Dolphins of the
English Channel & Bay of Biscay

Bottlenose Dolphin: Tursiops truncatus

Where is it usually seen?

• Occurs in any part of the Bay and outer channel. Inshore pods occur around the Breton archipelagos, and off the Dorset coast, though groups can be seen in deep water.

Frequency of sightings:

• Regularly seen throughout the year, especially in summer. Occurs usually in small groups of up to 20.

Recognition:

• Large, robust dolphin, up to 4 metres in length. Can appear surprisingly large at sea.

• Grey upper parts, often with blotching. Can appear black in dull light. Underside paler.

• Short but distinct beak, can be quite stubby.

• Well proportioned falcate dorsal fin is positioned centrally. Perhaps more raked back than in other species of dolphin occurring in the region.

Behaviour:

• Occurs in groups of usually no more than 20, sometimes joins with other species.

• Often demonstrative, leaping clear of the water in fast swimming, performing somersaults, etc.

• Not always hyperactive active. In slow swimming, often only the back breaks the surface.

• Bow and wake rides.

Confusion species:

• Risso's Dolphin; is also grey, but has a thinner and proportionally taller dorsal fin. When seen, it has a very snub nosed appearance, with no beak.

• Other dolphins in the region are strongly patterned.

Status and distribution summary:

• Occupies low to mid latitude, warmer waters around the world, including most semi-enclosed seas. Scottish populations are among the most northerly in the world. Persecuted by fishermen in the tropics as a competitor, and is the most common dolphin kept in captivity.

  ^^ top  

Common Dolphin: Delphinus delphis

Where is it usually seen?

• Throughout the Bay and well into the Channel to at least the Channel Islands at times.

Frequency of sightings:

• The most frequently encountered cetacean in the region. Seen in pods of from 3 or 4, up to hundreds. In winter is more frequently encountered in the Northern Bay and Channel than in the Southern Bay where it can be quite scarce at that time. In the summer is much more frequent over deep water in the Southern Bay than in the north.

Recognition:

• Highly distinctive.

• Up to 2.5 metres in length.

• Diagnostic inverted black triangle beneath the dorsal fin and 'hourglass' pattern when viewed from the side.

• Often has a brownish tinge to pelage, with a usually pale tan panel back from the eye to the mid point, with grey tail stock.

• Upper parts black to blackish brown (dark chocolate).

• Relatively tall dorsal fin, usually with a swept back, quite straight leading edge, pointed tip, and concave trailing edge.

Behaviour:

• In tight or dispersed pods.

• Often very active at the surface, with frequent leaps when travelling, acrobatic somersaults, and tail slapping.

• Bow and wake rides frequently. As well as playing pooh-sticks, charging under the ferry from side to side.

• Sometimes mixes with other species, including large whales.

• Possibly aggressive to potential predators of their calves, such as bottlenose dolphin and Pilot Whales.

Confusion species:

• Striped Dolphin; is similar in size and behaviour and is also patterned. However, lacks inverted triangle and hourglass.

• Atlantic White-sided Dolphin; has similar combinations of colours, but lacks the inverted triangle and hourglass, and is rare in the area.

Status and distribution summary:

• Has a pan-global distribution in warm and temperate waters. Abundant in several areas. However, some authorities consider there to be at least three species, with two in the Pacific Ocean and at least one elsewhere. As the Atlantic Ocean populations are largely isolated from all others, it is possible that this is also a separate species. Further study is required to determine the true situation, and therefore the status of whichever species are involved.

^^ top  

Harbour Porpoise: Phocoena phocoena

Where is it usually seen?

• Usually in shallow, shelf waters of the Northern Bay and Western Approaches.

Frequency of sightings:

• Variable from year to year. In good years can be commonly encountered as individuals or in large groups. In poor years can be absent. Most sightings are in late summer.

Recognition:

• Smallest cetacean in the region, reaching no more than 1.7 metres.

• Dark grey above, usually without any markings or scars.

• Small low dorsal fin, with a broad base.

• Tapering head, with no beak.

Behaviour:

• Usually in small groups of 2 to 10, occasionally in large dispersed groups.

• When steady swimming only shows very briefly at the surface to breath, showing only a small part of back and a quick glimpse of the dorsal fin, so is often difficult to see, and almost impossible in rougher seas.

• When fast swimming, may leave the water (hence 'porpoising'), otherwise is not normally demonstrative at the surface.

• Audible, but not visible, blow, hence the alternate name of 'Puffing Pig'!

Confusion species:

• Only confusable at long range, its small size and the low broad-based dorsal fin should distinguish it at other times.

Status and distribution summary:

• Limited to shelf waters in the Northern Atlantic and Northern Pacific oceans. Locally common, but is under threat from pollution, especially around estuaries, and from frequent by-catch in fishing nets.

^^ top  

Striped Dolphin: Stenella coeruleoalba

Where is it usually seen?

• Occurs predominantly over the deeper waters in the Southern Bay, though sometimes over shelf waters in the Northern Bay.

Frequency of sightings:

• Common in the summer, when thousand may be encountered, but appears to leave the area in the winter, presumably for warmer seas.

Recognition:

• Up to 2.5 metres in length.

• Dark grey upper parts, with blue-grey flanks, and thin dark stripe between flank and white underneath.

