Beyond fishing: loggerhead turtle impalement by swordfish


  • Fernando N. Fiedler Centro Nacional de Pesquisa e Conservação da Biodiversidade Marinha do Sudeste e Sul (CEPSUL), Avenida Carlos Ely Castro 195 Centro, 88301-445 - Itajaí, Brazil
  • Gilberto Sales Centro Nacional de Pesquisa e Conservação de Tartarugas Marinhas e da Biodiversidade Marinha do Leste (Centro TAMAR/ICMBio), 88061-160 - Florianópolis, Brazil
  • Rodrigo Barreto Centro Nacional de Pesquisa e Conservação da Biodiversidade Marinha do Sudeste e Sul (CEPSUL), Avenida Carlos Ely Castro 195 Centro, 88301-445 - Itajaí, Brazil
  • Caiame J. Nascimento Independent researcher, 42830-034 - Camaçari, Brazil
  • Bruno B. Giffoni Fundação Centro Brasileiro de Proteção e Pesquisa das Tartarugas Marinhas (Fundação Projeto Tamar), 11688-670 - Ubatuba, Brazil



Sea turtle, incidental capture, species interaction, fisheries, Southwestern Atlantic Ocean


Sea turtles are susceptible to a wide range of impacts. In Brazil, the loggerhead turtle Caretta caretta (Linnaeus, 1758) is the main sea turtle species caught incidentally by longline fishing fleets that target the blue shark Prionace glauca (Linnaeus, 1758) and swordfish Xiphias gladius (Linnaeus, 1758). The latter is well known for its predation strategy, which consists of using the rostrum to injure and catch prey. In this study, we recorded for the first time the impalement of a juvenile loggerhead sea turtle by a swordfish during a fishing operation of a Brazilian longline vessel in 2018. Two videos of this interaction were recorded by the shipmaster around 260 km from the Brazilian coast. The sea turtle was incidentally caught with a hook and subsequently attacked by the swordfish. The rostrum initially pierced the anterior left shoulder of the turtle and passed through the body, exiting from the right posterior carapace. Given the position of the attack, considerable internal damage was most certainly done to the turtle. Although the turtle was hauled aboard to remove the hook and then returned to the sea alive, it probably died due to the extent of the injuries caused by the rostrum having passed through the center of the body. Since both swordfish and turtle are pelagic and these interactions are poorly recorded, such encounters may be relatively common. Therefore, this type of information should be included in the data collection protocols of fishery monitoring programs to better understand and scale the bill-stab phenomenon, not only for sea turtles but also in relation to other groups of fauna.


Download data is not yet available.


Metrics Loading ...

Author Biographies

Fernando N. Fiedler, Centro Nacional de Pesquisa e Conservação da Biodiversidade Marinha do Sudeste e Sul (CEPSUL), Avenida Carlos Ely Castro 195 Centro, 88301-445 - Itajaí, Brazil

Gilberto Sales, Centro Nacional de Pesquisa e Conservação de Tartarugas Marinhas e da Biodiversidade Marinha do Leste (Centro TAMAR/ICMBio), 88061-160 - Florianópolis, Brazil

Rodrigo Barreto, Centro Nacional de Pesquisa e Conservação da Biodiversidade Marinha do Sudeste e Sul (CEPSUL), Avenida Carlos Ely Castro 195 Centro, 88301-445 - Itajaí, Brazil

Caiame J. Nascimento, Independent researcher, 42830-034 - Camaçari, Brazil

Bruno B. Giffoni, Fundação Centro Brasileiro de Proteção e Pesquisa das Tartarugas Marinhas (Fundação Projeto Tamar), 11688-670 - Ubatuba, Brazil


Achaval F, Prigioni C. 1988. Reporte de colisión de ‘Marlin’ (Makaira nigricans) a una tortuga Laud (Dermochelys coriacea). V Reunión Iberoamericana de Conservación y Zoologia de Vertebrados, Montevideo, 26-30 julio. 93 p.

