Efforts to sustainably manage fisheries will also reduce bycatch, a new study suggests. The study further highlights key species that will benefit from more sustainable fishing approaches. Recent studies suggest that more than half of the world's fisheries are being overfished, and that rebuilding these fisheries could increase global fishing yields by roughly 15%, increasing associated profits by as much as 80%. Fisheries also affect many protected, non-target species that are incidentally caught (a phenomenon known as "bycatch"); among bycatch species are megafauna such as marine mammals, sea turtles, seabirds, and sharks. Matthew Burgess and colleagues sought to explore how reducing the extent of current fisheries might affect species that are typically caught as bycatch. They looked at estimates of the changes in fishing pressure needed to maximize long-term profits (termed "maximum economic yield," or MEY), comparing the data to the changes in bycatch mortality needed to reverse ongoing declines in several bycatch populations. These species included nine marine mammal, six sea turtle, and three seabird populations that are considered endangered and are particularly threatened by the possibility of becoming bycatch. Results by Burgess et al. suggest that managing fish stocks sustainably - in a way that still meets the fisheries' economic objectives - will in turn halt the declines of seven to 13 of the bycatch populations (or roughly half of the populations evaluated in this study). However, eliminating bycatch completely is insufficient to halt declines of one turtle and one bird population across much of the world, due to other factors, the authors found.