Huge group of bottlenose dolphins in Galway Bay

28th Mar 2007 As part of my PhD, funded by the National Parks and Wildlife Service, based at GMIT, dedicated transects are carried out in Galway Bay, weather permitting once per month. These monthly transects are ongoing since May, 2005. Harbour porpoises have been the most frequently sighted species while bottlenose dolphin sightings have rarely been recorded. Other species recorded have included minke whales and common dolphins.

On Monday, 26 March a monthly transect was scheduled and we departed Spiddal, Co.Galway in ideal weather conditions. After deploying acoustic equipment off Spiddal, the Maiden Mara skippered by Kevin McGabhann of Galway Bay Fishing Charters resumed our usual route from Spiddal towards Black head on the south shore of the bay.

A number of undergraduate students from GMIT were present onboard for this transect and observations were carried out from the bow of the vessel. We were positioned just north of Fanore when a single bottlenose dolphin was sighted. Within seconds and to huge delight more animals started to appear.

A group of between 20-40 (3 juveniles) animals were surrounding the vessel but travelling quickly in a northerly direction. We altered our course to move in the same direction as the animals and try to capture images of their dorsal fins. After a few minutes our attempts to keep up with this group failed, as they were moving so quickly. However, as we altered out course in a southerly direction we noticed another group approaching from the south, this group consisted of about 30 individuals (4 juveniles) also travelling quickly in a northerly direction.

We again attempted to follow the animals to capture some more fin images for photo-identification purposes. We managed to track this group back towards Blackhead lighthouse when again their fast momentum proved too much for our able vessel. Bursting with excitement after encountering between 50-70 animals and obtaining some dorsal fin images we altered track back towards Fanore.

Within minutes we were surrounded by another group of animals that had come from the south. We estimated there to be 20+ (2 juveniles) individuals in this group. On this occasion 6 animals approached the vessel and began to bow ride as we moved yet again in a northerly direction. A best estimate of 70 to 100 animals in total was sighted for the duration of the encounter.

The rare event of encountering bottlenose dolphins in Galway Bay is always an exciting occasion; however experiencing such a vast number on a single transect was indescribable. This event provided an opportunity for photo-identification to be carried out. A number of the animals were very well marked and over the coming weeks analysis of these images will seek to match these individuals to the 150+ dolphins that are catalogued in the Shannon estuary. Comparisons will also be carried out with other pods of dolphins encountered around our coasts where photo-identification was carried out.

Joanne O'Brien,

Galway-Mayo Institute of Technology

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