Ataman A, Gainsbury AM, Manire CA, Hoffmann SL, Page-Karjian A, Hirsch SE, Polyak MMR, Cassill DL, Aoki DM, Fraser KM, et al. 2021. Evaluating prevalence of external injuries on nesting loggerhead sea turtles Caretta caretta in southeastern Florida, USA. Endang Species Res. 46: 137-146. DOI:

Barceló C, Domingo A, Miller P, Ortega L, Giffoni B, Sales G, McNaughton L, Marcovaldi M, Heppell SS, Swimmer Y. 2013. High-use areas, seasonal movements and dive patterns of juvenile loggerhead sea turtles in the Southwestern Atlantic Ocean. Mar Ecol Progr Ser. 479: 235-250.

Brock RE. 1985. Preliminary study of the feeding habits of pelagic fish around Hawaiian fish aggregation devices or can fish aggregation devices enhance local fisheries productivity? Bull Mar. Sci 37: 40-49.

Carey FG. 1982. A brain heater in the swordfish. Science. 216 (4552): 1327-1329. DOI:

Carey FG, Robison BH. 1981. Daily patterns in the activities of swordfish, Xiphias gladius, observed by acoustic telemetry. Fish Bull. 79 (2): 277-292.

Carvajal JMG, Madueño JJM, Bómez BB, Paniagua JMR. 2002. Swordfish attack: an usual cause of penetrating thoracic wound. Eur J Cardio-Thorac Surg. 21: 926.

Clarke MR, Clarke DC, Martins HR, Silva HM. 1995. The diet of swordfish (Xiphias gladius) in Azorean waters. Arquipel Life Mar Sci. 13 (A): 53-69.

Domingo A, Bugoni L, Prosdocimi L, Miller P, Laporta M, Monteiro DS, Estrades A, Albareda D. 2006b. El impacto generado por las pesquerías en las tortugas marinas en el Océano Atlántico Sud Occidental. WWF Programa Marino para Latinoamérica y el Caribe, San José Costa Rica. 72 p.

Domingo A, Sales G, Giffoni B, Miller P, Laporta M, Mauruto G. 2006a. Distribución y composición de tallas de las tortugas marinas (Caretta caretta y Dermochelys coriacea) que interactúan con el palangre pelágico en el Atlántico Sur. Collect Vol Sci Pap ICCAT. 59 (3): 992-1002.

Ellis R. 2013. Swordfish: a biography of the ocean gladiator. Chicago: The University of Chicago Press.

Fiedler FN, Sales G, Giffoni BB, Port D, Sant’ana R, Barreto AS, Schwingel PR. 2015. Spatio-temporal distribution and target species of longline fisheries off Southeastern/Southern Brazil between 2000 and 2011. Braz J Oceanogr. 63: 83-97.

Fierstine HL. 1997. An Atlantic blue marlin, Makaira nigricans, impaled by two species of billfishes (Teleostei: Istiophoridae). Bull Mar Sci. 61 (2): 495-499.

Fierstine HL, Cailliet GM, Neer JA. 1997. Shortfin mako, Isurus oxyrinchus, impaled by blue marlin, Makaira nigricans (Teleostei: Istiophoridae). Bull South Calif Acad Sci. 96 (3): 117-121.

Figueiredo JL, Menezes N. 2000. Manual de peixes marinhos do sudeste do Brasil. VI. Teleostei (5) São Paulo: Museu de Zoologia, Universidade de São Paulo. 116 p.

Frazier JG, Fierstine HL, Beavers SC, Achaval F, Suganuma H, Pitman RL, Yamaguchi Y, Prigioni CM. 1994. Impalement of marine turtles (Reptilia, Chelonia: Cheloniidae and Dermochelyidae) by billfishes (Osteichthyes, Perciformes: Istiophoridae and Xiphiidae). Environ Biol Fishes. 39: 85-96.

