The Effects of River Impoundment and Hatchery Rearing on the Migration Behavior of Juvenile Steelhead in the Lower Snake River, Washington

Abstract

We used radiotelemetry to monitor the migration behavior of juvenile hatchery and wild steelhead Oncorhynchus mykiss as they migrated through Lower Granite Reservoir and Dam on the lower Snake River, Washington. From 1996 to 2001, we surgically implanted radio transmitters in 1,540 hatchery steelhead and 1,346 wild steelhead. For analysis, we used the inverse Gaussian distribution to describe travel time distributions for cohorts (>50 fish) of juvenile steelhead as they migrated downriver. Mean travel rates were significantly related to reach‐ and discharge‐specific water velocities. Also, mean travel rates near the dam were slower for a given range of water velocities than were mean travel rates through the reservoir, indicating that the presence of the dam caused delay to juvenile steelhead over and above the effect of water velocity. Hatchery steelhead took about twice as long as wild steelhead to pass the dam as a result of the higher proportions of hatchery steelhead traveling upriver from the dam. Because upriver travel and the resulting migration delay might decrease survival, it is possible that hatchery steelhead survive at lower rates than wild steelhead. Our analysis identified a discharge threshold (∼2,400 m3/s) below which travel time and the percentage of fish traveling upriver from the dam increased rapidly, providing support for the use of minimum flow targets to mitigate for fish delay and possibly enhance juvenile steelhead survival.

Linking individual behaviour and migration success inSalmo salarsmolts approaching a water withdrawal site: implications for management

“…Thus, the water withdrawal zone is considered an adverse habitat (Svendsen et al 2010). Second, milling behaviours are coupled with increased risk of predation by wild piscivores Venditti et al 2000;Plumb et al 2006). In the present study, the milling smolts covered a larger area, travelled longer, and spent longer time inside the hydrophone array (Table 1).…”

“…A number of studies have reported Pacific salmon smolts performing milling behaviours in anthropogenically altered channels (Venditti et al 2000;Plumb et al 2006;Nestler et al 2008). The present study showed that milling behaviours also occur in Atlantic salmon smolts (Fig.…”

“…upstream excursions and circular swimming behaviour) in anthropogenically altered channels (Venditti et al 2000;Plumb et al 2006;Nestler et al 2008), however few studies have examined the consequences of these behaviours. The present study had two purposes.…”

A Field Evaluation of an External and Neutrally Buoyant Acoustic Transmitter for Juvenile Salmon: Implications for Estimating Hydroturbine Passage Survival

“…The 65-rkm distance from the mouth of the Snake River to McNary dam was covered in a median of 5.7 d by the hatchery-origin fish used in this study compared to a median of approximately 2 d for a concurrent study on run-of-river wild subyearling Chinook salmon in the same river reach of the Columbia River basin (Geoff McMichael, Pacific Northwest National Laboratory, unpublished data, 2012). Slower travel times in fish recently released from hatcheries are common [42], [43], [44]. For example, travel rates of wild juvenile steelhead were found to be twice as fast as hatchery-reared steelhead and the hatchery-reared fish were observed moving upstream after release, delaying their seaward migration [43].…”

“…Slower travel times in fish recently released from hatcheries are common [42], [43], [44]. For example, travel rates of wild juvenile steelhead were found to be twice as fast as hatchery-reared steelhead and the hatchery-reared fish were observed moving upstream after release, delaying their seaward migration [43]. Behavioral and physiological changes occur in juvenile salmonids during the smoltification period cueing migration to begin.…”