Using population viability analysis to examine the potential long-term impact of fisheries bycatch on protected species

•Fisheries management is made challenging by uncertainty around bycatch estimates.•Population viability analysis (PVA) can simulate the potential effects of bycatch.•PVA was applied to bycatch of grey seals in static net fisheries.•Demonstrated potential effects of immigration and age/sex-bias in bycatch mortality.•PVA can inform fisheries management, despite uncertainty around bycatch estimates.