Song of the grey seal

A full moon over Inishturk is the prize for getting up before dawn. With the wind in the north and the surf almost listless after its recent convulsions, the silence this side of the hill is the sort that rewards Carthusian monks with their minds on higher things.

Gazing out from my desk to the black silhouettes of the islands, a sound suggests itself to my imagination: not plain-chant exactly, but a meditative, antiphonal crooning that drifts through the autumn dark on the wilder islands of the west. I have listened to it on the Inishkeas and on neighbouring Duvillaun, where it carried even above the rush and rumble of gales.

It is the sound of grey seals gathered ashore to give birth, suckle pups and then to mate again. It's a feminine sound, mostly: a lullaby from mother to pup. But one hears it at other times, also, from seals hauled out together in hundreds at some sandy island cove, to moult and groom. Then it can seem aimless, a sort of mutual soothing. Grey seals live on both sides of the Atlantic and also in the Baltic, and seem to make very local choices about the best time of year to give birth. It seems perverse of our seals to choose the stormy months of autumn. In some seasons, a third or more of the pups - white-furred little barrels, fat with milk - are dragged off the shore by the waves, to starve or drown.

Yet the protection developed in Ireland and Britain has given the species a new, even flourishing, security. About half the world's 220,000 grey seals live in the waters around these islands and the British population has been increasing recently at about 7 per cent a year, adding perhaps 7,000 seals annually to the maritime community.

The really big breeding colonies are in the Outer Hebrides. Ten thousand gather at North Rona, and as many at the tiny Monach Isles off North Uist. The Irish colonies, by comparison, are very small. The largest single group of grey seals, perhaps 900 or more, use the Inishkeas and Duvillaun and other shores around the Mullet Peninsula.

A pup census in that area in 1994 suggested that the breeding population had remained remarkably stable for more than a decade. One suggestion is that the Irish colonies are small enough to be bossed and bullied by a handful of experienced bulls, forcing most young bachelors to go off to the "seal cities" of the Scottish isles to try their luck. There is also a return migration: recently, two juvenile seals accidentally caught and drowned in gillnets off north Mayo wore tags from the Monach Isles.

Fishermen and seals have been in conflict since Roman times, and today's complaints about grey seal damage and competition are part of a predictable resentment of protection. It is 16 years since the notorious clubbing of pups took place on the Inishkeas, and increasing reports of illegal culling have been reaching the Irish Seal Sanctuary, based at Garristown in Co Dublin.

The I.S.S., led by Brendan Price, has a surprisingly good relationship with inshore fishing communities: it has never, as he says, fallen into line with Britain's "seal-hugging conservation and welfare organisations, demonising and marginalising fishermen". It rejects the idea of culls until fisheries scientists can show their value, but also takes the side of the small inshore fishermen in their struggles to survive. It wants continuing protection for the seals, but also compensation payments for the damage they cause. It welcomes investigation into seal interaction with fisheries, but wants "independent" monitoring of the research.

A few months ago, Bord Iascaigh Mhara published the first instalment of its EU-funded programme of research, not only into the physical damage that grey seals do, but into their actual diet - the first Irish work of its kind. The research team, attached to UCD, have used the help of fishing boats from the little ports of north Mayo, fishing cod locally in spring, and bigger boats from Dingle sailing out to the Porcupine in summer to set nets for hake. The skippers kept records for the research team and sometimes carried observers.

Damage to fish in the nets is as much as 10 per cent, some of it caused not by seals at all, but by crabs and small crustacea. And, off North Mayo, the seals paid quite heavily for their take-away raids: in the three years of the study, 51 of them, mostly inexperienced yearlings or juveniles, were entangled and drowned in the nets.

Their stomachs have provided part of the data on diet. The rest has come from scats collected at the haul-out on Inishkea North - a "blind sample" not matched to particular seals of known age or sex. In both kinds of sampling it is the residual otoliths, or ear-bones, of fish, that allow scientists to identify the species consumed.

It's not a perfect method: salmon otoliths are fragile and don't survive; others shrink as they dissolve; cartilaginous fish like rays and dogfish don't have otoliths at all. The remains from a stomach are in better shape than from scats and are specific to a particular seal. But young "bycaught" animals are not a representative sample - hence the decision last spring to license one of the research team to shoot up to 45 grey seals a year, mostly along the north-west coast.

In the interim, the diets suggested by the two different sorts of samples have been strikingly different. The bones in the stomachs showed low numbers of whitefish, such as pollack and ling, and high numbers of non-commercial species, such as pouting, wrasse, sandeels, squid and octopus (whose beaks survive digestion). In the scats, however - a more plentiful material - the opposite was true, and the otoliths of cod, plaice and sole were found only in these samples.

Each day, a seal needs the energy provided by about 4kg of sandeels or 7.5kg of cod. But marine mammalogists are agreed that killing seals will not help declining commercial fish stocks to recover: only fishing controls or closures can achieve this. So far, the Irish research team, "reconstructing" the original fish lengths from the otoliths, find that seals may, indeed, be competing with the fishermen, but that they settle for considerably smaller fish.