Bottom trawl catch comparison in the Mediterranean Sea: Flexible Turtle Excluder Device (TED) vs traditional gear

Autoři: Claudio Vasapollo aff001;  Massimo Virgili aff001;  Andrea Petetta aff001;  Giada Bargione aff001;  Antonello Sala aff001;  Alessandro Lucchetti aff001
Působiště autorů: National Research Council (CNR), Institute of Biological Resources and Marine Biotechnologies (IRBIM), Largo Fiera della Pesca, Ancona, Italy aff001;  Department of Biological, Geological and Environmental Sciences, University of Bologna, Piazza di Porta San Donato, Bologna, Italy aff002
Vyšlo v časopise: PLoS ONE 14(12)
Kategorie: Research Article
doi: 10.1371/journal.pone.0216023


The Mediterranean Sea is a biodiversity hotspot where intense fishing pressure is associated with high bycatch rates of protected species (sea turtles and cetaceans) and top predators (sharks). Since the conservation of these species has become a priority, fishery scientists are faced with the challenge of reducing incidental catch, which entails high rates of mortality. Among the species threatened by fishing activities, the loggerhead turtle (Caretta caretta) is a charismatic species considered as “vulnerable” at the global scale. In the Mediterranean Sea trawl nets are the gears with the highest probability of catching protected species incidentally. A new flexible Turtle Excluder Device (TED) was tested for the first time on commercial bottom trawlers to assess its effectiveness in reducing bycatch in the Mediterranean Sea. Analysis of the total catches of the hauls made with and without the TED showed that the difference in terms of weight was not significant. The catch of the main commercial species showed similar rates without a significant loss of size (i.e. total length) with the exception of the largest anglerfish (Lophius spp.). The bycatch of control nets included mostly rays and sharks, but never turtles, although the authors learned from the crews of other vessels operating in the same areas at the time of the trials that they had caught some loggerhead turtles. Our study demonstrates that TED scan be adopted without significantly affecting commercial catch. This informs fishers and managers for a practical and effective means that may reduce the bycatch of threatened species in coastal Mediterranean demersal multispecies fisheries. The measures involving gear modifications require significant investment but they are technically feasible and are capable of improving the conservation prospects of these endangered species. Besides ensuring normal earnings, the TED induced a significant reduction of debris and litter in the codend, thus reducing catch sorting time and improving catch quality.

Klíčová slova:

Conservation science – Endangered species – Fish – Fisheries – Fisheries science – Italian people – Mediterranean Sea – Turtles


1. Bianchi CN, Morri C. Marine biodiversity of the Mediterranean Sea: Situation, problems and prospects for future research. Mar Pollut Bull. 2000;40: 367–376. doi: 10.1016/S0025-326X(00)00027-8

2. Colloca F, Cardinale M, Maynou F, Giannoulaki M, Scarcella G, Jenko K, et al. Rebuilding Mediterranean fisheries: A new paradigm for ecological sustainability. Fish Fish. 2013;14: 89–109. doi: 10.1111/j.1467-2979.2011.00453.x

3. Tudela S. Ecosystem effects of fishing in the mediterranean. An analysis of the major threats of fishing gear and practices to biodiversity and marine habitats. Stud Rev Gen Fish Comm Mediterr. Rome: FAO; 2004;74: 44. doi: 10.1017/CBO9781107415324.004

4. Worm B, Barbier EB, Beaumont N, Duffy JE, Folke C, Halpern BS, et al. Impacts of biodiversity loss on ocean ecosystem services. Science (80-). 2006;314: 787–790. doi: 10.1126/science.1132294 17082450

5. Bearzi G. Interactions between cetaceans and fisheries in the Mediterranean Sea. In: Notarbartolo di Sciara G, editor. Cetaceans of the Mediterranean and Black Seas: State of the knowledge and conservation strategies. Monaco: ACCOBAMS; 2002. p. 92.

6. Casale P. Sea turtle by-catch in the Mediterranean. Fish Fish. 2011;12: 299–316. doi: 10.1111/j.1467-2979.2010.00394.x

7. Ferretti F, Myers RA, Serena F, Lotze HK. Loss of large predatory sharks from the Mediterranean Sea. Conserv Biol. 2008;22: 952–964. doi: 10.1111/j.1523-1739.2008.00938.x 18544092

8. Commission European. Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora. Council of the European Communities (CEC). Off J Eur Communities. 1992;206: 7–50.

