Bycatch of franciscana dolphins Pontoporia blainvillei and the dynamic of artisanal fisheries in the species' southernmost area of distribution

Abstracts

In Argentina, the franciscana dolphin is one of the most vulnerable cetaceans regularly entangled in coastal artisanal fishery nets. The aim of this paper is to estimate the species' incidental mortality on the Southern coast of Buenos Aires province through interviews with the captains of artisanal fishing vessels, in the period 2006-2009. Franciscana bycatch was reported for gillnets and shrimper gear all year round but it occurred more frequently between October and February, at 5 km offshore and 10-20 m depth. The estimated mean annual incidental mortality was 107 dolphins (CI 95% = 87-129), 92 caught in gillnets (CI 95% = 73-112) and 15 in shrimpers' gear (CI 95% = 8-25) with a capture per unit effort of 0.029 dolphins per km of gillnet (CI 95% = 0.023-0.036) and 0.022 per shrimpe r's net (CI 95% = 0.012-0.035). Annual fluctuations were due to differences in the number of gillnetting fishing days. If mortality estimates for the Northern coast are also taken into account, values attain a maximum of 360-539 dolphins bycaught in the entire Buenos Aires province, representing 2.5-3.7% of the species' abundance in Argentina. This will inevitably lead to the decline of franciscana dolphin populations in the near future unless alternative fishing grounds are identified and alternative gearadopted.

Franciscana dolphin; Pontoporia blainvillei; Incidental mortality; Artisanal fisheries; Southwestern Atlantic Ocean

Na Argentina, a toninha é um dos cetáceos mais vulneráveis devido às capturas por rede de pesca artesanal. O presente estudo teve como objetivo estimar as capturas acidentais no sul da província de Buenos Aires, através de entrevistas aos capitães de barcos de pesca artesanal, entre os anos 2006-2009. As capturas foram reportadas para redes de emalhe e de camarão; com as mais altas frequências entre outubro e fevereiro, a 5 km da costa e 10-20 m de profundidade. A mortalidade acidental média anual estimada foi de 107 golfinhos (IC 95% = 87-129), 92 em redes de emalhe (IC 95% = 73-112) e 15 em redes de camarão (IC 95% = 8-25), com uma captura de 0,029 golfinhos/km de rede de emalhe (IC 95% = 0,023-0,036) e 0,024/rede de camarão (IC 95% = 0,012-0,035). As flutuações anuais responderam principalmente às diferenças nos dias de pesca. Considerando o último levantamento estimativo feito para o norte costeiro da província, estima-se uma mortalidade entre 360-539 golfinhos/ano em toda a província de Buenos Aires. Esses valores correspondem de 2,5-3,7% da abundância populacional da Argentina; o que traria como consequência um declínio populacional da espécie, tornando-se fundamental encontrar alternativas de pesca para a área.

Toninha; Pontoporia blainvillei; Capturas acidentais; Pesca artesanal; Atlântico Sul-Ocidental

• ARIAS, P. Artes y métodos de pesca en aguas continentales de América Latina. COPESCAL Doc. Ocas., v. 4, 1988. 178 p,
• BAIRD, R. W.; STACEY, P. J.; DUFFUS, D. A.; LANGELIER, K. M. An evaluation of gray whale (Eschrichtius robustus) mortality incidental to fishing operations in British Columbia, Canada. J. Cetacean Res. Manage, v. 4, n. 3, p. 289-296, 2002.
• BASTIDA, R.; RODRÍGUEZ, D.; SECCHI, E.; DA SILVA, V. Mamíferos Acuáticos de Sudamérica y Antártida. Buenos Aires: Vázquez Mazzini Ed., 2007. 368 p.
• BEARZI, G. Interactions between cetacean and fisheries in the Mediterranean Sea. In: NOTARBARTOLO DI SCIARA, G. (Ed.), Cetaceans of the Mediterranean and Black Seas: state of knowledge and conservation strategies. A report to the ACCOBAMS Secretariat, Mónaco, 2002. p. 1-209.
