Population Parameters of Chama coralloides (Bivalvia: Chamidae) in the Rocky Intertidal of the South-Central Mexican Transitional Pacific

Abstract

The density, dispersion, size, growth, longevity, natural mortality, and recruitment of Chama coralloides Reeve, 1846, a bivalve captured in artisanal fisheries, were studied. Sample collection was carried out in November 2016, March 2017, and February 2018 at eight sites in the rocky intertidal zone, located in the south-central region of the Mexican Transitional Pacific. Using a 1 x 1 m quadrat, 10 random quadrats were conducted at each site. Density was determined with Pennington's method of Δ distribution. The dispersion was estimated with the Morisita index and modal groups with multinomial analysis. Growth, natural mortality, and recruitment parameters were estimated with FiSAT II. Variable density between sampling dates and sites was observed, with the highest densities found at sites 1 and 4. The largest interquartile range of lengths was observed at site 6, and the smallest at site 5. Five modal groups were determined in November 2016 and March 2017, and four in February 2018. Estimated growth parameters were L ∞= 74.5 mm and K= 0.63; longevity was A .95 = 4.4 and A .99= 6.9 years, growth performance index ∅′= 3.5 and natural mortality M = 1.05 yr–1. Continuous recruitment was observed with a maximum peak in summer.