Climate change puts fish at risk

Posted: 18 November 2005

Fish populations are increasingly threatened by the effects of climate change as temperatures rise in rivers, lakes and seas. According to a new report from WWF the hotter water means less food, less offspring and even less oxygen for marine and freshwater fish populations.

Two weeks ahead of a key meeting on the Kyoto Protocol in Montreal, the report shows that climate change is causing the world's waters to warm as well as bringing changes to rainfall patterns, currents and sea levels. Hotter temperatures are expected to stunt the growth of some fish, resulting in fewer offspring. Normally fish metabolisms speed up as temperatures rise, and insufficient food supplies could slow their growth and reproduction rates. Some temperate fish like salmon, catfish and sturgeon cannot spawn at all if winter temperatures do not drop below a certain level. Andrew Lee, Director of Campaigns for WWF-UK said: "As climate change increases the pressure on fish populations that are already strained to the limit by over fishing in the marine environment, we must act urgently to reduce both carbon dioxide emissions and fishing pressures to protect fish populations as they are one of the world's most valuable biological, nutritional and economic assets." Meanwhile, hotter average temperatures mean that fish populations could move to cooler waters in an effort to maintain the temperature normal for their habitat and this could impact on many species' ranges and ability to survive, including cod, plaice and halibut. In the North Sea, many fish species are already moving north into cooler water.

Breeding failure

This year has seen the worst breeding record ever for some seabirds around the coasts of the UK with internationally important populations of kittiwakes and puffins plummeting. They are suffering near-total breeding failure, with chicks found starved to death. This was attributed to the lack of sandeels as climate change adds to years of industrial over fishing. Worldwide, marine and freshwater fisheries generate over £70 billion annually, employ at least 200 million people and feed billions of people reliant on fish as an important source of protein. WWF is calling for governments that are meeting in Montreal later this month to commit to starting negotiations for deeper cuts in global CO2 emissions in the post 2012 commitment period, as the current commitment period of the Kyoto Protocol runs out in 2012. Emily Lewis-Brown, Marine Research Officer for WWF-UK said: "The UK government needs to set legally binding targets for reducing damaging climate change emissions. To protect the remaining fish stocks we must place further restrictions on fishing effort, in line with recent ICES advice (International Council for the Exploration of the Sea). 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."

Freshwater fish To make matters worse, the WWF report shows that freshwater fish particularly may not have enough oxygen to breathe as waters become warmer. Fish filter oxygen from water, but the amount of oxygen dissolved in water decreases as temperatures rise. Predictions suggest that the UK will experience hotter, drier summers, reducing flows in rivers already facing pressure from over-abstraction. The impact is likely to be particularly severe on some of the country's most important fish species. Salmon, for example, need abundant quantities of cold, clear water, and suffer significantly when our rivers are reduced to a summer trickle. Tom Le Quesne, Freshwater Policy Officer for WWF-UK said: "Fishermen around the country who have seen rivers almost disappearing in the last few summers are already providing vivid testimony to the impacts of climate change."

For a copy of the colour leaflet 'Are we putting our fish in hot water?' and for the full scientific reports on 'Climate Change and Freshwater Fish' and 'Climate Change and Marine Fish', as well as the five regional case studies (Australia, India, South Africa, the Mediterranean and the southeast United States) go to www.panda.org/climate/fish

WWF-UK is part of Stop Climate Chaos, an alliance of groups aiming for tougher action to reduce emissions at www.stopclimatechaos.org.uk

For more information on WWF UK's Climate Change Campaign look at www.wwf.org.uk/climatechangecampaign