Journal of Fish Biology (2011) 78, 1944–1953 doi:10.1111/j.1095-8649.2011.02964.x, available online at wileyonlinelibrary.com Round goby Neogobius melanostomus attraction to conspecific and heterospecific egg odours S. Yavno* and L. D. Corkum Department of Biological Sciences, University of Windsor, Windsor, Ontario, N9B 3P4 Canada (Received 14 September 2010, Accepted 23 February 2011) In this study, cannibalistic and predatory responses of juvenile Neogobius melanostomus (either fed or deprived of food and caught during the reproductive summer or non-reproductive winter season) to water washings of fertilized eggs from conspecifics (N. melanostomus ), heterospecifics (rainbow trout Oncorhynchus mykiss ) and control lake water were tested. Fed juveniles (summer season) spent significantly more time on the side of the flume containing stimuli from conspe- cific eggs over control water, while significantly preferring control water to heterospecific stim- uli. In addition, fish showed a significant preference towards stimuli from conspecific eggs over heterospecific stimuli by associating near conspecific egg odours 1·5 times longer [Correction added after online publication 28 April 2011, text changed]. Fish that were deprived of food, regardless of whether caught during the summer or winter season, did not show any prefer- ence towards either conspecific or heterospecific stimuli. These findings show that conspecific egg odours attract fed juveniles and that there is a potential to lure fish to odour traps as a means of control.  2011 The Authors Journal of Fish Biology  2011 The Fisheries Society of the British Isles Key words: food limitation; invasive fish; non-kin intercohort cannibalism; rainbow trout. INTRODUCTION Food availability in an aquatic environment can have a significant effect on the behaviour of fishes. When the density of a population increases, food can become scarce, which leads to high levels of intraspecific competition among individuals (Elgar & Crepsi, 1992) [Correction added after online publication 28 April 2011, text changed]. In such cases, cannibalism may be an adaptive behavioural response wherein fish prey on conspecifics to survive (Wootton, 1971; Amundsen, 1994). Rather than consuming fully developed fry, eggs and embryos are usually eaten (i.e. non-kin intercohort cannibalism) because they are easier to handle (Smith & Reay, 1991; Acha et al., 2002). In fact, freshwater fishes from several taxa con- sume eggs (through cannibalism or otherwise) (Roseman et al., 2006; Frommen et al., 2007; Johnson et al., 2009a). Some species guard their nests to increase offspring survival (Cheney, 2008), but eggs are still lost to conspecifics because individuals are usually in very close proximity to one another (e.g. in a colony) ∗Author to whom correspondence should be addressed at present address: Environmental & Life Sciences, Trent University, 1600 West Bank Drive, Peterborough, Ontario, K9J 7B8 Canada. Tel.: +1 705 748 1011 ext. 7256; email: stanyavno@trentu.ca 1944  2011 The Authors Journal of Fish Biology  2011 The Fisheries Society of the British Isles