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
Predation by Fish-Eating Birds on Juvenile Salmonids in the Columbia River Basin

BPA project number   5505900

Business name of agency, institution or organization requesting funding
Oregon State University/CRITFC

Sponsor type   OR-University

Proposal contact person or principal investigator
 NameDaniel D. Roby
 Mailing addressOregon Cooperative Wildlife Research Unit
Oregon State University
Corvallis, OR 97331-3803

BPA technical contact   , EWI

Biological opinion ID   

NWPPC Program number   

Short description
This project will estimate the magnitude of avian predation on juvenile salmonids (in particular, chinook salmon) in the lower Columbia and Snake rivers, identify factors that influence the intensity of avian predation, and provide recommendations to reduce predation by fish-eating birds.

Project start year   1996    End year   2000

Start of operation and/or maintenance   0

Project development phase   Implementation

Section 2. Narrative

Related projects
BPA-82003, USACE-1491-WA07. This project is looking at smolt dispersal rates and survival under different management strategies at Columbia River dams. Avian predation is one source of mortality for the radio-tagged smolts used in this study. We will work cooperatively with these agencies to collect, analyze, and present results concerning avian predation on radio-tagged smolts.
BPA-9008000. This PSMFC project will recover pit tags from selected breeding colonies of fish-eating birds as a means to assess the incidence of avian predation on juvenile salmonids. If requested, we will assist this agency in the recovery of pit tags at breeding colonies.

Project history

Biological results achieved

Annual reports and technical papers

Management implications

Specific measureable objectives
The objectives of this study are to: (1) identify areas on the Columbia and Snake rivers where fish-eating birds are most abundant, specifically where large breeding colonies exist; (2) describe the diets and foraging range of fish-eating birds to identify areas, species, and times where predation on salmonids is most prevalent; (3) estimate the magnitude of salmonid losses to avian predators, in particular, threatened and endangered Snake River salmon; (4) investigate the population dynamics of the important avian predator populations; (5) evaluate current management strategies to reduce avian predation; and (6) develop recommendations to reduce predation by fish-eating birds and thereby increase natural production of salmonids.

Testable hypothesis
The testable hypotheses of this study are: (1) the magnitude of avian predation poses a significant threat to the survival of salmonids in general, and threatened and endangered Snake River salmon specifically; (2) the majority of salmonid losses to avian predators occurs near breeding colonies of colonial-nesting species (e.g., gulls and terns) and at sites where smolts are concentrated at or near the water surface (e.g., dams); (3) avian predator populations are growing as a result of anthropogenic factors; and (4) expanded or new management practices directed at avian predators can significantly reduce current levels of predation by fish-eating birds.

Underlying assumptions or critical constraints
Logistical and other critical constraints include: (1) permission to access restricted areas where fish-eating birds forage (e.g., mainstem hydroelectric dams) and nest; and (2) availability of permits for the collection of birds for diet analysis and the gathering of other pertinent biological information. Due to limits on funding, simplifying assumptions concerning bird metabolism, diet, and activity budgets are likely to be used in the construction of the bioenergetics model. Field activities conducted as part of this work will focus on measuring the input variables having the greatest affect on the accuracy of the model output (i.e., total consumption of juvenile salmonids by avian predators).

Until we are able to complete Phase I (proposed for FY 96; see below) of this research, it is difficult to identify the specific methods required in Phase II (beginning FY 97). In general, a bioenergetics approach will be employed to estimate the number of salmonids lost to significant avian predator populations on the lower Columbia and Snake rivers. A sensitivity analysis using an individual parameter perturbation method, coupled with a review of the data currently available, will be conducted to determine which model input variables need direct measurement as part of Phase II. If necessary, selected avian predator populations may be monitored using radio-telemetry (to commence in FY 98 according to schedule for funding listed below) to measure foraging range and activity budgets, and identify important foraging locations utilized by breeding birds at selected colonies. In addition, direct observations of fish-eating birds will be conducted at breeding colonies and in areas where they are concentrated to feed on juvenile salmonids. The relative abundance of fish-eating birds and their consumption rates on juvenile salmonids will be measured to identify locations where, and times when, management activities are likely to be most effective in reducing predation by fish-eating birds. A detailed proposal for work to be conducted in the initial year (Phase I) of this research is forthcoming.