9. FAO. International Guidelines on bycatch management and reduction of discards. [Internet]. FAO International Guidelines. 2011. ISSN 2070-6987

10. Lewison RL, Johnson AF, Verutes GM. Embracing Complexity and Complexity-Awareness in Marine Megafauna Conservation and Research. Front Mar Sci. 2018;5: 1–11. doi: 10.3389/fmars.2018.00043 29552559

11. Casale P, Tucker AD. Caretta caretta. IUCN Red List Threat Species 2015. 2015;8235: 20.

12. Casale P. Caretta caretta (Mediterranean subpopulation). IUCN Red List Threat Species 2015. 2015; e.T83644804A83646294.

13. Lucchetti A, Vasapollo C, Virgili M. An interview-based approach to assess sea turtle bycatch in Italian waters. PeerJ. 2017;5: e3151. doi: 10.7717/peerj.3151 28462017

14. Lucchetti A, Sala A. An overview of loggerhead sea turtle (Caretta caretta) bycatch and technical mitigation measures in the Mediterranean Sea. Rev Fish Biol Fish. 2010;20: 141–161. doi: 10.1007/s11160-009-9126-1

15. Casale P. Incidental catch of marine turtles in the Mediterranean Sea: Captures, mortality, priorities. Rome, Italy: WWF; 2008.

16. Lucchetti A, Pulcinella J, Angelini V, Pari S, Russo T, Cataudella S. An interaction index to predict turtle bycatch in a Mediterranean bottom trawl fishery. Ecol Indic. Elsevier Ltd; 2016;60: 557–564. doi: 10.1016/j.ecolind.2015.07.007

17. Lazar B, Margaritoulis D, Tvrtkovic N. Tag recoveries of the loggerhead sea turtle Caretta caretta in the eastern Adriatic Sea: implications for conservation. J Mar Biol Assoc UK. 2004;84: 475–480. doi: 10.1017/S0025315404009488h

18. Casale P, Laurent L, De Metrio G. Incidental capture of marine turtles by the Italian trawl fishery in the north Adriatic Sea. Biol Conserv. 2004;119: 287–295. doi: 10.1016/j.biocon.2003.11.013

19. Epperly S. Fisheries-related mortality and turtle excluder devices (TEDs). In: Lutz P, Musick J, editors. The biology of sea turtles. Boca Raton, FL: CRC Press; 2003. pp. 339–353.

20. Lewison R, Wallace B, Alfaro-Shigueto J, Mangel JC, Maxwell SM, Hazen EL. Fisheries bycatch of marine turtles: lessons learned from decades of research and conservation. In: Wyneken J, Lohmann KJ, Musick JA, editors. Biology of sea turtles, vol 3. Boca Raton, FL: CRC Press; 2013. pp. 329–351.

21. Atabey S, Taskavak E. A preliminary study on the prawn trawls excluding sea turtles. J Fish Aquat Sci. 2001;18: 71–79.

22. Sala A, Lucchetti A, Affronte M. Effects of Turtle Excluder Devices on bycatch and discard reduction in the demersal fisheries of Mediterranean Sea. Aquat Living Resour. 2011;24: 183–192. doi: 10.1051/alr/2011109

23. Lucchetti A, Punzo E, Virgili M. Flexible Turtle Excluder Device (TED): an effective tool for Mediterranean coastal multispecies bottom trawl fisheries. Aquat Living Resour. 2016;29: 1–12. Available:

24. Lucchetti A, Bargione G, Petetta A, Vasapollo C, Virgili M. Reducing Sea Turtle Bycatch in the Mediterranean Mixed Demersal Fisheries. Front Mar Sci. 2019;6: 387. doi: 10.3389/fmars.2019.00387

25. Mitchell J, Watson J, Foster D, Caylor R. The Turtle Excluder Device (TED): a guide to better performance. 1995.

26. Eayrs S. A Guide to Bycatch Reduction in Tropical Shrimp-Trawl Fisheries. Fao. 2007; 124. Available:

27. Quinn G, Keough M. Experimental Design and Data Analysis for Biologists. Cambridge University Press; 2002.

28. Zuur A, Ieno E, Walker N, Saveliev A, Smith G. Mixed effects models and extensions in ecology with R. New York: Springer; 2009.

