The Effects of Invasive Rainbow Smelt on Native Fishes in Two Wisconsin Lakes

Rainbow smelt (Osmerus mordax) is a species of fish originally native to the northeastern parts of the United States. Often used as live bait for recreational fishing, it has become invasive to multiple lakes throughout the midwestern United States, including Sparkling Lake and Crystal Lake in Vilas County, Wisconsin. These two lakes hold native populations of Walleye (Sander Vitreus) and Yellow perch (Perca flavescens). Walleye feed on both Yellow perch and Rainbow smelt which are in competition with each other as they are of similar sizes and share the same feeding habits. In this study I looked at the effects that Rainbow smelt have on these Walleye and Yellow perch in Crystal and Sparkling Lakes using data collected by the Northern Temperate Lakes Long-term Ecological Research Network over the past 40 years. Rainbow smelt were first observed in these lakes in the 1980’s and their populations began to grow steadily over time. Removal efforts took place in Sparkling Lake from 2001 to 2009 in an effort to return the fish community to its natural state, however it was unsuccessful, and Rainbow smelt populations began to grow again following the termination of removal. By comparing the populations of these species to one another for both lakes, I attempted to find any changes in native fish populations throughout the periods in which Rainbow smelt became invasive. No significant relationships between the three species were found. I had predicted that increases in Rainbow smelt would lead to a decline in Yellow perch but there was no proof of this occurring. Through management practices such as increases in the stocking of Walleye fry and limiting the number that can be removed by recreational fishing, Rainbow smelt have the potential to be controlled through the predation of Walleye