BPA Fish and Wildlife FY 1997 Proposal
Section 1. Administrative
Section 2. Narrative
Section 3. Budget
see CBFWA and BPA funding recommendations
Title of project
Changes in Gas Bubble Disease Signs and Survival of Migrating Juvenile Salmonids Experimentally Exposed to Supersaturated Gases
BPA project number 9602400
Business name of agency, institution or organization requesting funding
Sponsor type WA-Federal Agency
Proposal contact person or principal investigator
|Mailing address||National Marine Fisheries Service
2725 Montlake Blvd. E.
Seattle, WA 98112
BPA technical contact , EWI
Biological opinion ID
NWPPC Program number
PIT-tagged hatchery fish will be exposed to water containing supersaturated dissolved atmospheric gases, examined for signs of GBD, and released into the forebay of Little Goose Dam. A percentage of these fish will be recaptured at the Little Goose Dam collection facility and reexamined. The survival of the fish not collected at Little Goose Dam will be compared to control fish as they pass downstream dams.
Project start year 1996 End year 1997
Start of operation and/or maintenance 0
Project development phase Implementation
1) GBD monitoring of juvenile salmonids under FPC.
If GBD signs are changing as a result of passage through the bypass/collection system at dams, or if GBD signs are not seen because of mortality upstream, locations of monitoring sites and/or other methods of monitoring GBD (i.e. purse seines, trawls, or traps) may be required.
Biological results achieved
Annual reports and technical papers
Specific measureable objectives
We will measure changes in signs of GBD (external subcutaneous emphysema ) in juvenile salmonids as they migrate through a bypass\collection facility at Little Goose Dam. Such changes could be induced by the sounding required by the fish to enter the gatewells before migrating through the rest of the system. We will also measure relative survival of juvenile salmonids allowed to migrate after exposure to levels of supersaturated atmospheric gases that induced signs of GBD in 50% of the population.
Hypothesis 1: Juvenile salmonids with signs of GBD do not lose these signs by passage through a gatewell into bypass systems at dams on the Snake or Columbia Rivers.
Hypothesis 2: An increase in mortality of juvenile salmonids with GBD does not affect the ability to detect signs of GBD at bypass/collection facilities on the Snake or Columbia Rivers.
Underlying assumptions or critical constraints
We have assumed that we will be able to recover approximately 24% of the treatment fish with signs of GBD. This is based on a 10% mortality rate to the dam, a 10% loss of GBD signs, and a 30 % recovery rate of in-river PIT-tagged migrating spring chinook ((100% -20%) X 30%)). Given these assumptions, a 7% change in prevalence of GBD signs from release to recovery will be significant at I = 0.05
To evaluate relative survival, we must assume that fish guidance efficiency at downstream dams (2 or more days following experimental exposure to dissolved gas supersaturation) will be equal for both test and control fish.
To provide enough fish for a statistically valid assessment of changes in GBD signs during dam passage, 6 replicate releases of 300 test fish will be made for each of the 3 test series (yearling chinook salmon and steelhead). Similar sized groups of control fish will be released and 150-fish groups exposed to supersaturation will be retained in 5 m net-pens in the forebay. Test and control groups will be anesthetized and coincidentally Pit tagged. Fish groups will be placed into separate but identical holding tanks with degassed river water at densities less than 60 g/L (0.50 lb/gal.). The dissolved gas levels in the test fish tank will be increased to and held at about 120% of saturation using a bubbleless membrane aeration system installed in the water line. Both control and test fish will be held an additional 1 to 2 days until about 50% of the test fish display signs of GBD.
For each test replicate, when prevalence of GBD signs reaches 50% or mortality begins, test fish will be extracted (in small groups), anesthetized, and visually examined at 5- to 20-power magnifications for subcutaneous emphysema and emboli in lateral line scale pockets. Severity of emphysema will be broken down into percentage of body area affected and relative size and shape of emboli. Coincidentally, control fish will be extracted, anesthetized, and a subsample examined for GBD, while others will be held out of the water for approximately the time required for GBD examination. After examination, test and control fish will be placed in a common tank, transported, and released about 400 m upstream from the Little Goose Dam powerhouse. Since the examination process will take an extended period of time, multiple releases will be made. We plan to make the releases near dusk to facilitate rapid passage through the dam and bypass system.
