Behavioural responses of female round gobies (\u3ci\u3eNeogobius melanostomus\u3c/i\u3e) to putative steroidal pheromones

Although reproductive (RF) and non-reproductive (NRF) female round goby are attracted to washings of conspecific reproductive males and RF, respectively, behavioural responses of females to synthesized steroids has not been studied. We tested attraction and avoidance of RF and NRF to different blends of steroids previously shown to be either produced by reproductive males and/or detectable at a concentration of at least 10–8 M by the olfactory epithelium of RF. Three blends of steroids were used, including: etiocholanolone (3α-hydroxy-5β-androstan-17-one), 11-oxo-etiocholanolone (3α-hydroxy-5β-androstane-11,17-dione), androstenedione, 11β-hydroxy-androstenedione, and 11-ketotestosterone (‘free’ steroid blend); etiocholanolone glucuronide, etiocholanolone sulfate, 11-oxo-etiocholanolone glucuronide and 11-oxo-etiocholanolone sulfate (‘conjugated’ steroid blend); and all nine steroids together (‘total’ steroid blend). NRF were attracted to the free steroid blend and avoided the conjugated blend. RF did not reveal any significant bias to the steroid blends, but there was a tendency for RF to prefer conjugated steroids and avoid free steroids. Because there was no significant attraction by RF to particular blends of synthesized steroids tested, other compounds (sex attractants) not yet identified from the male round goby are likely responsible for initiating courtship and/or spawning behaviours in reproductive females