Point pattern analysis as a tool for assessing disease spread and population features in remaining sanctuaries of the critically endangered bivalve Pinna nobilis

•A total of 2,697 live individuals were marked in the total of 14 Ha evaluated.•No recent mortality, large adults among empty shells (97.3%), and few juveniles (3.2%).•Low scale aggregation with no clear evidence for habitat or conspecific selection.•Enhanced empty shells’ aggregation suggest a former outbreak in the Trabucador site.•New tool for assessing overall population condition at different times scales.