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Bull Trout Telemetry Synthesis


For more information on the synthesis project contact:

Matthew R. Dare
Research Assistant Professor
Department of Biology
Boise State University


Phone: 208 463 2923

Due to their unique life history traits, pristine habitat which they occupy, and reduced range and abundance, bull trout Salvelinus confluentus management has become an important issue in the Northwestern United States and Western Canada. In 1998, this species was listed as Threatened by the U. S. Fish and Wildlife Service under the Endangered Species Act. Past recovery successes suggest that a coordinated research and management program is the cornerstone to protecting this species and eventually removing it from the Endangered Species List. The first step in establishing sound and achievable management objectives is the development of a thorough understanding of the species throughout its distribution.

Bull trout school - photo by Jason Dunham. Click for a larger view. Bull trout are a species of char that are native to the Northwestern United States and Western Canada. Although the species are widely distributed throughout their native range, "strong" populations are rare (Rieman et al. 1997). Bull trout populations are patchy across the landscape and genetic analysis suggests that gene flow is infrequent and the long-term persistence of this threatened species is contingent on protecting local populations (Leary et al. 1993; Kanda and Allendorf 2001).

Habitat alterations and fragmentation have been identified as causative agents in declines in bull trout numbers (Rieman et al. 1997). Because of this, much research effort has been directed at identifying bull trout populations and characterizing the habitat components necessary for their existence. A number of research projects have been conducted on bull trout movement and habitat use throughout the Columbia River Basin for over a decade. Recently, several projects have been funded to identify the extent of movement and entrainment through Columbia River Dams. However, these projects are typically focused on single populations and designed to address a myriad of questions, most commonly associated with a proposed or on-going management action. In reality, because of the variability in life histories among populations (Rieman and MacIntyre 1993; Haas and McPhail 2001) little is known about the species as a whole.

USBR Fisheries Biologist Tammy Salow holding a newly tagged adult bull trout. Notice the archival temperature tag attached to the back. In response to requests by the USFWS, USFS, and Western Division of the American Fisheries Society (WDAFS), we propose to assimilate and synthesize the existing data regarding bull trout habitat use and movement into a database and several peer-reviewed articles. The database and publications would fill a void in the literature associated with broad-scale questions of bull trout biology and ecology.

Once synthesized, these data would allow researchers working with particular populations to extend their inferences beyond a small number of individual bull trout observed for discrete period. Given the considerable variation among populations, the ability to draw on previous research should greatly streamline a case-by-case management approach.


A synthesis of information on bull trout radio telemetry studies will provide important information for evaluating the quantity and quality of information now available. The bull trout recovery plan and critical habitat designations are currently under review and these data could play an important role in identifying research questions and watersheds that require further investigation. Furthermore, the database will allow us to better describe and model habitat relationships for migratory bull trout. These results will lead to development of better study guidelines for future telemetry studies, and provide a broad understanding of ecological patterns that are relevant to bull trout recovery in natural and regulated systems. Finally, the synthesis of will be invaluable for identifying key information gaps.

Some specific objectives to be addressed by a synthesis could include the following:

  1. Identify the driving forces for investigating bull trout using radio telemetry, including:
    1. Basic and applied research questions addressed by each study.
    2. Specific management issue addressed by each study.
    3. Specific goals and objectives addressed by each study.
    4. Geographic scope of each study.
    5. Temporal scope of each study.
    6. Funding sources.
  2. Document the range of study methods used. This could include information on:
    1. Number and size of fish tagged.
    2. Size and type of transmitter.
    3. Frequency, duration, and timing of location recordings.
    4. Variation in surgical and other tag attachment procedures.
    5. Patterns of mortality associated with tagging.
    6. Other methods used to examine bull trout movement and habitat use.
  3. Define broad scale patterns of habitat use including clines of variation across the current range of bull trout. This could include:
    1. Comparison of growth, movement, and survival in natural vs. hydropower-modified systems.
    2. Identifying the frequency of observed movement through the Columbia and Snake River hydropower projects.
    3. Determining the environmental conditions associated with migration timing and distance, including: photoperiod, temperature, and discharge.
    4. Identifying relationships between distance and destination of migration and landscape features.
    5. Identifying patterns in spawning behavior including the frequency of repeat vs. alternate-year spawning, relationships between age and size and probability of spawning, and proportion of migrating individuals that actually spawn vs. those making refuge migrations.
    6. Determine the extent of homing behavior in repeat spawners.
  4. Develop protocols for surgical techniques for bull trout. This could include:
    1. Compare and contrast surgical implantation techniques used in previous studies with respect to mortalities observed and longevity of fish and tags.
    2. Developing guidelines for the standardization of surgical implantation of radio tags.
  5. Develop guidelines for designing telemetry studies, for example:
    1. Compare and contrast tracking methodologies with respect to study objectives, person power, and applicability of statistical analyses.
    2. Determine the number of fish necessary to address study objectives.
    3. Determine the number and frequency of relocations necessary to insure adequate statistical power.
    4. Determine basic metadata requirements.
    5. Compare and contrast methods for archiving data.
  6. Identify critical gaps (spatial, temporal, methodological, etc.) in the existing body of knowledge pertaining to bull trout. These could include:
    1. Identify watersheds within the current range of bull trout with unique characteristics or potentially important management questions.
    2. Determine the frequency of study of each life stage of bull trout.
    3. Evaluate the efficacy of radio telemetry (or other methods) for gathering statistically sound data for the analysis of bull trout movement, habitat use, home range size, etc.

