Validation of a Critical Assumption of the Riparian Habitat Hypothesis for White Sturgeon; Scientific investigations rept

摘要

In June 2005, we confirmed that white sturgeon Acipenser transmontanus embryos, free embryos, and larvae could be found in shallow seasonally flooded riparian habitat in the Columbia River downstream of Bonneville Dam. This validates a critical assumption of the Coutant Riparian Habitat Hypothesis that during white sturgeon spawning, embryos are either deposited in, or transported to, seasonally flooded riparian habitat. Sampling for early life stages of white sturgeon took place in the vicinity of Ives and Pierce islands using eight types of collection gear. A total of 1,372.9 hours of sampling was completed with 254 embryos, 6 free embryos, and 1 larva collected. Surface substrates were characterized in August 2005 for 9 of the 21 sites where embryos, free embryos, and larvae were found. The sites characterized were composed of 0.35 percent fines, 53.56 percent gravel, 45.69 percent cobble, and 0.41 percent boulder.