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SMALL CETACEANS (DOLPHINS & PORPOISES) INCLUDING HARBOUR PORPOISE (PHOCOENA PHOCOENA)
LOCAL BIODIVERSITY ACTION PLAN

Links to associated HAPs

None

Current Status

Status changes for these species is difficult to assess due to lack of quantitative data.

Harbour porpoise Phocoena phocoena
There is some evidence of a decline in numbers of small cetaceans in UK waters since the 1940s, especially in the southern North Sea and English Channel. The conservation status of the species around the whole UK coast is unknown, but the recent "SCANS" survey of small cetaceans in the North Sea, Channel and Celtic Sea indicated the population in those waters was approximately 350,000.

Bottlenose dolphin Tursiops truncatus
The bottlenose dolphin is locally frequent nearshore off the coasts of western Ireland, north-east Scotland, in the Irish Sea (particularly Cardigan Bay and south-east Ireland), and in the English Channel. Although overall population estimates do not exist, studies indicate a resident population of 130 bottlenose dolphins in the Moray Firth whilst the population in Cardigan Bay has been variably estimated at 130-350 bottlenose dolphins. Neither population is closed, and individuals may join up for periods of time from elsewhere. Numbers at most UK sites are greatest between July and October (with a secondary peak in some localities in March-April).

Risso`s dolphin Grampus griseus
Although present in UK waters throughout the year, numbers are greatest between May and September. The major UK population occurs around the Hebrides, with a regular presence in the Northern Isles, and in the Irish Sea, particularly around Bardsey Island. Elsewhere, it is fairly common in south-east Ireland and western Ireland. A study in the North Minches of Scotland has identified at least 142 individuals but no population estimate has yet been made.

White-beaked dolphin Lagenorhynchus albirostris
This species is common in UK and Irish waters, occurring most abundantly in the central and northern North Sea across to north-west Scotland, although it also occurs occasionally in southern Ireland, the Irish Sea and western Channel. A population estimate of between 4000-13,300 was made in July 1994 for the North Sea and Channel with a further estimate in the same area of 6000 to 18,500 small dolphins (both white-beaked and white-sided dolphins, but not differentiated). In UK waters, the species is most common in late summer (June to September) although present in northern Britain throughout the year.

Common dolphin Delphinus delphis
In UK waters, it is common in the western approaches to the English Channel and the southern Irish Sea (particularly around the Celtic Deep, off Pembrokeshire) and around the Inner Hebrides north to Skye. It is also common west of Ireland. In some years, the species occurs further north and east - around Shetland and Orkney, and in the northern North Sea. It is generally rare in the southern North Sea and eastern portion of the Channel. No overall population estimate exists, but the population around the Celtic Deep was estimated to be between 23,000-249,000. Records of common dolphins are more frequent in northern Britain during the 1990s than they were in the 1980s. This suggests a possible recent northward extension of their range, whilst bottlenose dolphins are reported to be less frequent in the southernmost North Sea than they were in the 1960s and 1970s.

There are five small cetacean species occurring regularly in the Irish Sea.
The harbour porpoise is the commonest species stranded in the Liverpool Bay area and the British Isles as a whole. The harbour porpoise is considered common in the North West region, with on average one porpoise a week stranded on the north-west coastline. Cheshire's sightings and stranding records follow the same trend, however local opinion is that the harbour porpoise is seen less frequently than forty years ago, parallel with the national status. Cheshire Wildlife Trust's Cetacean Watch project started in January 1997. Since then four sightings of live harbour porpoises and one stranding record have been received. On 22.9.99 an immature specimen approximately 3ft. long was discovered drowned, in a net, on Moreton beach. A 4ft long immature harbour porpoise was washed up alive but in a very poorly condition in Leasowe Bay on 16/9/01.

Small Cetaceans are currently protected under:
· Schedule 5 of the Wildlife and Countryside Act (1981),
· Appendix II of the Bonn convention,
· Annexes II and IV and V of the EU Habitats and Species Directive and
· Appendix II of CITES.
· Appendix II of the Bern Convention

The Habitat Directive requires that member states monitor the incidental capture and killing of all cetaceans.
Under Annex II candidate marine SACs (Special Areas of Conservation) for bottlenose dolphins are established in the Moray Firth, (north-east Scotland) and in Cardigan Bay (west Wales).

An Agreement on the Conservation of Small Cetaceans in the Baltic and North Seas (ASCOBANS), a regional agreement under the Bonn Convention, formulated in 1992, has now been signed by seven European countries, including the UK. Under the Agreement, provision is made for protection of specific areas, monitoring, research, information exchange, pollution control and heightening public awareness. Measures are included aimed specially at protecting dolphins and porpoises in the North and Baltic Seas and cover the monitoring of fisheries interactions and disturbance, and recommendations for the establishment of specific protected areas for cetaceans.

