SEAL FACTS

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There are two species of seal resident in the U.K. and most of those live around the Scottish coast and islands. These are the grey seal and the common or harbour seal.

Other breeds of seal do make occasional visits to Scottish waters and, although no accurate figures are kept, it is thought these incidents are becoming more frequent as several injured non-native seals have turned up at sanctuaries in the last few years. These have included bearded, harp, hooded and ringed seals as well as the odd walrus.
This could be due to changes in sea temperature, diminishing food sources forcing seals to hunt further afield or disturbance from marine fish farms.

Our largest native seal is the grey seal (Halichoerus grypus). Its smaller resident cousin is the common seal (Phoca vitulina).

Male grey seals can grow to 3.3m long and weigh up to 315kg. Females average 2.5m and reach 200kg. However, as with many species, the females usually outlive the male. Grey seal females can live as long as 46 years while bulls are lucky if they see 35.

Common seal males can reach 1.85m in length and tip the scales at 105kg while females are about ten centimetres shorter and twenty kilos lighter. Like the greys it is the female common seal which is likely to outlive the male with a maximum lifespan of around 25 to 30 years.

Apart from size you can distinguish between grey and common seals by the shape of their heads and faces. The grey seal has a prominent "roman" nose with nostrils which are fairly wide apart. The common seal has a rounder, flatter face with narrower nostrils. When you see a common seal's head as it swims towards you, you might mistake it for a large dog.

If you listen to fishermen's' tales, you might think there are millions of seals and that they produce vast litters of pups every year. In fact seals only produce one pup a year with greys giving birth between September and December and commons during the summer months of May to July. Seal numbers are recovering from years of human persecution and the first seal virus epidemic of 1988.

The best estimate on UK seal numbers comes from the Marine Mammal Research Unit. They estimate that in 2000 there were around 120,000 grey seals in British waters, which, at nearly half the world population, should make them a priority for protection. The common seal is not so common around Britain and our waters are home to about 36,000 from a global population of circa 500,000.

The big question is what do seals eat? The short answer is that they eat quite a lot! They have to to maintain their size and keep a good insulting layer of blubber to protect them from the cold. Fishery interests, depending on which branch you speak to, know all about the diet of seals. Ask a salmon netsman, angler or farmer and he or she will tell you seals eat salmon. Ask the master of a white fish trawler and you will learn that seals eat nothing but prime cod, halibut and pollock. Have a word with the lobster catcher and low and behold you discover that seals don't bother catching fish they just pinch the stinking bait out of lobster creels.
The reality is that seals eat fish, just about any fish they can catch. However scientific research indicates that they make no real difference to commercially sought fish stocks. The prime consumers of fish are…… fish! Every fish a seal eats might eat thousands of fish during its lifetime. Seals eat eels which in turn eat the eggs and young of other fish including salmon and sea trout.

Despite seals having a rather limited diet (they only eat fish) they are fourth in the fish-eating food chain, coming after fish, birds and humans. Seals are part of a complex food chain which would find it's own natural balance if it was not for the fact that humans, for every fish they keep, destroy hundreds of small fish (before they can reach breeding age) and non-target fish. We also catch around four tonnes of wild fish to produce every tonne of farmed salmon!

Contrary to popular belief the seal is not at the top of the marine food chain around our coasts. Orcas (the proper name for "killer" whales) often call in for a seal supper. In Shetland the Orcas catch seals close to shore and tourists go to see this example of nature in the raw.

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