Reproductive female round gobies (Neogobius melanostomus) are attracted to visual male models at a nest rather than to olfactory stimuli in urine of reproductive males

Fish are known to communicate in many ways and commonly use olfactory and visual signals. When round goby (Neogobius melanostomus) males become reproductive, they change from mottled grey to black and release sex steroids in their urine. In this study, we conducted a laboratory experiment to determine if reproductive female round gobies were attracted to a combination of olfactory (urine) and visual (silicone models) stimuli, representing reproductive and non-reproductive male round gobies. Females spent significantly more time at a nest with a black reproductive male model compared with a mottled non-reproductive male model. Neither urine type nor the interaction between model type and urine affected the time spent by reproductive females at a nest. Knowledge of the reproductive habits of the round goby may enable researchers to develop a method of species control for this invasive fish by manipulating its breeding habits.