Some Behavioral Interactions of Spottail Shiners (Notropis hudsonius), Yellow Perch (Perca flavescens), and Northern Pike (Esox lucius)

Abstract

Dense schools of spottail shiners (Notropis hudsonius) are common in shallow water in Beaver Lake, generally 0.25–0.30 m below the surface, with smaller individuals more numerous towards the top. Position in the shcool is maintained by short radius behavior. The course of an individual is maintained by a beat of the tail, a glide, a hesitation, and a change of direction. Each glide path represents the chord of an arc of short radius about some neighbor. Shiners respond to disturbance by flash expansion of loose cruising association. Schooling is obligatory. The black caudal spot is probaly multifunctional as a recognition mark and releaser.Yellow perch (Perca flavescens) show an ontogeny of behavior through young-of-the-year, aggregation-sized perch (aggp), subadults, and adults. They behave as individuals or associate as streams. Disturbance will cause a group of aggp to disperse or to stream. The adult manifestation of streaming is pack-hunting. The activity of one perch attracts the attention of others; this leads to streaming or pack-hunting. Pack-hunting improves the chance of some members of the pack, not necessarily the initiator, capturing active prey, by countering the allaesthetic protean escape reactions of organisms such as the spottail shiner. Large mixed aggregations of spottail shiners and aggp are fortuitous.Northern pike (Esox lucius) are lone, opportunistic predators whose hunting technique combines in sequence motionlessness, axial tracking, and lunging. Prey may be swallowed head- or tailfirst, or sideways.The species studied here show a range of gregariousness, from the solitary pike, through the facultative nonpolarized and polarized schools of perch, to obligate nonpolarized and polarized schools of shiners.