Changes in shell dimensions of pearl oysters, Pinctada mazatlanica (Hanley1856) and Pteria sterna (Gould 1851), during growth as criteria for Mabepearl implants

摘要

The relationship between the shell dimensions of pearl oysters, Pinctada mazatlanica (Hanley 1856) and Pteria sterna (Gould 1851), was studied to determine the possible change of form of the shell during growth. The intention was to determine the number, size and location of nuclei that could be implanted in oysters used for Mabe pearl production. Using the database of our Pearl Culture Research Programme developed in Bahia de La Paz, Mexico, we obtained measurements of 500 shells of P. mazatlanica and 500 shells of P. sterna, representing 3 years of continuous growth under extensive culture conditions. The height-length, height-thickness and the height-weight relationships of both species were analysed, as was the height-wing length relationship for P. sterna. There was isometric growth up to 100 mm shell height, and negative-allometric growth after 120-125 mm for P. mazatlanica. The height-thickness relationship followed a linear model, whereas the height-weight relationship was exponential. No clear allometric pattern was found in P. sterna and all relationships fitted the power equation.