Bull. Jpn. Soc. Fish. Oceanogr. 78(2), Page 75-85, 2014   Growth characteristics and reproductive biology of three sympatric Acentrogobius (Perciformes: Gobiidae) species in Maizuru Bay, Kyoto Prefecture Shoko Matsui1†, Masahiro Ueno2 and Yoh Yamashita1 1 Field Science Education and Research Center, Kyoto University, Kitashirakawa Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan 2 Maizuru Fisheries Research Station, Field Science Education and Research Center, Kyoto University, Nagahama, Maizuru, Kyoto 625-0086, Japan † E-mail: shom@kais.kyoto-u.ac.jp Three gobiid fishes, Acentrogobius sp. (Japanese name: Tsumaguro-sujihaze), A. virgatulus (Sujihaze), and A. pflaumii (Moyou-haze), are widely distributed around the Japanese archipelago, and are important food resources for many coastal fishes, including several commercial species. Despite their importance, little information has been reported on their life history traits, mainly because they were recognized as a single species “A. pflaumii” until recently. To elucidate and compare the growth characteristics and reproductive biology of the three species, we collected specimens of the three species at the same site in Maizuru Bay (one of the sub-basins of Wakasa Bay, in the Sea of Japan) every week (during the spawning season) or every month (during the non-spawning season) from 2009 to 2010. We estimated the growth characteristics and reproductive biology including life span, spawning season, pelagic larval duration, at maturing size, and spawning times, based largely on seasonal changes in length composition, gonadosomatic index (GSI), egg size, and numbers of eggs in the ovaries. The three species were found to have a similar life span (1-2 years) and pelagic larval duration (about two months), but a different spawning season (earliest and longest in A. pflaumii) and at maturing size (smallest in A. pflaumii). By comparing their reproductive traits with their distribution characteristics, we discuss the adaptive significance of the three species. Several reproductive traits of A. pflaumii (such as longer breeding season and smaller size at maturity than the other two species) may be associated with its distribution being farther offshore; larvae hatching at sites farther offshore would likely disperse more widely and experience more varied environments, and their mortality rate would probably be higher during the pelagic larval stage and at the settlement stage. Key words: Acentrogobius sp., A. virgatulus, A. pflaumii, life history, habitat