This study investigated the effectiveness of retention bans for reducing shark mortality in longline and gillnet fisheries, as reported in 160 relevant studies across 341 shark species. Results suggest that retention bans can reduce shark mortality when averaged across all species, but that species with lower intrinsic population growth rates benefit less from a retention ban than those with higher rates of population growth. The authors stress that retention bans alone cannot address unsustainable shark bycatch and mortality, and that efforts should be combined with other mitigation measures such as spatial/temporal fishery closures. Smaller-bodied species are more likely to die at the vessel, whereas deep-water species are more likely to experience mortality post-release.