There is no complete abundance estimate of common dolphin populations in the Atlantic near the UK,but advice from the International Council for the Exploration of the Sea (ICES) suggests that approximately 500,000 common dolphins inhabitthis area.
The number of animals that die as bycatch every year is unknown, as it is not feasible to monitor all fishing operations. Bycatch has been monitored in the bass pair trawl fishery. An average of 180 dolphins per year were bycaught in the bass pair trawl fishery between the 2000-01 and 2004-05 winter seasons. Estimates for each year are provided below.
2000-01 189 2001-02 39 2002-03 114 2003-04 429 2004-05 145 Total 916
Bycatch is known to occur in gillnet fisheries in the Channel and western approaches, but there are no recent estimates of the numbers involved. The most recent estimate dates from the early 1990s, when around 200 common dolphins were being bycaught in the English and Irish gillnet fishery for hake.
The known level of bycatch of common dolphins in the two fisheries mentioned above is about 0.076 per cent of the population per year.
There has been no bycatch of bottlenose dolphins observed in over 7,000 fishing operations monitored in Defra-funded research programmes since 1996. Local populations of bottlenose dolphins number about 130 in both Cardigan Bay and the Moray Firth. My understanding is that only two bottlenose dolphins have been recovered from beaches around the Moray Firth (in 1993 and 1999) and one from Cardigan Bay (in 1996), under the Defra-funded cetacean strandings scheme, which were subsequently found to have died in fishing-related accidents.