Signs of GBD among test fish may be changing during the period prior to passage through the dam. Therefore, a third group of PIT-tagged fish from the supersaturated test condition will be examined and then placed in a forebay net pen (5-m deep) to allow documentation of changes in GBD signs through time at ambient dissolved gas concentrations in Little Goose Dam forebay.
Using separation by code, test and control fish will be automatically separated from other fish passing through the bypass system at Little Goose Dam and examined immediately to determine any changes in the prevalence and severity of GBD signs. Interrogation of PIT-tagged test and control fish at Little Goose, Lower Monumental, Ice Harbor, and McNary Dams will provide an estimate of differential survival during migration.
Approximately 5,000 hatchery fish will be needed for each test series. Possible fish sources include:
1) Marked hatchery steelhead could be sorted from the Little Goose Dam collection system.
2) Yearling chinook salmon from Looking Glass, Lyons Ferry, or Kooskia Hatcheries.
Brief schedule of activities
The PIT-tag rotating gate must be fabricated and installed at Little Goose Dam prior to mid -March to allow preliminary testing. The experimental holding facilities, dissolved gas generator, and net-pens must be fabricated and installed by the end of March to allow preliminary testing.
Tests with yearling chinook salmon will commence in mid- to late April, about 1 week following fish transfer to the site and steelhead will be tested in mid- to late May. Each test series is expected to take about 2 weeks.
This study has been designed to answer 1) if migrating juvenile salmonids lose signs of GBD while passing through a bypass/collection facility, and 2) if fish exposed to supersaturated dissolved gases die in the reservoir before reaching bypass/collection facilities. Answer to these questions will help determine the usefulness of monitoring sites at dams in detecting signs of GBD in migrating salmonids.
Two important questions remain unanswered regarding the effectiveness of biological monitoring to evaluate impacts to juvenile salmonids from GBD: 1) Do signs of GBD change as a result of changing hydrostatic pressure experienced by juvenile salmonids during their passage through turbine intakes, gatewells, and bypass conduits of dams?, and 2) Do the physical detriments from GBD cause a decrease in survival resulting from direct or indirect effects such as predation during migration through reservoirs? Not addressing these questions may limit the use of spill for improving fish passage at dams. Proponents of the theories that signs of GBD in juvenile salmonids disappear prior to examination by smolt monitoring personnel at dams, and/or that all fish with signs of GBD die or are eaten by predators prior to arriving at the smolt monitoring site, argue for a decrease in total dissolved gas levels to a “safe” saturation of 110% (consistent with water quality standards established by the Environmental Protection Agency, Oregon Department Environmental Quality, Washington Department of Ecology, Idaho Department of Environmental Quality, and the National Marine Fisheries Service Gas Bubble Disease Working Groups.
The answers to these questions will be difficult to obtain and will be confounded by changing river conditions, locations, time of year, predator abundance, and fish stocks and condition. However, we believe that the general magnitude of changes in GBD signs and survival can be evaluated.
Summary of expected outcome
All data shall be analyzed by the December 1996. This will produce a database which should answer questions to the critical uncertainties mentioned above.
Dependencies/opportunities for cooperation
The only known risk is the inadvertent handling of in-river migrants which are PIT tagged as part of other up river projects. With installation and preliminary testing of a rotating gate at Little Goose Dam, separation by code should be over 95% efficient (as seen at Lower Granite Dam during testing and in use as part of a subyearling study, Sandra Downing NMFS Manchester, WA, pers. comm.) This would minimize this risk.
Approximately 24 % of the released fish with signs of GBD should be recovered at the Little Goose Dam collection/bypass facility within 8 to 48 hours of their release (Based on 1995 research at John Day, Lower Granite, and Ice Harbor Dams by R. Shiveley and D. Rondorf, National Biological Service, Cook, WA., and George Swan, National Marine Fisheries Service, respectively, pers. comm.). Since these fish will be immediately reexamined, any changes in the general prevalence of GBD signs should be available with 2 to 3 days of each release.
Data on comparative survival of these fish as they pass through the downstream dams will be available as they are interrogated and loaded onto the PIT-Tag Information Service database. This information will be downloaded and updated on a weekly basis after the first release.
|Historic costs||FY 1996 budget data*||Current and future funding needs|
|(none)||New project - no FY96 data available||1997: 228,000|
* 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.
CBFWA funding review group Mainstem
Recommendation Tier 1 - fund
Recommended funding level $228,000
BPA 1997 authorized budget (approved start-of-year budget) $228,000