Identification of beaked whales at sea can be difficult, especially of juvenile animals. Northern bottlenose whales are perhaps the most easily recognised due to their large size (adults can reach up to 9.8 m in length),robust body and prominent bulbous forehead and beak.They have a brown/olive colour and a prominent falcate dorsal fin located two-thirds of the way along the back (with adults often being mistaken for minke whales if the bulbous head is not seen).The pectoral fins are paddle shaped and sit into grooves on the flanks of the body. The data collected includes observations, relative abundance, search for and range of Beaked Whales recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.

The fin whale is Irelands most common large baleen whale and grows to a maximum body length of 24 m in the north Atlantic. Body colour is grey with a white underside. The head is v-shaped with a prominent rostrum in front of the blowhole. Jaw-colour is asymmetrical with the right lower jaw being white in colour and the left being grey, this is diagnostic for the species. A pattern of light and dark grey chevrons is noticeable behind the head in good light conditions. The dorsal fin is prominent and located two-thirds of the way along the back. It is variable in shape, though typically falcate or triangular. The species produces a tall columnar blow up to 6 m high which is very noticeable. The blow can sometimes appear angled if the animal blows while surfacing from depth. This species almost never flukes or breaches in Irish waters. Lunge feeding at the surface is sometimes seen off the south coast. The data collected includes observations, relative abundance, search for and range of Fin Whale (Balaenoptera physalus) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.

Adult humpbacks range from 11-16 m in length, with females being slightly larger than males. The head is broad with a series of fleshy knobs on rostrum (and sometimes on the lower jaw), called tubercles. Body colour is black with white on the throat and belly. The pectoral fins are extremely long (one-third of the body length) with scalloped leading edges. They are typically white in colour but may have a dark upper surface, with white beneath.The tail fluke typically has a dark upper surface with white beneath, however the under-surface can be dark in some individuals. The scarring, colour pattern and shape of each tail fluke is unique and provides for identification and tracking of individuals. The dorsal fin is small with a broad base, raised hump in front and "knuckles" behind. The blow is typically low and bushy and has a distinct V-shape when viewed from directly behind or in front of the animal. The data collected includes observations, relative abundance, search for and range of Humpback Whale (Megaptera novaeangliae) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.

Striped dolphins have a maximum body length of 2.6 m.They are a sleek dolphin species with a slender beak,similar in shape to common dolphin but slightly smaller.A falcate dorsal fin (dark grey in colour) is located half-way along the back. The body coloration consists of a dark grey cape extending from the beak to behind the dorsal fin. The flanks are a lighter grey, leading to pink-white undersides.A thin dark stripe runs from the eye to the anus (between the grey and white areas), while a broad dark band runs from the cape, just below the dorsal fin and tapers to a point on the flanks above the pectoral fins. The striped dolphin is a fast active swimmer which sometimes bow-rides, but not as frequently as the common dolphin, which it resembles in body size and shape. The data collected includes observations, relative abundance, search for and range of Striped Dolphin (Stenella coeruleoalba) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.

Common dolphins are Irelands most widespread and abundant dolphin species.They have an average body length: of 1.7 – 2.6 m.The beak, and back are dark brown to black, and the underbelly is white. The front flank patches are yellow and the rear flanks and the sides of the tailstock are streaked light grey. These features give a distinctive hourglass pattern on the sides, below the dorsal fin.The eye is surrounded by black, and a narrow stripe runs forward to the melon.Another dark stripe runs from beak to flipper and several beak-to-anus stripes may also be visible. A falcate dorsal fin is located mid-way along the back.The general body shape is sleek with the head having a prominent black beak. Common dolphins often approach vessels to bow ride and frequently breach clear of the water. Melanism is sometimes seen in this species, with elanistic animals lacking yellow pigmentation, which is replaced with black. The data collected includes observations, relative abundance, search for and range of Common Dolphin (Delphinus delphis) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.

