The HRA, as defined by the latest edition of Best Management Practices for Protection against Somali Based Piracy (BMP4), will now have an eastern limit of 065°E, while the southern limit is reduced to 5°S. It will now only stretch to 15°N in the Red Sea and 22°N in the Gulf of Oman.
The move is said to have the support of the International Group of P&I Clubs.
The new geographic limits of the HRA are set to come into force on 1 December 2015 in order to give crews and shipping companies adequate time to adapt.
Organisations representing the shipping and oil industry said the reduction was "in response to the ongoing containment of pirate attacks in the Indian Ocean."
But the group, which comprises BIMCO, the International Chamber of Shipping (ICS), Intercargo, Intertanko and the Oil Companies International Marine Forum (OCIMF) stressed that "a serious threat remains and that correct reporting and vigilance remains crucial".
"The reduction of the HRA takes full account of recent shipping industry experience, and follows extensive consultation with governments through the diplomatic Contact Group on Piracy off the Coast of Somalia, and military naval forces, including NATO, Combined Maritime Forces and EU NAVFOR, which continue to provide vital protection to shipping," BIMCO said in a statement.
Dryad Maritime, the UK maritime intelligence company, welcomed the announcement as a decision that takes account of the changing strategic and threat context in the region and the important views of a number of coastal states.
"The news is the first step in a welcome de-escalation that will ultimately see a shift from the widespread use of armed guards towards more appropriate, and less costly, methods of mitigating risk in the High Risk Area," it said.
However, the West of England Club warned that although the size of the HRA is being reduced, there remains "a serious piracy risk off Somalia".
The club said it is still recommended that a vessel's movements be registered with MSCHOA, reports be made to United Kingdom Marine Trade Operations (UKMTO), and a full risk assessment be completed prior to arriving in the area, considering the guidance contained in BMP4 and the latest security information.
