(CNN) -- Twenty-eight suspected pirates were taken into custody Friday by the European Union Naval Force after a handful of failed attacks on fishing vessels in the Indian Ocean, the EU mission said.
A helicopter from the French warship FS Nivose then tracked the vessels and saw the suspects throwing things overboard, the mission said.
When a French team arrived at the scene, it found 11 suspected pirates and "pirate paraphernalia" in the skiffs: a rocket launcher, grappling hooks and several fuel barrels.
The forces destroyed the pirate ship and a skiff and took the suspected pirates into custody. The fate of the second skiff was not immediately known.
Soon after, pirates tried to attack a French fishing vessel near two other fishing boats, said Cmdr. John Harbour, spokesman for the EU Naval Force.
The French fishing vessel collided with the suspected pirates' vessel and sank it, Harbour said. Six suspected pirates were picked out of the water by the EU force, he said. It was not immediately clear if they had been transported to the FS Nivose, although that had been planned, he said.
Later, pirates tried to attack a Spanish fishing vessel, Harbour said. The boat alerted the EU Naval Force, and air and naval units intervened, he said.
Eleven suspected pirates were taken into custody and were on board the Nivose, Harbour said.
Harbour said an increase in pirate attacks was likely over the next few weeks as the monsoon season was ending and the ocean was becoming calmer, he said.
"The pirates have been preparing for it. ... We are prepared as well," he said.
On Thursday, pirates on two skiffs in the Indian Ocean attacked the Spanish fishing vessel Albacan, the EU Naval Force said. The pirates fired a rocket-propelled grenade, which exploded on the Albacan's deck and burst into flames, force said.
Armed guards on the Albacan fired shots at the skiffs and repelled the attack, it said. No crew members were injured, and the small fire was extinguished.
The EU mission tries to deter and stop piracy off Somalia, which has been mired in chaos since the early 1990s. It escorts vessels in the Gulf of Aden and Indian Ocean carrying World Food Program humanitarian aid to displaced people in Somalia.
It also seeks to protect "vulnerable vessels" in the Gulf of Aden and off the Somali coast, according to the mission's Web site.