Japan plans to slash by half the amount of juvenile bluefin tuna taken from the Northern Pacific starting in 2015, compared to the 2002-2004 average, reports said Sunday.

The Fisheries Agency has decided to increase protection for bluefin tuna amid international concerns about declining stocks, according to major media, including the Yomiuri Shimbun and the Mainichi Shimbun.

Studies have found stocks of bluefin tuna, prized by sushi lovers, have fallen dramatically, with juveniles forming the majority of specimens now being caught, pushing the species closer to extinction.

Last year, an international conference involving Japan agreed to cut each nation's quota for juvenile bluefin tuna in 2014 by more than 15 percent from the 2002-2004 average, according to Kyodo News.

But Japan, the world's biggest tuna consumer, has concluded bluefin tuna stocks will not sufficiently increase unless the quota is significantly reduced, the Yomiuri said.

The Japanese plan is aimed at encouraging other nations to adopt bigger cuts in their tuna catch quota, Kyodo said.