Alaska's summer heat wave has been pleasant for humans but punitive for some of its fish.

Overheated water has been blamed for large die-offs of hatchery trout and salmon stocks in at least two parts of the state as hot, dry weather has set in, according to the Alaska Department of Fish and Game.

Hundreds of grayling and rainbow trout died in June after being placed in a Fairbanks lake, the department reported. An unusually cold spring caused lake ice to linger much longer than normal, before the water quickly became too warm. Surface temperatures in the lake rose to about 24 degrees Celsius.

A similar incident occurred in mid-July at the Crystal Lake Hatchery south of Petersburg in southeast Alaska.

An estimated 1,100 hatchery king salmon died while returning to a lake to spawn, local public radio station KFSK reported.

Record-breaking heat has also created elevated wildfire risks in Alaska, even in the normally rain-soaked Tongass National Forest in the state's southeastern panhandle.

Wildfires have charred more than a million acres across Alaska, according to state and federal wildfire managers, more than the five-year season-total annual average of 952,113 acres. Some 75 active fires were still burning on Friday, with much of the fire season still to come.