Effects of leader type and gear strength on catches of coastal sharks in a longline survey around Bimini, The Bahamas

Our study assessed the influence of leader type (monofilament vs stainless steel cable) and gear strength (i.e., hook size and leader thickness) on species composition, catch rates, and size distribution of sharks captured in a fisheries independent longline survey near Bimini, The Bahamas. A total of 28 surveys were conducted, resulting in 50,400 hook hours. Catches consisted of 167 sharks from eight species. Overall, catches were higher on monofilament leaders for light duty gear, but there was no difference for heavy duty gear. When bite-offs were combined with catches to form 'total shark contacts' the rates were not significantly different between the two leader types. Tiger sharks were the only species to show differences in mean pre-caudal lengths between light and heavy duty gear, likely due to the wide range of size classes encountered for this species. These results further highlight the importance of understanding selectivity of terminal gear (gear strength and leader material), especially for comparing catches across surveys conducted by multiple agencies or organizations.

Automated summary

The study examined the impact of leader type and gear strength on the species composition, catch rates, and size distribution of sharks. Results showed differences in catches between leader types, particularly for tiger sharks. The importance of understanding and considering the selectivity of different gears in catch surveys was emphasized.