Mr Sharmarke is appealing for international help to stop piracy
Somalia's prime minister has said his government will eradicate piracy off its coast within the next two years.
On a visit to the UK, Omar Sharmarke told the BBC that his war-torn country lacked enough resources to tackle the problem but was seeking help abroad.
Analysts say to date the government has had minimal influence on the fate of those kidnapped by pirates, who tend to be released unharmed for hefty ransoms.
At least seven vessels are being held with about 179 crew members.
Mr Sharmarke also told the BBC World Service that his government would do everything it could to find a missing British couple hijacked by pirates days ago.
"The pattern has been that they don't harm the captives, these pirates, because they want money.
"But I want to assure the family that we will not rest until until we see the freedom of this couple," he said about Paul and Rachel Chandler.
Mr Sharmarke rejected the suggestion that as his transitional government has limited reach across Somalia, it is powerless to tackle piracy.
He said he would eradicate piracy through a civil affairs and information campaign, backed by military force.
"We're not powerless but the capacity to handle this issue is not all there. And that's why we're seeking assistance and investors.
"We have to understand that the cost of doing nothing is far greater than the cost of doing something."
Given that the government only controls a few districts of the capital, Mogadishu, it is difficult to imagine how it will deal with the pirates, who operate in areas outside government control, reports the BBC's Mary Harper.