Invasive Silver Carp Detect a Unique Range of Steroids and F-Type Prostaglandins That Likely Function as Sex Pheromones

Since its introduction forty years ago in Arkansas, the silver carp, Hypophthalmichthys molitrix, has been steadily advancing northward while destroying vast areas of river habitat whose biomass it comes to dominate. Because of its elusive nature, monitoring presence and movement of this fish is extremely difficult. Pheromones, chemical signals that pass between conspecifics, play essential roles in carp social behavior and are presently being used to sample and remove adult common carp, Cyprinus carpio. This species, like most fishes, uses unique complexes of hormone-derived products as sex pheromones. This study explored this possibility in the silver carp by examining its sensitivity to over 200 steroid hormones and F prostaglandins (PGFs). We discovered that the silver carp olfactory system detects a unique combination of 9 sex steroids and 3 PGFs at picomolar concentrations with high specificity and the sensitivity of masculinized fish to PGFs is especially pronounced.  Behavioral tests also find that masculinized carp are attracted to PGFs. Future studies are planned to examine how these putative sex pheromones function as part of odorous complexes and might be used to attract carp in the field so that they (or their waters) might be reliably sampled (Funded by the USGS).