The principal market for purse seine-caught tuna is Europe [7]. Here consumer pressure for sustainably sourced fish is strong and seafood certification schemes, such as that of the Marine Stewardship Council (MSC), are popular [28]. In this environmentally-aware social climate, becoming associated with sustainable production has business advantages. To date one purse seine fishery in the Western and Central Pacific convention area has been awarded certification by the MSC, although this has been exclusively for free schools of skipjack tuna, and in the Indian Ocean at least one fishing company (Echebastar) has formally explored the possibility for MSC certification for free school catches (http://www.msc.org/track-a-fishery; accessed 12th June 2015).