Shark's fin soup has a lot to answer for

ANOTHER LIFE:JUST north of Quilty, at the southern edge of Liscannor Bay, in Co Clare, is a green-topped islet that you can reach by scrambling over the rocks at low tide. Perched upon it, the experienced shore angler, able to cast half a mackerel up to 150m, may connect with a blue shark or even a porbeagle, thereupon to battle – jaw jutting, feet spread – heedless of the tide swirling in behind him.

Such fantasies have nurtured Ireland’s growing sport-fishing industry, helped along by photographs on the charter-boat websites offering easier ways of catching deep-water sharks, and even releasing them again.

Fantasies are also fed by the odd awesome memento of classic encounters of the past. In the front bar of Achill Head Hotel, in Co Mayo, for example, you may admire the trophy head of the big porbeagle caught by Dr O’Donnell-Browne in 1932, its 166kg still the Irish record for the species.

It’s all a different scene from the commercial slaughter that kills up to 73 million of the world’s sharks each year, much of it to satisfy the rising demand in China for glutinous and expensive shark’s fin soup.

At this spring's big conference of the Convention on International Trade in Endangered Species, the grossly overfished porbeagle ( Lamnus nasus) was one of the sharks finally granted protection, only to lose it in a plenary vote as part of a manoeuvre that Japan led in order to protect its trade in the even more endangered blue-fin tuna.

In European waters, at least, the severe persecution of the porbeagle, mainly for meat for Continental markets, with the fins as a bonus, has been halted, but not before its numbers have fallen by an estimated 90 per cent from its virgin population of half a century ago.

A separate population in the northwestern Atlantic, largely off Canada, is at the very beginning of recovery after a second collapse of its fishery had left very few large sharks and even fewer females.

No signs of recovery have yet been found on this side of the ocean, bringing extra urgency to research by marine scientists in Ireland and Britain.

There are still big gaps in our knowledge about a big ocean predator we have fished out in the North Atlantic almost past the point of no return. Like most sharks, the porbeagle has a potentially long life, grows extremely slowly, matures late and has few young.

It’s this month that brings porbeagles inshore off the south and west of Ireland, where the females give birth to just four pups, fruit of a nine-month gestation. An Irish science team, led by the Marine Institute’s Dr Maurice Clarke, is hoping to tag large adult females to find out the location of the shark’s birthing grounds. (Protection of these is part of the Canadian conservation plan.)

The use of pop-up satellite telemetry has already helped to picture more of the life of the porbeagle – its chosen depths, habitats and travel patterns. A British led-study showed how the sharks’ summer gatherings in heavily fished coastal waters make them vulnerable as a by-catch for long-line fisheries.

In 2008 the Marine Institute team, helped by expert shark angler Peter McAuley, tagged three sharks off Downings, in Co Donegal, and tracked them through nine months of swimming. One young male migrated more than 2,400km to winter off Madeira. Another travelled to the Bay of Biscay, a hot spot for other big predators, such as albacore tuna.

Global long-line fishery, either baited directly for sharks or aimed at tuna, swordfish or other species and catching oceanic sharks by chance, is exacting a catastrophic toll on top-of-the-food-chain predators essential to the balance of ocean ecosystems.

To find that the principal cause of this decline is human consumption of a culturally prestigious soup almost beggars belief. So does the common fishery practice of hacking the dorsal fin from sharks and heaving them overboard, often still living but unable to keep swimming and therefore to die.

Shark’s fin itself is a slippery taste of nothing much, but it intensifies the flavour of other marine ingredients simmered and reduced with it for hours. As a prized luxury food for wedding feasts and corporate dinners, the soup can cost up to €80 per bowl, which gives the largest fins (even the basking shark is not immune) a value of up to €1,000.

A recent report on the shark-fin industry by Oceana, an international marine conservation organisation, found Spain the leading contributor to the nearly 10 million kilos of dried and frozen shark fins imported into Hong Kong, the world’s largest single market for them, in 2008. Among the leading species are the blue shark, a common by-catch of tuna and swordfish long-liners from Spain, Japan, Korea and elsewhere. Slowly migrating around the Atlantic, they are due any day now within casting distance of that little island near Quilty.

EYE ON NATURE:

I was distressed to witness a vicious swan fight on the Cong River. A cob, father of seven cygnets, crossed into the territory of another swan family of six and violence ensued for an hour. I have never seen birds so aggressive.

The two cobs were exhausted, and the pen made several attempts to keep the intruder’s head under water. Eventually, staff from a nearby hotel, with the aid of a boat, carried the trespassing cob back to his area. But, on release, he immediately went back up again.

Pádraic Breathnach, Limerick

At the end of May I noticed that the tadpoles in my pond had started to grow legs. How long more will it take until they develop into frogs totally?

Malachy Daly, Killadoon, Co Mayo

The metamorphosis of the tadpole should be complete towards the end of June or the middle of July, depending on conditions.

I was tending to my allotment when I saw an earthworm that had a white maggot firmly embedded in its side. Was it a parasite or a predator?

Adam Trodd, Stepaside, Dublin 18

It sounds like the larva of the cluster fly, which tunnels into earthworms and feeds on them.

Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo. E-mail viney@anu.ie. Please include a postal address