Common Carp Implanted with Prostaglandin F _2α Release a Sex Pheromone Complex that Attracts Conspecific Males in Both the Laboratory and Field

When ovulated, female fish of many species are known to release a F-prostaglandin-derived sex pheromone that attracts conspecific males. Recently, this pheromone was identified in the common carp as a mixture of prostaglandin F _2α (PGF _2α) and unidentified body metabolites, which we termed a 'pheromone complex'. The present study sought to test the activity of this pheromone complex in the field by developing a system using carps implanted with PGF _2α as pheromone donors. An initial experiment determined that osmotic pumps that delivered up to 0. 4 mg of PGF _2α per hour could be implanted into carp without any apparent effects on their health. A second experiment found that PGF _2α-implanted male and female carp released biologically relevant (and equivalent) quantities of PGF _2α, along with two of its seemingly inactive metabolites, for up to 2 weeks. Laboratory experiments demonstrated that the odor of PGF _2α-implanted carp was highly attractive to male conspecifics, and included necessary body metabolites; it attracted males as strongly as ovulated carp odor, and much better than PGF _2α alone. Finally, a field test demonstrated that PGF _2α-implanted female carp attracted mature male, but not female carp, from a distance of 20 m. This is the first demonstration of the activity of a PGF _2α-based pheromone in a natural environment and confirms the use of a PGF-pheromone complex in the carp. We suggest that the implant technique may be useful in future studies of how PGF pheromones function and could be further developed to attract invasive fish for use in control.