The amount for "free school" tuna is expected to double in 2017 according to the Parties to the Nauru Agreement (PNA).
Purse seiners favour tuna fishing around Fish Aggregating Devices (FADs) which are man-made fixed or floating platforms that exploit the tendency of fish on the open ocean to gather under floating objects.
But the PNA, which controls the world's largest sustainable tuna purse seine fishery, is promoting the practice of "free school" caught skipjack and yellowfin tuna which does not involve FADs.
The practice is certified by the Marine Stewardship Council (MSC) and is touted as more sustainable than fishing around FADs as it limits the amount of by-catch which can include, sharks, dolphins turtles, rays and other species of tuna such as juvenile Bigeye Tuna.
Growing global market demand for MSC-certified tuna and fishing industry interest is responsible for the projected doubling of "free school" tonnage said the PNA's chief executive Ludwig Kumoru.
He said tuna fishing fleets complying with MSC requirements delivered over 55,000 metric tons of sustainably caught free school tuna to the market.
Mr Kumoru said he expects the volume to double to about 100,000 metric tons in 2017 based on existing orders.
He said this benefits everyone including the fisheries industry, retailers, and PNA members because catching tuna without using FADs means tuna are being fished sustainably.