• BELDEN, D. Estimates of cetacean and pinniped bycatch in the 2005 northeast sink gillnet and mid-Atlantic coastal gillnet fisheries.U. S. Dep. Commer., Northeast Fishery Science Centre Ref. Doc. 07-08, 16 p, 2007.
• BORDINO, P.; THOMPSON, G.; IÑIGUEZ, M. Ecology and behaviour of the franciscana (Pontoporia blainvillei) in Bahía Anegada, Argentina. J. Cetacean Res. Manage., v. 1, n. 2, p. 213-222, 1999.
• BORDINO, P.; SICILIANO, S.; BASTIDA, R.; CREMER, M. Report of the working group on distribution and behaviour. Lat. Am. J. Aquat. Mamm., v. 1, n. 1, p. 21-23, 2002.
• BORDINO, P.; ALBAREDA, D. Incidental mortality of franciscana dolphin Pontoporia blainvillei in coastal gillnet fisheries in Northern Buenos Aires, Argentina. In: INT. WHAL. COMMN. MEETING, Sorrento, Italy. 2004. (Paper SC/56/SM1).
• BURNHAM, K. P.; ANDERSON, D. R. Model Selection and Multimodel Inference: A Practical Information-Theoretic Approach Second edition. New York, USA: Springer-Verlag, 2002.
• CAPPOZZO, H. L.; NEGRI, M. F.; PÉREZ, F. H.; ALBAREDA, D.; MONZÓN, F.; CORCUERA, J. F. Incidental mortality of franciscana dolphin, (Pontoporia blainvillei) in Argentina. Lat. Am. J. Aquat. Mamm., v. 6, n. 2, p. 127-137,2007.
• CHIARAMONTE, G. E. Shark fisheries in Argentina. Mar. Freshwater Res., v. 49, n. 7, p. 601-609, 1998.
• CORCUERA, J. Incidental mortality of franciscanas in argentine waters: the threat of small fishing camps. Rep. Int. Whal. Commn., v. 15, p. 291-294, 1994.
• CORCUERA, J.; MONZÓN, F.; CRESPO, E. A.; AGUILAR, A.; RAGA, J. A. Interactions between marine mammals and the coastal fisheries of Necochea and Claromecó (Buenos Aires Province, Argentina).Rep. Int. Whal. Commn., v. 15, p. 283-290, 1994.
• CRESPO, E. A.; CORCUERA, J. F.; LÓPEZ CAZORLA, A. Interactions between marine mammals and fisheries in some coastal fishing areas of Argentina. Rep. Int. Whal. Commn., v. 15, p. 269-281, 1994.
• CRESPO, E. A.; HARRIS, G.; GONZÁLEZ, R. Group size and distributional range of the franciscana Pontoporia blainvillei. Mar. Mammal Sci., v. 14, n. 4, p. 845-849, 1998.
• CRESPO, E. A.; PEDRAZA, S. N.; GRANDI, M. F.; DANS, S. L.; GARAFFO, G. V. Abundance and distribution of endangered franciscana dolphins in argentine waters and conservation implications. Mar. Mammal Sci., v. 26, n. 1, p. 17-35, 2010.
• D'AGROSA, C.; VIDAL, O.; GRAHAM, W. C. Mortality of the vaquita (Phocoena sinus) in gill net fisheries during 1993-94. Rep. Int. Whal. Commn., v. 16, p. 283-291,1995.
• DAWSON, S. Incidental catch of Hector's dolphins in inshore gillnets. Mar. Mammal Sci., v. 7, n. 3, p. 283-295,1991.
• DI BENEDITTO, A. P. M. Interactions between gillnet fisheries and small cetaceans in northern Rio de Janeiro, Brazil: 2001-2002. Lat. Am. J. Aquat. Mamm, v. 2, n. 2, p. 79-86, 2003.
