WASHINGTON — Acts of piracy in the treacherous waters around the Horn of Africa have fallen sharply in 2012, according to statistics released by the United States Navy. The Navy credits aggressive patrolling by international forces and increased vigilance by the commercial shipping industry for the decrease.

Data released by the Navy last week showed 46 pirate attacks in the area this year, compared with 222 in all of last year and 239 in 2010. Nine of the piracy attempts this year have been successful, according to the data, compared with 34 successful attacks in all of 2011 and 68 in 2010.

Even so, senior Navy officers have been careful not to declare victory.

“The pirates are very adaptable, and they are very flexible,” said Vice Adm. Mark I. Fox, the Navy’s deputy chief for operations, plans and strategy. “We are watching carefully.”

The prospect of renewed political turmoil in the region, especially in Somalia and Yemen, may again drive up attempts at the lucrative business of piracy, since lawless areas in these countries provide havens for pirates to launch their raids and to hold captured vessels and hostages. Further economic collapse may prompt more farmers and fisherman to choose piracy.