Habitat use and diet composition of invasive smallmouth bass, Micropterus dolomieu, Japanese dace, Pseudaspius hakonensis, and pale chub, Opsariichthys platypus, were studied for two years in the Middle Chikuma River, Nagano, Japan. Habitat use of dace and chub overlapped both years but showed differences from smallmouth bass. Additionally, smallmouth bass habitat use differed greatly between years, as young smallmouth bass were found in uncharacteristically fast flowing habitat in 2018 and predominantly in more typical slow flowing habitat in 2019. This use of fast flowing habitat in 2018 appears to be influenced by the high overall fish density, especially for smallmouth bass. Diet composition, studied in 2018, overlapped significantly between the three species in riffle habitat and overlap became less significant in run and pool habitat where smallmouth bass fed increasingly on fish prey. We therefore suggest that the interactions between smallmouth bass and dace and chub shift from predominantly predation in slow flowing habitat to resource competition in faster flowing habitat.

栖息地使用和侵入性小口黑鲈，饮食组成Micropterus的Dolomieu，日本鲮，Pseudaspius hakonensis，和苍白鲐，马口鱼鸭嘴兽在日本长野县的筑波中川进行了为期两年的研究。栖息地使用da和and的做法在两年中有所重叠，但与小嘴鲈鱼有所不同。此外，不同年份之间小口鲈的栖息地使用也有很大不同，因为年轻的小口鲈在2018年出现在异常快速流动的栖息地中，主要在2019年出现在更典型的缓慢流动的栖息地中。2018年这种快速流动的栖息地的使用似乎受到高潮的影响。鱼的总体密度，特别是小嘴鲈鱼。在2018年进行的研究中，日粮的组成在浅滩栖息地中的三个物种之间显着重叠，而在小口鲈鱼越来越多地以鱼为食的奔跑和泳池栖息地中，重叠的重要性降低。