrient additions and the enclosure experiments will shed little light on this question. Reviewers are not convinced of the need for this task, suggesting it is redundant with work done elsewhere.

Modified by Dal Marsters on 4/16/2012 11:01:02 PM.

The response was very thorough and well organized. Each issue raised in the previous ISRP review was explicitly addressed. The additional information on previous studies that have been conducted as part of the effort to restore the focal fish species in Lake Pend Oreille was especially helpful in clarifying the questions raised by the ISRP in the previous review.

The ISRP agrees that working in this large natural lake poses many difficult challenges, but the responses indicate that IDFG is making a good faith effort to incorporate the latest information into their studies and have enlisted the help of very qualified specialists. The ISRP appreciates that additional details about the results of previous investigations have been incorporated into the proposal. Links to annual reports and other reports summarizing data are useful, but they do add to the difficulty of assessing scientific merit when a link must be followed. Where possible, concise summaries of main findings, in addition to the links, are very much appreciated and make the review process more efficient. We also appreciate that the field methods pertaining to this study in Monitoringmethods.org have been reclassified so that details are now accessible.

Overall, the ISRP is satisfied that this project will continue to generate useful data on the management of Lake Pend Oreille and its fisheries, and are confident that the sponsors have thought carefully about addressing these issues in this complex lentic ecosystem.

ISRP Retrospective Evaluation of Results

The Lake Pend Oreille Kokanee Mitigation project is a good example of a study where project staff has done an excellent job of seeking outside assistance in tackling a very tough scientific problem. While the project title suggests that it focuses on kokanee, it is clear that the project's scope has broadened to other fishes as well as the limnological dynamics of the Pend Oreille ecosystem itself. This project is almost 20 years old, and a publication summarizing what has been learned over the last two decades would be a valuable contribution, as well as useful in informing fishery managers in other large lake systems.

The Lake Pend Oreille fishery has received a lot of attention because it focuses on the historically large non-native kokanee population, which is in decline although apparently recovering slowly, as well as a trophy rainbow and bull trout fishery, which is also depressed. Many restoration actions are occurring simultaneously, and it will be difficult to determine the efficacy of individual program elements on both the harvest and conservation objectives. Nevertheless, this project has contributed valuable information on the ecosystem processes supporting the lake's salmonid populations over the last decade, and it is likely to provide useful data in the future.

The ISRP requests clarification on several points before providing a final recommendation.

1. What is the likely role of lake whitefish in reducing abundance of Mysis?
2. Additional justification is requested for adding spawning gravel to select shorelines to increase kokanee spawning.
3. A summary of what has been learned over the past 15 years of management actions in the context of the overall objective of increasing harvest is needed.
4. What has been learned from Lake Pend Oreille research that has helped IDFG balance conservation and harvest objectives?
5. What are likely reasons why rainbow trout have increased in abundance by 50% from 2009 to 2010?
6. Other questions and concern are embedded in the comments provided below. The ISRP suggests the sponsors examine these items as a response is prepared.

Apart from specific questions, the ISRP feels the restoration of native resident bull trout and westslope cutthroat trout in Lake Pend Oreille deserves additional attention. This proposal devotes little attention to these species, even though other proposals in the region do. For example, there may be adfluvial populations of cutthroat trout that could or do provide important sport fisheries, and management could consider restoration actions in Lake Pend Oreille’s tributary habitats. Ongoing lake trout suppression would also benefit these other native species, but increased kokanee production would not likely benefit whitefish or most cutthroat trout

See the ISRP’s programmatic comments on fish stocking.

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

This project has been in place for a long time, and the plan of work was reviewed by the ISRP in 2006, when it was given a favorable assessment. It is important to note that Lake Pend Oreille represents a large natural lake with a highly altered fish community. Of the three primary focal species, two are not native (kokanee and Gerrard stock rainbow trout) and the third (bull trout) is primarily of interest from a conservation standpoint, not a harvest standpoint. Additionally, the food web in Lake Pend Oreille has been strongly affected by the invasion of a non-native zooplankton (Mysis diluviana), which has acted as a competitor with kokanee and also helped to fuel the expansion of the non-native lake trout population, a significant predator on mysids as well as kokanee and juveniles of other salmonid species. As with many large lakes with increasing human development in the watershed, management challenges in Lake Pend Oreille are complex.

The project sponsors have done a good job of describing the relationship of this project to other regional resident fish management efforts, and their description of the technical background was also well done.

The proposal makes clear that recovery of the Pend Oreille fishery is the project's primary goal. Conservation of the two native salmonid species, bull trout and westslope cutthroat trout, is acknowledged in the work, but the primary emphasis is either research that addresses factors limiting kokanee and trophy trout recovery or habitat improvements that benefit kokanee reproductive success, such as addition of spawning gravel. Reduction of the lake's population of lake trout, generally viewed as a negative influence in the Pend Oreille ecosystem, also figures prominently in the work.

