Using Conspecific Alarm Cues to Manipulate Sea Lamprey Migrations

Control of the invasive sea lamprey (Petromyzon marinus) in the Laurentian Great Lakes relies on physical and electrical barriers to limit the distribution of spawning adults and lampricides to dispatch their stream-dwelling progeny. The ability to direct lamprey habitat selection could dramatically increase the efficiency of current management practices. Migratory sea lampreys avoided the area of a laboratory raceway treated with a dilute concentration of conspecific alarm cues.  However, animal behavior is context dependent, often yielding contrasting field and laboratory results. Therefore, we aimed to determine whether migrating lampreys use the presence of conspecific alarm cues to select spawning habitat within a stream. We extracted the semiochemicals from dead sea lamprey carcasses via soxhlet extraction. At sunset, we released groups of migratory phase sea lampreys downstream of a river confluence and monitored their movement using passive integrated transponder (PIT) antennas. We activated one channel with sea lamprey alarm cues at a concentration of 1 000 000:1 (alarm cue: stream water) and hypothesized that lampreys will select the channel lacking the alarm cue. Less than 1 % of lampreys entered the channel receiving the alarm cue. These results demonstrate that these semiochemicals can be used to direct the migration of sea lampreys.