Changes in the distribution density of locate, Thaisella chocolata (Duclos, 1832) (Gastropoda, Thaididae) as an indicator for predicting their reproductive events

Abstract

For a population of locate, Thaisella chocolata, in La Rinconada, Chile, on a grid of 39 stations distributed along three 910 m-long transects at depths of 5 to 18.5 m, Moran and Morisita indices were used to evaluate whether density variations along the depth distribution are related to the stratification of larger sizes at the beginning of their reproductive process. Results indicate that before, during, and after forming reproductive aggregations, there is a T. chocolata increase in density in the shallow stratum (5 to 13 m). This finding is corroborated by the Moran index, which showed a greater autocorrelation in January-May, September-October, and January 2010, and by the Morisita index; thus, it is validated as a potentially easy-to-use indicator for assessing the reproductive process of this species. This index could also alert fishermen to the prevalence of reproductive aggregations in an area and that these aggregations should not be exploited as is currently the case to ensure the reproductive success of this species.