Endangered Lost River and shortnose suckers in Lake Ewauna and use of the Link River Dam fish ladder, Oregon

Passive Integrated Transponder (PIT) tags were used to investigate endangered adult Lost River sucker Deltistes luxatus and shortnose sucker Chasmistes brevirostris use of the Link River fish ladder to return to Upper Klamath Lake, Oregon. Suckers were tagged in Lake Ewauna throughout the late winter and early spring of 2008 and 2009 using trammel nets set one hour before sunrise. We PIT tagged 126 suckers in 2008 and 519 suckers in 2009, of which the strong majority was shortnose. The U.S. Geological Survey (USGS) Klamath Falls Field Station is monitoring sucker movements through the Link River Dam fish ladder using four PIT tag antennas arranged throughout the ladder. In 2009, USGS detected 21 suckers using the fish ladder; four were later detected at other USGS monitoring sites in the upper reaches of Upper Klamath Lake. Although Lake Ewauna is considered unsuitable for suckers, this study suggests they may be able to survive in numbers. Data suggests suckers moving through the ladder are smaller than those represented in net catches. This study will provide information on the degree of connectivity between Upper Klamath Lake and Lake Ewauna suckers, and lead to refined operational procedures for the Link River Dam fish ladder.