Another Life: Seals thrive where tangle nets offer easy and meaty takeaways
But the same nets also snare and drown seals, especially inexperienced juveniles
Grey seal: a protected species under EU habitats directive. Illustration: Michael Viney
One summer long ago, before Charles Haughey annexed its solitude, I had myself cast away for three weeks on Inishvickillane in the Blaskets, an island then shared by storm petrels, shearwaters, puffins and sheep. Catching fish for food was part of my plan, and the deep crystal waters of the landing cove offered promise of pollack. With camp set up above the cliffs, I had a fish on my hook within minutes. But, reeling it in, a sudden, gleaming shape engulfed it underwater, leaving a limp and empty line.
What worried me more than the theft of the pollack was the grey seal’s consumption of my spinning bait, a heavy twist of silver metal ending in three sharp hooks. This was now somewhere in the animal’s gullet, and while I had a few replacements, feeding them to seals was unthinkable. Enough black labrador heads gazed hopefully up from the water to confirm that fish was off the menu for the rest of my stay.
Even fresh from the sea, pollack is not quite a match for the taste of cod or haddock. But as we empty the ocean of edible fish, even such modest inshore species are in growing demand. Uptake of the Irish pollack quota, currently 1,030 tonnes, remains high. Most of the fish are caught in gill nets set off the west and southwest coasts on difficult, rocky ground or near wrecks, but the risk of net damage is now exceeded by the loss of catch to the powerful jaws of Halichoerus grypus (rón mór or grey seal).
Counting the netted, bitten fish along with those snatched from the meshes, an expert estimate of annual cost reaches up to more than €1 million – almost equal to the catch’s actual value at the quayside. Like colleagues setting gill nets for hake, or tangle nets for monkfish, the pollack fisherman’s enmity for seals, therefore, has never been more bitter. Once it was the toll on inshore gill-netted salmon that dramatised the perennial feud; now, it ranges far into the deeps.
The average visible damage from the seals – 18 per cent of pollack, 10 per cent of hake, 59 per cent of monkfish – is estimated in a survey for Bord Iascaigh Mhara by a seven-strong scientific team drawn also from the Marine Institute and UCC. It spent 91 days at sea to observe 358 hauls of more than 1,000km of gear and while its report uses such headings as “Zero inflated negative binomial model of depredated pollack”, it also offers much practical advice.
Fishermen will welcome the recognition that the economic impact on inshore netting “may have increased substantially”. Less pleasing, perhaps, will be the obvious conclusion that, like increases in seabird species that swoop on fish discarded from trawlers, seals are thriving where set nets offer easy takeaways. The largest increases in local seal populations, such as those on Mayo’s Inishkea Islands and the Blaskets, match areas with most tangle nets set for crawfish. Seals munch on the meaty tails of monkfish caught up in the big, loose meshes of tangle nets, especially those left set for long periods. Indeed, many tangle-net trawlermen have written off the damage to monkfish against the gourmet premium of the crawfish. But tangle nets snare and drown seals as well, especially inexperienced juvenile males. In the 91 sea-days of the BIM study, one tangle-net fishery off Mayo drowned most of the survey’s total of 58 grey and 10 harbour seals.
While it’s true that many grey seals don’t survive their first year anyway, they are a protected species under the EU habitats directive, and the study team urges smaller meshes and higher visibility for tangle- nets. And since the seals bite at so many pollack as gill nets are being hauled in, more hands on deck to clear the meshes should allow faster retrieval and a smaller loss.
Natural controls on wildlife populations are the available habitat, food supply, disease and predation. Even globally, wild predators on seals are remarkably few – polar bears in the Arctic, the bigger sharks and killer whales. Historically, humans readily took on that role for human benefit, but changing needs and social mores have largely ended it. YouTube offers a much-visited video of killer whales – orcas – riskily seizing leopard-seal pups from a lonely beach in Patagonia; perhaps, indeed, the most unforgettable piece of mammalian predation ever filmed.
The Irish Whale and Dolphin Group notes that “grey seal colonies feature strongly on the list of Irish killer whale ‘hotspots’” but so far backs the consensus that orcas in Irish waters are mainly fish-eaters. The whales vary from region to region in their eating habits, and while a Scottish group has been filmed attacking harbour porpoises in the Hebrides, those off Ireland have been seen on trawler sonar hunting the same shoals of mackerel and herring.