An experimental study of stranding of juvenile salmonids on gravel bars and in sidechannels during rapid flow decreases
✍ Scribed by Bradford, Michael J
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 111 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0886-9375
No coin nor oath required. For personal study only.
✦ Synopsis
Juvenile salmonids can become stranded over gravel bars or trapped in off-channel habitat during rapid ¯ow decreases that often occur in regulated rivers. In a stream channel experiment that simulated stranding over a gravel bar, more juvenile chinook salmon (Oncorhynchus tshwytscha) were stranded when the water was 6 C compared with 12 C. The rate of ¯ow decrease was not a signi®cant factor in the incidence of stranding. In contrast, the number of chinook and coho (O. kisutch) salmon juveniles that became trapped in side channels built in the stream channel increased with increasing rate of dewatering, and for coho salmon, more ®sh were trapped at night compared with the day. Even at the slowest rate of ¯ow decrease some ®sh remained in the side channels after the channels became disconnected from the main ¯ow. My results suggest that mortality as a result of trapping in side channels or pot-holes will be decreased, but may not be eliminated, by ¯ow ramping, although this result needs to be corroborated with ®eld studies.