In April 2011 we retrieved some new data from a tag that was deployed on a small female porbeagle (67.1 kg) caught off Donegal in July 2010. The tag popped-up off Portugal on the 12th of April and transmitted a full nine month data set back to us via satellite over a two week period. To our knowledge, this is the longest time-series collected for a porbeagle in the northeast Atlantic so far.
View 2010 Porbeagle tag in a larger map
Our data show that the shark spent a lot time in the surface waters (approximately 0-80 m) during the summer months when the shark was living around the shelf-break off Ireland (green dots). These results highlight further that the waters around Ireland are important areas for porbeagles during the summer months. The shark then migrated away from Ireland around December and travelled to the Bay of Biscay region off northern Spain. During this migration, the shark travelled through deep, oceanic regions and occurred much deeper in the water column during the autumn/winter period, diving to depths of up to 1100 m. This migration and diving behaviour could be related to the availability of food sources in the water column. Our tag also recorded the temperature of the water in which the shark lived (orange dots) and the data show that the shark mainly occupied waters between 10 and 15 °C.