A recent study reveals that the size of parent walleye and their living conditions during spawning are the top factors influencing the growth of Lake Erie walleye.
The researchers were taken aback by these results, as they initially thought that factors like recent temperatures and food supply would have a greater effect on the growth of walleye.
The analysis indicated that harsher winters and larger maternal fish were linked to quicker growth in walleye offspring aged 3 to 5. This suggests that climate change, which may bring about warmer winters, could result in smaller fish generations in the future.
Moreover, these findings imply that ecological studies on other species should consider parental experiences to gain a better understanding of animal health today, according to the researchers.
Lead author Zoe Almeida, who conducted the research as a PhD student at The Ohio State University, expressed, “We initially believed recent environmental conditions would exert the most significant impact. Typically, when analyzing growth factors, temperature and food availability are key considerations. Surprisingly, these factors had minimal influence and were not the primary determinants.”
The research was published on August 13 in the Journal of Animal Ecology.
Growth rates serve as a health indicator for many species, influenced by both genetics and the environmental experiences. According to a 2024 Ohio Division of Wildlife (ODNR-DOW) status report, the current condition of the Lake Erie walleye population is regarded as very healthy.
“The Lake Erie walleye population is thriving at the moment,” Almeida stated, now serving as a senior research associate in natural resources and the environment at Cornell University. “However, we should question if there are underlying issues that we might not detect until much later due to their delayed impact.”
To explore this, Almeida and her team utilized extensive walleye data collected by ODNR-DOW, which has been monitoring the Lake Erie population for many years.
The group studied five growth-affecting factors: recent environmental conditions — including food availability and temperatures; traits from the prior year, such as growth rates; population density, suggesting competition levels during early life; early size at birth; and parental conditions along with their environmental backgrounds.
The analysis focused on annual groups of walleye between the ages of 3 and 5 from 1982 to 2015, a stage where they are maturing yet still experiencing rapid growth. Data from ODNR-DOW also recorded the proportion of spawning walleye yearly. Researchers examined how these factors relate to growth rates using statistical models.
Almeida noted, “What primarily influenced cohort growth was based on the experiences of their parents. The sizes of these parents and the winter conditions they faced determined whether the cohort grew faster or slower compared to the previous year’s trends for individuals aged 3 to 5.”
In contrast, no significant impact on growth was linked to the expected influences of recent food sources, temperatures, or fishing pressures (as anglers are the principal predators of walleye). While these factors do have some effects, they are not the most significant, Almeida pointed out.
The study’s results have significant implications for wildlife management and ecological research.
“This research aids in setting realistic expectations and provides insights into the underlying mechanisms influencing wildlife. When managers forecast the future of this population over the next three to five years, they should recognize that historical events are shaping current conditions, and this should inform their management strategies,” Almeida advised.
“I believe this holds true for other species as well. What occurs during early life or parental experiences might be more impactful than current environmental conditions, which we often overlook.”
This research received support from the National Science Foundation, a Distinguished University Fellowship from Ohio State, the American Fisheries Society, the International Association of Great Lakes Research, and The Federal Aid in Sport Fish Restoration Program managed collaboratively by the U.S. Fish and Wildlife Service and ODNR Division of Wildlife.
The study’s co-authors include Stuart Ludsin and Elizabeth Marschall from Ohio State, along with Matthew Faust from ODNR.