The species covered in this plan are protected under ASCOBANS' parent Convention, the Bonn Convention, but the ASCOBANS agreement does not include the Irish Sea.

Threats

• Four main human activities are recognised as currently likely to be detrimental to dolphins: activities leading to ecosystem changes; interactions with fisheries; boat activities; and contaminant inputs.

  • Ecosystem changes resulting from the widespread over-exploitation of marine biological resources have the potential to affect reproduction and survival of all dolphins and porpoises including the depletion of their prey or food.
  • All the dolphin species considered here have been recorded as by-catches (incidental/accidental capture) of various fisheries. There is evidence of substantial numbers of dolphins caught in pelagic trawls (targeting tuna, hake, bass, horse mackerel, mackerel and herring) in the south-west approaches and the Celtic Sea. Post-mortem studies of 138 common dolphins washed ashore on UK coasts between 1990 and 1995 revealed at least 62% of animals died as a result of by-catch.
  • Boat activities (merchant shipping, seismic, military and recreational) in coastal waters pose threats to dolphins and porpoises by direct physical damage (collisions, and propeller damage) and by the sounds introduced into the environment, where potential harm may be caused by direct auditory damage at close distances and interference with navigation, food-finding, and communication further away. In recent years, seismic activities have started in the Iris Sea, parts of the Channel, and along the Atlantic Frontier, west and north of Scotland and Ireland, following earlier emphasis on the northern and central North Sea.
  • Contaminants, including organocholorines, may impact the reproductive potential or cause suppression of their immune system. High concentrations of bioaccumulating chemicals have been detected in the tissues of marine mammals, and long-lived animals such as cetaceans are more at risk of accumulative heavy pollution burdens than shorter-lived ones. In Cardigan Bay, a few years ago the body of a dead bottlenose dolphin calf was found to have one of the highest levels of contaminants such as PCBs, DDT and mercury ever found in a mammal.
  • Global climate change may also have an effect on small dolphins but impacts on marine mammals are very difficult to predict

How are we helping to conserve Small Cetaceans in the Cheshire region?

• Nationally the Natural History Museum is creating a database of stranded cetaceans for the entire coastline. Dr. Peter Evans, Seawatch Foundation, is collating sightings of live cetaceans at sea.
• Several international and national organisations are involved in the conservation of cetaceans, including Whale and Dolphin Conservation Society (WDCS) and International Dolphin Watch.
• Distribution studies have been undertaken by JNCC since 1980. The Sea Mammal Research Unit co-ordinated the international "SCANS" survey in 1994.
• Experiments to increase the acoustic detectability of fishing nets have been undertaken to reduce by-catch.
• Guidelines to minimise the effects of acoustic disturbance from seismic surveys have been agreed with the oil and gas industry and published by DEFRA.
• Post mortem and tissue studies of stranded corpses are carried out on stranded specimens to establish the cause of death and condition of the animals at the time of death.
• Conservation, management and research action is being undertaken and planned under ASCOBANS.
• In 1998, the EU Fisheries Council decided to ban the catching of tuna with drift-nets by 1 January 2002.
• Guidance has been drawn up by DEFRA and JNCC to encourage recreational users (including whale-watching operators) to minimise disturbance to dolphins. These include avoidance of sudden alteration in vessel speed or direction and pursuit of animals. Recommendations have also been made to limit the number of vessels in close proximity, and length of time of encounter.
• Regionally, Dr. John Baker is responsible for carrying out post-mortems on fresh strandings in Wales and the North West of England.
• Simon Hayhow, Fleetwood Museum, is attempting to collate all cetacean records for 'old' Lancashire, which incorporates Merseyside.
• Cheshire Wildlife Trust has established Cetacean Watch, carrying out regular sea watches and co-ordinating sightings by sea watch volunteers.

Objectives, Targets and Actions

Progress so far

How to find out more about Small Cetaceans

Contact details

References & Glossary

Chubb, J.: Marine Mammals of Liverpool Bay.
Corbet, G. and Harris, S. (1991): The Handbook of British Mammals 3rd edition, Blackwell Scientific Publications, Oxford.
HMSO (1995): Biodiversity: The UK Steering Group Report, Volume 1: Meeting the Rio Challenge, London.
HMSO (1995): Biodiversity: The UK Steering Group Report, Volume 2:Action Plans, London.
Hilbre Bird Observatory (1993-1995): Hilbre Island Bird Observatory Reports.
Liverpool Museum records.
Muir, A. (1996): Records, Natural History Museum, unpublished.
Sea Mammal Research Unit (1994): Annual Report 1992-1994, Natural Environment Research Council.

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