Warming seas are changing the body temperatures of aquatic species used for food, affecting their metabolism, growth rate, reproduction and susceptibility to diseases and toxins, the Food and Agriculture Organization said at the start of a four-day scientific seminar on climate change and marine fisheries.

The Atlantic Ocean in particular is showing signs of warming deep below the surface, the FAO said.

Warmer-water species are also increasingly found closer to the South and North poles, the agency said.

Salinity in near-surface waters in hotter regions has increased and decreased in colder areas because of greater precipitation, melting ice and other processes, the agency said.

In addition, the oceans are becoming more acidic, threatening to harm if not kill coral reefs and calcium-bearing organisms, the FAO said.

High-latitude fishing communities will be most exposed to the devastation of climate change, while fisheries in deltas, coral atolls and ice-dominated coasts will be vulnerable to flooding and coastal erosion because of rising sea levels, the agency said.

Fish is the world's most widely traded food and a key source of export earnings for many developing countries.