Grim outlook for fish as climate change makes waters warmer

AN ENVIRONMENTAL pressure group called for urgent action on global warming yesterday, after a report warned that fish populations in rivers, lochs and seas were being increasingly threatened by climate change.

WWF Scotland said rising water temperatures were leading to both marine and freshwater species raising fewer offspring, while food supplies dwindled and they were increasingly deprived of oxygen.

Its report warned that some temperate fish, such as salmon, would be unable to spawn at all if winter temperatures did not drop below a certain level.

Dr Richard Dixon, the director of WWF Scotland, said: "As climate change increases the pressure on fish populations, already strained to the limit by over-fishing, pollution and habitat loss, the outlook is pretty grim for our marine species.

"We must act urgently on both climate emissions and fishing to protect fish populations, as they are one of the world's most valuable biological, nutritional and economic assets.

"The Scottish Executive needs to take action to prevent the worst-case scenario for both our climate and fish. To protect the climate, they must set Scottish targets for reducing damaging climate change emissions. To protect remaining fish stocks, we should place further restrictions on fishing effort, in line with recent ICES [International Council for the Exploration of the Sea] advice. If we fail to secure deeper reductions in greenhouse gas emissions, we will increase the pressures on fish and the billions of people that depend on them as an important source of protein."

The WWF report, published ahead of this month's meeting in Montreal of key parties to the Kyoto Protocol on global warming, claimed higher water temperatures were likely to stunt the growth of some fish, resulting in fewer offspring. Normally, fish metabolisms speed up as temperatures rise, but insufficient food supplies could slow their growth and reproduction rates.

The report said freshwater fish, in particular, might not have enough oxygen to breathe as waters got warmer. Fish filter oxygen from water, but the amount of oxygen dissolved in water falls as temperatures rise. In the summer of 2003 - Scotland's warmest year on record - hundreds of adult salmon died in rivers due to lack of oxygen.

WWF said rising temperatures would also result in some species, such as cod, plaice and halibut - vital for the Scottish fishing fleet - moving to cooler waters to try to maintain the normal temperatures for their habitat, and this could have a big impact on their ability to survive.

"In the Gulf of Alaska in 1993, as fish moved into cooler waters, around 120,000 sea birds starved to death as they were unable to dive deep enough to reach their relocated prey," Dr Dixon said.

"This year has seen the worst breeding record for seabirds around the coasts of Scotland, with internationally important populations of gannets, kittiwakes and puffins plummeting, many found with chicks starved to death. This was attributed to the lack of sand eels, with climate change added to years of industrial over-fishing.

"WWF wants governments meeting in Montreal to commit to starting negotiations for deeper cuts in emissions once the current commitment period of the Kyoto Protocol runs out in 2012."