Bycatch of a Critically Endangered Shark Glyphis glyphis in a Crab Pot Fishery: Implications for Management

The speartooth shark Glyphis glyphis is a Critically Endangered whaler known from few tropical river systems in northern Australia and Papua New Guinea. There limited genetic exchange populations residing Australian rivers that are greater than 100 km apart. In Queensland, the species only found Wenlock Ducie River flow into Port Musgrave. Juveniles confined to upstream reaches of these with seasonal downstream movement related freshwater influx. This region also supports commercial recreational fisheries including crab pot gillnet fisheries. Being obligate ram-ventilators, entrapment pots results mortality bycaught sharks after hours. Following anecdotal reports juvenile being captured pots, we investigated catch rates experimentally examined fishing effort logbook data. Twenty four (55–80 cm TL) were experimental Tentpole Creek (a tributary River) high; up 0.82 (±1.86 SD) –1 day . Experimental varied between distance highest areas density based on detection acoustically tagged over 7 years line per unit Although varies spatially temporally relation current market demands, consistent monthly overlap core distribution occurred throughout year. Using CPUE data multiplied by Creek, estimate November alone, 51 279 potentially high effort. Bycatch poses significant threat this genetically isolated small population. Urgent management intervention drastically reduce bycatch either through gear modifications or spatial closures required ensure viability