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Cañón de Avilés - May and June Campaign - CEMMA
The “Cañón de Avilés I” expedition carried out by CEMMA took place between May 30th and June 6th 2011 on board the Gran Bahía II catamaran.
On this expedition, CEMMA observers took a sampling of cetaceans and seabirds in both the Cañón de Avilés area of study and three adjacent subareas.
Two observation posts were established for the sampling of cetaceans in order to properly approach the sweeps of the sea surface in search of cetaceans. One data collection post was also established where one person took down pertinent data including information on the vessels’ location and the sea conditions.
When species to be tracked by photo-identification were sighted, such as the bottlenose dolphin and long finned pilot whales, the vessel would approach the group of cetaceans in such a way as to disturb them as little as possible and take photographs of their dorsal fins. Depending on these fins’ individual characteristics, studies can be done and comparisons made to those photo-identified in the waters off the coast of Galicia.
For other species for which this type of photo-identification is not possible, a sighting sheet must be filled out where the observer notes down general information (date, time, GPS waypoint, position, depth, course, and speed of the vessel) as well as other pertinent data at the time of sighting (type of detection, distance between the cetaceans, photographical and/or acoustic records of the species, and so forth).
A total of 13 sightings of cetaceans took place, including individuals from the following species: bottlenose dolphins (Tursiops truncatus), long-finned pilot whales (Globicephala melas), goose-beaked whales (Ziphius cavirostris), striped dolphins (Stenella coeruleoalba), common dolphins (Delphinus delphis) and an unidentified delphinidae.
It has been clearly established over the course of various expeditions in the Avilés Canyon that species such as the bottlenose dolphin and the goose-beaked whale are observed every year. Other species such as the striped and common dolphin and the Risso’s dolphin appear certain years.
Sightings of large cetaceans have also given rise to irregular results over the various expeditions. For instance the minck whale (Balaenoptera acutorostrata) was only seen the first year, while the common rorqual (Balaenoptera physalus) was cited on five different expeditions. Sowerby’s beaked whale (Mesoplodon bidens) was only cited on the second 2010 expedition, while the number of sightings of Cuvier’s beaked whale has increased yearly.
Insofar as seabirds are concerned, CEMMA team members were in charge of taking down the data using a “snap-shot” methodology based on the following information: time, coordinates every 20 minutes, species, number of individuals, plumage, number of individuals by age, total number of individuals, distance between the birds and the vessel, and course whether or not the birds were in flight.
A total of roughly 28 hours of seabird observation were carried out and more than 400 individuals from 10 different species were recorded, such as: the yellow-legged gull (Larus michahellis), the European Storm petrel (Hydrobates pelagicus), Wilson’s storm petrel (Oceanites oceanicus), the northern gannet (Morus bassanus), the Balearic shearwater (Puffinus mauretanicus), the pomerine jaeger (Stercorarius pomarinus), the common tern (Sterna hirundo) and the northern fulmar (Fulmarus glacialis). The petrel was the most numerous group sighted.