LED lights halve unwanted fish in nets, research finds: Attaching LED lights to larger holes in nets, intended to allow non-target species to escape, dramatically reduced the numbers killed unnecessarily

Ok so the article is not actually about dolphins as the others are saying here, the TLDR is somewhat misleading. The lights here aren't actually helping certain species escape nets in general, they're helping certain species escape nets already designed to allow those species to escape.

They were finding that their nets that allow haddock and flatfish to escape were not functioning at depth or at night because the fish couldn't find the exits. These lights guide fish to the exits that are already designed for haddock and flatfish.

Different fish species have different responses when netted, swimming in different directions and that kinda thing. Haddock and flatfish being bottomfish, it's possible that their response is swimming down towards the sea floor and the target species for the net to actually catch may swim up. Therefore, putting an escape hatch in the bottom of the net would allow non target haddock and flatfish to escape. (I don't know actual responses, this is just a clarifying example based on how these nets are generally designed, in my experience). The lights around this exit would help attract the haddock and flatfish to the exit in the dark.