MORE than 10 years after its closure, Canada鈥檚 Atlantic cod fishery is showing virtually no sign of recovery. Fisheries experts now think they know why 鈥� if they are right it may already be too late to save Europe鈥檚 cod stocks from a similar fate.
The cod fishery on the Grand Banks of Newfoundland and adjacent waters was once among the world鈥檚 richest. But persistent overfishing in the 1980s led to a crash in stocks, which bottomed out at just a few per cent of their long-term averages. In 1992, fishing was banned until stocks recovered, which scientists expected would take 5 to 10 years.
Yet cod stocks have at best increased by less than a fifth in some places, and have fallen further in others. 鈥淲e have learned depleted stocks are much less productive than healthy stocks, and if you predict recovery times based on what you know about healthy stocks you will be over-optimistic,鈥� says Jake Rice, chief science adviser to the Canadian Department of Fisheries and Oceans. That misplaced optimism led Canada to prematurely resume fishing.
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One problem, Rice explained to the annual scientific conference of the International Council for the Exploration of the Sea in Tallinn, Estonia, this week, is that scientists assume a certain tonnage of mature cod will produce a certain tonnage of surviving offspring. But Canadian scientists have confirmed that depleted stocks, which are composed mainly of young fish spawning for the first time, are much less productive.
They are also very vulnerable to predators. The natural mortality rate of three to five-year-old cod has more than doubled since the fishing ban.
The twin pressures of low production and doubled predation mean that five years was far too short a time to allow fisheries to recover. Yet the Canadian government provided financial aid to coastal communities for only five years. When the money ran out, pressure to resume fishing became intense and the government allowed small catches from depleted stocks even though there had been hardly any recovery.
The aid had been used to retrain fishermen in other fields, such as electronics, but when the fishing resumed they used their training to improve their boats with electronic equipment such as GPS satellite navigation, which allows fishing in fog, adding weeks to their time at sea. 鈥淲e retired 20 per cent of the boats, but fishing efficiency increased 160 per cent. They took all or more of what little increase in stocks there was,鈥� says Rice. Fishing the stricken stocks was once again banned this year.
A similar picture appears to be emerging in Europe (快猫短视频, 27 January 2001, p 16). A three-year recovery plan has not increased cod stocks in the Irish Sea, scientists told the conference this week. Yet pressure from fishing communities is already leading to the plan being scaled back. The parallels with Canada are ominous.