The security drill with about 100 officers was aimed at guarding the southwestern town of Taiji before hunting season starts in September, a Wakayama prefectural police official said.

The officers practiced responding to a ship carrying several activists intruding in the bay and damaging a fishnet.

In a mock chase in the cove, a coast guard patrol ship stopped the protest boat and arrested a pair of activists for trespassing and vandalizing the net. On the ground, police officers practiced arresting other activists trying to block a truck carrying a freshly harvested dolphin.

The drill ended safely without incident, the official said on condition of anonymity for security reasons.

The bay is where the Oscar-winning documentary "The Cove" was secretly filmed. Its shocking scene of about a dozen fishermen scaring and culling the animals outraged many around the world, but Japan defended the hunts as tradition even though many Japanese have never eaten dolphin meat.

Since the success of the movie, Taiji has been inundated with a growing number of foreign protesters, including the environmental group Sea Shepherd that has also stepped up violent protests against Japan’s research whaling in the Antarctic waters in recent years.

"We understand that people have different views about dolphin hunts in Taiji, but we must crack down on actions such as harassment, slander, vandalism and trespassing, which clearly constitute crime," Wakayama Gov. Yoshinobu Nisaka said last week.

Police will be added in the town before the hunts begin to deter anticipated standoffs between activists and townspeople, the governor said.

Japan allows about 20,000 dolphins to be caught each year. Only about 2,000 of those are taken in Taiji, but it has caught attention because the town’s practice is to push the animals to shore and slaughter them in shallow water, as opposed to harpooning them at sea.