ON FLATFISH FARM CAN FISH BE FARMED AS POULTRY NOW ARE?

Press, Volume CX, Issue 32210, 31 January 1970, Page 10

ON FLATFISH FARM CAN FISH BE FARMED AS POULTRY NOW ARE?

(Reprinted from the “Iconomist")

Britain’s 1100 trawlers are running out of fish to catch. The tonnage landed in 1970 is expected to be 10 per cent down on last year—and the same goes for Iceland and Norway. And for the last year the sardine canneries in Portugal and the massive fish protein plants in Latin America have been ticking over waiting in vain for the rich catches of the past Every year bigger and more elaborately equipped fleets chase fewer fish and as returns diminish it is being realised that the oceans are no longer the unlimited reserve of food they were long assumed to be. In the last decade whales have been hunted to near extinction; the same could be hanneninonow with white fish, just as with herring.

The fishing industry has previously consoled itself with the thought that if things z got too bad it would be possible to breed fish in captivity and release them in their thousands to grow in the sea and repopulate the depleted fisheries. This turns out not to be so. The mortality of the young fish has turned out to be prohibitively high: 30 per cent of the small fry released into the Irish sea in a pilot scheme a few years ago died in their ' first month. Grandiose schemes for raising large numbers of fish this way were quietly buried, for, apart from losses, it was discovered that to breed fish in tanks and then release them into the sea merely added an extra load of breeding expenses on to traditional fishing costs. Japanese Technology Now the idea of restocking the oceans has been replaced by something run much more on the lines of the ordinary land-based stock farm, where the fish are confined within farm boundaries all their life. And this is a concept the fishing industry will find it hard to live with. Fresh water fish, carp, trout and the like, have been fanned in ponds and tanks since the Middle Ages, but it was only at the turn of the century that the Japanese began to raise marine fish. They now lead the world in fish farming technology, with five government - sponsored farms and many private ones that grow more than 500,000 tons of oysters, prawns and flatfish in the Inland Sea and on old salt farms. In Britain most of the work has been done by the White Fish Authority on a tiny budget that allows only £40,000 a year for research. But the authority has brought several projects almost to the marketing stage and, encouraged by this work, Unilever has be gun a farm of its own close by the authority’s in Inver-ness-shire. The Right Fish Much of the research has gone into finding the right fish to farm. There is a big market for lobsters, but they grow too slowly and, as they eat one another, cannot be kept in high concentrations. Herring, cod and salmon are difficult because they are long-distance swimmers by nature and become distraught in captivity. Flatfish, on the other hand, are astonishing; they grow quickly and, being rather

placid, burn up little energy swimming around. They live in captivity at a density well over a thousand times as high as they do under natural conditions. Plaice, sole and turbot will thrive, crowded five to the square foot, and so far without outbreaks of disease. They are said to be perfectly palatable, too. In experimental tanks using the warm water effluent of the Hunterston nuclear power station, plaice have been grown to a marketable size within 18 months, half the time it would take in the open sea. Hunterston pours out 300,000 gallons of seawater a minute from its cooling towers at a temperature around 16 degrees centigrade. At the moment only a small amount of this is passed through the fish tanks where the plaice grow rapidly, stimulated by the warm waiter and fed at an accelerated rate. Quick Growth Likely If needs be, there is enough warm water discharged from Britain’s power stations to raise sufficient fish to supply approximately a quarter of the home market, equivalent to the catch of 250 trawlers. There is no sign that farms will be established at this rate, but intensive fish farming could grow very quickly once a few remaining problems are sorted out There are no predators, mortality rates are low and actual catching costs are nil. The fish can be grown close to the market and supplied as demand dictates with no gluts and considerably fresher fish. Transport and storage are greatly simplified. It might even be possible to farm fish right betides the main markets using the effluent of, say, London’s Battersea power station and the water of the proposed Thames barrage.

But on the debit side the cost of building and maintaining the tanks is at this moment high, even though the tanks will probably be replaced in time by an arrangement of larger paddocks along the shoreline constructed out of nets or conceivably even fences of air bubbles. The heavy cost of feeding the fish is the bigger snag. Almost all fish are carnivorous and.* farm has to rely ultimately on an ocean eaten for its feed. This could make the exercise at least partially self-defeating and experiments are being made to convert the fish to a vegetarian diet. On The Range Range farms are one way of cutting costs. Young fish, artificially raised, are re-

leased into an enclosed range of several acres like a loch or an inland sea, which is then stocked with a certain amount of food. Costs are proportionately lower, but mortality is higher and the fish take longer to grow to a marketable she. At the moment it is too early to say which system is better. The Japanese use each with profit and both the ’White Fish Authority and Unilever have begun to experiment with open range farms. But the most developed and profitable fish farms grow shellfish. Oysters and clams do not swim away and, since they eat plankton, do not need to be fed. Costs consist of sowing, thinning and cropping the farm beds. The market is huge and the profits are good. But Britain, again, has been slow off the mark. A hundred years ago oysters were, with tripe, one of the cheapest foods available in Britain. Pollution and disease have reduced the annual crop to a mere 5 million oysters and even this depends on young oysters imported from the continent. It is this lack of new stock that has bogged down the industry. A N.Z. Strain The White Fish Authority has now developed a regular supply of young seed oysters and isolated a particular New Zealand strain that is fast growing and hardy. From its hatcheries in North Wales, the authority estimates that it could establish a supply of 100 million oysters a year. The market is certainly there: in France where oyster farming is well established the crop is three times this size already. With modern techniques for keeping down disease and predators, an oyster can be grown on a cultivated bed within two years; twice the normal rate. But the oyster growers in Britain seem confined to a tiny luxury market and apparently have not gone after the huge demand in the tinned, frozen and export markets. The established fishing industry, which pays for all this work, now feels threatened and is naturally distrustful. It can hardly be expected to embrace with enthusiasm a technique that threatens so much of its investment with obsolescence. It seems sensible that other food-processing industries, with more to gain from the work, should now assume responsibility for sponsoring this aspect of the White Fish Authority’s work. They would be likely to get things moving much faster than the trawlermen would want to do.'