Draft to BPA, 12/5/05
Lake Pend Oreille Fishery Recovery Project
Statement of Work and Budget FY2006

BPA Project Number:  1994-047-00
BPA Project Title: Lake Pend Oreille Fishery Recovery Project
Contract Number:  CR-71742
Contract Title: Lake Pend Oreille Fishery Recovery Project
Performance/Budget Period:  March 1, 2006 to February 28, 2007

Technical Contact Name:  Melo Maiolie
Technical Contact Title: Principal Fishery Research Biologist
Idaho Department of Fish and Game
16805 Limekiln Rd. PO Box 806
Bayview, ID     83803
Technical Contact Phone: (208) 683-9218 / Fax: (208) 683-3054
mmaiolie@adelphia.net

James Lau
Chief of Administration
Idaho Department of Fish and Game
600 S. Walnut St, PO Box 25
Boise, ID 83707
Contracting Contact Phone: (208) 334-3781 / Fax: (208) 334-2148
jlau@idfg.state.id.us

Financial Contact Name: Conan Chiu
Financial Specialist
Idaho Department of Fish and Game
600 S. Walnut St, PO Box 25
Boise, ID 83707
Financial Contact Phone: (208) 287-2813 / Fax: (208) 334-2148
cchiu@idfg.state.id.us

This project addresses the impacts of the federal hydropower system on kokanee, and the indirect effects to bull trout, and rainbow trout in Lake Pend Oreille.   Drawing the lake down to the maximum extent possible each fall (elevation 2051'msl) caused major impacts. This reduced the amount of gravel along the shoreline of the lake that is usable for kokanee spawning. It also draws the Pend Oreille River down into the river channel causing the loss of much of the warmwater fish habitat.  Fish populations declined commensurate with these habitat losses.  

In 1996 the Northwest Power Planning Council (NWPPC) requested that the Corps of Engineers change lake levels to benefit fisheries.  Results of the first 9 years of changed lake levels showed a 2.4 fold increase in egg-to-fry survival during the years of elevated lake levels (excluding the flood year of 1997)(p=0.05).  The ISRP and USFWS recommended the study run for 10 years to make the results more definitive.  Lake level changes are specified in the USFWS's Biological Opinion for Bull Trout in Lake Pend Oreille.  These changes were requested to increase kokanee abundance and thereby increase the forage for bull trout.  Although not directly intended, a side benefit was that warm water fish habitat in the Pend Oreille River would increase seven fold.  The goal of this proposal is to recover these impacted fish populations and to protect the threatened bull trout population. We propose to document the response of the fish populations to these new lake levels.  We also propose to monitor changes in the shoreline spawning habitat to see that it is maintained in good quality.  Information gained by this study will be presented to the USFWS in its annual review of lake level changes.  This allows flexibility in the management of lake levels in future years.  However, the kokanee population remains low.  The stocking of hatchery-produced kokanee may be necessary to keep kokanee from disappearing in the short term.  Past stocking, however, has not produced the anticipated increase in adult kokanee.  Since all hatchery kokanee for the last 9 years have been marked, we have the unique opportunity to examine and compare the survival of each year class of hatchery and wild fish.   By doing so we can determine when survival is relatively the poorest, and gain insights into how to improve the hatchery program.

     Overall problem: Lake Pend Oreille was the most productive resident fishery in the state of Idaho until the mid-1960's.  An average of one million fish were caught annually between 1952 and 1966 (Maiolie and Elam 1993).  Albeni Falls Dam was built on the outflow of the lake in 1952 and Cabinet Gorge Dam was built on the inflow the same year.  Blocking the Clark Fork River (by Cabinet Gorge Dam) caused immediate declines in bull trout and cutthroat trout abundance since spawning areas became limited.  The lake remained an exceptional fishery for kokanee and Kamloops rainbow trout until the mid-1960's when Albeni Falls Dam began lowering the lake 11 feet each fall for additional power production.  This started a down turn in the kokanee population that continues to this day.

     Maiolie and Elam (1993) reported that deeper drawdowns in 1957, and 1961 reduced the kokanee fishery five years later.  Conversely, higher water levels in the winter of 1958, 1959, and 1960 produced better fisheries five years later.  They also found that somewhat higher lake elevations in 1982, 1983 and 1985 produced 39% more kokanee recruited to the fishery than years before or after these years.  Fredericks et al. (1995) found that the two best years on record for egg-to-fry survival were 1982 and 1983 when the lake was 3 to 4 feet higher than normal during the winter.  A second important factor is that the lake cannot be lowered once kokanee spawning has taken place (Hassemer 1984, and Maiolie and Elam 1993).  Drawdowns of less than 1 m can have a noticeable effect on the resulting fisheries if they occur during the egg incubation period; mid-November to June.

