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Ingestion of marine debris by loggerhead sea turtles, Caretta caretta, in the Adriatic Sea
Bojan Lazar, Romana Gračan, 2011, original scientific article

Abstract: We examined the occurrence of marine debris in the gastrointestinal tract of 54 loggerhead sea turtles (Caretta caretta) found stranded or incidentally captured dead by fisheries in the Adriatic Sea, with a curved carapace length of 25.0-79.2 cm. Marine debris was present in 35.2% of turtles and included soft plastic, ropes, Styrofoam and monofilament lines found in 68.4%, 42.1%, 15.8% and 5.3% of loggerheads that have ingested debris, respectively. The dry mass of debris per turtle was low, ranging from <0.01 to 0.71 g, and the ingestion was not significantly affected by sex or body siye (all p > 0.05). Marine debris averaged 2.2 +- 8.0% of dry mass of gut content, with a maximum of 35% found in a juvenile turtle that most likely died due to debris ingestion. Considering the relatively high occurrence of debris intake and possible sub-lethal effects of even small quantities of marine debris, this can be an additional factor of concern for loggerheads in the Adriatic Sea
Keywords: Sea turtles, Caretta caretta, marine debris, plastic, pollution, Adriatic Sea
Published in RUP: 15.10.2013; Views: 3618; Downloads: 142
URL Link to full text

4.
Prioritizing fishery management for loggerhead turtle (Caretta caretta) conservation in the northern Adriatic Sea from reproductive value analysis
Bojan Lazar, Selina S. Heppell, 2009, published professional conference contribution abstract

Abstract: Fisheries bycatch often affects particular size classes of turtles. Because of the late age at maturity, the reproductive value (RV) of small juvenile, large juvenile and adult loggerheads vary by orders of magnitude. RV provides a relative measure of value for individuals, thereby allowing us to estimate the effects of different stressors based on the number of animals killed. Using RV as a comparative index, we assessed the relative impact of trawl and gillnet fi sheries operating in the northern Adriatic Sea on loggerhead populations. We tested several scenarios for bycatch in both fi sheries which signifi cantly differs in the size of captured animals and mortality. Despite high bycatch rates, bottom trawl fi sheries result in direct death of fewer loggerheads (156-260 vs. 346-486 in gill nets), but affect individuals that are older and hence have higher RVs. Because of data limitations for vital rates and bycatch estimates, we looked at a distribution of potential impact for each fi shery. Lessons learned include the need for relative impact assessment because of the sensitivity of adult RV to parameters such as clutch frequency, sex ratio and remigration interval. We anticipate that our analysis will help managers prioritize needs for regulation and mitigation among different fi sheries.
Keywords: sea turtles, bycatch, population modelling, reproductive values, marine conservation
Published in RUP: 15.10.2013; Views: 3826; Downloads: 87
URL Link to full text

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