Inter-specific kairomone alarm cues reduce larval lake sturgeon predation independent of distributional or phylogenetic relationships

We experimentally tested whether lake sturgeon (Acipenser fulvescens), a native species of conservation concern, could use associative learning to detect and respond to predator odors and alarm cues from other species (kairomones) to reduce predation risk. Alarm cues emitted by round goby (Neogobius melanostomus), a historically geographically separated non-native species in the Great Lakes region and white sucker (Catostomus commersonii), a common native co-distributed species with lake sturgeon were used. Lake sturgeon larvae were experimentally exposed to odorants in four replicated experimental treatments (1) conspecific lake sturgeon alarm cue and predator rock bass (Ambloplites rupestris) odors, (2) historically geographically separated round goby alarm cue and predator rock bass odors, (3) historically geographically co-distributed white sucker alarm cue and predator rock bass odors, or (4) predator rock bass odor only with distilled water as a negative control. Larval lake sturgeon survival was highest in experimental trials where lake sturgeon larvae had prior exposure to lake sturgeon alarm cue and rock bass predator odors. Survival rates for larval lake sturgeon from odor treatment groups exposed to geographically separated round goby alarm cue and groups exposed to geographically co-distributed white sucker alarm cue were significantly higher than those that were exposed to rock bass predator odor alone (with no conspecific or heterospecific prey odorant exposure). Results demonstrate that the presence of hetero-specific alarm cues can have considerable influence on survival and population levels of recruitment of taxonomically diverse stream prey communities during highly vulnerable early life stages. Management efforts designed to increase survival of numerically depressed species during critical early life stages may benefit from managing river ecosystems to promote high abundance and recruitment of co-distributed prey taxa.