The identification of suitable habitat and hotspot areas for cetaceans are increasingly urgent to inform decision makers on spatial management plans and to tackle anthropogenic threats and global changes. Little or no survey effort has been carried out so far in offshore waters of the Canary Basin (NE Atlantic Ocean) where most of protected areas are coastal or islands areas. As a consequence, there is a lack of data on distribution of many sensitive pelagic species. This is particularly the case of beaked whales. In order to fill this gap, 48 sea-surveys along fixed transects between Continental Portugal and Madeira Island were performed in 2012 and 2013, from July to October. We used GAMs to identify the role of environmental variables in shaping cetacean distribution. Then we built an Environmental Envelope model to map and predict species hotspots in the region.Results show the richness of offshore waters: in a total of 10636nm sampled, we recorded 234 sightings accounting for at least 9 cetacean species. GAM results highlight the importance of seamounts for all species, though habitat segregation occurs among groups. We recorded 28 sightings of beaked whales, all within a distance of 40nm from the base of the seamounts. Moreover, beaked whales were always sighted further than 55nm from the coast and 50% of the sightings were between 180nm to 240nm from the coast, with a median depth of about 4300m, proving the importance of sampling offshore waters. Maps produced by the Environmental Envelop model highlight that hotspots for beaked whales were also described by dynamic variables, in particular by the presence of productive mesoscale eddies.Considering ACCOBAMS priorities and EEZ extension for the area, and the urgent need for management plans, we suggest maintaining these sea-surveys to improve habitat modelling and cetacean occurrence prediction.

Identification of suitable habitats for cetaceans in the Canary Basin, NE Atlantic Ocean: evidences of hot-spots for beaked whales

TEPSICH, PAOLA;
2014

Abstract

The identification of suitable habitat and hotspot areas for cetaceans are increasingly urgent to inform decision makers on spatial management plans and to tackle anthropogenic threats and global changes. Little or no survey effort has been carried out so far in offshore waters of the Canary Basin (NE Atlantic Ocean) where most of protected areas are coastal or islands areas. As a consequence, there is a lack of data on distribution of many sensitive pelagic species. This is particularly the case of beaked whales. In order to fill this gap, 48 sea-surveys along fixed transects between Continental Portugal and Madeira Island were performed in 2012 and 2013, from July to October. We used GAMs to identify the role of environmental variables in shaping cetacean distribution. Then we built an Environmental Envelope model to map and predict species hotspots in the region.Results show the richness of offshore waters: in a total of 10636nm sampled, we recorded 234 sightings accounting for at least 9 cetacean species. GAM results highlight the importance of seamounts for all species, though habitat segregation occurs among groups. We recorded 28 sightings of beaked whales, all within a distance of 40nm from the base of the seamounts. Moreover, beaked whales were always sighted further than 55nm from the coast and 50% of the sightings were between 180nm to 240nm from the coast, with a median depth of about 4300m, proving the importance of sampling offshore waters. Maps produced by the Environmental Envelop model highlight that hotspots for beaked whales were also described by dynamic variables, in particular by the presence of productive mesoscale eddies.Considering ACCOBAMS priorities and EEZ extension for the area, and the urgent need for management plans, we suggest maintaining these sea-surveys to improve habitat modelling and cetacean occurrence prediction.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11567/790864
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