Nearly 70,000 fishing crew are currently at sea catching the ecolabeled tuna in your sandwich or sushi. Their catch equals half of the world’s tuna supply. The purpose of this research was to collect tuna data from the website of the Marine Stewardship Council (fisheries/msc.org) to learn what the data reveal about protecting tuna fishers from labour violations while fishing on certified vessels. The standard-setter does not have a fishing labour standard but posts data to its website (fisheries/msc.org) it says demonstrate that vessels in the program operate with well-managed labour risks. To confirm this, a database of 3260 tuna vessels was built from vessel lists, annual catches, and labour statements and queried for fishing job identifiers. Fishing employers (vessel owners) were identified in the vessel data for 1291 vessels representing 26% of the ecolabeled tuna catch. In labour statements, employers were identified for 1238 vessels and 14% of the tuna catch. Flag state labour laws were identified for 1617 vessels and 50% of the tuna catch. Few tuna vessels were owned by the certificate-holding entities (4%) that submitted labour statements and these data were scant on vessel practices. Certificate-holders disavowed debt bondage, forced and child labour as “non-applicable” on MSC-engaged vessels overall. Jobs, risks, and vessel employment practices could not be tracked from the data. Seven vessels currently listed in the program were reported by fishers for forced labour. Yet, all owners of certified vessels gain logo rights and benefits, due to certification’s pooling mechanism.