Data collection and analysis

This project constitutes a synthesis of raw data from individual research projects conducted over a broad geographic area and time. The analysis of data collected during individual studies yields information for a specific collection of individuals in one location and at one time. Our goal is to use analytical techniques that are appropriate for such studies (evidenced by publication in a peer-reviewed journal or textbook) and apply them to the large-scale data set created from the collection of individual research projects. In this manner, our analysis differs from a strict meta-analysis where the objective is to look at variation in effect size for one parameter among individual studies (Gurevitch and Hedge 1997). However, our study will possess one of the limitations of any meta-analysis: the quality of our analysis will depend on the quality of available data.

Our analysis is dependent upon the quantity and the quality of the data currently available; therefore, we cannot outline specific analytical tools that will be used in order to ask the questions outlined above. However, it is important to establish how the data will be organized, what constitutes the sampling unit and an observation, and propose several analytical tacks (assuming the necessary quantity and quality of data will be available). The data will be organized and stored in a database and spreadsheet so that it can easily be moved into other applications for analysis. We intend to group the studies by geographic area and season. As will other studies using radio telemetry, an individual animal will constitute the sampling unit (White and Garrott 1990; Millspaugh and Marzluff 2001). Using an individual animal as the sampling unit is biologically meaningful and avoids the potential for pseudoreplication. During each study, a number of observations should have been made on each individual. These observations will allow us to generate summary statistics pertaining to migration distance and timing and macro- and microhabitat use. We will then be able look for differences in these parameters among groups of individuals from defined geographic regions (see Objective 3). These analyses will likely be based on a combination of ANOVA and regression techniques to be determined specifically after the data are collected.

Intended products

We will develop a database that summarizes all available research projects conducted on bull trout in the last 10 years. This database will have two main uses: 1) allow researchers to determine how their data fits within the context of what has been done and what is known about bull trout; 2) allow researchers to determine what we still do not know about bull trout. Bull Trout (right) angled by Wade Thorson. The latter use is potentially of paramount importance, considering radio telemetry studies typically address similar questions. It is possible information gaps exist because of technological or logistical limitations.

The biological and ecological questions we will address as part of this study will examine bull trout as a species. Therefore, data analysis will transcend watershed, forest, state, and international boundaries to examine patterns of movement, survival, spawning, and habitat use at the species level. Manuscripts intended for publication will not usurp any contributor's right to publish a paper based on the data collected during an individual study. If needed, a standard memorandum of understanding will be issued to cooperators wishing to have an agreement in writing. While the exact number and scope of manuscripts cannot be determined at this time, we intend to target journals such as those published by the American Fisheries Society, Ecological Society of America, and Society for Conservation Biology for publication.



The project is a cooperative effort among several entities including: Boise State University, the U. S. Bureau of Reclamation, the U. S. Fish and Wildlife Service, and the U. S. Forest Service Boise Rocky Mountain Research Station.

Funding for this project has been provided by the U. S. Bureau of Reclamation and U. S. Fish and Wildlife Service.

Other support has been provided by the Salvelinus confluentus Curiosity Society and the Western Division of the American Fisheries Society.


Gurevitch, J. and L. V. Hedges. 1997.
Meta-analysis: combining the results of independent experiments. Pages 378-398 in S. M. Scheiner and J. Gurevitch, editors. Design and analysis of ecological experiments. Chapman and Hall, New York.
Haas, G. R., and J. D. McPhail. 2001.
The post-Wisconsinian glacial biogeography of bull trout (Salvelinus confluentus): a multivariate morphometric approach for conservation biology and management. Canadian Journal of Fisheries and Aquatic Sciences. 58:2189-2203.
Kanda, N., and F. W. Allendorf. 2001.
Genetic population structure of bull trout from the Flathead River basin as shown by microsatellites and mitochondrial DNA markers. Transactions of the American Fisheries Society 130:92-106.
Leary, R. F., F. W. Allendorf, and S. H. Forbes. 1993.
Conservation genetics of bull trout in the Columbia and Klamath River drainages. Conservation Biology 7:856-865.
Millspaugh, J. J., and J. M. Marzluff. 2001.
Radio tracking and animal populations. Academic Press, New York.
Rieman, B. E., and J. D. McIntyre. 1993.
Demographic and habitat requirements for conservation of bull trout. U. S. Forest Service General Technical Report INT-308.
Rieman, B. R., D. C. Lee, and R. F. Thurow. 1997.
Distribution, status, and likely future trends of bull trout within the Columbia River and Klamath River Basins. North American Journal of Fisheries Management 17:1111-1125.
White, G. C. and R. A. Garrott. 1990.
Analysis of wildlife radio-tracking data. Academic Press, New York.
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