Callum Roberts charts the damage to oceans and marine life, and radical plans to curb predation more

Callum Roberts is a marine biologist, ecologist and writer. His career has taken him around the world to study the world's reefs, banks and seabed and his latest book, Ocean life

provides a detailed analysis of the problems now afflicting these places: plastic pollution in the oil slick from the polar caps with increased levels of acid water, and the disintegration of the proliferation of coral reefs harmful algal blooms. However, Roberts says we can save our seas still besieged.

The picture you painted of our oceans is very dark. Is there any hope?

I think there is. We have this enormous challenge, I admit. The oceans are changing faster than at any time in human history, in fact millions of years in the past. But I think we can respond to these changes, if we act quickly and carefully.

well, so we first describe the damage.

There are three main lines of destruction currently underway. The first relates to the speed at which we will eliminate life in the oceans. Consider British waters. In 1938, fish in the UK fishing fleet has declined by more than five times what I do now. However, trawlers of today is full of high-tech equipment such as echo-locate and scanners. We can not match the previous catch rates because we have caught many fish in the oceans. Our fish stocks are heading towards collapse, while our dredges are removing the seabed, making complex marine habitats in the extensions development monotonous gravel, sand and mud.

The second issue is pollution. We are poisoning the seas, in myriad ways. Some of them involve chemicals such as brominated flame retardants and DDT. They are used on land, but is washed by streams and rivers to the seas. The oceans are well-finals and generally, these toxins are deposited on the seabed, but because we are dredging the seabed systematically the mixture of toxins in water. Consequently, many forms of marine life, from birds to whales - have been found at high levels of toxins in their tissues. Rising levels of carbon dioxide in seawater becomes more acidic and more difficult for shellfish to form shells.

Then there is the destruction of habitat. We destroy mangroves, salt marshes and beaches to make way for hotels, resorts and ports. And above all people is the issue of climate change. As the ice cap melting, pouring cold fresh water from Greenland and Antarctica, and threaten to disrupt the flow, including the Gulf Stream which keeps Britain warm.

not much to be optimistic about ...

There are steps we can take, but we must realize that things will get worse before it gets better, and will involve a radical reorganization of how the steward of the sea
First, we need to limit fishing to about half the current level, and much of the fishing ban beyond a depth of half a mile. The deeper you go, the fish take longer to grow and reproduce to take longer to recover from exhaustion, there. We need to remove fishing gear the most destructive, including equipment used to dredge the seabed scallops and other benthic species.