摘要：River Neretva Estuary, located in the middle South-Eastern Adriatic coast, is a very important traditional fishery ground and biodiversity-rich ichthyologic area. Historically, the estuary situated in Croatia and Bosnia and Herzegovina was composed of wetlands, lakes, and lagoons, but in the 20th century, it was changed into a large agriculture area, settlements and port facilities. The major flow was channelled with large banks to prevent floods. All these activities enabled significant intrusion of seawater 20 km into the inland area. This led to the marinization of major flow freshwater ecosystems. This article presents data on summer fish migrations along with the major flow of River Neretva, during the May-September period. The temperature and salinity showed that seawater started to enter inland major flow from middle May up to the end of September. In total, the 1,429 fish individuals were caught. The numerically dominant species were Atherina boyeri (23.58%), Sardina pilchardus (21.62%), Sparus aurata (11.20%), Chelon ramada (8.19%) and Solea solea (7.63%). Dominant species in the total mass were: Chelon ramada (43.45%), Solea solea (14.27%), Sparus aurata (10.14%), Chelon aurata (7.66%) and Anguilla anguilla (3.75%). The major result of this study points to the fact that major Neretva flow of 20 km in length from the river mouth is under seasonal summer impact of seawater, which leads to salinization and complete marinization of this ecosystem during the warm period of the year. The marinization of the large Neretva flow area creates new nursery and feeding grounds for marine estuarine opportunist fish species, such as small pelagics European pilchard and anchovy, and also enlarge these grounds for the marine estuarine dependent species, such as grey mullets, sea breams, and flatfishes.
关键词：fish migrations; summer salinization; fish species composition; River Neretva estuary
