Freshwater fishes in Bahía Ballena and Puerto Cortés, Osa, Costa Rica

Abstract

In order to know the diversity of freshwater fish, its structure and taxonomic composition in rivers near the coast in Bahía Ballena and Puerto Cortés in the southern Pacific of Costa Rica were determined. Through electric fishing, 162 individuals belonging to 12 species and 7 families were collected in four sampling stations. The minimum size (standard length, LS) corresponded to an individual of Sicydium salvini in the Morete River (1.70 mm). The maximum size corresponded to an individual of the species Awaous transandeanus in the Coronado River (22.60 mm). Five species were dominant with 86.42% of total catches. Both the Coronado River and the Ballena Creek recorded 8 species, the Morete 6 River, while the Tortuga River recorded 7 species. The largest number of individuals were collected in the Coronado River (n=53), followed by Quebrada Ballena (n=41), the Morete or Higuerón River (n=35), while the lowest number of individuals was recorded in the river Turtle (n=33). The replacement of species between sites can be considered high, registering the sharing in taxonomic assemblies between sites between 76.31% (Ballena stream and Morete river), these two sites being the most similar and 35.29% (Morete river and Tortuga river). The alpha diversity by sampling sites was low, the highest being recorded in the Tortuga River (H´=1.81), while the lowest was recorded in the Morete River (H´=1.19). In general, the ichthydiversity of these rivers, and in this region is relatively homogeneous, with dominance of secondary estuarine (peripheral) and freshwater fish species.