Even though temps from 1998-2010 had no effect on studied population size.
Climate change is a known threat to fish that rely on cold water for survival. Now, research conducted in an upstate New York lake is revealing just how dangerous warmer waters might be for a common species of trout.
Brook trout typically lay their eggs in late summer or fall, but nesting data gathered from a lake in the Adirondack Mountains reveal that hotter summers are delaying those spawning times — and sometimes trout are too hot to bother laying eggs at all.
“It suggests that having warm, hot summers is not going to be good for brook trout,” said Cliff Kraft, a professor of natural resources at Cornell University and co-author of the new study, published in Global Change Biology this month. He says hotter weather forces the cold-water fish to “basically shut down” and wait for the temperature to drop, so they can continue feeding, growing and reproducing.
Kraft and his fellow researchers looked at spawning data from 1998 to 2010 — a time period that saw eight of the 10 warmest years in the last century — and found that for every 1 degree Celsius (nearly 2 degrees Fahrenheit) increase in average temperature, the trout postponed laying their eggs by one week and constructed nearly 65 fewer nests, or “redds.” The summer of 2005 was so intense that the fish did not even try reproducing and opted to wait for better weather the following year.
Surprisingly, the overall trout population in the lake did not decline. Year-to-year temperatures varied enough for the fish to bounce back, and juveniles survived in spite of the delayed spawning times each fall…