English - Caribbean Environment Programme

eastern Channel does not seem to have had a similar increase in porpoise numbers. DuringSCANS (in July 1994) none were sighted off south east England. During SCANS II, a moderatedensity of 0.331 animals/km 2 was recorded for the block that included this area but spatial modellingof the results suggests higher densities of animals were in the western Channel, and only the verynorthern part of the eastern Channel stretching down from the region of high density off eastEngland (see Figures 4.5 and 4.6, p.22).South west EnglandThe waters off south west England are a further area where the SCANS surveys showedsignificant changes in distribution of harbour porpoises in 10 years. SCANS (in July 1994)recorded no porpoises in the English Channel region and a relatively low density for the CelticSea and Bristol Channel 144 (see Figure 4.3, p.21). Ten years later during SCANS II, moderatedensities were recorded in the English Channel (0.331 animals/km 2 ) and high densities in theCeltic Sea and Bristol Channel (0.408 animals/km 2 ) (see Figure 4.5, p.22). Spatial modelling ofthe SCANS II dataset predicted moderate densities for a large area of the Celtic Sea and the verywestern edge of the English Channel 145 (see Figure 4.6, p.22).An increase in the summer occurrence of harbour porpoises in the English Channel has also beensuggested by an 11-year study (1996-2006) using data collected from ferries travelling acrossthe English Channel and the Bay of Biscay 146 . Findings indicate that this increase has occurredsince 2002 and may only be the result of an increase in summer abundance, not a consistentyear-round increase 147 .Analysis of over 20 years of harbour porpoise data for UK waters highlighted several hotspotsfor harbour porpoises in this region 148 . North Devon was determined to be important, with highconcentrations of porpoises in several months of the year, particularly during the April to Septemberperiod. An area in the Outer Bristol Channel, south to north west Cornwall, was rated as animportant site, but with fewer months of high concentrations than north Devon. High densities ofharbour porpoises during the summer months, the time of year when these animals breedand produce young, suggest these waters may be important for these functions and thisshould be investigated further.Data were lacking for the western English Channel region but significant concentrations ofporpoises were still noted for the first quarter of the year 149 .Little other data were found for the north Devon coast. One study investigated the fine-scale habitatuse by harbour porpoises of two sites in this area and determined that one, Morte Point, was animportant feeding ground for harbour porpoises 150 . Morte Point is a headland with an area of tidalrapids nearby and porpoises were observed to spend 60% of their time in the area foraging. Thisactivity predominantly occurred within the tidal race 151 which is similar to results from other locationswhere porpoises are seen to take advantage of the aggregating effect of high tidal flow. At thesecond site, Lee Bay, porpoises were also observed feeding but spent more time travelling in thisarea and it seems to be used mainly as a corridor between more productive feeding sites 152 .Some survey work has taken place in the western English Channel and close to the Scilly Islesduring the winter 153 . Although overall relative abundance was fairly low, porpoises were not evenlydistributed, with large groups of apparently foraging porpoises seen at times 154 . A land-basedsurvey conducted at the same time of year reported relatively high densities of porpoises off Land'sEnd and frequently observed them to be foraging here 155 . These surveys would seem to supportother analyses of data from the region that found there to be concentrations of porpoises in thewestern English Channel during the first few months of the year 156 . Analysis of multiple years ofcetacean sighting data from the coastal waters of Cornwall, investigating spatial and temporal patterns,also found harbour porpoises were predominantly sighted off Land's End, with a peak in winter 157 .28144Hammond et al, 1995145SCANS II, 2006146Macleod et al, 2009147Ibid148Evans and Wang, 2002149Ibid150Goodwin, 2008151Ibid152Ibid153De Boer and Simmonds, 2004; WDCS, 2005b; De Boer and Saulino, 2007154De Boer and Simmonds, 2004155De Boer and Saulino, 2007156Evans and Wang, 2002157Pikesley et al, IN PRESS