Climate change could make it hard for yellow perch to breed
The yellow perch living in Lake Erie have long faced challenges breeding after short, warm winters and some scientists believe that climate change could thus cause further problems for them.
A newly published paper in Nature Communications looks at field data involving Lake Erie yellow perch from 1973 to 2010.
It's based on research that Troy Farmer, a post-doctoral researcher at Auburn University, did for his PhD dissertation at Ohio State University.
In a telephone interview, Farmer said the research shows a "long-term correlation" with strong years of yellow perch production in Lake Erie following long, cold winters.
Similarly, he said that a diminished frequency of long, cold winters has arrived alongside decreased years of strong yellow perch production in the lake.
"Scientists had speculated cool-water species like yellow perch might actually benefit from warmer temperatures and so we were a little bit surprised to see that correlation," Farmer said in a telephone interview with CBC News on Tuesday morning.
The paper that Farmer and several Ohio State faculty members contributed to, says that after short, warm winters, these fish ended up producing fewer juveniles, which in turn produced a smaller subsequent population of mature perch.
When these female perch have been exposed to a longer winter, they have tended to lay larger eggs, which hatch at higher rates.
Conversely, during shorter winters, these perch would end up laying smaller eggs. And this happened at a later point in the spring, when temperatures were warmer then when this process would otherwise take place.
"When springs warmed exceptionally early, yellow perch females did not move up their spawning time to match that early arrival of spring," said Farmer.
"We've seen a lot of cold-blooded animals that when spring arrives early, they can spawn earlier in response to that early warming, but we did not see that in the female yellow perch."
Instead, Farmer said that the female perch appears to spawn at the same time of the year, regardless of when spring arrives or doesn't.
Food source a concern
"That may have really important implications for larval survival," said Farmer, noting that yellow perch larvae rely on zooplankton, a food source that may not respond the same way to an early spring.
"If zooplankton peak earlier in response to early spring warming and the yellow perch are not moving up their reproduction earlier, then the yellow perch larvae may have less food to eat and therefore, they may have lower survival as well," he said.
Ultimately, Farmer said the research suggests that the change in winters may be harmful enough to yellow perch to limit or negate any advantage they get from a longer growth period during a longer summer.
"Our results suggest that climate warming during winter may negatively affect yellow perch populations, primarily by reducing reproductive success," said Farmer.
"And that suggests that even if summer conditions are better for growth under a warmer climate, that that might mean little if the number of offspring produced has already been limited by short, warm winters."
Farmer said more work needs to be done to better understand if other types of cool water fish may have the same issues as a result of living through shorter, warmer winters.
"There's some suggestions from this work that this may be a broader trend, but that would need future research to really understand how widespread it is across other species," Farmer said.
According to the U.S. Geological Survey, yellow perch in Lake Erie that account for millions of dollars in net economic value.