This study is based on the populations of otter, Lutra lutra which is identified in Kızılırmak River and Delice River in Kırıkkale Province between March 2012 and April 2013. Otter is a nocturnal and semi-aquatic animal. Faeces analysis have shown that, fish, birds and mammals as vertebrates and crab, crayfish, snails and insect species as invertebrates are important in the diet of otter. The otter is an indicator species for the habitat that it lives. It was determined that otter was effected with water pollution orginated from industry and it was not found in regions where waste was mingled. In addition, the activities of sand and gravel quarries at rivers causes habitat loss and activity areas of otter is decreased. Dams built on the Kızılırmak River changes water regime and affects otter’s feeding behavior. This study revealed the existence of new otter localities. Lutra lutra must be protected within the framework of international and national legislations. Otter, which is a component of biodiversity, is among the priority species of conservation biology.