• FAO. Resumen informativo sobre la pesca por países. La República Argentina. Food and Agriculture Organization of the United Nations FID/CP/ARG. 2005.
• FORTUNA, C. M.; VALLINIA, C.; FILIDEI Jr., E.; RUFFINO, M.; CONSALVO, I.; DI MUCCIOA, S.; GION, C.; SCACCO, U.; TARULLI, E.; GIOVANARDI, O.; MAZZOLA A. By-catch of cetaceans and other species of conservation concern during pair trawl fishing operations in the Adriatic Sea (Italy). Chem. Ecol., v. 26, p. 65-76, 2010.
• FRANCO-TRECU, V.; COSTA, P.; ABUD, C.; DIMITRIADIS, C.; LAPORTA, P.; PASSADORE, C.; SZEPHEGY, M. By-catch of franciscana Pontoporiablainvillei in uruguayan artisanal gillnet fisheries: an evaluation after a twelve-year gap in data collection. Lat. Am. J. Aquat. Mamm., v. 7, n. 1-2, p. 11-22, 2009.
• IÑIGUEZ, M. A.; HEVIA, M.; GASPARROU, C.; TOMSIN, A. L.; SECCHI, E. R.Preliminary estimate of incidental mortality of Commerson's dolphins (Cephalorhynchus commersonii) in an artisanal setnet fishery in La Angelina beach and Ría Gallegos, Santa Cruz, Argentina. Lat. Am. J. Aquat. Mamm., v.2, n. 2, p. 87-94, 2003.
• KINAS, P. G. The impact of incidental kills by gill nets on the franciscana dolphin (Pontoporia blainvillei) in southern Brazil. B. Mar. Sci., v. 70, n. 2, p. 409-421, 2002.
• LASTA, C. A.; CAROZZA, C. R.; RUARTE, C. O.; JAUREGUIZAR, A. J. Ordenamiento pesquero en el ecosistema costero bonaerense. Mar del Plata, Buenos Aires: Technical report INIDEP 25, 1999. 20 p.
• MANGEL, J.;ALFARO-SHIGUETO, J.; VAN WAEREBEEK, K.; CACERES, C.; BEARHOP, S.; WITT, M. J.; GODLEY, B. J. Small cetacean captures in peruvian artisanal fisheries: high despite protective legislation. Biol. Conserv, v. 143, p. 136-143, 2010.
• MCCULLAGH, P.; NELDER, J. Generalized Linear Models Second Edition. Boca Raton, USA: Chapman and Hall/CRC, 1999. 511 pp.
• NÉDÉLEC, C.; PRADO, J. Definición y clasificación de las diversas categorías de artes de pescaFAO Fisheries Technical Paper. No. 222. Revision 1, 92 p. 1990.
• PÉREZ MACRI, G.; CRESPO, E. A. Survey of the franciscana, Pontoporia blainvillei, along the Argentine coast, with a preliminary evaluation of mortality in coastal fisheries. Occasional papers IUCN SSC, v. 3, p. 57-63, 1989.
• PERRIN, W. F.; DONOVAN, G. P.; BARLOW, J. Report of the workshop on mortality of cetaceans in passive fishing nets and traps. Rep. Int. Whal. Commn., v. 15, p. 6-57, 1994.
• READ, A. J. Incidental catches of small cetaceans In: SIMMONDS, M. P.; HUTCHINSON, J. D. The conservation of whales and dolphins: Science and practice. Chichester: John Wiley & Sons, 1996. p. 109-118.
• REEVES, R.; LEATHERWOOD, S. Dolphins, porpoises, and whales: 1994-1998 action plan for the conservation of cetaceans. Gland, Switzerland: International Union for the Conservation of Nature, 1994. 92 p.
