BPA Fish and Wildlife FY 1997 Proposal

Section 1. Administrative
Section 2. Narrative
Section 3. Budget

see CBFWA and BPA funding recommendations

Section 1. Administrative

Title of project
Lake Pend Oreille Fishery Recovery

BPA project number   9404700

Business name of agency, institution or organization requesting funding
IDFG

Sponsor type   ID-State/Local Agency

Proposal contact person or principal investigator

BPA technical contact   Charlie Craig, EWP 503/231-6964

Biological opinion ID   None

NWPPC Program number   10.6E.1

Short description
Determine the effects of holding the winter water elevation at Albeni Falls Dam 4 feet high than normal operation on warm and coldwater fish in Lake Pend Oreille. This will cause a 7 fold increase in warm water fish winter habitat, and increase kokanee spawning gravel. Develop resident fish loss assessments that demonstrate which losses are attributable to dam operation.

Project start year   1996    End year   2001

Start of operation and/or maintenance   2001

Project development phase   Implementation

Section 2. Narrative

Related projects

Project history
Research on Lake Pend Oreille kokanee began in 1952 when Albeni Falls Dam was built. Forty years of work, some of which was BPA funded, point to Albeni Falls Dam operation as significantly impacting the lake’s fisheries. When deeper drawdowns began in 1966, kokanee harvest declined from 1 million fish annually to 100,000 to 200,000; a reduction of 80-90%. Studies also showed that warm water fish habitat in the Pend Oreille River is nearly eliminated with the deeper drawdowns. This project passed in the councils program in Oct. 95, but lake was drawn down that fall. Currently, U.S. Army Corps of Engineers is preparing to keep the lake higher in 1996. The Council put together work groups in 1994 and 1995 to design this study and develop the proposal. Preliminary studies in 1994 were conducted to demonstrate that changing lake levels would not adversely affect bull trout.

Biological results achieved

Annual reports and technical papers

Management implications
This project will greatly aid our understanding of the effect of drawdown on warm and cold water fish populations in several waters. It will enable us to do a much better job of balancing the needs of fish with the dam’s constraints for flood control and power production. It will also enable us to develop “biological and integrated rule curves” for Lake Pend Oreille which are based in fact on actual empirical data. Changing the limiting factors and monitoring the populations response is by definition adaptive management of the lake. This project’s findings may well constitute the best chance at adverting collapse of the entire kokanee population which has continued to decline in recent years. Higher lake levels on Lake Pend Oreille will mean more water will flow downstream during the spring. This water will be available for anadromous fish flows. Since kokanee are forage for bull trout, rainbow trout, squawfish, perch, bass, and cutthroat trout, project will enhance populations of non-target species as well.

Specific measureable objectives
1. Determine if increased gravel at a higher winter lake level results in an improvement in kokanee production.
2. Determine if lake level changes cause only a short term increase in spawning habitat, but affect the long term stability of shoreline gravels at higher elevations.
3. Determine effects of higher lake levels on warm water fisheries in the Pend Oreille River upstream of Albeni Falls Dam.
4. Determine whether other factors could be limiting the recovery of kokanee including: low zooplankton, predation, and Mysis shrimp.
5. Determine if the higher winter pool elevation will allow the establishment of Eurasian watermilfoil.

Testable hypothesis
1.1 The correlation of lake elevation to survival rate from eggs to fry will be positive and significantly different from a slope of 0.
1.2 Survival rates from eggs to fry will be significantly higher in years of higher winter water levels than previous years of low winter lake levels.
1.3 Kokanee abundance during test years of higher water levels will define a higher, more resilient, stock-recruitment curve.
1.4 The abundance of kokanee in each year class produced under higher lake levels will show a significant increase when compared to kokanee abundance in the last 7-14 years.
1.5 Estimates of fry produced at historic spawning areas will be significantly higher in years of a higher winter elevation.
2.1 There will be no net change in area of usable spawning gravels below the test elevation.
2.2 There will be no net increase in the silt content of the available spawning gravels below the test elevation.
3.1 Younger age classes of warm water fish will increase during years of higher winter water levels in the Pend Oreille River above Albeni Falls Dam.
4.1 Food is not limiting kokanee of any age class at this time.
4.2 Timing of thermal stratification of the lake will not affect fry survival.
4.3 Predation is not a limiting factor for the kokanee population.
4.4 Mysis shrimp consumption of zooplankton is not sufficient to reduce kokanee fry abundance.
5.1 Eurasian milfoil will not become established in Lake Pend Oreille during the course of this study.

