As reported in the NYTimes:
The waters off the 530-mile Nigerian coastline have been called the most dangerous in the world by a maritime watchdog group after a precipitous rise in the number of attacks over the past year. And while kidnappings of foreigners and attacks on oil installations in Nigeria have gained international attention, it is often those with a far lower profile who bear the greatest burden of the lawlessness at sea.The Nigerian Navy is working the problem, but...
Pirate attacks on fishing trawlers increased from 4 reported cases in 2003 to 107 in 2007, according to the Nigerian Trawler Owners Association. In January this year, there were 50 attacks on fishing boats. At least 10 fishermen were killed.
After more than 200 foreigners were kidnapped in the Delta in 2007, foreign oil companies pulled out their nonessential employees and increased security rather than rely on the undermanned Nigerian Navy. With foreign vessels no longer an easy target, pirates have been forced to look elsewhere for their victims.
They found them in the defenseless fishing trawlers that chug up and down the coastlines, never far enough from shore to be out of reach of the pirates’ gun-mounted speedboats.
The surge in deadly attacks on fishing crews caused the Nigerian Trawler Owners Association to call the fleets of its members, nearly 200 vessels, back to shore in February. That meant a work stoppage for an estimated 20,000 workers and the drying up of the bulk of the local fish market.
My suggestions would be fishing boat convoy operations and taking on the pirate's shore bases.