As mentioned above, management challenges are complex and restoring a desired balance of species, that is a balance that favors angler harvest of kokanee and trophy trout, will require that a number of potential limiting factors be addressed simultaneously. This will essentially mean a trial and error approach, and that is what IDFW have been doing for the last 15 years. A strong monitoring program will be essential for detecting the signal of programs such as lake trout reduction, winter lake level manipulation, kokanee stocking adjustments, and possible nutrient additions.

The role of lake whitefish in reducing abundance of Mysis is mentioned once but is not addressed again. Could this be important?

The objective to increase kokanee spawning success by adding spawning gravel to select shorelines needs additional scientific justification. When gravel is added in streams or lakes without addressing the hydrogeomorphic factors that create clean spawning gravel, for example upwelling and wave action, the usual result is that the gravel simply becomes unsuitable, requiring either more gravel or manual cleaning, all at great expense. Additionally, we wonder whether studies of kokanee egg survival in the laboratory and in boxes buried in lake substrate will answer the question of interest: what conditions are necessary for high survival, and how does survival vary with sediment deposition? It is clear that survival should be low when sediment is high, but at moderate levels of sediment, it is not clear whether human-placed egg boxes or eggs monitored in the laboratory will mimic those from egg pockets placed by female fish sufficiently to generate useful data. 

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

The proposal does a good job of summarizing the administrative accomplishments of the project. More details could have been given on results to date. A single graph was presented showing lake trout abundance from 1999 to 2008 but with only 5 years sampling data, while it would have been helpful to have seen similar summaries as graphs or tabular data for the other salmonid species. Over the last 15 years a variety of management actions have been implemented such as lake trout netting, experimental winter drawdowns, hatchery operations, and angler programs. A summary of what has been learned from these actions in the context of the overall objective of increasing harvest is needed. It does appear that predator control has had some success, but what about other efforts? Also, there was little mention of warm-water fishes. Have these introduced fishes had negligible impact on focal species in other areas of the lake?

More information is also needed on how the results of the Lake Pend Oreille research have been incorporated into management changes. In particular, the potential for conflict between conservation and harvest objectives needs additional clarification. What has been learned from the research that has helped IDFG balance these two important objectives?

Other questions on accomplishments include:

Why have rainbow trout increased in abundance by 50% from 2009 to 2010? Is this difference significant, or are the confidence intervals around these estimates wide? If the difference is real, and not owing to high variability, then what is the explanation – high recruitment rates of small fish?

Lake trout marking – lake trout are reported as being marked in 2011 to estimate abundance by mark-recapture, but in the rest of the proposal all the lake trout were removed. When and where were these lake trout marked, how many, and of what sizes?

Management changes have focused on better targeting lake trout removal efforts in response to new data, and thereby reducing bull trout bycatch. The project sponsors acknowledge pressure from kokanee and rainbow trout anglers to increase abundance of these fishes and expand the fisheries, but how has this pressure driven management decisions as opposed to a focus on conservation and restoration of resident native fishes?

ISRP Retrospective Evaluation of Results

It is clear that the food web dynamics in the lake are changing, but it also seems clear that the primary focal species have not returned to a level of abundance that support harvest objectives. There is no question that the studies proposed here will help address some of the most important problems; however, the proposal itself did not supply very many details about the results of previous management experiments, with the possible exception of the lake trout netting program. Sorting out the benefits of the various initiatives including predator control, habitat improvements, hatchery releases, and nutrient manipulations will be very difficult when they are all happening at the same time and will require very creative field experiments and analyses.

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

Because this project has a long history and Lake Pend Oreille has been intensively studied, the suite of potentially limiting factors has been adequately characterized. The project also seems to be well integrated into other work taking place in the Pend Oreille watershed.

The questions being asked specific to kokanee restoration seem appropriate, for example, where do lake trout spawn and at what locations in their daily or seasonal movements will they be particularly vulnerable to capture? Additional work is needed on understanding the role of winter drawdown in regulating kokanee reproductive success, whether physical addition of gravel along shoreline spawning areas can be cost-effective, and whether deliberate nutrient supplementation can achieve desired food web benefits. Fortunately, the proposal contains elements that address these matters.

The proposal did not supply much detail regarding how salmonid releases from hatcheries would be carried out to maximize learning opportunities nor did it give many details about existing or planned monitoring efforts except for the acoustic tracking work on lake trout, which was adequately covered. It was also unclear how project staffs are exchanging information with other RME practitioners in the region, although the explicit call for an annual science review meeting to discuss results is an excellent idea.

