Commercial fishing gear modifications to reduce interactions between Atlantic sturgeon ( Acipenser oxyrinchus oxyrinchus ) and the southern flounder ( Paralichthys lethostigma ) fishery in North Carolina (USA)

Bycatch of protected species in commercial fishing operations is a primary concern to fishery managers because it threatens the conservation, protection, and recovery of fragile species, such as the Atlantic sturgeon ( Acipenser oxyrinchus oxyrinchus ). One potential solution to reduce the risk associated with commercial fishing operations is to design commercial fishing gear that is more selective in terms of interactions between Atlantic sturgeon and commercial fisheries. Given the need to reduce commercial fishery interactions, the overarching goal was to reduce Atlantic sturgeon fishery interactions and maintain southern flounder ( Paralichthys lethostigma ) catch in North Carolina. The specific objectives of this study were to design and evaluate the effectiveness of a modified gillnet. Overall, the results proved that lowering the profile and amount of webbing had a beneficial impact at reducing Atlantic sturgeon encounters and bycatch. The modified gillnet reduced bycatch and Atlantic sturgeon encounters by 49.4% and 60.9%, respectively. We also found the modified gear entangled 51.6% less southern flounder, which corresponded to a 32% reduction in total weight; the experimental sections entangled slightly larger individuals than the control sections. Our findings showed the number of Atlantic sturgeon encounters was positively associated with mean water depth, with more Atlantic sturgeon encountered in deeper than shallower waters; 75% were encountered at depths between 4.6 and 6.1 m. In addition, we found that 41% of the Atlantic sturgeon encountered were in warmer (26‒30°C) than colder water.