Effects of fishing practice changes on pelagic shark longline captures in the Gulf of Gabes, Tunisia

摘要: In order to increase their catches, longliners targeting sharks in the Gulf of Gabes, Tunisia, have increased number hooks per basket and included new bait types instead mackerel (Scomber scombrus). This paper reports effects these changes on catch composition, rates, size distribution, life‐stage captures, mortality at haulback. Data from 48 96 longline sets, carried out during shark fishing seasons 2007 2008, with two basket, 2016 2017, five respectively, were examined assess effect gear change. Moreover, inspected based 33 sets using whole mackerel, 19 salema (Sarpa salpa) halves, 27 pieces stingray (Dasyatis spp.), sampled 2017. The species composition indicated that expand vertical distribution operate surface bottom. catches both designs dominated by sandbar (Carcharhinus plumbeus). Despite changes, rate C. plumbeus decreased 42.21%, suggesting population decline. a shift towards larger specimens, mainly adult females, which could jeopardize population. main haulback seems be affected design longline. used, stingray, significantly shark, suggests greater attractiveness bait; however, fish rates unchanged response variation. fishery operates nursery grounds, exposes (principally C. plumbeus) considerable exploitation pressure. practices intensified pressure thus risk rapid depletion populations. To preserve area, use attractive should banned.