A week ahead of a key Meeting of the Parties to the Kyoto Protocol in Montreal, Canada, the global conservation organization's report " Are we putting our fish in hot water? " shows that global warming is causing the world's waters to warm while rainfall patterns, currents and sea levels are changing.
"The balance is set to tip, as climate change continues the pressure on fish populations already strained by overfishing, pollution and habitat loss," said Katherine Short, a fisheries officer with WWF's Global Marine Programme. "We must act to protect fish, both marine and freshwater, they are one of our most valuable biological, nutritional, and economic assets."
The report shows that hotter temperatures are expected 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. Some temperate fish like salmon, catfish and sturgeon cannot spawn at all if winter temperatures do not drop below a certain level.
To make matters worse, the WWF report shows that freshwater fish particularly may not have enough oxygen to breathe as waters grow warmer. Fish filter oxygen from water, but the amount of oxygen dissolved in water decreases as temperatures rise.
Meanwhile, hotter temperatures mean that fish populations could move to cooler waters in an effort to maintain the temperature normal for their habitat. However, this can leave other species in dire straits that are dependent on these fish as a food source. 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.
Worldwide, marine and freshwater fisheries generate over US$130 billion annually, employ at least 200 million people, and feed billions of people reliant on fish as an important source of protein.
WWF wants governments meeting in Montreal to commit to starting negotiations for deeper cuts in CO2 emissions once the current commitment period of the Kyoto Protocol runs out in 2012.
"If we fail to secure deeper reductions in greenhouse gas emissions, we will increase the pressures on fish and billions of people that depend on them as an important source of protein," said Stephan Singer, Head of WWF's European Climate and Energy Policy Unit.
"Unless governments slow the rate and extent of climate change we're all going to feel like fish out of water."
" The European Union, other governments and many civil society groups have committed themselves to keeping the rise of global average temperature below 2°C above pre-industrial levels.