Photographs of a fin whale visiting the River Great Ouse in the centre of Kings Lynn has been reported this morning on social media. The scientists at Sea Watch Foundation are very pleased to realise how positively the general public responds to these encounters and how much they enjoy getting involved in reporting sightings of whales, dolphins and porpoises around the UK. The time and dedication volunteer sea watchers have spent searching for these species and the subsequent reporting of sightings have allowed the Sea Watch Foundation to improve the knowledge and understanding about the population status of local cetacean species around the British Isles. The Sea Watch Foundation is very proud of the time, energy and effort, that has gone into reporting public sightings spanning over four decades which are the backbone of their national database.
The fin whale, Balaenoptera physalus, has a sleek and streamlined body with a dorsal fin which tends to be taller, more falcate, and set farther forward on the tailstock compare to blue whales, and which sets further back and rises at a shallower angle than those of other large balaenopterids (sei, and Bryde’s whale). The profile of the dorsal fin, the shape, location of body marks, and the shape of light grey V-shaped ‘chevrons’ and the asymmetrical colouration of the head are the best identification features and they are used to differentiate individuals.
Fin whale (Balaenoptera physalus) showing a streamlined body and a tall, large and broad dorsal fin. Photo credit: Gavin Ball.
The fin whale was reported at around 8:00 am this morning swimming close to the edge of the river Great Ouse. It also looked disoriented and showed fresh scars on the dorsum, flank and head, maybe caused by swimming in the river.
Fin whale (Balaenoptera physalus) showing fresh scars on the dorsum, flank and head. Photo credit: Gavin Ball.
The animal was estimated to be approximately 5 meters in length, so it was hypothesized to be an immature as it is known that adults can reach a maximum of 24 meters in length in the Northern Hemisphere.
A total of 9 historical sightings of fin whales in Norfolk span between 1842 and 2015. The most recent UK sighting was of an adult and juvenile fin whales which was reported in the Kessock Channel an area of water forming part of the inner Beauly Firth last week.
“It would be more typical of a Minke Whale to enter the River Great Ouse but historically there have been two other records of Fin Whale within the river. Therefore it’s not so outlandish that this individual that can grow to be the second largest animal on the planet came to visit King’s Lynn today. The latest good news is the whale was last seen heading back out to sea”, Sea Watch Regional Coordinator for Norfolk, Carl Chapman said.
Sea Watch Chair of Trustees, Robin Petch, has alerted British Divers Marine Life Rescue and they are sending a team to assess the situation.
“With the help of the British Divers Marine Life Rescue we really hope this fin whale is going to be able to swim back to the open sea as the tide is going out and time is ticking”, said Chiara Giulia Bertulli, Sightings Officer for Sea Watch Foundation.
Anyone who would be interested in spending more time looking for whales, dolphins and porpoises around the UK should visit the Sightings Network webpage (www.seawatchfoundation.org.uk/regional-groups/) or submit their sightings online at www.seawatchfoundation.org.uk/sightingsform/.
A historical record of all cetacean sightings in Norfolk is to be published soon by Carl Chapman, Norfolk Cetacean Recorder and Sea Watch Foundation Regional Coordinator.
Fin whale facts
Scientific name: Balaenoptera physalus
Description: The fin whale, Balaenoptera physalus, is the second largest of all whales. In the northern hemisphere, females are from 20-24 metres, and males from 18.5-22 metres in length. In the southern hemisphere, both sexes grow ca. 1-2 metres larger. At close range, a distinctive feature is the lower jaw, which is white on the right, but black on the left. The baleen plates are black, with exception of the front third on the right side, which is cream-coloured or white. The body colour is a uniform slate grey, with a light grey, V-shaped chevron across the back behind, and a “blaze” on the right side of the head. Fin whales have a slender head, which looks V-shaped and flattened from above with a single prominent median ridge. They have a relatively small, backwards pointing dorsal fin with little curvature situated one-third from the back. The tail flukes are not usually shown when diving. The blow is tall (4- 6 m high) and shaped like an inverted cone.
Distribution: The species occurs worldwide in mainly temperate and polar seas of both hemispheres. In the eastern North Atlantic, it is uncommon, occurring mainly in deep waters (200-4,000 m depth, particularly around the 1,000 m isobath) from Iceland and Norway south to the Iberian Peninsula, and east into the Mediterranean (particularly the Ligurian Sea). In northern Europe, fin whales are most frequently seen in the Norwegian Sea west of Norway, north and west of Scotland (particularly south and south-east of the Faroe Islands in the Shetland-Faroe Channel), off Southern Ireland east into the St George’s Channel, and across the Bay of Biscay. Most sightings in coastal UK waters come from the Shetland Islands, Outer Hebrides, SW Ireland and in the Celtic Sea between southern Ireland, West Wales and SW England. Although fin whales in polar seas may undergo a seasonal latitudinal migration, remaining there only during summer months, those further south around the British Isles appear to be present year-round. Most sightings in northern Britain occur between June and August, and in southern Britain between September and February, and there is some indication from sightings observations that fin whales make a general northward movement off NW Scotland from June to October.
Diet: Fin whales feed mainly on planktonic crustacea (mainly euphausiids such as Meganyctiphanes norvegica but also copepods), but they also take fish (e.g. herring, capelin, sandeel, mackerel and blue whiting), and cephalopods. A relationship between fin whale distribution and Meganyctiphanes abundance has been demonstrated in the western Mediterranean The animals may use a variety of feeding methods ranging from engulfing prey from behind by distending the throat grooves and taking a large gulp of water and prey, to side- and lunge-feeding which may involve some herding of the prey into a tight concentration.
