Rising summer temperatures pose a threat to coldwater brook trout in the Adirondacks, a recent study shows.

Photo: Ohio Dept. of Natural Resources

Researchers recorded air and water temperatures over the course of 11 summers and correlated readings to spawning activity. A rise of 1.8 degree Fahrenheit delayed spawning by approximately one week and reduced the number of nests. Late spawning is likely to delay the emergence of fry, which could uncouple synchronicity with the emergence of prey.

Water temperatures near 70 degrees Fahrenheit stress the fish, which do not have sufficient energy to feed. Consequently the growth of their reproductive organs slowed. High temperatures effectively caused the trout to shut down in the middle of the summer, the paper’s authors said.

However, hot summers presently pose less of a threat to brook trout than non-native species and habitat loss, says co-author Cliff Kraft, a professor of natural resources at Cornell University. But if temperatures continue to climb, at some point there will be no brook trout. Without quick and dramatic curbs on greenhouse gas emissions, climatologists currently estimate that Earth will warm by more than 7 degrees Fahrenheit by the end of the century.