English - Caribbean Environment Programme

Porpoises are present throughout the year in southern Cardigan Bay but with slight peaks duringthe winter months 177 . They are widespread throughout the inshore and offshore areas but havebeen found to have some preferred areas — densities on the whole are higher in the southern partof Cardigan Bay than further north 178 , and presence is greatest around New Quay head, Aberporth,Ynys Lochtyn, and between Cemaes Head and Ceibwr Bay 179. Abundance has been estimated atbetween 167 and 214 for harbour porpoises in the southern Cardigan Bay SAC 180 .Along the south coast of Wales, the Gower Peninsula has also been highlighted as an area ofpossible importance to harbour porpoises as it was found to have concentrations in some monthsof the year 181 . There are few data available for this region but one study looking at fine scaledistribution found from acoustic and visual surveys that Mumbles Head and Burry Holms on theGower Peninsula were high-use areas 182 .To the north coast of Wales, analysis of multiple-year data has found the Isle of Anglesey and theLleyn Peninsula to have high relative densities of harbour porpoises, with concentrations for severalmonths of the year 183 . A higher than average proportion of calves to adults was found to occur offAnglesey in July, suggesting the area’s importance for calving.Studies of the waters around Anglesey have found them to support high densities of harbourporpoises, particularly Point Lynas and South Stacks on the north and west of the island 184 .A three-year study (May-September) recorded the highest densities of porpoises at Point Lynas, anarea of strong tidal currents and races, along with a high degree of aggregation of animals at thissite 185 . Based on this, and that other studies have observed large aggregations of porpoises feedingin the area, researchers suggest it is likely an important foraging and feeding site for harbourporpoises. At South Stacks, porpoises were not found to be so highly aggregated and behaviouraldata for the area is not currently available, so conclusions about site use are harder to reach.However, high densities of porpoises are found here and the area contains the oceanographicfeatures (tidal races and eddies for example) that seem to facilitate foraging for harbour porpoisesso it may also be a site used for feeding 186 .The Lleyn Peninsula and Bardsey Island just off the coast have been the subject of study for anumber of years in recognition of the high numbers of porpoises found in these waters 187 . Mostsurvey work has taken place in spring and summer, with the highest levels of sightings in April andlate July-September, and the lowest sighting levels in early July 188 . April seems to be a particularlyfavoured time of year for porpoises to aggregate and feed in the Sound that separates BardseyIsland from the mainland 189 . The waters around Bardsey Island are influenced strongly by the fastand complex tidal currents that occur and porpoise activity was found to be related to tidal state,with peaks observed during the low water period, and following the neap tide 190 . As at otherlocations, porpoises were observed holding their position into the current, apparently using theconditions to aid feeding. Lower numbers recorded during spring tides are possibly due to the tidesbecoming too strong and energetically demanding for porpoises to forage.In addition to feeding, the area is also believed to be important as a porpoise breeding and nursingsite 191 . A high proportion of sightings (10-24%) are females with young, particularly in August butalso September and July 192 . They appear to favour the calmer, inshore waters, an observation thathas been made at other sites (e.g. Ramsey Sound, south Wales).Analysis of five years of stranding data from around England and Wales found that strandings ofneonate porpoises occurred more often in Wales than anywhere else, suggesting that CardiganBay and west Wales is an important breeding and calving ground for harbour porpoises 193 .Little information for this area is available from outside the spring and summer months. One surveythat took place in the autumn of 2002 and included the waters of northern Cardigan Bay noted acluster of harbour porpoise sightings in the northern Cardigan Bay-Bardsey Island area, indicatingthat this area may still be important to harbour porpoises later in the year 194 .30177Pesante et al, 2008178Although there has been much more survey effort in southern Cardigan Bay179Pesante et al, 2008180Ibid181Meaning it was found to have porpoises present in at least three months of the year, with concentrations in atleast two months although not necessarily during the AprilSeptember period (when calving takes place), andwith records over several years182Watkins and Colley, 2004183Evans and Wang, 2002; Baines and Evans, 2009184Shucksmith et al, 2008185Ibid186Ibid187WDCS, 2002, 2003, 2004, 2005a, 2006; De Boer and Simmonds, 2003188WDCS, 2005a189Ibid190Ibid191Ibid192Ibid193Bennett et al, 2002194De Boer and Simmonds, 2003