Using electromyogram telemetry to study the spawning migration of sea lamprey (Petromyzon marinus L.)

Abstract

Laboratory and field experiments were conducted to assess activity patterns in adult sea lamprey (Petromyzon marinus L.) using electromyogram (EMG) telemetry. The good correlation between EMG values and sea lamprey activity levels observed during laboratory trials, allowed us to study in situ the behaviour of these animals during their spawning migration. Special attention was given to the sea lamprey activity patterns observed during the upstream migration when negotiating obstacles in specific reaches of the River Mondego, Portugal. High activity levels were usually associated with subsequent periods of low activity or rest periods. When swimming through stretches free from obstacles, the EMG values showed a constant pattern of activity. Intense activity peaks were frequently observed when lamprey negotiated difficult passage areas, less common during negotiation of smaller obstacles, and seldom recorded for stretches free from obstructions.