ASSESSING THE POPULATION-SIZE OF THE EUROPEAN STORM-PETREL (HYDROBATES PELAGICUS) USING SPATIAL AUTOCORRELATION BETWEEN COUNTS FROM SEGMENTS OF CRISSCROSS SHIP TRANSECTS

European storm petrels were counted on criss-cross ship transects on t he continental shelf between Ireland and Spain. No element of randomis ation was involved in the selection of the sampled area. A geostatisti cal model which explicitly considers the spatial autocorrelation betwe en observations from transect segments, was therefore used to predict population size in the study area. The model also provides standard er rors of the prediction. Although some of the underlying assumptions of the model were questionable, several alternative approaches yielded a lmost similar predictions, suggesting model robustness. The prediction of the total number of European storm petrels present in the study ar ea is equivalent to 255 000 breeding pairs. This is much higher than p revious estimates of the total breeding population of the region, rang ing from 50 000 to 100 000 pairs. (C) 1995 International Council for t he Exploration of the Sea