The ANOVA model results from this experiment reveal that only female gonad weight varied significantly between winter treatments in Ohio with the short treatment having a lower mass than the long treatment. This could be due to short winters having a higher metabolic cost; resulting in less energy going towards gonad or soma growth and more energy allocated towards base metabolic processes. Somatic growth in both northern and southern populations was not affected by winter treatments, which suggest non-reproductive growth during winter is minimal and not traded off against reproductive development. Both South Carolina male and female fish appeared to show higher soma development during the winter than Ohio fish, showing that South Carolina fish were still actively growing during the winter. Likely taking advantage of warmer winters in southern latitudes. All male gonads showed negative percent difference values, this is likely because fish were measured after the spawning season and were spent of milt. We saw no difference between the boxplots of Ohio and South Carolina female gonads.
Ohio females concurred with our hypothesis that Ohio fish would allocate more energy to reproduction in the long winter, however all other models countered our hypothesis that cold winter would lead to more energy to reproduction, as they showed no significant difference in the allocation of energy to reproduction between long and short winter treatments. Previous studies show Ohio GSI tends to be higher than South Carolina GSI. However we did see that South Carolina fish put on more soma in the winter in comparison to Ohio fish, which concurs with our hypothesis that warm winters would allow for greater somatic growth.
Our findings are significant in that they provide insight into how shorter, warming winters can affect fish, such as Yellow Perch. When looking at current global climate change trends, we can expect for these northern populations, such as Lake Erie Yellow Perch, to undergo warmer winters in the future that are more aligned with temperatures mimicking South Carolina. Due to these warmer temperatures, Ohio fish may take on life history traits similar to that of South Carolina’s current life history traits. Changes to Ohio fish life history traits may necessitate changes in management and regulation of fish in that area.It’s possible that these effects could also be seen in other fish species such as salmonids, esox, and other members of Percidae. Fish collected from both Ohio and South Carolina experienced the same kind of water system, as well as feeding simulations, making climate the focus of the study. A common-garden experiment in this study would have possibly yielded more accurate results in regards to the winter temperature treatments, but in the case of this study would not have been possible, due to the time difference in studies, as well as the extreme temperature change that the fish may have undergone. To more accurately predict the trends of overwinter energy allocation in this study, we would have liked to have a larger sample size of both male and female fish from Ohio and South Carolina populations, as well as possibly add another origin reference to better understand the latitudinal trend of warming winters affecting growth. In studying overwinter energy allocation of fish species, we suggest future studies further look into mechanisms driving metabolic cost in overwinter allocation, as well as look more into current and well validated bioenergetics models for Yellow Perch and other cool water species as bioenergetics models used for this study were outdated and no current models existed for this or similar species.