Effects of leader type and gear strength on catches of coastal sharks in a longline survey around Bimini, The Bahamas
•Monofilament leader material caught a higher rate of overall sharks than cable leaders for lighter strength gear.•Surprisingly, bite off rates did not differ between monofilament and cable leaders on heavy gear.•Lighter gear caught smaller sharks and a great diversity of species than large hooks. O...
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Veröffentlicht in: | Fisheries research 2021-08, Vol.240, p.105989, Article 105989 |
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Sprache: | eng |
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Zusammenfassung: | •Monofilament leader material caught a higher rate of overall sharks than cable leaders for lighter strength gear.•Surprisingly, bite off rates did not differ between monofilament and cable leaders on heavy gear.•Lighter gear caught smaller sharks and a great diversity of species than large hooks.
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. |
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ISSN: | 0165-7836 1872-6763 |
DOI: | 10.1016/j.fishres.2021.105989 |