Cormoran: explain how the pike attractant Double Fish works

As typical microsmatic visually guided fish, pike, Esox lucius, and other representatives of Esox genus do not respond to food odors (Devitsyna & Malyukina, 1977). Pike larvae decrease the frequency of attacks on zooplankton prey and show other anti-predator responses on chemical cues of Eurasian perch, Perca fluviatilis (Lehtiniemi, 2005; Lehtiniemi et al., 2005). Chemical cues of perch (water from under adult predators, 15 cm length, fed on pike larvae until experiments) affect alone, but chemical and visual cues offered together are more effective. Among pheromones, pike are respond to the conspecific sexual pheromone (Devitsyna & Malyukina, 1977). Furthermore, it is shown that pike are attracted by alarm pheromone of fathead minnow, Pimephales promelas (Mathis et al., 1995; Chivers et al., 1996; indirect data by Wisenden & Thiel, 2001). In addition, pike demonstrate distinct foraging responses to artificial hypoxanthin-3(N)-oxide (Mathis et al., 1995) identified as an active component of ostariophysan fish alarm pheromones. On this background, Daiwa Cormoran Co., Germany, offers the pike attractant Double Fish. The exact composition of this attractant is unknown. As feeding attractant (with food extracts, amino acids and related chemicals), it cannot work. Nothing is known whether pheromones are included. Basic References Chivers D.P., Brown G.E., Smith R.J.F. 1996. The evolution of chemical alarm signals: attracting predators benefits alarm signal senders. The American Naturalist 148, 649-659 Devitsyna G.V., Malyukina G.A. 1977. On the functional organization of the olfactory organ in macro- and microsmatic fishes. Journal of Ichthyology 17, 493-502 Lehtiniemi M. 2005. Swim or hide: predator cues cause species specific reactions in young fish larvae. Journal of Fish Biology 66, 1285–1299 Lehtiniemi M., Engström-Öst J., Viitasalo M. 2005. Turbidity decreases anti-predator behaviour in pike larvae (Esox lucius). Environmental Biology of Fishes 37, 1-8 Mathis A., Chivers D.P., Smith R.J.F. 1995. Chemical alarm signals: predator detterents or predator attractants? The American Naturalist 145, 994-1005 Wisenden B.D., Thiel T.A. 2001. Field verification of predator attraction to minnow alarm substance. Journal of Chemical Ecology 28, 417-422