White-beaked dolphins are large,robust dolphins with an average body length of 2.7 m.They have a short but distinct beak which is usually white or light grey. Some animals in the south of their geographical range are reported to have dark or even black beaks. White-beaked dolphins have a very prominent dark dorsal fin mid-way along the back, which is large and sickle shaped.The dorsal fin, flukes and pectoral fins are a uniform dark grey. A distinctive white or pale-grey saddle is present behind the dorsal fin and is characteristic of this species.Two white patches are normally found on the flanks, one either side in front of the dorsal fin and the others on the flank behind the dorsal fin.These patches may merge into the pale saddle behind the dorsal fin. They are strong swimmers, and often swim very energetically along the surface and breach on occasion.They occasionally bow ride vessels, especially larger ships. The data collected includes observations, relative abundance, search for and range of White-beaked Dolphin (Lagenorhynchus albirostris) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.

Sperm whales are Irelands most widespread and abundant deep water whale species and indeed may be the most abundant large whale species within the Irish EEZ. They have a maximum body length of 15-18 m.The body profile is characteristic, with a large square head with and under slung jaw.The head forms one-third of the overall body length. There is no true dorsal fin, but two-thirds of the way down the back is a raised dorsal hump and beyond this are a series of 4 or 5 knuckles.The pectoral fins are short and stubby, but the tail flukes are broad and powerful.The scarring and shape of each tail fluke is unique and provides for identification of individuals. Body colour is typically dark grey to brown. There are often white blotches on other parts of the head or body.The skin on the head is frequently patterned with circular scars formed by the suckers of giant squid on which the whales feed. They have a short bushy blow which is angled forward and slightly to the left (caution: the blows of other species may appear similar when surfacing at an angle).The blow sequence is characteristic with logging animals blowing every 20-30 seconds. The breathing rate increases as the animal prepares to dive. The data collected includes observations, relative abundance, search for and range of Sperm Whale (Physeter macrocephalus) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.

The common bottlenose dolphin is one of Irelands most recognisable cetacean species.They have a robust, muscular body shape with an average body length: of 1.9m – 3.8 m.The body colour is grey with a light grey (that can show variations of grey patterns) or white underside.A tall falcate dorsal fin with a broad base sits half-way along the back. Bottlenose dolphins exhibit a moderately keeled tailstock. The head has a short,rounded beak with the lower jaw protruding slightly beyond the upper. A soft mouth line curves upwards at back to give the familiar‘smile’ that is characteristic for this species. They often approach vessels to bow ride in inshore waters and in the Shannon Estuary and frequently display acrobatic activity at the surface. Conversely offshore animals often appear wary of approaching vessels. The data collected includes observations, relative abundance, search for and range of Common Bottlenose Dolphin (Tursiops truncatus) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.

Killer whales are the largest dolphin species, with adults reaching up to 9.5 m in length.The blow is low and bushy with a sharp sound, audible from a distance. The head is rounded with an indistinct blunt beak. The triangular dorsal fin, located half-way along the back, is the largest of any cetacean species and reaches 1.8 m in height in males.The dorsal fin on females and juveniles is falcate and more dolphin-like. Body colour is jet-black above and on the flanks. They have white undersides with a white patch above and slightly behind the eye and a white patch stretching from the underside onto the flanks. A lighter coloured saddle patch varies in colour from white to grey to brownish. Identification at sea is easy if the group contains an adult male, which they almost always do, as there is no mistaking the male dorsal fin. Even females and sub-adults have a noticeably larger dorsal fin than other species. The striking body colouration is also diagnostic. The data collected includes observations, relative abundance, search for and range of Killer Whale (Orcinus orca) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.

Harbour porpoises are Irelands smallest cetacean species with an average body length of 1.5 m. Their body colour is dark-grey with a white underside extending up the sides a little beneath the dorsal fin. The head is rounded with no distinct beak. A small triangular dorsal fin is situated half-way along the back, with a slightly curved trailing edge.Typically no blow is visible but in calm conditions a short sharp exhalation can be heard, giving rise to the common name of ‘puffing pig’,sometimes used for this species. Harbour porpoises rarely approach vessels or breach clear of the water. The data collected includes observations, relative abundance, search for and range of Harbour Porpoise (Phocoena phocoena) recorded from marine mammals observations on board ships of opportunity between 2005 and 2011.