A whole-lake experiment to control invasive rainbow smelt (Actinoperygii, Osmeridae) via overharvest and a food web manipulation

Invasive rainbow smelt (Osmerus mordax) have spread rapidly throughout inland lakes of North America with detrimental effects on several native fishes. To test for the potential to control this species, we conducted an experimental removal of rainbow smelt in Sparkling Lake, Wisconsin during 2002–2009. We combined intensive spring harvest of rainbow smelt with an effort to increase predation on this invasive through restricted angler harvest of walleye and increased stocking of walleye (Sander vitreus). Over 4,170 kg of rainbow smelt were harvested during the experiment; up to 93% of adults were removed annually. We observed a significant decline in rainbow smelt gillnet catches during the removal. However, rainbow smelt relative abundances began increasing upon cessation of the removal effort. Bioenergetics modeling suggested that despite achieving higher than the regional average walleye densities, walleye consumed only a fraction of the rainbow smelt standing stock biomass. Our findings suggest that removal of rainbow smelt from invaded lakes may be difficult, and reinforce the importance of prevention as a strategy to limit the expansion of this invasive fish.