Frietsches KA, Brill RW, Warrant EJ. 2005. Warm eyes provide superior vision in swordfishes. Curr Biol. 15: 55-58. DOI:

Galarza M, Alfaro R, De la Rosa P, Piqueras C. 2016. Delayed spinal cord herniation after a swordfish attack. Oper Neurosurg. 12 (3): E307-E308. DOI:

Georgiadou D, Zografos GN, Vaidakis D, Avlonitis S, Katopodi A, Tzirakis EN, Sioutos P, Drossos C, Lampropoulou P, Papastratis G. 2010. Swordfish bill injury involving abdomen and vertebral column: case report and review. BMC Surgery. 10: 2-8. DOI:

Giffoni B, Domingo A, Sales G, Fiedler FN, Miller P. 2008. Interacción de tortugas marinas (Caretta caretta y Dermochelys coriacea) con la pesca de palangre pelágico en el Atlántico Sudoccidental: uma perspectiva regional para la conservación. Collect Vol Sci Pap ICCAT. 62 (6): 1861-1870.

Gooi BH, Khamizar W, Suhani MN. 2007. Swordfish attack-death by penetrating head injury. Asian J Surg. 30 (2): 158-159.

Gorbunova NN. 1969. Breeding grounds and food of the larvae of the swordfish Xiphias gladius Linnaeu (Pisces, Xiphllidae). Probl Lchthyol. 9: 375-387.

Gorni GR, Goiten R, Amorim AF. 2013. Description of diet of pelagic fish in the southwestern Atlantic, Brazil. Biota Neotrop. 13 (1): 61-69.

Gorni GR, Loibel S, Goiten R, Amorim AF. 2012. Stomach contents analysis of swordfish (Xiphias gladius) caught off Southern Brazil: a Bayesian analysis. Col Vol Sci Pap ICCAT. 68 (4): 1594-1600.

Gudger EW. 1940. The alleged pugnacity of the swordfish and the spear-fishes as shown by their attacks on vessels. A study of their behavior and the structures which make possible these attacks. Mem Roy Asiat Soc Bengal. 4: 272-273.

Habegger ML. 2014. Functional morphology and feeding mechanics of billfishes [PhD thesis]. Tampa: Scholar Commons, University of South Florida.

Habegger ML, Dean MN, Dunlop JWC, Mullins G, Stokes M, Huber DR, Winters D, Motta PJ. 2015. Feeding in billfishes: inferring the role of the rostrum from a biomechanical standpoint. J Exp Biol. 218: 824-836. DOI:

Habegger ML, Huber DH, Lajeunesse MJ, Motta PJ. 2017. Theoretical calculations of bite force in billfishes. J Zool. 303 (1): 15-26. DOI:

Haddad VJr, Figueiredo JL. 2009. Attack upon a bather by a swordfish: a case report. Wilderness Environ Med. 20: 344-346.

Hazin H, Erzini K. 2008. Assessing swordfish distribution in the South Atlantic from spatial predictions. Fish Res. 90: 45-55. DOI:

Hirama S, Witherington B. 2012. A loggerhead sea turtle (Caretta caretta) preying on fish within a mixed-species feeding aggregation. Chelonian Conserv Biol. 11 (2): 261-265. DOI:

Jambura PL, Türtscher J, Kriwet J, Al Mabruk SAA. 2020. Deadly interaction between a swordfish Xiphias gladius and a bigeye thresher shark Alopias superciliosus. Ichthyol Res. 68: 317-321. DOI:

Jonsgard A. 1959. New find of sword from swordfish (Xiphias gladius) in blue whale (Balaenoplera musculus) in Antarctic. Nor Hvalfangst-Tid. 48 (352): 355-356, 359-360.

Jonsgard A. 1962. Three finds of swords from swordfish (Xiphias gladius) in the Antarctic fin whale Baleonoptera physalus. Nor Hvalfangst-Tid. 51: 287-291.

Kotas JE, Santos S, Azevedo VG, Gallo BMG, Barata PCR. 2004. Incidental capture of loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles by the pelagic longline fishery off southern Brazil. Fish Bull. 102: 393-399.

