Applying Geostatistics to the Estimation of a Population of Bivalves

This case study was carried out on the measurements of the number and biomass of a certain type of bivalve, the spisule Spisula ovalis, which is found in the sand in shallow waters (in this case from 6 to 17m in depth) near the Ile d'Yeu on the Atlantic coast of France. The sampling procedure consisted of finding the limits of the sand bank and of estimating the overall biomass from random sampling using a Hamon grab.

The aim of this study is to show how geostatistics can be used to quantify the characteristics of the spatial distribution of the spisules and to estimate the total quantity. The geostatistical technique, kriging, was used to estimate the insitu reserves.

In addition to krigirig the variables, some more advanced geostatistical techniques including disjunctive kriging and conditional simulations were used to assess the recoverable reserves, that is, to estimate the quantity above a cutoff value.