The Private Life of Cornish Seals by Sue Sayer
17th October 2009
Around 35 members were treated to a fascinating evening on Saturday, 17th October 2009 at Gweek Village Hall, when Sue Sayer of the Cornwall Seal Group spoke with great enthusiasm on The Private Life of Cornish Seals, illustrating her talk with a large number of photographs, drawings and video clips.
Most of the seals around this coast are Grey Seals, one of the rarest of seal species and the UK’s largest land-breeding mammal, averaging 2.3m in length and weighing around 230kg. Common Seals, which are smaller, with different head shape, nostrils and patterns, are rare in Cornish waters, with only 14 sightings since 2001. Grey Seals can be found in the eastern USA and around the coasts of Greenland, Iceland and Scandinavia, but the UK has 40% of the World’s Grey Seals, mostly around Scotland but with Cornwall being one of its strongholds and a hub for movements to France, Wales and Ireland. The Cornish seals are genetically different from the Scottish ones. Seals have to haul out on beaches and rocks to moult, breed, rest and digest their food. If disturbed by humans, for example by noise or leisure craft, a panicked return to the sea can be harmful, particularly for pregnant females. Consequently they are studied from a distance, using binoculars and telephoto lenses, and their favoured haul out sites are kept secret to minimise disruption. Some sites may contain over a hundred seals.
Each Grey Seal has a unique fur pattern of spots, blotches and irregular shapes which has enabled the Seal Group to compile a data base of 700 animals and thus chart their movements around Cornwall and beyond, as well as recording parentage of the offspring. Colours range from white through creamy, grey and chocolate to black. Males tend to be dark and females paler and more spotty. Moulting occurs in the Spring and breeding peaks in October, on beaches where a dominant male ‘beachmaster’ is the sire. A seal pup is suckled for 18-21 days, rapidly becoming larger and fatter, and then left to fend for itself. Mating occurs shortly after birth, but the fertilised egg remains dormant until the female has regained strength and is then implanted. With about 9 months of gestation the birth cycle becomes annual.
The audience were amused and impressed at the imagination shown in name selection based on the fur patterns!
Powerful shoulders and claws enable seals to haul out on steep slippery rocks and, if necessary, to move with considerable speed across the beach. In the water the animals are flexible and agile, swimming by sideways movements of the rear flippers and reaching speeds of 4km per hour. They can dive to 70m for up to 12 minutes. On returning to the surface, muscles open the nostrils to breathe. They can sleep in the sea, either vertically (‘bottling’), or horizontally (‘logging’). When bottling, seals sink between breaths. A reflex twitch of the rear flippers returns them to the surface for the next breath. The food for Grey Seals consists of sand eels, cod, other white fish, plaice and other flat fish. However, they learn that easier meals are obtainable by following boats for jettisoned fish and food waste and this can create problems between the boat owners and the animals. Being naturally curious, seals will explore old discarded nets and can become entangled, occasionally, also, in current working nets. At present about 65 seals in Cornwall live with entangled netting.
The Cornwall Seal Group collaborates closely with British Divers Marine Life Rescue and the National Seal Sanctuary to locate and rescue animals in distress, for example because of net entanglement, oiling or injury. A dated information tag attached to the rear flipper of a released animal provides a further means of identification in future sightings. Seals can live 20-30 years in the wild and up to 40 years in captivity.