In parts of Kerry and Clare, it is quite common for the purveyors of periwinkles to come into pubs selling bags of their produce accompanied by tiny pins to extract them from their shells. The English Market in Cork sells them too - but is this delicacy now being over-harvested?
When Gerry Gorman, a Co Louth-based seafood wholesaler, saw that suppliers were bringing him periwinkles which were at least 30 per cent undersized, he knew it was a classic sign of over-harvesting. He called in Dr Gavin Burnell, a lecturer in zoology and animal ecology at UCC. Specifically he wanted to know if periwinkles could be reared in a controlled environment until they had reached the right size.
Dr Burnell tried some feed experiments using various products, including seaweed. "The results were encouraging, but ultimately not very successful," he says. "We approached a Kilkenny-based commercial feed company called Red Mills, which produces feed for the bloodstock industry as well as for a wide range of other animals, including ostriches, land snails, trout and deer."
The result was a £60,000 applied science grant split between Red Mills and Forbairt. Rapidly it became clear that other species would have to be taken into the equation if commercial viability was to be assured. "So we looked at two other species - sea urchins and abalone, with similar herbiforous diets," he adds.
According to UCC, the statistics are pretty stark. There's a lot to be learned about the management of the Irish marine environment. Sea urchins have been over-fished. They are worth up to £20,000 a tonne here but are now very scarce. Having been almost fished out in European waters, abalone can command up to £40,000 a tonne in some markets.
When it comes to periwinkles, the drill is to take the mature ones and leave the smaller ones alone. When you get them home you soak them in fresh water. A bucket is best with a lid: they will crawl out of an unlidded container overnight. The periwinkle does not rate highly on menus but if properly managed, a huge commercial reward is there. Periwinkles vary in value from about £600 a tonne in summer to a high price of £1,500 in winter. Not the most valuable of seafoods, the volumes, nevertheless are large. The problem is that while up to 7,000 tonnes are picked each year in this country, one-fifth of that number is undersized and accordingly of little commercial value.
Taking immature periwinkles off the rocks is doing nothing for the survival of the species. If an extra 1,000 tonnes of periwinkles could be reared to their full weight, more than £1 million of new business could be generated each year. The UCC project is about putting together diets for the three species which can last in water over a period of two or three days, but which are attractive to the feeders.
The diet must also produce growth better than that achieved under natural conditions. Periwinkles, says Dr Burnell, are fussy feeders and grazers; a re newable protein with a seaweed flavour is needed for them.
Being a more exotic species, abalone and sea urchins will be receiving a more enriched diet as part of the experiment; the poor old periwinkle will get the bread-and-butter portion. But it started the entire project in the first place and it is the periwinkle whose social and economic potential will be studied as part of the UCC exercise. For this, the Cork-based university will involve colleagues in Galway.
The periwinkle is a delicacy worth preserving. In places like Kilkee, Co Clare, or parts of Co Kerry, like Listowel, the whole experience can be enlivened when the vendors offer dilisk, or dulsk, basically seaweed, to go with the delicacy. Bon appetit.