"Evaluating the impact of local fisheries on loggerhead turtle mortality rates in the waters surrounding the island of Linosa (35° 51'N 12° 51'E, Italy) is one of the main goals of the EU-Life Project Urgent conservation measures of Caretta caretta in the Pelagie islands (LIFE99NAT/IT/006271). Reports of by-catches of Caretta caretta collected since 1994 suggest that long-line fishing has a strong impact on the local population. In order to reduce loggerhead by-catches by long-line fishing in the Pelagie islands, without negative impact on swordfish (Xiphias gladius) catch size, we first surveyed the local fishing methodology, then we tested experimentally the possibility (1) to reduce bait attractiveness, (2) to reduce fishing device attractiveness and (3) to utilise acoustic deterrents. Experiments have been carried out on 11 turtles (7 youngs, 4 subadults) lodged in tanks. (1) Results show that attractiveness of red, blu and yellow colours is partially age dependent. Turtles are significantly more attracted by mackerel-containing sheaths. Moreover, among plastic artificial baits, the yellow cuttlefish-shaped ones were higher than that of empty sheaths. Among plastic artificial baits, the yellow cuttlefish-shaped bait was the least attractive. (2) Results show that long-line buoys do not attract turtles, whether they were provided with signalling lights or not. (3) Finally, pure sounds of frequencies between 20 and 300 Hz may elicit turtle avoidance. Thanks to the co-operation of local fishermen, the experimental protocol derived from this research will be tested in open sea. "

Experimental evaluation of Caretta caretta by-catch Reduction Devices.

PIOVANO, SUSANNA;BALLETTO, Emilio;GIACOMA, Cristina;
2002

Abstract

"Evaluating the impact of local fisheries on loggerhead turtle mortality rates in the waters surrounding the island of Linosa (35° 51'N 12° 51'E, Italy) is one of the main goals of the EU-Life Project Urgent conservation measures of Caretta caretta in the Pelagie islands (LIFE99NAT/IT/006271). Reports of by-catches of Caretta caretta collected since 1994 suggest that long-line fishing has a strong impact on the local population. In order to reduce loggerhead by-catches by long-line fishing in the Pelagie islands, without negative impact on swordfish (Xiphias gladius) catch size, we first surveyed the local fishing methodology, then we tested experimentally the possibility (1) to reduce bait attractiveness, (2) to reduce fishing device attractiveness and (3) to utilise acoustic deterrents. Experiments have been carried out on 11 turtles (7 youngs, 4 subadults) lodged in tanks. (1) Results show that attractiveness of red, blu and yellow colours is partially age dependent. Turtles are significantly more attracted by mackerel-containing sheaths. Moreover, among plastic artificial baits, the yellow cuttlefish-shaped ones were higher than that of empty sheaths. Among plastic artificial baits, the yellow cuttlefish-shaped bait was the least attractive. (2) Results show that long-line buoys do not attract turtles, whether they were provided with signalling lights or not. (3) Finally, pure sounds of frequencies between 20 and 300 Hz may elicit turtle avoidance. Thanks to the co-operation of local fishermen, the experimental protocol derived from this research will be tested in open sea. "
22nd Annual Symposium on Sea Turtle Biology and Conservation
Miami, Florida, USA
2002
22nd Annual Symposium on Sea Turtle Biology and Conservation
22nd Annual Symposium on Sea Turtle Biology and Conservation
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PIOVANO S.; BALLETTO E.; BARONE B.; DELL'ANNA L.; DI MARCO S.; DOMINICI A.; C. GIACOMA; MARI F.; MIGLIETTA F.; ZANNETTI A.; SOLINAS M.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2318/18183
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