climate change puts fish at risk, WWF warns [Archives:2005/897/Health]
World Wild Fund ( WWF) , which is independent conservation environmental organizations , warned last Friday that Climate change is warming oceans, rivers and lakes and threatening fish stocks . WWF's report titled “Are we putting our fish in hot water?” showed 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.”
According to WWF report that Higher temperatures means hotter water means less food, less offspring and even less oxygen for marine and freshwater fish populations 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.
The WWF report explained 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. For example , 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. Even slight changes in temperature can force economically important fish to move their feeding and breeding grounds, hurting local, small-scale fishing activity most. For example, cod, plaice and halibut are expected to become scarce in U.S. and southern Canadian waters, and cod is likely to disappear from the southern North Sea, one of its main spawning areas, the WWF said.
The WWF urged a coming United Nations meeting in Montreal, Canada, from Nov. 28-Dec. 9 to set tougher targets for reducing greenhouse gases from power plants, factories and cars, which many scientists say are driving up temperatures worldwide.
The meeting will review the U.N.'s Kyoto protocol and ways to widen it to non-participants including the United States and developing states like China and India when it runs out in 2012.
WWF said it was critical to hold any rise in global temperature to below 2 degrees Centigrade, considered the trigger level for dramatic climatic and environmental changes.
Temperatures have risen by 0.7 of a degree since the industrial revolution, but some scientists forecast they could climb by 1.4-5.8 degrees this century.
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.
“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.”