HR: 08:20h
AN: H31H-02 INVITED     [Abstracts]
TI: Overview of Endangered Suckers in the Klamath Basin: Does it Take One to Know One?
AU: * Shively, R S
EM: Rip_Shively@usgs.gov
AF: U.S. Geological Survey, 2795 Anderson Ave, Suite 106, Klamath Falls, OR 97601
AU: Vanderkooi, S
EM: Scott_Vanderkooi@usgs.gov
AF: U.S. Geological Survey, 2795 Anderson Ave, Suite 106, Klamath Falls, OR 97601
AB: Severe water quality problems in the Klamath Basin of Oregon and California have led to critical fisheries concerns for the region. In the Upper Klamath Basin, two fish species, the Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were listed as federally endangered in 1988. These species are large, long-lived, lake-dwelling fishes endemic to the Upper Klamath Basin. Declining population trends for both species were noted as early as the mid 1960's, however, the severity of these declines were not evident until the mid 1980's. At the time of listing, population structures were dominated by older individuals with little evidence of recent significant recruitment into adult populations. In the early 1990s there was evidence of recruitment for Lost River suckers. Successive years of large fish kills in Upper Klamath Lake from 1995 to 1997, however, substantially reduced adult populations of both Lost River and shortnose suckers. Additionally, the 1995 and 1996 fish kills appeared to have been selective for larger-sized individuals and would have disproportionately affected females and resulted in an overall lower reproductive potential. Water quality and physical habitat limitations are considered to be the most limiting factors to species recovery. Life history patterns of Lost River and shortnose suckers in Upper Klamath Lake have been severely disrupted by recurrent periods of poor water quality that appear to be the root cause of fish kills and likely negatively influence the production of juvenile suckers. Habitat degradation around Upper Klamath Lake and in its tributaries likely contributes to water quality problems and also limits the physical habitat needed for successful adult sucker spawning as well as larval and juvenile rearing. Ultimately, a better understanding of the factors that influence water quality in Upper Klamath Lake as well as developing a sound strategy for habitat restoration is needed to promote recovery of these species. Future challenges fisheries biologists in the Klamath Basin face include developing a better understanding of sucker population dynamics and habitat requirements at different life stages. One of the largest challenges, however, will be the integration of biological information on suckers with an improved understanding of water quality and physical habitat processes.
DE: 1871 Surface water quality
DE: 1890 Wetlands (0497)
DE: 1899 General or miscellaneous
SC: Hydrology [H]
MN: Fall Meeting 2005