• The pattern below the dorsal fin is distinctive; the grey of the flank cuts back into the dark upper parts.

• Dark falcate dorsal fin set at the midpoint.

• Pronounced beak.

Behaviour:

• Highly social, usually in groups of between 10 and 1000.

• Very energetic; swims fast, leaps frequently, somersaults, back somersaults, and even spins.

• Associates with Common Dolphins regularly.

• Sometimes bow rides.

Confusion species:

• Common Dolphin; is the only other patterned dolphin that regularly occurs in the area. It has a browny hue, compared to the bluish hue of Striped Dolphins, and the inverted triangle is diagnostic, as is the pattern of Striped Dolphins.

• White Beaked Dolphin; could be confused, though is more robust and has dark flanks and a stubby beak.

• Atlantic White-sided Dolphin; is potentially confusable, with broadly similar patterning, but the yellowish patches on the side of the tail stock is diagnostic, also has stubby beak.

Status and distribution summary:

• Pan-global distribution in warm to warm-temperate waters offshore. Abundance is patchy, is at least partially migratory, moving to warmer waters in winter.

^^ top  

Risso’s Dolphin: Grampus griseus

Where is it usually seen?

• Can be seen any where in the area, though probably more often close to coasts.

Frequency of sightings:

• Quite uncommon, and infrequently recorded. Seen more often in summer, though this could be a function of calmer seas making viewing easier.

Recognition:

• Large for a dolphin, reaching 3.5 metres in length.

• Upper parts are all grey, which becomes increasingly pale with age.

• Usually covered in whitish scars, inflicted by other Risso's Dolphins.

• Very tall, thin, slightly falcate dorsal fin, which is more upright than in other dolphins, and is round tipped.

• Blunt headed, with a heavily domed forehead.

Behaviour:

• Usually seen in small pods (3 - 10), but can congregate into groups of over 100 at times.

• Often swims slowly, mills lazily, or logs on the surface.

• Breathes regularly, every 15 seconds or so when at the surface. Dives for variable periods, up to 30 minutes.

• When active, will half-breach frequently, lob-tail or spy-hop.

• In steady swimming, domed forehead breaks the surface when breathing, often before dorsal fin is seen.

Confusion species:

• Bottlenose Dolphin; is similar in size and overall colouration, but can have shorter more falcate dorsal fin, lacks extensive scarring, and the distinct beak is often visible at the surface.

• Female and juvenile Killer Whales; have similar dorsal fins, but are black with white head patches and no scarring.

• Grey Cuvier's Beaked Whales; are possibly confusable, with similar paling of upper parts, however, the dorsal fin is set well back, and is small and falcate in that species.

Status and distribution summary:

• Occurs in all temperate to tropical seas of the world, concentrated along the shelf edges and inshore near headlands. Not known to be migratory. Locally common in some areas, for example the west coast of Ireland.

^^ top  

White-beaked Dolphin: Lagenorhynchus albirostris

Where is it seen?

• Generally seen in the more northerly areas of the North Atlantic.

Frequency of Sightings:

• Very rarely seen from the ferry although it has been recorded in northern Biscay.

Recognition:

• Large robust dolphin 2.3–3.1m

• Short thick beak with variable amounts of white.

• Dark grey, black and white fuzzily edged patterning – not sharply delineated.

• White stripes from head to tail stock and white saddle.

• Dark flippers and tail.

• Tall, dark falcate fin

Behaviour:

• Fairly shy dolphin though sometimes bow rides for a short period.

• Fast, powerful swimmer.

• Not particularly demonstrative but breaches and leaps.

• Mixes with Atlantic White-sided Dolphin, Common Dolphin and rorquals.

• Usually in groups of 5-50 but sometimes in aggregations of up to 1,500.

Confusion species:

• Atlantic White-sided Dolphin though this is a more slender dolphin with clearly delineated blazes – white on flank and yellow/mustard on tail stock.

Status and Distribution summary:

• The population is probably in the region of 100,000 and is found in the temperate and cold shelf waters of the North Atlantic.

^^ top  

Atlantic White sided Dolphin: Lagenorhynchus acutus

Where is it seen?

• Usually around and north of the Scottish Isles however this species has been recorded in the area of the continental shelf in the Northern Bay of Biscay.

Frequency of Sightings:

• Rarely seen from the ferry though it has been recorded on the Continental Shelf of Northern Biscay.

Recognition:

• Large and robust with thick tail stock 1.9-2.8m

• Black or grey upper body.

• Well defined blazes; white on flank beneath fin with adjacent yellow/mustard blaze on tail stock above a grey stripe reaching from the head almost to tail.

• Very short beaked.

• Tall dark falcate fin.

Behaviour:

• Usually in groups of 5-50 inshore with pods of up to 1,000 recorded offshore.

• Fast swimmer and often breaches and lobtails.

• Fairly shy but will occasionally bow ride boats and large whales.

Confusion species:

• White-beaked Dolphin which is heavier with more white but less distinct markings and no yellow blaze and Common Dolphin which can be differentiated by its smaller size and distinctive hourglass pattern.

Status and Distribution summary:

• Population is unknown. Usually found in temperate and cold waters.

^^ top  

Copyright of BDRP, 2003