Warmer summers could shrink trout populations

Mar 27, 2012 By Liz Lawyer
Warmer summers mean later spawning times and fewer nests for brook trout.

(PhysOrg.com) -- 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 .

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 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 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 journal March 13, the researchers argue that 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.

"The last brook trout in this lake is not about to drop dead, but warming temperatures present a substantial threat," Kraft said.

Dana Warren, Kraft's former Ph.D. student who is now at Oregon State University, said warmer temperatures also mean earlier ice breaks, earlier turnover times for lakes and earlier peaks for plankton blooms.

All of these factors can affect the available for the young fish when they do emerge. If fish are relying on that plankton when they hatch, they may be weeks too late, and the natural synchrony of the blooms and the hatching period are pulled out of whack in two directions, Warren said.

The study used a long time frame to look beyond acute effects and discover potential latent effects of , Warren added.

The researchers believe unstratified lakes -- or lakes shallow enough not to have layers of water at different temperatures and densities -- will become more common. That could pose further threats to fish like trout, which take refuge in cool water, Warren said.

"This study highlights the importance of looking at residency and non-migratory populations," he said.

Explore further: Pakistan releases smuggled turtles into the wild

add to favorites email to friend print save as pdf

Related Stories

Climate threatens trout and salmon

May 17, 2010

Trout and salmon are among the world's most familiar freshwater fishes, but numbers have fallen over recent decades - in some areas, dramatically.

Study finds way to cut sea lamprey numbers

Oct 03, 2005

Minnesota scientists say they've found a way to reduce sea lamprey populations in the Great Lakes by attracting them to areas where they can be sterilized.

Recommended for you

Preserving crucial tern habitat in Long Island Sound

32 minutes ago

Great Gull Island is home to one of the most important nesting habitats for Roseate and Common terns in the world. The estimated 1,300 pairs of Roseate terns that summer on the 17-acre island at the eastern ...

California's sea otter numbers holding steady

52 minutes ago

When a sea otter wants to rest, it wraps a piece of kelp around its body to hold itself steady among the rolling waves. Likewise, California's sea otter numbers are holding steady despite many forces pushing ...

22 elephants poached in Mozambique in two weeks

14 hours ago

Poachers slaughtered 22 elephants in Mozambique in the first two weeks of September, environmentalists said Monday, warning that killing for ivory by organised syndicates was being carried out on an "industrialised" ...

Pakistan releases smuggled turtles into the wild

19 hours ago

Pakistani officials and environmentalists on Monday released some 200 rare turtles into the River Indus after the reptiles were retrieved from a southwestern Chinese town where they were seized by customs ...

User comments : 0