Wildlife experts at the Ohio State University (OSU) discovered that the continued rise in water temperatures due to global warming is threatening the population of yellow perch in the Great Lakes region.
In a study featured in the journal Nature Communications, a team of OSU researchers, led by biology professor Stuart Ludsin, found that the warm waters in Lake Erie are causing the yellow perch to lay less hardy eggs, while their larvae become less likely to survive the harsh environment than before.
The findings also showed that the fish are having difficulties in adjusting their spawning method to match temperatures similar to those of spring.
Ludsin and his team believe this could pose a major problem, especially if zooplanktons in the lake, which are the main source of food of the yellow perch, make an adjustment of their own. This could lead to fewer zooplanktons by the time the larvae of the perch need to feed.
"If not enough food is available, the larvae will grow slowly and be vulnerable to predators like invasive white perch," Ludsin said.
The perch eggs produced in cold winter conditions in a laboratory experiment are on average 30 to 40 percent larger compared to other eggs, while the resulting hatchings were three- to four-fold more successful than the ones produced during warm and short winter conditions.
This problem with fish survival could provide an explanation as to why the population of yellow perch in Lake Erie has been on decline since 2003. The numbers of the fish is estimated at half the population observed during the yellow perch's peak in the 1960s and 1970s
Ludsin said that there are a number of potential factors that could cause the decrease in yellow perch population in Lake Erie, but the increase in the lake's water temperatures is clearly a significant one. He added that there are no easy ways to address the problem for different management agencies.
Ludsin first studied the link between warmer winters and the decrease in the number of juvenile yellow perch in the lake while finishing his dissertation for OSU over 15 years ago. Much of his scientific career has been spent collaborating with fishery managers in Lake Erie to find out why the population of the fish has fluctuated significantly in the past forty years.
Photo: USFWS Mountain-Prairie | Flickr
