Tracking wakes: The nocturnal predatory strategy of piscivorous catfish

Swimming fish leave wakes containing hydrodynamic and chemical traces. Thes e traces mark their swim paths and could guide predators. We now show that nocturnal European catfish (Silurus glanis) locate a piscine prey (guppy. P oecilia reticulate) by accurately tracking its three-dimensional swim path before an attack in the absence of visible light. Wakes that were up to 10 s old were followed over distances up to 55 prey-body lengths in our setup. These results demonstrate that prey wakes remain sufficiently identifiable to guide predators, and to extend considerably the area in which prey is d etectable. Moreover, wakes elicit re ar attacks, which may be more difficul t to detect by prey. Wake tracking may be a common strategy among aquatic p redators.