APL is the third carrier to leave the WTSA over the past decade, following in the footsteps of MOL`s departure in June 2005 and previously Maersk Line, which was known at the time as Maersk Sealand and left the group in July 2002.
This reduces WTSA members to nine shipping lines: Hapag-Lloyd, Hyundai Merchant Marine (HMM), "K" Line, NYK Line, OOCL Cosco, Evergreen, Hanjin and Yang Ming.
According to Alphaliner estimates, the remaining WTSA carriers, as of August, control 55 per cent of the total westbound Asia-North America capacity.
It said the 15 member ocean liners of the WTSA`s eastbound counterpart, the Transpacific Stabilisation Agreement (TSA), control an estimated 92 per cent of total capacity on the Asia-North America route.
TSA members include: APL, Maersk, China Shipping, CMA CGM, Mediterranean Shipping Company (MSC) and Zim.
The WTSA was established in 1990 to replace a more rigid rate conference system for the US-Asia market. It offers a discussion forum for its members to develop non-binding guidelines relating to freight rates, surcharges and other fees.