Cetaceans living in offshore waters are under increasing pressure from anthropogenic activities. Yet, due to the lack of survey effort, relatively little is known about the demography or ecology of these populations. Spatial and temporal distribution of cetaceans in mid-Atlantic waters were investigated using a long term dataset collected from boat surveys and land-based observations around the Azores. From 1999 to 2009, 7307 cetacean schools were sighted during 271717 km of survey effort. In 4944 h of land-based observations, 2968 cetacean groups were detected. Twenty-four species were recorded: seven baleen whales, six beaked whales, eight dolphin species, Physeter macrocephalus, Kogia breviceps and K. sima. Overall, Delphinus delphis was the most frequently sighted species but its encounter rate decreased in JuneNovember, coinciding with presence of Stenella frontalis in the region. Tursiops truncatus, P. macrocephalus and Grampus griseus were frequently encountered yearround, whereas large baleen whales showed a distinct peak in encounter rates in March-May. Mesoplodonts were fairly common and appear to be present throughout the year. These findings fill-in a significant gap in the knowledge of cetaceans occurring in a poorly studied region of the North Atlantic, providing much needed data to inform management initiatives.

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, and warrants further examination. In this paper we use data from a fishery observer program to examine whether the predicted higher abundances of tuna, marine mammals, sea turtles and seabirds actually occur around Azores seamounts and to map the distribution of the various species. Our results indicate that some marine predators (skipjack Katsuwonus pelamis and bigeye tuna Thunnus obesus, common dolphin Delphinus delphis and Cory's shearwater Calonectris diomedea borealis) were significantly more abundant in the vicinity of some shallowwater seamount summits. Our methodology, however, failed to demonstrate a seamount association for bottlenose dolphins Tursiops truncatus, spotted dolphin Stenella frontalis, sperm whale Physeter macrocephalus, terns Sterna hirundo and S. dougalli, yellow-legged gull Larus cachinnans atlantis and loggerhead sea turtles Caretta caretta. Seamounts may act as feeding stations for some of these visitors. 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.

Marine spatial planning and ecological research call for high-resolution species distribution data. However, those data are still not available for most marine large vertebrates. The dynamic nature of oceanographic processes and the wide-ranging behavior of many marine vertebrates create further difficulties, as distribution data must incorporate both the spatial and temporal dimensions. Cetaceans play an essential role in structuring and maintaining marine ecosystems and face increasing threats from human activities. The Azores holds a high diversity of cetaceans but the information about spatial and temporal patterns of distribution for this marine megafauna group in the region is still very limited. To tackle this issue, we created monthly predictive cetacean distribution maps for spring and summer months, using data collected by the Azores Fisheries Observer Programme between 2004 and 2009. We then combined the individual predictive maps to obtain species richness maps for the same period. Our results reflect a great heterogeneity in distribution among species and within species among different months. This heterogeneity reflects a contrasting influence of oceanographic processes on the distribution of cetacean species. However, some persistent areas of increased species richness could also be identified from our results. We argue that policies aimed at effectively protecting cetaceans and their habitats must include the principle of dynamic ocean management coupled with other area-based management such as marine spatial planning.

We characterized the seamount distribution of the economic exclusive zone (EEZ) of the Azores (Portugal) using 2 bathymetry datasets. Our algorithm showed that peaks and seamounts are common features in this region of the North Atlantic. The density obtained of 3.3 peaks of all sizes per 1000 km 2 is in the same order of magnitude as that obtained on the Mid-Atlantic Ridge by a few other studies. A total of 63 large and 398 small seamount-like features are mapped and described in the Azorean EEZ. Our distribution of seamounts predicts that about 57% of the potential Azores seamounts lie in the zone protected from MATERIALS AND METHODSIn the present study, seamounts are defined as any topographically distinct seafloor feature that is at least 200 m higher than the surrounding seafloor, but which does not break the sea surface. We classify seamounts as being large or small, depending on whether the height exceeds 1000 m (regardless of depth). This height separation is useful in isolating large seamounts, the global distribution of which is well resolved by satellite altimetry, from small seamounts, the distribution of which can only be derived from less encompassing local acoustic mapping.An automated methodology adapted from Kitchingman et al. (2007) was used to identify topographic structures with high probability of being seamounts. Two bathymetric datasets with different resolutions were used as the topographic bases.The MOMAR (monitoring the Mid-Atlantic Ridge) mesoscale bathymetric map (Lourenço et al. 1998; www.ipgp.jussieu.fr/rech/lgm/MOMAR/Data/Plateau _bathy.grd) was the finest scale bathymetrical grid available for the Azores region at the date of the analysis (February 2006) and was used for the area constrained by the parallels 36°and 41°N and the meridians 24°and 32°W. This dataset is supplied at a 1 min cell resolution, thus allowing a reasonable scale at which to perform an analysis for large seamountlike features. The 'global seafloor topography from satellite altimetry and ship depth soundings' database (Smith & Sandwell 1997; http://topex.ucsd.edu/sandwell/sandwell.html) at a 2 min cell resolution was used as the bathymetry dataset for the remaining area. The version used still contained some artefacts, such as a spurious deep trough in the NE region of the study area.The methodology followed 3 succeeding steps run on a cell-by-cell analysis over the bathymetric grids:(1) identifying all detectable peaks in the bathymetry dataset with the Environmental Systems Research Institute (ESRI) ArcGIS software flow direction and sink algorithms (www.esri.com), (2) isolating peaks with heights > 200 m above surrounding seafloor and displaying an approximately circular or elliptical shape and (3) isolating large seamount-like features (height >1000 m). The datasets produced after Step 1 will be called the 'peaks dataset', while the dataset produced after Step 3 will be used as the 'Azores seamount dataset'. The dataset produced after Step 2 minus that produced after Step 3 will be called the 's...