FY07-09 proposal 200102800

Jump to Reviews and Recommendations

Section 1. Administrative

Contacts

Section 2. Locations

Province / subbasin: Columbia Plateau / Crab

Section 3. Focal species

Section 4. Past accomplishments

Section 5. Relationships to other projects

Section 6. Biological objectives

Section 7. Work elements (coming back to this)

Section 8. Budgets

Itemized estimated budget

Total estimated FY 2007-2009 budgets

Cost sharing

Section 9. Project future

Future O&M costs: the costs for staff, goods and services, and travel will be similar to costs in FY2009, with a slight increase for cost of living.

Termination date: none
Comments: M&E can continue to evaluate at least 3 marked age classes of kokanee from modified release/rearing strategies.

Final deliverables: Final deliverables will be a comprehensive final project report to BPA and portions will be published in peer reviewed journals.

Section 10. Narrative and other documents

Reviews and recommendations

ISRP PRELIMINARY REVIEW (Jun 2, 2006)

Recommendation: Not fundable

NPCC comments: This proposal is for adding an “implementation phase” to the past investigation of Banks Lake fishery potential, in which the sponsor would try to boost kokanee production by creating an artificial spawning channel for the lake. The ISRP considers the kokanee plan scientifically unsound and thus not fundable because the sponsor maintains major fisheries for walleye and bass in the lake (as well as burbot population) and all of these species prey on kokanee. The project’s studies to date have shown that predation by walleye is a limiting factor for kokanee in the lake. Bass are even more abundant than walleye and may be another major predation source. The Narrative p 8 (near bottom) states: "Predation has been identified as the predominate factor affecting survival of kokanee in Banks Lake. Annual kokanee losses to walleye predation are 13-17% (Polacek et al. 2004); however, this is a conservative estimate since acute predation occurs during stocking events (Polacek, unpublished data)." However, it is said at end of the Abstract that and overall project goal is to "maintain quality fisheries for walleye (Sanders vitreus), bass (Micropterus spp.), and burbot (Lota lota)." It is indicated on p 2 that smallmouth bass are about 3 times more abundant than walleye, butthe effect of small mouth bass on kokanee is not mentioned in the project history. Moreover, even if the proposed artificial channel were to increase kokanee reproduction, a concentrated source of kokanee fry could attract walleye to the entry area. In other words, the new production would just feed the existing predators. The effort to manage for a significant kokanee fishery in the lake should 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. In short, the proposal should clearly eliminate alternative hypotheses for low numbers of kokanee before accepting the alternative that shortage of spawning habitat is the problem. The ISRP recognizes that although it was not mentioned in the proposal, a strategy of eliminating walleye and bass from the lake probably would be impractical from a management standpoint and undesirable for the lake’s present anglers. It would be advisable for the sponsor henceforth to manage the lake as a fishery for walleye and bass, given the fact that those non-native species dominate the sport-fish community. A detail: The proposal’s method dealing with investigation of predation states: “Fish prey [from stomachs] will be identified to species . . .” but the sponsors present no study design for sampling the predators. The ISRP is not requesting a response, because the proposal presented enough information to determine, based on science, that the management strategy described has a very low probability of success; i.e., the proposal does not meet the ISRP criteria of benefit to fish and wildlife.

ISRP FINAL REVIEW (Aug 31, 2006)

Recommendation: Fundable in part

NPCC comments: 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.