Growth and natural mortality of Diadema mexicanum A. Agassiz, 1863, from west-central Mexico

Abstract

Abstract: Population parameters of Diadema mexicanum have not yet been studied; therefore, the objective of this work was to describe, for the first time, the growth and mortality by age of this sea urchin. The growth curve was determined by applying a modal progression analysis of the length-frequency distribution sample to determine the number of cohorts present through multinomial statistics based on a probability function. The cohort that was best represented over time was then used to fit von Bertalanffy’s stationary growth model. Empirical methods were used to estimate the natural mortality and natural mortality-at-age rates. Results indicate that this species presents a negative allometric curve with the following parameters: a = 1.57 ± 0.18, b = 2.23 ± 0.07. The growth parameters were L∞ = 9.47 cm, k = 0.46 year-1, t0 = -0.1 years, C = 1.00, and ts = 0.26. The average natural mortality observed in juveniles was Mtjuv = 2.52 year-1 (8% survival per year) and in adults, Mtadu = 1.92 year-1 (15% survival per year). These results represent a contribution to understanding the life history traits of Diadema mexicanum in Mexico’s Pacific region.