A sticker on a seafood package is meant to tell a simple story: the fish was caught sustainably. The consumer pays a little more, and that extra money finds its way back to the fisher, rewarding those that take extra care to protect the fishery.

Yet in many of the world's small-scale fisheries, that story doesn't hold, a new study says.

Researchers at Conservation International spent time with fishing communities in India, Indonesia and the Maldives mapping seafood supply chains and interviewing fishers enrolled in eco-label and fishery improvement programs. They found little evidence that the premium consumers and buyers pay reaches the people doing the fishing. Most of the value stays with retailers, distributors and exporters.

“We weren't able to find much evidence of a measurable change for fishers participating in these programs,” said Conservation International’s Shreya Yadav, who led the research.…