More juvenile fish survive river trip

More juvenile fish survived last year’s outward migration in the Snake and Columbia River system than have in all but one year on record.

The National Oceanic and Atmospheric Administration reported about 95 percent of yearling salmon and steelhead passed safely through each of the eight Snake and Columbia river dams. At some dams the survival rate was 99 percent.

The number of returning fish was 21 percent above the average of records kept since the 1990s.

A release from the Bonnevile Power Administration said higher survival rates were likely due to two factors: the spill of water to carry young fish past dams and new surface passage systems that slide fish through dams.

The agency also said higher spring run off contributed to higher survival rates.

All eight dams now have surface bypass systems to help juvenile fish downstream. In addition, new aerial wires below John Day Dam have cut bird predation. The Dalles Dam built a spill wall to guide fish away from predators.

A new spillway weir, or fish slide, was installed at Little Goose Dam in 2009 to speed young fish through the spillway. As fish travel faster, they are less exposed to predators.