Larval Shortnose and Lost River Sucker Response to Large Scale Wetland Restoration of the North Half of the Williamson River Delta Preserve, Oregon

Hydrologic reconnection of deltaic wetlands at the mouth of the Williamson River with portions of Agency Lake and Upper Klamath Lake, Oregon is a restoration strategy aimed at increasing the amount of nursery habitat available for larval Lost River suckers Deltistes luxatus and shortnose suckers Chasmistes brevirostris. We examined the response of larval suckers to this large scale wetland restoration project at the Williamson River Delta by assessing discrepancies in catch rates, habitat preferences, and fish condition (size and gut fullness) at restored and existing lakeshore fringe wetlands. Differences in habitat associations existed between the two wetland types, as larval suckers preferred shallow, vegetated areas in the restored areas of the Williamson River Delta while in existing wetlands deep, non vegetated areas were occupied more frequently. Mean larval sucker length and gut fullness in the restored areas were on average greater than means in existing wetlands, a strong indication that larvae were rearing in the restored wetlands of the Williamson River Delta. Our monitoring suggests that wetland restoration efforts at the Williamson River Delta may contribute to the recovery of these two endangered species through the increase of larval nursery habitat.