     The mechanism for why lake levels control fish abundance can be explained rather simply.  Shoreline gravels around the lake rely on wave action to remain clean and well sorted from sand and cobble.  At whatever elevation the lake is held, gravel bars appear just above this elevation.  Fredericks et al. (1995) documented that quality spawning gravel was relatively sparse below the low pool elevation likely because wave action had not affected this part of the shoreline since 1953 when the dam became operational.  The consistency of drawing the lake to the same elevation each year prevented clean wave washed gravel from forming below the low pool elevation.

The previous studies funded by BPA demonstrated the effect of changing lake levels. At the beginning of these studies, surveys of potential spawning areas around the lake found that an additional 1.8 million square feet of gravel would be available for kokanee spawning if the lake was held 4 feet higher throughout the winter (Fredericks et al. 1995).  Fredericks estimated only 380,000 square feet of gravel were below the low pool elevation.  Improvements in kokanee survival were noted after raising the lake elevation during winter for four consecutive years.  Kokanee egg-to-fry survival increased from 1.4% in 1995 to 10.0% in 1998.

     Previous studies also monitored the quality of gravel in shoreline spawning areas. Good spawning gravel (a high percentage of gravel, low in fines and cobble) declined after being underwater for a period of years. Degradation was not due to an increase in the amount of fine material, but rather, due to an increase in the percent of cobble (material over 32 mm)(Maiolie et al 2000).   After three years, degradation was very noticeable.  This led researchers to the recommendation to lower the lake once every four years to clean and resort shoreline gravels.

        A review of this project by the ISRP and USFWS recommended that this project extend the lake level changes for 10 years instead of three.  This would continue the lake level objectives until 2007.   We propose to again monitor kokanee survival changes and annually compare them to lake elevations.  Information will then be reviewed by the USFWS and used to formulate the next year's lake management strategy, and devise long-term lake management plans.

     The Lake Pend Oreille Predation Research Project, 2002-009-00, was combined with this project in 2004.  It attempts to develop the means to balance predator and prey in the lake.  Sport fisheries in the lake have been severely impacted by hydropower development on both the inflow and the outflow of the lake (Maiolie and Elam 1993, Fredericks et al. 1995 , Paragamian et al.1991).  Consistently drawning the lake down 11 feet annually has taken  the adult kokanee population from an estimated 5 million fish (able to support a 1 million fish harvest) to a population unable to support a sport fishery.  The low kokanee population has declined to the point where it can no longer support the populations of rainbow trout, bull trout, and lake trout in the lake.  (The diet of all three of these species is 60 to 80 % kokanee.)  Until kokanee recover, it appears the predator population needs to be reduced.  To our knowledge, no literature exists which describes the balance point between a kokanee population and its predators.  However, it appears we have passed this point, since kokanee survival rates from age 1 to age 2 have dropped from 80% to less than 20%.  This bottleneck in the population has prevented good year classes of kokanee from recruiting to the older age classes and benefitting the next generation.  Reductions in survival of this magnitude could extirpate kokanee from the lake.  Should kokanee collapse, bull trout, rainbow trout, and lake trout will be in direct competition for a limited forage base.  This consitutes enough of a threat to the bull trout population that the USFWS in their draft Biological Opinion has recommended that the action agencies "shall evaluate the effects of varying winter lake level elevations on all life stages of kokanee in Lake Pend Oreille, and predator/prey dynamics."
    

     We also propose to develop methods to quantify pelagic predators in the lake (rainbows and bull trout) by using hydroacoustics.  Downscanning methods were found to miss many of the surface oriented rainbow trout.  During the summer of 2006, we propose to test "uplooking" hydroacoustics to test its feasibility to provide accurate population estimates.  Secondly, the project proposes to define the balance point between predators and prey.  Previous bioenergetic studies, with their many assumptions, have failed to estimate this point with much confidence. The kokanee population showed sharp declines in survival once the ratio of  predator to prey rose above 1 kg of predators to 6 kg of prey.  Therefore we will use this as a starting point for our work.  Lake Pend Oreille at the current time is a real world example of the conditions that exist as a kokanee population collapses. We can gain valuable empirical data about the balance of predator and prey by monitoring both predator and prey abundance, enhancing the kokanee population, and reducing the predator population.  We can then document kokanee survival rates and abundance to determine the balance point.  Balancing predator and prey will be considered from the standpoint of mass balance and production versus yield.
      Numerous studies discuss the balance of predator and prey, dating back to Swingle's articles in the 1950's.  To our knowledge, no prediction of balance for a kokanee prey base exists in the literature.  Many recent articles utilized bioenergetics as an approach to finding the balance point. Some studies, such as Negus (1995), point out the many assumptions and erroneous results that occur.  Vidergar (2000) used bioenergetics to determine that predators were eating approximately 154 tons of kokanee per year (+ or - more than 80%), or roughly 60% of kokanee production.  In this project we propose to empirically define the balance point by monitoring both predator and prey as the situation improves. This will be done two ways.  First we propose a mass balance approach that compares pounds of pelagic predators to pounds of prey.  These ratios will be compared to kokanee survival rates to determine the balance point.  Secondly, we will estimate kokanee production and yield at different densities to determine the point at which kokanee production can no longer sustain the amount of yield.