(CNN) -- Somali pirates are not building palaces with swimming pools with the ransoms they collect from international shipping companies and hostages, but they are helping the local economy, a new report finds.
"There is a very clear trickle-down effect," said author Anja Shortland, of Brunel University in the United Kingdom, who based her conclusion on everything from satellite pictures to local cattle prices.
High-resolution satellite imagery shows construction in the inland towns of Garowe and Bosasso, including radio towers, walls and new buildings, she said.
She's not seeing much construction on the coast itself, she said.
"There are no light emissions on the coastal villages. But the settlements inland ... that's probably where the money is going," she said of the estimated hundreds of millions of dollars Somali pirates have claimed in the past several years.
Shortland's report, "Treasure Mapped: Using Satellite Imagery to Track the Developmental Effects of Somali Piracy," was produced for Chatham House, a British think tank.
The waters off the largely lawless country have become one of the world's busiest piracy zones, with ever-bolder pirates in small, highly maneuverable craft seizing everything from small yachts skippered by retirees to oil tankers and cargo loads of heavy weaponry.
They normally demand a ransom for the safe return of vessel and crew.
Military operations have been launched to try to protect ships traversing the region, but attacks continue.
And the ransoms are having "a developmental effect" on Somalia, said Shortland.
The construction seems to be modest, she added.
"We don't see palaces, no swimming pools," she said. "Consumption seems to be constrained by local norms on sharing."
She also said she had seen no direct evidence that the pirates were cooperating with the local al Qaeda-linked militant Islamist group Al-Shabaab -- although some experts believe they are.
"They're very clever businesspeople," Shortland said of the pirates, saying they knew that proof of links to terrorism could bring an even tougher international military response down on them. "I haven't seen any proof."