Fourteen brands of canned tuna on the Thai market failed to meet basic standards in a recent questionnaire, Greenpeace says.
Greenpeace Southeast Asia (GSA) surveyed 14 canned tuna firms and said it found the processing of the canned products failed to meet traceability, sustainability and equity standards.
GSA sent questionnaires to canned tuna manufacturing companies.
Thailand has more than 50 tuna processing plants but the questionnaire was sent to only 14 companies, and of them, only 10 filled it out.
Greenpeace gave the four firms which refused to fill the questionnaire an automatic fail.
The group released the From Sea to Can: Thailand Canned Tuna Ranking report Tuesday, which evaluated the production procedures of 14 brands of canned tuna sold in Thailand.
The report found most companies that make the products do not have adequate measures to establish the origin of the fish, types of fishing gear used to catch them, and the welfare of fishing workers.
Of the 14 brands, five received failing scores, with Greenpeace finding their production procedures and management need improvement, and nine received fair scores. The score 0-39 is classified as a fail, 40-69 is fair and 70-100 is good.
"Consumers have a right to know what is really in the can," said GSA's oceans campaigners Anchalee Pipattanawattanakul.
"It's vital for canned tuna companies to ensure their tuna can be traceable to where and how they were caught, whether it is linked to trans-shipment at sea, illegal fishing, destructive fishing methods or a forced labour issue."
The questionnaires referred to tuna's traceability, sustainable tuna stocks and fishing methods used, fishing legality, workers' conditions, companies' commitment to sustainability, transparency and consumer information access.
Ms Anchalee said most of the brands could not trace the origin of the tuna because it was unclear how often the catch had changed ships while at sea. Some of them were found to be using tuna breeds which are at risk of extinction.
The government was working on traceability measures five years ago. That process accelerated this year after the EU issued Thailand with a "yellow card" for its failure to cope with so-called Illegal, Unreported and Unregulated fishing.
