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자료유형 :	NTIS
자료명/저널명 :	Quantifying the Behavioral Response of Spawning Chum Salmon to Elevated Discharges from Bonneville Dam, Columbia River. Annual Report, 2005-2006
개인저자 :	Tiffan, K. F. Haskell, C. A. Kock, T. J.
발행처 :	Geological Survey, Cook, WA. Columbia River Research Lab.
페이지수 :	24p
내용주기 :	Chum salmon Oncorhynchus keta that spawn in main-stem habitats below Bonneville Dam on the Columbia River, USA, are periodically subjected to elevated discharges that may alter spawning behavior. We investigated behavioral responses of spawning chum salmon to increased water velocities associated with experimental increases in tailwater elevation using acoustic telemetry and a dual-frequency identification sonar. Chum salmon primarily remained near their redds at base tailwater elevations (3.5 m above mean sea level), but displayed different movement and behavioral responses as elevations were increased to either 4.1 or 4.7 m for 8-h periods. When velocities remained suitable (<0.8 m/s) during elevated tailwater tests, female chum salmon remained near their redds but exhibited reduced digging activity as water velocities increased. However, when velocities exceeded 0.8 m/s, the females that remained on their redds exhibited increased swimming activity and digging virtually ceased. Female and male chum salmon that left their redds when velocities became unsuitable moved mean distances ranging from 32 to 58 m to occupy suitable velocities, but returned to their redds after tailwaters returned to base levels. Spawning events (i.e., egg deposition) were observed for five of nine pairs of chum salmon following tests indicating any disruptions to normal behavior caused by elevated tailwaters were likely temporary. We believe a chum salmons decision to either remain on, or leave, its redd during periods of unsuitably high water velocities reflects time invested in the redd and the associated energetic costs it is willing to incur.