4. Deliverables, Work Elements, Metrics, and Methods

The ISRP had several questions relative to project deliverables:

The proposal did not specify metrics and indicators in very much detail for some of the deliverables. Often the metrics were described in general terms, but not in a way that particular measurement protocols could be identified or assumed. Many of the protocols and methods in MonitoringMethods.org were in draft form and did not contain sufficient detail for scientific review.

The proposal also lacked information on what would be considered reference conditions for some of the deliverables. For example, if gravel is added to a kokanee spawning area, what would the reference condition be, pre-gravel enhancement egg survival or egg survival in an adjacent spawning area without gravel addition?

Can annual exploitation rates be accurately determined if only 30 lake trout are tagged with acoustic tags per year?

We were unsure why a gear efficiency study is necessary. Would it be more cost effective to buy a bigger boat and trawl and simply increase efficiency this way?

Modified by Dal Marsters on 4/13/2012 1:38:06 PM.

This is a clearly written proposal that presents a multi-pronged approach to improving the kokanee fishery in Dworshak Reservoir. In the response, the sponsors adequately explained their basis for concluding that underwater strobe lights will effectively reduce fish entrainment at Dworshak Dam.



Project objectives focus on increasing kokanee size and abundance, reducing entrainment through Dworshak Dam, and enhancing reservoir productivity. The Clearwater Subbasin Plan (Problem 5, objective 1 - strategy 2) specifies the installation of strobe lights and defines research to minimize fish entrainment through Dworshak Dam. The Subbasin Plan defines research to investigate the effects of loss or lack of nutrients due to federal hydropower-related loss of anadromous salmonids, and evaluate nutrient enhancement alternatives (section 4.3.1 Aquatics: I. General, Proposal 1). The project methods appear reasonable, and the experimental design is defensible.



The proposal describes links to other related projects including 1) the USACE Walla Walla District's Dworshak Reservoir Nutrient Enhancement Project; 2) the Confederated Colville Tribes' Chief Joseph Kokanee Enhancement Project (# 199501100) that is focused on assessing and reducing kokanee entrainment, monitoring kokanee abundance, and testing the effectiveness of underwater strobe lights at reducing fish entrainment; and 3) the Idaho Fish and Game studies of bull trout in the North Fork Clearwater, which is determining bull trout temporal and spatial distributions within Dworshak Reservoir.

This is a well-written proposal for continuation of work that has been productive. With the exception of the kokanee stocking, which both the sponsors and the ISRP question, the work is appropriate. There are a lot of challenges in these large lake systems. They have published work, gained understanding, and moved on. Earlier, they looked at recruitment problems with a lake level experiment looking at gravel spawning. Now they feel they have good recruitment. The study now is looking primarily at predation. Rainbow and lake trout are significant predators.

The proposal provides a good background for both the lake level work for kokanee spawning and the additional proposed studies to balance kokanee with other species. The problems are generally well described insofar as they are understood. The probable depression of reproductive fitness of wild kokanee by interbreeding with hatchery kokanee is not discussed.

The rationale includes regional bull trout conservation efforts, subbasin plan, IDFG five-year plans, and the Fish and Wildlife Program. The conceptual framework presented is helpful. The section is beautifully organized -- refers to specific plan sections for each task.

The proposal cites relationships to other Pend Oreille projects and similar project at Upper Priest Lake. The discussion does not adequately (if at all) link to proposed project 2007-060-00 (Lake Pend Oreille Invasive Fish), which would seem to deal with a major influence on matters that 1994-047-00 is trying to address. The project history gives an excellent overview showing how a well-planned program can, in 10 years, gain significant insight into a very complex system that is exceptionally difficult to sample. Map and figures were appreciated.

Objectives are nicely described and mostly justified, with good hypothesis testing in a challenging situation. Specifically, objectives 1, 2, and 3 are appropriate biological objectives. Objective 5 is for information dissemination. Objective 4, concerning kokanee stocking is the least justified and might be omitted. Research results of this project indicate that stocking hatchery-produced kokanee depresses egg-to-fry survival of wild kokanee (supposedly by stimulating excessive predation). The project should monitor possible increase of wild kokanee after the stocking program ceases and as efforts are continued to reduce rainbow trout, the main predator on kokanee (and to reduce other non-native predators). It appears there are too many objectives, i.e., the sponsor is trying to manage and measure too many things. Eliminating the stocking program should simplify matters and halt a counterproductive influence on the fishery. Methods are generally well described.

The project provides annual workshops, good communications, and good reports with an excellent link. The bottom line, after some very sound work, is that they are still trying to show real benefit to kokanee, bull trout and rainbow. Success with kokanee spawning management has led to realization that the species mix needs fixing, especially non-native lake trout.