As global climate change, droughts and hot summers continue, many streams and headwaters will flow with low water, which could put fish into a more vulnerable situation when being preyed on by birds such as hawks and eagles.
A new study has found that adequate shade and cover in streams could reduce bird consumption of trout by as much as 12 percent, from only one species of bird – the kingfisher. This study originated from the Oregon Hatchery Research Center in the Alsea River basin, and published in the journal Ecology of Freshwater Fish.
Using coastal cutthroat trout and suggested individual fish sought cover at least as large as their own bodies. The addition of in-stream cover reduced the rate of predation from kingfishers by 12 percent and maintained better survival in areas with greater shade.
Jason Dunham, an aquatic ecologist with the U.S. Geological Survey and co-author on the study stated, “It is generally assumed that shade is good for fish solely because of temperature.
This study shows shade can make it more difficult for kingfishers to spot and catch fish. Kingfishers are the number one predators of small trout.” said Penaluna, who led the research as a doctoral student in the Department of Fisheries and Wild- life at Oregon State University . She said, “We’re able to tell fisheries managers that they may be able to increase their trout population by 12 percent – and it may be higher. It is possible that adding shade and cover to small streams may help protect trout against other predators as well.”
With that said, would improving shade and natural cover to the Saugeen River headwaters and streams help boost steelhead populations?
Its possible.Source Article: http://oregonstate.edu/ua/ncs/archives/2015/may/study-finds-shade-cover-can-reduce-predation-birds-trout