Reaping the rich harvest of the deep

A coincidence of neap tide and placid sea, with the promise of a dry, sunny dawn, tempted us to take out the long-line, replenish the rusty hooks, and stretch it overnight between anchors in the surf - mere wavelets, as it turned out.

In more self-sufficient days we did well from the line (more properly, the spillet), often trudging back across the strand with a heavy bag of ray wings for the freezer. This was one of the other times, but we still ended up in credit. Three of last year's mackerel went to bait the hooks and what we got in return were two dinner-plate-sized turbot and a couple of flounders, undersides flashing in the 6 a.m. sun.

A genteel enough catch, which suited us: a big haul of thornback ray, half a metre across, could mean a long and gory session on our knees. If a mere two per cent of Europe's housewives now feel confident of filleting a thoroughly dead plaice from the fishmonger, a long line of flapping thornbacks with reproachful crocodile eyes would surely send them all screaming from the shore.

As stocks of "traditional" fish decline, the steady separation of food from its origins in nature has opened the way for a whole new range of species to be processed into ready-to-cook, generically fishy products. At a Year of the Ocean conference in Dublin Castle in 1998, a workshop panel tasted 23 species of fish, including sharks, trawled from depths of up to 2,000 metres in the Rockall Trough. A few had the whiff of ammonia; others had too many bones. But about half were preferred to cod as fillets, nuggets and fish-cakes.

One highly-rated species was "orange roughy", otherwise Hoplostethus atlanticus, a short, deep-bodied fish that hunts other fish and crustaceans in dark and bitterly cold water on the steep slopes of the continental shelf. Typical of its group, it grows and matures very slowly and then lives a remarkably long time - 70 years or more - in a habitat where change works to an entirely different pace from that on land or in shallow seas.

The late and sparing reproduction of the orange roughy makes it especially vulnerable: trawlers can scoop up more fish in a short time than the species can replace. At the end of one decade of big catches off New Zealand, 90 per cent had disappeared and there is still no sign of recovery.

Nonetheless, the fish is on the target-list of "non-quota" species, free of EU restrictions, together with round-nosed grenadier, forkbeard, moro mora, bluemouth, argentine, alfonsino, silky shark and other novelties. Some 50,000 tonnes of deep-sea fish were taken off the west of Ireland last year, and this summer a team of seven Irish trawlers, directed by BIM, is tracking down their densest concentrations. In the Government's whitefish renewal programme, skippers will be expected to include at least 30 per cent of the new fish in their catch, in competition with French, Spanish, Norwegian and Scottish deep-water fleets.

If little enough is known of reproduction rates and stock recruitment among the new species, even less can be predicted about their role, as predators, in the structuring of deep-sea ecosystems. Along with the over-0fishing that seems all too inevitable, the physical battering of the sea-bed by blindly-directed trawls could damage some of the most fragile habitats on the planet.

A new "state of the ocean" appraisal by the Oslo Paris Commission, Ospar, which monitors the health of the North-east Atlantic, has sounded special alarm about the uncontrolled fishing of deep-water species. Their sustainable management, it says, "is particularly difficult", to which our own Marine Institute, actively involved in the research since 1992, would have to agree.

The sheer expense and technological demands of research at such great depths is allowing catching to go ahead in the absence of adequate knowledge.

We need protected areas in the deep waters of the Irish shelf, especially around the reefs of cold-water coral that act as such vital hubs of the ecosystem. Inshore, too, we need science to prevail over politics in the conservation of permanent "nursery" areas. Zones of specially rich diversity, already marked out around the Irish coast by the BioMar survey, should be undersea equivalents of national parks and wilderness areas.

Meanwhile, back in the sandy bays, conservation-conscious sea anglers (who tag their "sports" species and put them back) have been noting some unusual declines. In Kerry, for example, the undulate ray - a southern species - seems to be vanishing from Tralee Bay, together with the monkfish (the true "angel shark", that is, not the splendidly hideous angler fish, whose tail bears that name on restaurant menus).

The most important sea-angling species in Ireland is the silvery, hard-fighting bass, a long-living, slow-growing, sub-tropical fish which is at the northern fringe of its range around these islands. It spends winter in schools in the Celtic Sea and then disperses around the Irish and British coasts as the water warms in spring and summer. Temperature, indeed, seems to have a lot to do with the level of its stocks.

In the eating-out revolution of recent decades, the high restaurant value of sea bass stepped up the inshore fishing pressure. Collapsing stocks forced a whole battery of regulations in the early 1990s in an attempt to extinguish commercial fishing altogether and save the fish for tourist sport. Even anglers have been rationed by a conservation bye-law to catching two bass in 24 hours.

Apart from creating a thriving clandestine trade in the fish, what has been the effect? In the mid-1990s a the belief among Irish inshore commercial and sport fishermen that the bass were back in strength in the south coast estuaries prompted a special study by the Marine Institute's Edward Fahy. His report finds the revival real but temporary - a spell of specially warm summer seas around 1990 had boosted recruitment and growth of juvenile fish. Since then, Dicentrarchus labrax has gone back to its fitful reproduction and slow-growing ways.

Eye on Nature is edited by Michael Viney, who welcomes observations sent to him at Thallabawn, Carrowniskey PO, Westport, Co Mayo. e-mail: viney@anu.ie. Observations sent by e-mail should be accompanied by postal address.