Klamath Falls Field Station
Research Snapshot - Monitoring Populations of Endangered Catostomids to Support Recovery Efforts
The KFFS was originally established to fortify USGS efforts to monitor the status of adult populations of Lost River and shortnose suckers in the Upper Klamath Basin. The objective of our research and monitoring program is to quantitatively evaluate the status and dynamics of the populations, including assessment of factors that might be inhibiting recovery, such as water quality, toxins, and disease. The primary sucker populations of interest are those in Upper Klamath Lake (Oregon) and Clear Lake Reservoir (California). Results of our research and monitoring are used by managers charged with recovering the populations and managing water resources in the Basin, namely the U.S. Fish & Wildlife Service and the Bureau of Reclamation. Climate change is expected to exacerbate many of the factors responsible for the imperilment of these species, such that the task of managing water resources to benefit the suckers will only become more difficult.
Our research and monitoring program is based on capture-recapture methods with passive integrated transponder (PIT) tags and relies on sampling at key areas during the spring spawning season. Since tagging began over 15 years ago, tens of thousands of each of the endangered sucker species have been tagged and released, and thousands more are newly tagged each year. In addition, thousands of Klamath largescale suckers have been tagged and released, providing valuable information for a species about which little is known. The current monitoring program continues past sampling efforts that targeted suckers with trammel nets, but has also undergone substantial changes to increase the probability of re-encountering PIT-tagged fish. Major changes to the program included (1) the addition of a resistance board weir and traps in the lower Williamson River, the primary spawning tributary, and (2) the large-scale implementation of remote detection systems for PIT tags. In recent years the remote detection systems have accounted for greater than 80% of annual re-encounters and have dramatically improved model-based inferences about population dynamics.
Physical captures of fish in trammel nets and remote detections of tagged fish are used in capture-recapture models to estimate annual survival probabilities and rates of change in population sizes. These estimates provide a comprehensive evaluation of the status of the populations. In addition to providing these essential metrics, the program provides sampling and data analysis platforms upon which multiple other investigations have been built, including:
- Age and Growth of Long-lived Catostomids
- Spawning Ecology and Habitat Use of Endangered Catostomids
- Avian Predation on Endangered Catostomids in the Upper Klamath Basin
- Integrative Klamath Basin Tagging Projects
- River Ecosystems Models and Science
- Habitat Complexity and Competition Between Bull Trout and Brown Trout
- Length and age composition data for both Lost River and shortnose sucker populations in Upper Klamath Lake show negligible recruitment to the spawning populations since the mid-1990s. Similar data for Clear Lake Reservoir indicates that some recruitment has occurred for both species in the last decade, but has been more frequent for shortnose suckers. A substantial recruitment event occurred for both species in the late 1990s.
- Lost River sucker populations in Upper Klamath Lake have declined by 30-60% since 2001; the shortnose sucker population in Upper Klamath Lake has declined by 60-80%.
- Two critical assumptions of capture-recapture models have been addressed: PIT tag retention rates are nearly 100% and effects of capture and tagging on post-release survival are negligible.
- Incomplete information about the spawning ecology of endangered sucker populations in Clear Lake Reservoir compromises capture-recapture inferences in that system. However, shortnose suckers are more abundant in Clear Lake, providing a contrast to the situation in Upper Klamath Lake where Lost River suckers are far more abundant.
- Hewitt, D.A., E.C. Janney, B.S. Hayes, and A.C. Harris. 2012. Demographics and run timing of adult Lost River (Deltistes luxatus) and shortnose (Chasmistes brevirostris) suckers in Upper Klamath Lake, Oregon, 2011. U.S. Geological Survey Open-File Report 2012-1193, 42 p.
- Hewitt, D.A., E.C. Janney, B.S. Hayes, and R.S. Shively. 2010. Improving inferences from fisheries capture-recapture studies through remote detection of PIT tags. Fisheries, 35(5):217-231.
- Barry, P.M., E.C. Janney, D.A. Hewitt, B.S. Hayes, and A.C. Scott. 2009. Population dynamics of adult Lost River (Deltistes luxatus) and shortnose (Chasmistes brevirostris) suckers in Clear Lake Reservoir, California, 2006-08. U.S. Geological Survey Open File Report 2009-1109.
- Janney, E.C., R.S. Shively, B.S. Hayes, P.M. Barry, and D. Perkins. 2008. Demographic analysis of Lost River sucker and shortnose sucker populations in Upper Klamath Lake, Oregon. Transactions of the American Fisheries Society, 137:1812-1825.
- Other annual reports for Upper Klamath Lake and Clear Lake Reservoir populations are available here.