Pumpkinseed sunfish (Lepomis gibbosus) counter spiny cladoceran (Bythotrephes longimanus) defenses

Abstract How do native species react to the presence of an invader? Consumption by resident fish is important in determining the yearly mortality of the invasive cladoceran Bythotrephes. In aquarium experiments, we discovered that small pumpkinseed sunfish (Lepomis gibbosus) were efficient at removing spines from Bythotrephes longimanus and consuming the adults. Experiments quantified how frequently pumpkinseeds showed successful removal of spines, and compared predatory performance relative to other species of fish. We also checked if Bythotrephes' resting eggs pass through the guts of pumpkinseeds in viable condition. The experiments revealed that pumpkinseed sunfish (45–70 mm total length, TL) from two geographic regions removed spines 87% of the time. Spine-handling techniques allowed pumpkinseeds to consume Bythotrephes faster than other species of small (