Résumé
Because tropical tunas are known to aggregate around floating objects, it has been suggested that the large number of drifting fish aggregating devices (FADS) built and deployed by purse seiners could act as an 'ecological trap'. This hypothesis states that these networks of drifting FADS could take fish to areas where they would not normally go or retain them in places that they would otherwise leave. Because the ecological trap hypothesis was first advanced for drifting FADs, some have argued that only studies using drifting FADs can test this hypothesis. However, because working with drifting FADs is difficult, accepting this precept would preclude the scientific community from providing urgently needed information to organizations charged with management of fisheries that exploit drifting FADs. We argue that because both anchored and drifting FADs alter the natural environment, the more easily accessible anchored FADs can be used to test the ecological trap hypothesis. Also, based on a comparative scientific approach, we argue that understanding the behaviour of tunas around anchored FADs can improve our general understanding of tunas around all types of floating objects and help design new, well focused studies for drifting FADs. As anchored FADs are easier to access and offer a greater potential for research, we encourage scientists to design and conduct studies (in particular on the behaviour of fish at FADS) around the moored structures. (C) 2010 Published by Elsevier B.V.