Purse seine fishing is generally considered more efficient and sustainable as compared to pelagic trawlers as it has no contact with the sea-bed and has low levels of by-catch provided the mesh size is large enough to let smaller fish free.
Despite certain regulations in place, with a lack of monitoring, the mesh size of these nets a really small (refer to photo), increasing by-catch.
For more info regarding the two types of fishing-https://www.msc.org/what-we-are-doing/our-approach/fishing-methods-and-gear-types/purse-seine
