Will farms keep fish on our dinner plates?
Aquaculture is overtaking traditional fishing in global production, the United Nations Food and Agriculture Organisation (UNFAO) reported recently. But a scientist with the organisation predicted that growth would slow as space for the food farms dwindled and concerns grew about their effects on the environment, reports www.megafishnet.com with reference to Hawaii Oceanic Technology Inc.
Fish farming is the fastest growing area of animal food production, having increased at a 6.6-per-cent annual rate from 1970 to 2008, the agency said in the report. Over that period, the global per-capita supply of farm-raised fish soared from 0.7kg to to 17.8kg.
In volume, aquaculture now makes up 46 per cent of the world's supply of consumed fish, and the sector appears to have overtaken wild fisheries in commercial value, reaching US$98.4 billion in 2008, compared with US$93.9 billion for fish caught in the wild.
"In terms of capture fisheries, we've now more or less peaked" at a current harvest of 90 million tons for fish caught in the wild, Dr Kevern Cochrane, director of the UNFAO's resources use and conservation division, said.
But fish farms will also run into limits, he warned.
"We're going to run into constraints in terms of space availability, water availability - particularly fresh water - and also environmental impacts and supply of feed," Dr Cochrane said. "Growth is not sustainable indefinitely at that level and we are currently seeing a reduction in the annual rate of increase."
The challenge for fishing countries will be to ensure that traditional fishery production is sustained at current levels without depleting stocks, he said.
About 32 per cent of world fish stocks are overexploited, depleted or still recovering and need to be urgently rebuilt, according to the report. Nonetheless, aquaculture has enabled people to eat more fish, it said, and annual fish consumption had risen to a global record of almost 16.8kg per person.
Countering Dr Cochrane's predictions, Mr Wally Stevens, executive director of the Global Aquaculture Alliance, a trade association, said that the industry's goal was to increase its annual output.
"Our attitude is that aquaculture production must double in the next 10 years to keep pace with global demand, and in particular the changes in demand coming from growth in middle-class populations in developing nations," he said.
Fish can be raised in tanks and ponds, and - with the aid of cages or nets - in oceans, lakes or rivers. With most of the world's traditional wild fisheries operating at the maximum yield at which stocks can be sustained - or even above - aquaculture is seen as the only way to increase the supply of fish in a world hungry for protein.
China, which raises freshwater and marine species including carp, tilapia, sea bream and sea bass, now accounts for 62 per cent of global farmed fish production.
That nation and some of its Asian neighbours have gone a long way toward fully developing their aquaculture potential, Dr Cochrane said, while other regions, particularly Latin America and Africa, still have significant room to increase output.
Many scientists have been critical of the practice of harvesting wild ocean species - often small fish like anchovies - to provide fish oil and fish meal for farmed carnivorous fish like salmon and tuna, arguing that it is an inefficient way of producing protein. From an environmental standpoint, it would make more sense for people to eat the anchovies directly, these scientists say.
Just over 80 per cent of all wild fish caught are intended for human consumption, the report said, with the remainder used mainly for fish meal and fish oil and in pharmaceuticals.
Dr Cochrane said his agency's position on feeding wild fish to farmed fish was that"as long as the fisheries are conducted in a sustainable and responsible manner, it's up to the countries".