Hawaii’s largest inter-island shipper is asking the Public Utilities Commission for permission to raise its rates by an average of 24 percent.

Young Brothers Ltd. says it’s doing so because cargo volumes have dropped sharply since 2008.

It also cited the commission’s recent decision to allow Pasha Hawaii Transport Lines to begin transporting inter-island cargo as a reason for the request.

The company’s last rate increase — of 13.46 percent — took effect in August 2009.

The company said in a statement Wednesday that the entrance of Pasha into the market makes its application more complex than previous applications.

The typical rate application factors in cargo volumes, costs of doing business and capital investments.