Test of an environmental flow release in a British Columbia river: does more water mean more fish?

摘要: Summary 1. Water managers must make difficult decisions about the allocation of streamflows between out-of-channel human uses and environmental flows for aquatic resources. However, effects on stream ecosystems are infrequently evaluated. 2. We used a 13-year experiment in regulated Bridge River, British Columbia, Canada, to determine whether an flow release designed increase salmonid productivity was successful. A hierarchical Bayesian model compare juvenile Pacific salmon (Oncorhynchus spp.) abundance before after release. 3. We found that total number salmonids did release, but most gains could be attributed rewatering previously dry channel located immediately below dam. In reaches had flowing water during baseline period, response individual species variable, there little change release. Our results were inconsistent with both habitat modelling, which predicted decrease quality increasing flow, holistic instream approaches, imply greater benefits larger flows. 4. We question biotic responses changes can reliably currently available methods suggest adaptive management or use decision tools account uncertainty is required when competing demands great.