Variation of Density and Biomass of the Ichthyofauna Associated to Soft Bottoms of a Western Coastal Lagoon of B.C.S., Mexico

Abstract

An analysis of the variation of the density and biomass of the fish communities of the lagoon of La Paz, Mexico was carried out from November 2016 to September 2017. A total of 2763 organisms were collected with a total biomass of 211,422.93 g in an area of 5022 m 2 , a density and biomass of 0.550 lnd/m 2 and 44.091 g/m 2 . The site with the largest biomass was recorded in Zacatecas (11.179 g/m 2 ) located north of the lagoon, while Grand Plaza recorded the lowest biomass (2.732 g/m 2 ). Regarding the density, the maximum value was recorded in the site Yate Hundido, located northwest of the lagoon (0.129 lnd/m 2 ) and the lowest was Las Palmas (0.036 lnd/m 2 ) located north of the lagoon. The most abundant species was Diapterus peruvianus with 683 individuals and a biomass of 37,507.57 g. The physicochemical variables showed two seasons with significant change where we can observe higher temperatures in the summer (average of 27.45 ° C) and minimum in winter (average of 22.49 ° C). The Shannon-Weaver diversity index showed a difference ( p = 0.050) between months, with the highest value recorded in April ( H ' = 2.133 bits/ind) and the lowest in June ( H ' = 1.041 bits/ind). The biomass and density values recorded in the lagoon were found to be associated with the spatio-temporal variation of temperature of the lagoon, as well as the resident and transitory species located in the area of study. In addition, the body sizes recorded corresponded to juvenile and young adult individuals.