Maverick activist Paul Watson gave children a lesson in saving the planet yesterday with an empowering talk at Somersfield Academy.

Captain Watson, a co-founder of Greenpeace and the President of the Sea Shepherd Conservation Society, told children they can all make a difference, no matter how young they are.

He told pupils: "You have the power to change the world, simply by standing up and fighting to defend what you believe. The best thing you can do is to use your imagination to come up with ideas to protect the planet and intervene.

"You can also send messages to Japan and Norway to say 'Don't kill the whales'. But one of the most important things you can do is protect the environment in which you live, protect the animals, insects, and the creatures in the sea where you live.

"Each and every one of you has a responsibility and that is to live on this planet and through your life leave it in a better position than when you were born. It is very difficult to do this and not many generations have achieved it, but that's what you have to strive for."

Captain Watson, 56, told students how his roots as an environmental activist began in his childhood, at the age of nine, growing up in the fishing village of Saint Andrew's, New Brunswick, Canada.

"There weren't a lot of children there, so my best friend was a beaver," he said. "I swam with this beaver for all of the summer, but the next year I couldn't find him. I then found out that trappers had caught and killed him."

Captain Watson said he joined the 'Kindness Club' and he and his friends would go out and release all the traps they could find. "Then, at 18, I co-founded Greenpeace, so I've really been doing this my whole life," he said.

The Somersfield Academy pupils, aged nine to 15, sat enthralled as Captain Watson explained how each lifeform on Earth depends on the others' survival. By helping to save whales and other marine animals, the Sea Shepherd Conservation Society (SSCS) is thus helping to ensure the survival of our entire planetary eco-system.

"If I found my crew popping rivets out of my engine room to go and sell ashore, if you pull out one rivet too many then the ship will sink. If we look at every species as a rivet, and as Earth as a spaceship held together by those rivets, then if you pull one too many, the whole spaceship that is Earth will collapse."

Captain Watson said even worms and insects had an important role to play as "custodians and engineers".

"They make your life on this planet possible, and that is so true for so many animals on this Earth. We are interdependent on them," he said. "If we're going to have a future at all we have to watch out for all our species. It's as simple as that."

Describing ocean plankton as "the foundation of all life on the planet", he added: "If we lose them we're in trouble. Eighty percent of the air you breathe comes from these plankton, and 20 percent from trees. There's a special relationship between these plankton and whales, which shows we are all interlinked."

He described whales as "the most intelligent species on the planet" but said that due to hunting, only three percent of species were left.

"Unfortunately we might lose them," said Captain Watson. "Killing whales is illegal but Norway is doing it and Japan is doing it. They are acting against international law and that's what our organisation does, we go down there and try to stop them."

Captain Watson said the SSCS was formed "to enforce international law to protect marine life and animals from harm". "We can protect this planet under the authority of the United Nations and that's what we do," he said.

"Some people say we're just nothing but pirates. I don't mind, I don't have a problem with that. There's nothing wrong with pirates. If you go back to the 1600s in the Caribbean, just around here, it wasn't the British Navy who stopped piracy but it was shut down by Henry Morgan, who was also a pirate. So we look at ourselves as pirates, but pirates of green."

Indeed, the sinister appearance of the SSCS flagship, the , usually leads to it being compared with a pirate ship. The black-painted vessel even bears the skull and cross bones of the Jolly Rodger.

The Farley Mowat is currently wintering at Dockyard ahead of a campaign in February when the crew will travel to Canada to try to stop the annual seal hunt.

Captain Watson meanwhile, is venturing down to the Antarctic to track down the Japanese whaling fleet who will be hunting endangered whales in the Antarctic Whale Sanctuary. Operation Migaloo aims to stop the slaughter of up to 1,000, including humpbacks and fin whales.

Defending marine wildlife all year round, the SSCS also visited the Galapagos Islands this summer to infiltrate the practice of shark finning for Chinese shark fin soup production.

"Just this last summer we seized 45,000 shark fins from poachers and cut off the top of the shark finning mafia in Ecuador," said Captain Watson.

He told the pupils: "If the sharks go extinct, the oceans die. It is the apex predator of the world's oceans. The shark has literally shaped the evolution of the oceans and we seriously upset the entire evolution process by killing sharks."

The Sea Shepherd Conservation Society has just celebrated its 30th anniversary at a celebrity-studded party in Los Angeles. Captain Watson said: "We've had 4,500 volunteers on our ships over the years and what they go away with is the feeling that they can each make a difference."