Lazar B, Maslov L, Romanic SH, Gracan R, Krauthacker B, Holcer D, Tvrtkovic N. 2011. Accumulation of organochlorine contaminants in loggerhead sea turtles, Caretta caretta, from the eastern Adriatic Sea. Chemosphere. 82: 121-129. DOI:

Lee H-J, Jong Y-J, Chang L-M, Wu W-L. 2009. Propulsion strategy analysis of high-speed swordfish. Trans Japan Soc Aero Space Sci. 52 (175): 11-20. DOI:

Lewison RL, Crowder LB. 2007. Putting longline bycatch of sea turtles into perspective. Conserv Biol. 21: 79-86. DOI:

Lewison RL, Crowder LB, Wallace BP, Moore JE, Cox T, Zydelis R, McDonald S, DiMatteo A, Dunn DC, Kot CY, et al. 2014. Global patterns of marine mammal, seabird, and sea turtle bycatch reveal taxa-specific and cumulative megafauna hotspots. Proc Natl Acad Sci USA. 111 (14): 5271-5276. DOI:

Lewison RL, Freeman SA, Crowder LB. 2004. Quantifying the effects of fisheries on threatened species: the impact of pelagic longlines on loggerhead and leatherback sea turtles. Ecol Lett. 7: 221-231. DOI:

López-Mendilaharsu M, Sales G, Giffoni B, Miller P, Fiedler FN, Domingo A. 2007. Distribución y composición de tallas de las Tortugas marinas (Caretta caretta y Dermochelys coriacea) que interactúan con el palangre en el Atlántico Sur. Collect Vol Sci Pap ICCAT. 60 (6): 2094-2109.

Machida S. 1970. A sword-fish sword found from a north Pacific sei whale. Sci Rep Whales Res Inst. 22: 163-164.

Major PF. 1979. An aggressive encounter between a pod of whales and billfish. Sci Rep Whales Res Inst. 31: 95-96.

Martin K. 2014. Trinidad Day 5. Canadian Sea Turtle Network. [accessed 2022 May].

Mazzoleni RC, Schwingel PR. 2002. Aspectos da biologia das espécies capturadas por espinhel pelágico na região sul das Ilhas de Trindade e Martin Vaz no verão de 2001. No-tas Téc FACIMAR. 6: 51-57.

McGowan C. 1988. Differential development of the rostrum and mandible of the swordfish (Xiphias gladius) during ontogeny and its possible functional significance. Can J Zool. 66: 496-503.

Mendonça-Caridad JJ, Lopez PJ, Rodriguez M. 2008. Swordfish bill injury involving the pterygomaxillary fossae: surgical management and case report. J Oral Maxillofac Surg. 66: 1739-1743. DOI:

Nakamura I. 1983. Systematics of the billfishes (Xiphiidae Andistiophoridae). Publ Seto Mar Biol Lab. 28 (5-6): 255-396. DOI:

Ndiaye A, Gaye M, Ba PS, Diatta S, Diop MS, Ndiaye M. 2017. Penetrating chest injuries caused by swordfish sword used as a weapon. Asian Cardiovasc Thorac Ann. 25 (3): 229-232. DOI:

[NRC] National Research Council. 1990. Decline of the sea turtles: causes and prevention. Washington DC: National Academy Press.

Oshumi S. 1973. Find of marlin spear from the Antarctic mink whales. Sci Rep Whales Res Inst. 25: 237-239.

Palko BJ, Beardsley GL, Richards WJ. 1981. Synopsis of the biology of swordfish Xiphias gladius Linnaeus. NOAA Tech Rep NMFS Circular 441, FAO Fish Synop. 127.

Penadés-Suay J, García-Salinas P, Tomás J, Aznar FJ. 2019. Aggressive interactions between juvenile swordfish and blue sharks in the western Mediterranean: a widespread phenomenon? Medit Mar Sci. 20 (2): 314-319. DOI:

Penadés-Suay J, Tomás J, Aznar FJ. 2017. Fatal impalement of a blue shark Prionace glauca by a swordfish Xiphias gladius. Medit Mar Sci. 18 (2): 340-343. DOI:

Pons M, Domingo A, Sales G, Fiedler FN, Miller P, Giffoni B, Ortiz M. 2010. Standardization of CPUE of loggerhead sea turtle (Caretta caretta) caught by pelagic longliners in the Southwestern Atlantic Ocean. Aquat Living Resour. 23: 65-75. DOI:

Romeo T, Ammendolia G, Canese S, Andaloro F, Battaglia P. 2017. Recent records of swordfish attacks on harpoon vessels in the Sicilian waters (Mediterranean Sea). Acta Adriat. 58 (1): 147-156.