29. Pinheiro J, Bates D. Mixed-Effects Models in S and S-PLUS. Springer, editor. 2000.

30. Holst R, Revill A. A simple statistical method for catch comparison studies. Fish Res. 2009;95: 254–259. doi: 10.1016/j.fishres.2008.09.027

31. Fryer RJ, Zuur AF, Graham N. Using mixed models to combine smooth size-selection and catch-comparison curves over hauls. Can J Fish Aquat Sci. 2003;60: 448–459. doi: 10.1139/f03-029

32. Fryer RJ. A model of between-haul variation in selectivity. ICES J Mar Sci. 1991;48: 281–290. doi: 10.1093/icesjms/48.3.281

33. Van Marlen B, Wiegerinck JAM, van Os-Koomen E, van Barneveld E. Catch comparison of flatfish pulse trawls and a tickler chain beam trawl. Fish Res. Elsevier B.V.; 2014;151: 57–69. doi: 10.1016/j.fishres.2013.11.007

34. Browne D, Minto C, Cosgrove R, Burke B, McDonald D, Officer R, et al. A general catch comparison method for multi-gear trials: Application to a quad-rig trawling fishery for Nephrops. ICES J Mar Sci. 2017;74: 1458–1468. doi: 10.1093/icesjms/fsw236

35. Sistiaga M, Herrmann B, Grimaldo E, O’Neill FG. Estimating the selectivity of unpaired trawl data: a case study with a pelagic gear. Sci Mar. 2016;80: 321–327. doi: 10.3989/scimar.04409.26b

36. R Core Team. R: A language and environment for statistical computing. [Internet]. R Foundation for Statistical Computing. Vienna; 2018. 3-900051-14-3

37. Pinheiro J, Bates D, DebRoy S, Sarkar D. nlme: Linear and Nonlinear Mixed Effects Models. 2018.

38. Bates D, Martin M, Bolker B, Walker S. Fitting Linear Mixed-Effects Models Using lme4. J Stat Softw. 2015;67: 1–48.

39. Strafella P, Fabi G, Despalatovic M, Cvitković I, Fortibuoni T, Gomiero A. Assessment of seabed litter in the Northern and Central Adriatic Sea (Mediterranean) over six years. Mar Pollut Bull. Elsevier; 2019;141: 24–35. doi: 10.1016/j.marpolbul.2018.12.054 30955731

40. Casale P, Broderick AC, Caminas JA, Cardona L, Carreras C, Demetropoulos A, et al. Mediterranean sea turtles: current knowledge and priorities for conservation and research. Endanger Species Res. 2018;36: 229–267. doi: 10.1136/bmj.b2700

41. Piovano S, Basciano G, Swimmer Y, Giacoma C. Evaluation of a bycatch reduction technology by fishermen: a case study from Sicily. Mar Policy. Elsevier; 2012;36: 272–277. doi: 10.1016/j.marpol.2011.06.004

42. Ortiz N, Mangel JC, Wang J, Alfaro-Shigueto J, Pingo S, Jimenez A, et al. Reducing green turtle bycatch in small-scale fisheries using illuminated gillnets: the cost of saving a sea turtle. Mar Ecol Prog Ser. 2016;545: 251–259. doi: 10.3354/meps11610

43. Virgili M, Vasapollo C, Lucchetti A. Can ultraviolet illumination reduce sea turtle bycatch in Mediterranean set net fisheries? Fish Res. 2018;199: 1–7. doi: 10.1016/j.fishres.2017.11.012

44. Lazar B, Tvrtkovic N. Marine turtles in the eastern part of the Adriatic sea: preliminary research. Nat Croat. 1995;4: 59–74.

45. Cox TM, Lewison RL, Žydelis R, Crowder LB, Safina C, Read AJ. Comparing effectiveness of experimental and implemented bycatch reduction measures: The ideal and the real. Conserv Biol. 2007;21: 1155–1164. doi: 10.1111/j.1523-1739.2007.00772.x 17883481

46. Finkbeiner EM, Wallace BP, Moore JE, Lewison RL, Crowder LB, Read AJ. Cumulative estimates of sea turtle bycatch and mortality in USA fisheries between 1990 and 2007. Biol Conserv. Elsevier Ltd; 2011;144: 2719–2727. doi: 10.1016/j.biocon.2011.07.033

47. Hall M, Nakano H, Clarke S, Thomas S. Working with fishers to reduce bycatches. In: Kennelly S, editor. Bycatch Reduction in the World’s Fisheries. Springer-Verlag; 2007.

Článek vyšel v časopise


2019 Číslo 12