Mating Pheromone Reception and Induced Behavior in Ovulating Female Sea Lampreys

Abstract

This study was conducted to determine how ovulating female sea lampreys Petromyzon marinus respond to water conditioned with spermiating males (spermiating male washings) and how trap efficiency can be improved through their use. The capture rate of ovulating female sea lampreys was observed in traps baited with continuous or pulsed spermiating male washings. The behavior of ovulating females around baited traps was quantified. Within 2 h, traps baited with continuous spermiating male washings captured 52% of ovulating females (n = 27) and traps baited with pulsed washings captured 28% (n = 25) of ovulating females. Unbaited traps did not capture ovulating females. The behavior of females near traps baited with pulsed spermiating male washings was characterized by significantly more downstream and side-stream movements than that of females near traps with continuous washings. We occluded the olfactory organ of ovulating females and tested whether they were attracted to spermiating male washings in a two-choice maze and whether they could locate spermiating males in a spawning stream. Ovulating females with occluded olfactory organs were unable to locate spermiating males in a spawning stream. Furthermore, anosmic females were not attracted to spermiating male washings in a two-choice maze. We conclude that traps baited with spermiating male washings are able to capture females and that females may use the structure of the pheromone plume to locate the exact source of pheromones. It is likely that olfaction is the only means for ovulating females to detect a pheromone that is released by spermiating males.