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
Snake River Sockeye Salmon Habitat

BPA project number   9107100

Business name of agency, institution or organization requesting funding
Shoshone-Bannock Tribes

Sponsor type   ID-Tribe

Proposal contact person or principal investigator

BPA technical contact   Jeff Gislason, EWN 503/230-3594

Biological opinion ID   NMFS

NWPPC Program number   7.5A.1

Short description
Investigate feasibility of restoring fertility of historic sockeye nursery lakes; if feasible, fertilize lakes; modify existing barrier dams at sockeye nursery lake outlets to allow passage and enumeration.

Project start year   1991    End year   

Start of operation and/or maintenance   

Project development phase   Implementation

Section 2. Narrative

Related projects
NMFS and IDFG broodstock programs, and the NMFS and UofI O. nerka genetic analysis. Habitat results generated by this project (e.g., lake fertilization) help direct decision making processes that relate to how many, when, and where sockeye produced from the broodstock programs should be released.

Project history
Project was started to monitor and enhance sockeye nursery lake habitat and to improve adult sockeye passage in the Sawtooth Valley of Idaho. Limnological and fish life history studies, in preparation for lake fertilization, were conducted from 1991 through 1995. Effects of different levels and applications of nutrient additions were tested in 1993 and 1994. Redfish lake was fertilized in 1995. Monitoring and evaluation of lake fertilization is ongoing. In 1995, the migration barrier on the outlet of Pettit was modified to facilitate outmigration and enumeration of juvenile sockeye.

Biological results achieved
1. Nutrient additions to Redfish Lake enhanced sockeye forage resources for the 90,000 sockeye juveniles released in the lake in 1995. The fertilization project should increase sockeye survival and outmigration numbers.

2. The modifications to the Pettit Lake Creek barrier allows juvenile sockeye to outmigrate safely and adults to return to spawn.

1. Redfish Lake was artificially ferilized to enhance food supply for the 90,000 sockeye juveniles released into the lake in 1995.
2. Biological and limnological monitoring of Stanley Basin nursery lakes was continued.

Annual reports and technical papers
1992 Annual Report (DOE/BP-22548-1), 1993 Annual Report (DOE/BP-22548-2), and 1994 Annual Report (DOE/BP-22548-3) are available.

Management implications
1. Limnological variables are used to estimate sockeye carrying capacity. Lake carrying capacity information is crucial in developing release strategies for juvenile sockeye. The limnology data also provided the ground work for lake fertilization projects.

2. Fish community studies have lead to changes in the way non-listed fish species are managed in the Sawtooth Valley Lakes. Kokanee numbers are being reduced to make room for sockeye and hatchery rainbow trout stocking practices are being altered to minimize potential impacts with juvenile sockeye.

Specific measureable objectives
Reestablishing a naturally-spawning run of sockeye salmon to the Sawtooth Valley of Idaho that will meet delisting criteria for Snake River sockeye salmon and modest harvest goals for tribal members.

Testable hypothesis
Will habitat enhancement projects in the nursery environments increase juvenile salmon survival and adult returns?

Will lake fertilization increase survival of rearing sockeye?

Do rainbow trout and other non-native fish species that where introduced to the Sawtooth Valley Lakes negatively impact rearing conditions for juvenile sockeye?
Will improved migration conditions in the Sawtooth Valley positively impact sockeye populations?

Underlying assumptions or critical constraints
The broodstock program will continue to produce juvenile sockeye for release in the Sawtooth Valley Lakes.

The broodstock program has sufficient genetic resources to produce fish that are capable of surviving in a natural environment (i.e., inbreeding drepression has not affected fitness).

Migration survival in the mainstem improves or remains constant.

Methods
Lake Fertilization
To increase forage resources and survival of stocked sockeye, liquid fertilizer was added to the surface of Redfish lake in 1995. Applications were by boat and occurred weekly starting at ice out and continued through October. The impacts of lake fertilization will be tested using a design reported by Stewart-Oaten et al. (1986) and repeated measures analysis of variance. Primary and secondary production in Redfish Lake will be compared to several control lakes also located in the Sawtooth Valley. Smolt survival and migration success will be compared with unfertilized years.

Barrier Modifications
In 1995, 8,572 juvenile sockeye were introduced to Pettit Lake. To evaluate in-lake survival and outmigration success, a weir will be deployed in the outlet stream April 1996. A subsample of smolts will be PIT tagged to evaluate overwinter survival, downstream migration rates, and smolt to adult return ratios.

Fish Community Research
Sockeye and kokanee populations estimates are made using split beam hydroacoustic technology. Hydroacoustic surveys for Redfish, Pettit, Stanley and Alturas Lakes are completed in September. Fry recruitment and spawning densities for competing kokanee populations are monitored with fry traps and by completing spawning surveys. Relative abundance and diet information for potential competitors and predators is collected using mid-water trawls and gill nets.

Brief schedule of activities
Fertilize Pettit and Redfish Lake to provide forage resources for juvenile sockeye

Operate Pettit Lake Creek smolt trap.

Continue fish community research and limnological monitoring programs in nursery lakes

Construct sockeye juvenile/adult monitoring weir on Alturas Lake Creek.

Biological need
Without lake fertilization and limnology studies, supplementation projects may exceed lake carrying capacity causing zooplankton crashes which would result in poor sockeye growth and survival. Fish community studies must be completed to minimize negative interactions. Also, non-game fish barriers prevent adult sockeye from entering three Sawtooth Valley nursery lakes. Those barriers must be modified or removed to allow passage. Delisting goals can not be reached without opening those systems to spawning populations.

Critical uncertainties
It is unknown how the hatchery produced sockeye will preform. Only 4% of the hatchery produced sockeye released to Redfish in 1994 survived to outmigrate in 1995. It is also unknown if juvenile sockeye from Redfish Lake broodstock will succeed in other Sawtooth Valley Lakes.

Summary of expected outcome
Habitat improvements, lake fertilization, and supplementation projects should increase adult returns. Those efforts should prevent extinction, but recovery goals can not be reached without increased smolt to adult survival.

Dependencies/opportunities for cooperation

Risks

Monitoring activity
The SBT will continue to monitor limnological parameters and fish populations in the Sawtooth Basin nursery lakes. Juveniles produced by the broodstock program will continue to be PIT tagged to evaluate various experimental mating, rearing, and release strategies.

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   Snake River

Recommendation    Tier 1 - fund

Recommended funding level   $600,000

BPA 1997 authorized budget (approved start-of-year budget)   $600,000