Stocks of wild Atlantic salmon are at their lowest ever levels 鈥� and unless countries agree stringent measures to protect stocks, wild salmon will disappear from many rivers in the US and Europe, says the Worldwide Fund for Nature (CHECK).
鈥淚n many countries, salmon populations are hanging on by a thread,鈥� says the WWF鈥檚 Elizabeth Leighton. 鈥淓ven in Scotland, where the situation is relatively healthy, there are some rivers that are seriously threatened by extinction for the first time in history.鈥�
Global wild Atlantic salmon catches have fallen by more than 80 per cent between 1970 and 2000. Salmon farming, habitat degradation and a mysterious rapid decline in sea stocks are primarily to blame, says Leighton.
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Philip Smith, an expert on wild salmon at the Southampton Oceanography Centre, UK, says: 鈥淚t鈥檚 certainly right to say there is a serious problem, and if you look at the catch statistics, the situation looks pretty catastrophic.鈥� But, he warns: 鈥淚t is impossible to generalise across rivers. For some, there are serious concerns. But others are doing okay.鈥�
WWF figures show that the populations of one third of salmon rivers in the UK are endangered. 鈥淎nd in the US, where salmon are left, we are counting very small numbers,鈥� says Leighton. 鈥淓ven if we put big efforts into attempting to save these populations, it鈥檚 questionable whether they would be successful.鈥�
Wild salmon populations are almost non-existent in much of continental Europe. But this is a century-old problem, says Smith. Industrial development in the 19th century polluted rivers so heavily that salmon stocks were almost eradicated.
The decline of ocean stocks is of most concern, say both Leighton and Smith.
鈥淭hroughout the north Atlantic, stocks have declined by about 50 per cent since the 1980s,鈥� says Leighton. 鈥淚t is not known how much of this is down to a natural cycle in fish stocks, which does exist, or to climate change and pollution.鈥�
鈥淭he marine decline is the big mystery,鈥� Smith agrees. 鈥淢uch more research is needed to understand the cause.鈥�
For wild salmon that do manage to reach rivers, salmon farms are a major threat. Sea lice thrive on closely packed farmed fish and are picked up by wild salmon. Escapees from fish farms also interbreed with, or replace, wild stocks.
Other problems include pollution from agriculture, a lack of shade-providing trees on river banks, and excess silting. But 鈥渢he number one issue is aquaculture,鈥� says Leighton.
Countries participating in the North Atlantic Salmon Conservation Organisation (NASCO) conference in Spain in early June must agree improved measures to control salmon farming, she says. 鈥淣ASCO is quite influential. If the countries at the table can come up with a code to control fish farms that everyone can sign up to, that would be a strong step forward.鈥�
The UK has made major efforts to protect stocks. Salmon anglers have been issued with strict quotas on the number of fish they can kill, and measures to reduce sea catches have been introduced. 鈥淲e applaud these efforts,鈥� says Leighton. But she calls for greater international co-ordination of conservation efforts.