https://www.msc.org/uk/fisheries-improving
While fisheries must be performing at a high level to be MSC certified, many sustainable fisheries make further improvements after certification.
mscukirelandcertifiedfisheries
https://www.msc.org/media-centre/press-releases/press-release/first-tuna-fishery-in-the-world-to-be-msc-certified-achieves-re-certification
msc certifiedfirsttunafisheryworld
https://www.msc.org/en-us/media-center/news-media/news/isf-icelandic-ling-is-first-ling-to-be-msc-certified
News from the Marine Stewardship Council (MSC) in the US and Canada
msc certifiedisficelandiclingfirst