Complex sentence: Despite the large scale extraction of forage fish, few management plans exist for guiding their sustainable harvesting, and not enough is known about the role of forage fish in marine ecosystem and how fishing effects them and the predators that feed on them.
Split into simpler sentences: Despite the large scale extraction of forage fish, few management plans exist for guiding their sustainable fishing. Not enough is known about the role of forage fish in marine ecosystem and how fishing effects them and the predators that feed on them.