"The other day, they switched back from east to west and we detected this with the drone."
Watson has 88 crew aboard three ships, two of which are equipped with drones. They act as spotters, finding the whalers and allowing Watson's ships to home in on them.
Watson has embarked on his annual expedition to stop the slaughter of thousands of whales - the Japanese consider this to be scientific research while critics call it cruel and archaic.
"Last year, they had a quota of over 1000 whales and they only caught 16 per cent. We saved at least 800 whales," said Watson, who has been known to ram the Japanese boats as part of his anything-goes tactics.
The advent of technologies such as drones may end the Japanese hunt, said Watson, who is also bringing publicity to the cause in Whale Wars, the Discovery Channel documentary series that tracks the hunts.
"Our goal is to bankrupt them and destroy them economically. Now that we can track them, it is getting easier."
Once exclusive to Israeli spy forces and the US Air Force, drones and other types of unmanned aerial vehicles are being sent on civilian missions such as crop inspections or marine mammal surveys.
In April, drones flew inside highly radioactive areas at the Fukushima nuclear power plant and recorded data from areas too dangerous for humans to enter.
Federal bodies in the United States, including the Federal Aviation Administration, are scrambling to monitor the burgeoning industry.
According to the Los Angeles Times, the FAA will issue proposals this month to clarify rules for the use of such craft in civilian and commercial roles.
While drones used to cost hundreds of thousands of dollars, some are now available for less than $1000.
The unit used by Sea Shepherd is a highly durable model known as the Osprey, which can run for hundreds of hours if properly maintained.
It was given to Sea Shepherd by Bayshore Recycling, a New Jersey-based solid waste recycling company that is committed to environmental protection.
In addition to paying for the drone at a cost of around $20,000, Bayshore also paid for pilot training to run the sensitive remote control equipment.
Eleanor Lister, 20, a Sea Shepherd crew member from Jersey, described the daily routine that begins when the ship's first mate holds aloft the Osprey drone, then tosses it into the wind.
After tracking the Japanese whalers, the drone ends its mission as it homes in on the Steve Irwin and is flown into a thick net, where crew members download video and photographs.
Despite severe weather in the Antarctic, the drone has flown dozens of flights and had no problems with ice build-up on the wings or trouble negotiating the gusty winds.
HIGH-TECH
* Anti-whaling activists in the Antarctic are using a battery-powered drone to track the whaling ships.
* While drones used to cost hundreds of thousands of dollars, some are now available for less than $1000.
* Sea Shepherd is using a unit known as the Osprey.
* It is highly durable and can run for hundreds of hours if properly maintained.
- Observer