Abstract

In the present work the assemblages of fish in the coastal system of Ría Lagartos were determined in relation to the different present types of habitat in the system. In order to fulfill this objective fish populations were sampled throughout a network of 31 stations during almost a year. A total of 13,015 organisms with a weight of 136 kg was collected of which, a total of 78 fish species was identified, distributed in 56 orders and 36 families being the month of April the one that presented/displayed greatest richness with 52 species. The most abundant species in number were Cyprinodon artifrons and Floridichthys polyommus which represents 42.2%. As far as biomass, Sphoeroides testudineus represented 55.2% of the total. Spatially, the stations of the mouth and one of the internal zones were those that contributed greatest density of organisms; whereas the stations located between Ría Lagartos and Las Coloradas were those that contributed greater biomass. The richness of species was greater in the stations located in the channel and the marine zone. According to the Index of Value of Importance (IVI) the dominant species were S. testudineus, F. polyommus, C. artifrons, Eucinostomus argenteus and three species more to make up more then 65%. Five habitats on the basis of temperature, salinity, dissolved oxygen, richness and biomass in dry weight of the marine grass were discriminated: Cuyo, Coloradas est, Coloradas west, Channel, and Marine. Significant differences were found among the five habitats.

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