Underlying assumptions or critical constraints
The winter elevation of Lake Pend Oreille is controlling both warm and cold water fish populations.

Methods
Experimental design is to change lake elevations and monitor the survival and abundance of kokanee and warm water fish. Kokanee abundance has been estimated annually for each year class of fish since 1977. Warm water fish abundance was estimated in 1991 and 1992. These will be the data bases for comparison. Kokanee abundance will be estimated by a stratified random survey, annual, using a mid-water trawl. Split-beam hydroacoustics will also be used for abundance estimates. Beach seining and gillnetting will be used for warmwater fish surveys. Parametric statistics will be used to compare kokanee of different year classes. Bioenergetics will be used to model Mysis-zooplankton-kokanee-predator interactions.

Brief schedule of activities
Hydroacoustic surveys will be conducted May through August. Trawling will be conducted during the new moon phase of September. Mysis density estimates will be made in June. Shoreline gravel sampling will be conducted in March and April. Zooplankton sampling will be conducted monthly throughout the summer. Bioenergetics modeling will be conducted throughout the year. Milfoil surveys and mapping will be done in late summer.

Biological need
Dewatering kokanee spawning areas has caused major reductions in the sport fishery. We need to know if raising the winter lake level can reverse this impact. Likewise, will increasing winter habitat for warm water fish produce seven fold increases in their abundance?

Critical uncertainties
The critical uncertainty is that increasing the amount of kokanee spawning area will increase the kokanee population. It is clear that decreasing spawning areas in the mid-1960's caused major declines in the population; we now need to prove that the reverse is true. Also, a critical uncertainty is to determine that warm water fish in the Pend Oreille River will increase with the increase in winter habitat caused by higher lake levels.

Summary of expected outcome
The expected outcome is that we will find that higher winter lake levels allow the kokanee population and warm water fish populations to expand. If this can be incorporated into long term lake management plans, we would expect the adult population of kokanee in Lake Pend Oreille to increase to 3.8 million fish which will be capable of supporting an annual harvest of 750,000 fish. The improvement in kokanee abundance will allow for an expansion in the population of bull trout, and Kamloops rainbow trout. The expansion of warm water fish will allow the Pend Oreille to become a productive fishery where currently almost 26 miles of river go unfished. Outcome will be the development of integrated rule curves which will aid the long term management of the lake. The increase in spring-time flows will be utilized to the benefit of anadromous fish.

Dependencies/opportunities for cooperation
Project is contingent on US Corps of Engineers changing lake levels. Their current recommendation, published in their news release, was to change lake levels in 1996.

Risks
One potential risk is that Eurasian milfoil could possibly become established in the lake, although it does not occur anywhere in Idaho at this time. Project design has addressed this concern. Deep lake draw downs after the third year of study will impact all vegetation growth around the lake. Site specific recommendations will be developed during this study to address any potential problems.

Monitoring activity
Trawling and hydroacoustics will be used to monitor kokanee abundance. Core sampling will be used to monitor shoreline gravels. Bioenergetics will be used to model changes in the food web. Seining, gillnetting and electrofishing will be used to monitor warmwater fish production. Mark and recapture will be used to monitor bull trout and Kamloops rainbow trout. Snorkeling will be used to look for Eurasian milfoil.

Section 3. Budget

* For most projects, Authorized is the amount recommended by CBFWA and the Council. Planned is amount currently allocated. Contracted is the amount obligated to date of printout.

Funding recommendations

CBFWA funding review group   Resident Fish

Recommendation    Tier 1 - fund

Recommended funding level   $315,480

BPA 1997 authorized budget (approved start-of-year budget)   $315,480