According to the report, attacks on ships last year totaled 264, with 300 people taken as hostages, and 12 ships completely hijacked.
There were an additional 28 attempted hijackings that failed.
Nigerian pirates were responsible for 31 out of 51 attacks in the west African region, holding 49 people hostage and kidnapping 36.
“Nigerian pirates ventured far into waters off Gabon, Ivory Coast and Togo, where they were linked with at least five of the region’s seven reported vessel hijackings,” the IMB said.
The number of pirate attacks worldwide was, however, down to a six-year low.