Idaho Fish and Game has suspended stocking rainbow trout in 17 ponds from Council to Mountain Home due to the summer heat, said Evin Oneale, a regional conservation educator for the Idaho Department of Fish and Game.
Bass, bluegill, and crappie were found floating Sunday and Monday on the surface of the pond at West Boise’s Redwood Park, 2675 N. Shamrock Ave. Though not stocked since 2009 because of its shallow water and muddy bottom, it’s an example of how a heat wave can affect a pond’s ecosystem. A past population of fish survived in the pond until the past week’s high temperatures created difficult conditions for the fish, Oneale said.
No other ponds in the area have reported dead fish.
The recent triple-digit temperatures, along with low oxygen levels, have created stressful environments for different species of fish, Oneale said.
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“The water temperatures heat up and the ponds become lethal,” Oneale said.
Many local ponds are shallow and unable to provide cool water for the fish when temperatures rise.
“If the fish are starting to stress out, that’s when you see them starting to die,” Oneale said.
It is unclear exactly how many fish have died in Redwood Pond, Oneale said.
The Boise Parks and Recreation Department reported the tally as “dozens” dead Monday afternoon. The pond supports largemouth bass, bluegill, catfish, crappie, and likely carp and goldfish.
According to a statement, the department is examining how to cool the pond with fresh water, also increasing oxygen levels for the remaining fish.
One option is to draw down the pond and add water from a nearby irrigation ditch, according to the department.
Fish and Game has suspended its fish-stocking program in Caldwell Pond No. 2, Duff Lane, Eagle Island, Eds, Heroes, McDevitt, Merrill Parkcenter, Quinns, Riverside, Rotary, Sawyers, Sego Prairie, Settlers, Veterans Park and Williams ponds. Fish and Game staff will resume stocking the suspended ponds in October when temperatures have cooled down.
The Snake River and the Boise River, which are managed differently than standing bodies of water, have not been affected in the same way by the record-setting temperatures, Oneale said.
Ponds across Southwest Idaho are still open for fishing warmwater species, Oneale said, including bass, bluegill, crappie and channel catfish, which are more tolerant to warmer temperatures than trout.
Rainbow trout are stocked in local ponds with suitable temperatures, as well as local rivers and higher elevation lakes like Bull Trout Lake, from July through September.
Grace Gibney can be reached at 377-6444.