Brief schedule of activities
This work will be conducted in two phases over five years. In Phase I (FY 96), we will gather information on the distribution and abundance of fish-eating birds, determine in general where these birds forage, and ascertain to what extent juvenile salmonids are important in the diet of fish-eating birds. As part of Phase I, data will be gathered from existing literature, unpublished sources in agency files, and, depending on funding availability, from preliminary field investigations in FY 96 (proposal forthcoming). In Phase II (FY 1997-2000), field investigations will focus on foraging strategies, diet composition, time-activity budgets, and bioenergetics modelling of important avian predator populations to estimate the number of juvenile salmon lost to avian predation. Also, predation rates will be measured at different locations throughout the juvenile salmonid outmigration to identify areas where, and times when avian predation activity is relatively high. Recommendations aimed at reducing avian predation will be developed, implemented, and evaluated as part of Phase II if warranted by the results of this study.

Biological need
The objectives of this study address concerns expressed in regional plans for Snake River salmon recovery and the FCRPS Biological Opinion. Avian predation is believed to be a significant source of mortality for out-migrating juvenile salmonids, which includes Snake River salmon listed as threatened or endangered under the Endangered Species Act. There is evidence that both numbers of avian predators and their rate of predation on salmonids have increased as a result of anthropogenic perturbations in the Columbia River System. Results from this study will help in understanding factors affecting the survival of salmon and will provide useful information in developing management plans aimed at reducing predation by fish-eating birds.

Critical uncertainties
It is not certain whether avian predation is a significant source of mortality for juvenile salmonids. Furthermore, if avian predation is determined to be significant, we do not know if there are practical management activities to address the problem.

Summary of expected outcome
We expect that under certain circumstances avian predation on salmonids will be a significant source of mortality. We will identify the important factors contributing to high avian predation rates on juvenile salmonids, and use that information to develop and test practical management alternatives to reduce predation-related mortality.

Dependencies/opportunities for cooperation
We will seek assistance from U.S. Army Corps of Engineers personnel in the collection of data on the seasonal abundance, distribution, and foraging behaviors of fish-eating birds at hydroelectric dams to reduce travel and personnel costs. Laboratory assistance from National Biological Service will be investigated to reduce the costs of diet analyses. Cooperation by regional agencies in gathering relevant unpublished data may reduce the amount of field work necessary to build the bioenergetics model. The use of borrowed equipment (e.g., radio-telemetry equipment, boats) will also help to reduce costs. We will pursue these and other opportunities to cut costs and to minimize duplication of effort.

This project poses little or no risk to human health or safety. Salmonids, both ESA and non-ESA stocks, will not be affected by this research. Risks to avian predator populations will be limited to a small number of birds collected for diet analysis and to potential nest failures due to collection of important population data at breeding colonies. The methods used will be designed to minimize these risks (e.g., investigate non-lethal methods for diet analysis, minimize disturbance to breeding colonies by conducting observations from blinds, or accessing colonies after dark).

Monitoring activity
We will follow an adaptive management approach in achieving our main objectives, whereby specific objectives and tasks will be modified based on our most current data. We will evaluate progress towards these objectives both in-season and annually to ensure that our main objectives are being met. If possible, we will complete the proposed work in less than five years.

Section 3. Budget

Data shown are the total of expense and capital obligations by fiscal year. Obligations for any given year may not equal actual expenditures or accruals within the year, due to carryover, pre-funding, capitalization and difference between operating year and BPA fiscal year.

Historic costsFY 1996 budget data*Current and future funding needs
(none) New project - no FY96 data available 1997: 125,000
1998: 250,000
1999: 350,000
2000: 300,000
2001: 250,000

* 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.

Funding recommendations

CBFWA funding review group   System Policy

Recommendation    Tier 1 - fund

Recommended funding level   $125,000

BPA 1997 authorized budget (approved start-of-year budget)   $125,000