Romeo T, Battaglia P, Macaluso D, Tagliavia G, Vicchio TM, Falautano M, Serena F, Andaloro F. 2020. When prey becomes killer: does a double lethal attack on a blue shark reveal a precise defensive strategy in young swordfish? J Mar Biol Assoc UK. 100 (5): 831-836. DOI:

Sagong W, Jeon W-P, Choi H. 2013. Hydrodynamic characteristics of the sailfish (Istiophorus platypterus) and swordfish (Xiphias gladius) in gliding postures at their cruise speeds. PLoS ONE. 8 (12): e81323. DOI:

Sales G, Giffoni, BB, Barata, PCR. 2008. Incidental catch of sea turtles by the Brazilian pelagic longline fishery. J Mar Biol Assoc UK. 88 (4): 853-864. DOI:

Sales G, Giffoni BB, Barata PCR, Maurutto G. 2004. Interação de tortugas marinas com a pesca de palangre pelágico na costa brasileira - 1999-2003. Resúmenes de la II Reunión Sobre Investigación y Conservación de Tortugas Marinas del Atlántico Sur Occidental-ASO. San Clemente del Tuyú, Argentina.

Schuyler Q, Hardesty BD, Wilcox C, Townsend K. 2014. Global analysis of anthropogenic debris ingestion by sea turtles. Conserv Biol. 28: 129-139.

Scott WB, Tibbo SN. 1968. Food and feeding habits of swordfish Xiphias gladius, in the Western North Atlantic. J Fish Board Can. 25 (5): 903-919. DOI:

Shamblin BM, Bolten AB, Abreu-Grobois FA, Bjorndal KA, Cardona L, Carreras C, Clusa M, Monzón-Argüello C, Nairn CJ, Nielsen JT, et al. 2014. Geographic patterns of genetic variation in a broadly distributed marine vertebrate: new insights into loggerhead turtle stock structure from expanded mitochondrial DNA sequences. PLoS ONE. 9 (1): e85956.

Spotila JR, Reina RR, Steyermark AC, Plotkin PT, Paladino FV. 2000. Pacific leatherback turtles face extinction. Nature. 405: 529-530.

Sriram PR, Jien TCT, Sellamuthu P. 2017. Backstabbing swordfish: a rare cause of traumatic hemiparesis. J Neurosurg Spine. 27: 158-160. DOI:

Vaske Júnior T, Lessa RP. 2005. Estratégia alimentar do espadarte (Xiphias gladius) no Atlântico Equatorial Sudoeste. Trop Oceanogr. 33 (2): 223-232. DOI:

Webb PW. 1986. Effect of body form and response threshold on the vulnerability of four species of teleost prey attacked by largemouth bass (Micropterus salmoides). Can J Fish Aquat Sci. 43: 763-771. DOI:

Weidner DM, Arocha F. 1999. South America: Atlantic, Part A, Section 2 (Segment B) in “Latin America”, World swordfish fisheries: an analysis of swordfish fisheries, market trends, and trade patterns, Vol. IV NMFS Silver Spring, Maryland/USA.

Wisner RL. 1958. Is the spear of Istiophorid fishes used in feeding? Pac Sci. 12 (1): 60-70.




How to Cite

Fiedler, F. N. ., Sales, G., Barreto, R., Nascimento, C. J. and Giffoni, B. B. (2022) “Beyond fishing: loggerhead turtle impalement by swordfish”, Marine and Fishery Sciences (MAFIS), 36(1), pp. 5–16. doi: 10.47193/mafis.3612023010102.