Cardigan Bay BIG 3

The Cardigan Bay Marine Wildlife Centre would like to introduce you to the Cardigan Bay Big 3!

Bottlenose dolphin
Harbour porpoise
Atlantic grey seal

Bottlenose dolphin (Tursiops truncatus)

Bottlenose dolphin ©Sarah Perry

Bottlenose dolphins are the archetypical dolphin found around the world. Some of the largest bottlenose dolphins live around the United Kingdom. There are two main semi-resident populations in the UK, one in the Moray Firth, Scotland the other larger one, right here in Cardigan Bay.

Bottlenose dolphins are sociable animals that live in groups called pods. The size of the pod can vary significantly from several to over a hundred. This happens when several smaller pods join together to feed on an abundant food source or to socialise. They are very active and like to surf in the bow wave in front of moving boats.

They are frequently seen tail slapping and leaping several metres out of the water, called ‘breaching’. Females reach sexual maturity at around 11/12 yrs and give birth between April and September to a single calf.

Video © Sarah Perry

What do they look like?
Bottlenose dolphins have a rounded forehead and short beak and a prominent sickle shaped dorsal fin. Adults have a light underside with light grey on the sides that gradually becomes darker on the back. New born calves are much paler and have distinct lines called ‘foetal folds’ down their sides that gradually fade as they get older.

What do they eat?
They eat a wide range of schooling fish, bottom-dwelling fish, squid and crustaceans, but they can adapt their feeding behaviour to local conditions, circumstances and food sources.

Where can I see them?
In Cardigan Bay during May to September bottlenose dolphins can be reliably spotted from various local locations along the Welsh coast including Aberystwyth, New Quay, Ynys Lochtyn, Aberporth and Mwnt. During the winter groups are found further offshore throughout Cardigan Bay.

Bottlenose dolphin vital statistics

Size Weight Lifespan
Male 2-4m 150-650kg Up to 50 years
Female Slightly smaller 150-650kg
Newborn 0.84-1.5m 15-30kg


Harbour porpoise (Phocoena phocoena)

Harbour porpoises © Janet Baxter

Porpoises differ from dolphins mainly by their shape and the smaller size of their body and dorsal fin. They are sometimes referred to as a “puffing pig” due to the noise they make when they breathe. Harbour porpoises can be difficult to observe due to their shy nature and generally only show their dorsal fin when surfacing to breathe. They are wary of boats and unlike dolphins do not bow ride. They are usually seen singly or in small groups of 2-3 animals. Females reach maturity at 3-4 years, giving birth between May and July to a single calf every 1-2 years.

What do they look like?
Harbour porpoises have small triangular dorsal fins, a rounded head and are dark grey in colour with a lighter underside. Calves are much paler and like bottlenose dolphin calves, have distinct lines called ‘foetal folds’ down their sides that are visible for the first few hours after birth.

What do they eat?
Harbour porpoise have a varied diet of small schooling fish such as sand eels, sprats, herring and mackerel plus crustaceans.

Where can I see them?
Harbour porpoises are found all around the UK. Most sightings occur within 10 km (6 miles) of land. Locally, good places to spot porpoises are from New Quay headland, Aberporth Bay and Mwnt. Elsewhere in Wales they can be seen at Strumble Head and Ramsey Sound in Pembrokeshire and Point Lynas, Anglesey and Bardsey Island in North Wales.

Harbour porpoise vital statistics

Size Weight Lifespan
Male Up to 1.6m Up to 61kg Up to 12 years
Female Up to 1.7m Up to 76kg
Newborn 0.70-1m 5kg

Atlantic grey seal (Halichoerus grypus)

Female Atlantic grey seal and pup © Janet Baxter

Grey seals are mammals that are closely related to bears. They are usually seen individually in the water or hauled out in small groups at sites called ‘rookeries’ where they rest, breed and moult. Females reach maturity at 5-6 yrs, giving birth to a single pup between September and December every year. Pups have white coats when they are born. They are nursed by their mothers for about 17 to 18 days. In this time the pup gains 2kg of weight a day due to the high fat content (60%) of its mother’s milk.

What do they look like?
Atlantic grey seals have a very distinctive head and their scientific name actually means “ sea-pig with a hooked nose”. Males are darker with light patches and an arched ‘Roman nose’. Females are lighter with dark patches and a smaller, straighter nose.

What do they eat?
They are opportunistic feeders and will eat a variety of fish including sand eels and cod, plus crustaceans, squid and octopus.

Monitoring seals
Photo-identification techniques have been developed to help scientists recognise individual seals from permanent colouration patterns in their fur. This can help to monitor populations and movements of animals.

Where can I see them?
Nearly half of the world’s population is found around the British Isles, mostly in Scotland but a number live along the Welsh coast. One of their favoured breeding grounds is Cardigan Bay with a population of 5500 found south of Aberystwyth. Ramsey Island and Cardigan Island are popular breeding areas for grey seals as well as various beaches and caves locally including Cwm Tydu.

Atlantic Grey Seal vital statistics

Size Weight Lifespan
Male (Bull) Up to 3m Up to 250kg Up to 25 years
Female Slightly smaller 150-180kg Up to 35 years
Newborn 0.8-1.5m 15-30kg