The New York state fish could be jeopardy due to climate change, warn Cornell scientists.
Warmer summers mean later fall spawning times and fewer nests for brook trout, which could eventually affect the fish’s population numbers.
Cliff Kraft, associate professor in the Department of Natural Resources, and four other researchers looked at 11 years of data from Rock Lake in the Adirondacks to find the link between summer temperatures and spawning times for brook trout. Cornell has a 60-year history of research in Adirondack lakes, providing the researchers with long-term data on temperatures and brook trout spawning times.
"The key thing is they are cold-water fish and need groundwater to spawn," Kraft said.
The warmer summer temperatures have had a "sub-lethal effect," Kraft said. Warmer summers don’t kill the fish, but lead to fewer nests -- called redds -- and a late start for those eggs that are laid.
"These trout can’t build gonads in the summer," Kraft said. "They’re burning more energy to survive, so they don’t have energy to produce eggs. The warmer it gets, the fewer fish are spawning; some just give up."
In a study published in the Global Change Biology journal March 13, the researchers argue that temperature can be linked to the delay in spawning.
An average difference in mean summer daily air temperature of 1 degree Celsius delayed spawning by about one week and reduced the number of redds constructed by 65, they found.