Abundance Of Seamounts In The Azores And Their Effect On Aggregating Visiting Species

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It has been suggested that seamounts hold higher abundances of some “visiting” animals, such as tuna, sharks, billfishes, marine mammals, sea-turtles and even seabirds, but this has been based on sparse records, warranting further examination. In this paper we (1) characterized the seamount distribution of the Economic Exclusive Zone of the Azores and (2) examine whether the predicted higher abundances of tuna, marine mammals, sea turtles and seabirds actually occur around those mapped seamounts. Our algorithm showed that peaks and seamounts are common features in this region of the North Atlantic. Sixty three large and 398 small seamount-like features are mapped and described in the Azorean EEZ. Our results indicate that some marine predators (skipjack and bigeye tuna, common dolphin and Cory's shearwater) were significantly more abundant in the vicinity of some mapped shallow-water seamount summits. Our methodology, however, failed to demonstrate a seamount association for bottlenose dolphins, spotted dolphin, sperm whale, terns, yellow-legged gull, and loggerhead sea turtles. Not all seamounts, however, seemed to be equally important for these associations. Only seamounts shallower than 400 m depth showed significant aggregation effects. These seamounts may be considered hotspots of marine life in the Azores and a special effort should be made in order to ensure a sustainable management of these habitats. This paper describes the major findings of Morato et al. (2008a, b).