• REEVES, R. R.; SMITH, B. D.; CRESPO, E. A.; NOTARBARTOLO DI SCIARA, G. Dolphins, whales and porpoises: 2002-2010 conservation action plan for the world's cetaceans. Gland, Switzerland and Cambridge: International Union for the Conservation of Nature, 2003. 139 p.
• REEVES, R. R.; DALEBOUT, M. L.; JEFFERSON, T. A.; KARCZMARSKI, L.; LAIDRE, K.; O'CORRY-CROWE, G.; ROJAS-BRACHO, L.; SECCHI, E. R.; SLOOTEN, E.; SMITH, B. D.; WANG, J. Y.; ZERBINI, A. N.; ZHOU, K. Pontoporia blainvillei. In: IUCN 2010. IUCN Red List of Threatened Species. 2008.
• RODRÍGUEZ, D.; RIVERO, L.; BASTIDA, R. Feeding Ecology of the Franciscana (Pontoporia blainvillei) in marine and estuarine waters of Argentina. Lat. Am. J. Aquat. Mamm., v. 1, n. 1, p. 77-94, 2002.
• ROSAS, F. C. W.; MONTEIRO-FILHO, E. L. A.; OLIVEIRA, M. R. de. Incidental catches of franciscana (Pontoporia blainvillei) on the Southern coast of São Paulo State and the coast of Paraná State, Brazil. Lat. Am. J. Aquat. Mamm., v. 1, n. 1, p. 161-167, 2002.
• RUARTE, C. Resultados de distribución de juveniles de pescadilla en la campaña de invierno EH-07-01, con relación al área de la veda estival. Informe Técnico INIDEP, 2001. 8 p.
• SECCHI, E. R. Taxa de crescimento potencial intrínseco de um estoque de franciscanas, Pontoporia blainvillei (Gervais and D'Orbigny, 1846) (Cetacea, Pontoporiidae) sob o impacto da pesca costeira de emalhe. 1999. 152 p. Master Thesis - Fundação Universidade Federal do Rio Grande, RG, Brazil.
• SECCHI, E.R.; FLETCHER, D. Estimating survival rates of franciscana by fitting the Siler model to data on age-at death of beachcast and bycatch and by a modeling approach using life tables of similar species: a comparison. Int. Whal. Commn. Scientific Committee Paper SC/56/SM16. 2004.
• SECCHI, E. R.; OTT, P. H.; CRESPO, E. A.; KINAS, P. G.; PEDRAZA, S. N.; BORDINO, P. A first estimate of franciscana (Pontoporia blainvillei) abundance off southern Brazil. J. Cetacean Res. Manage., v. 3, n. 1, p. 95-100, 2001.
• SECCHI, E. R.; DANILEWICZ, D.; OTT, P. H. Applying the phylogeographic concept to identify franciscana dolphin stocks: implications to meet management objectives. J. Cetacean Res. Manage., v. 5, n. 1, p. 61-68, 2003.
• SECCHI, E. R.; KINAS, P. G.; MUELBERT, M. Incidental catches of Franciscana in coastal gillnet fisheries in the Franciscana Management Area III: period 1999-2000. Lat. Am. J. Aquat. Mamm., v. 3, n. 1, p. 61-68, 2004.
• SEPÚLVEDA, M.; PÉREZ, M.; SIELFELD, W.; OLIVA, D.; DURÁN, L.; RODRÍGUEZ, L.; ARAOS, V.; BUSCAGLIA, M. Operational interaction between south american sea lions Otaria flavescens and artisanal (small-scale) fishing in Chile: results from interview surveys and onboard observations. Fish. R., v. 83, p. 332-340, 2007.
• SHIGUETO, J.A.; MANGEL, J.C.; VAN WAEREBEEK, K. Small cetacean captures and CPUE estimates in artisanal fisheries operating from a port in northern Peru, 2005-2007. Paper SC/60/SM19 presented to IWC Scientific Committee Meeting, 2008.
• SICILIANO, S. Review of small cetaceans and fishery interactions in coastal waters of Brazil. Rep. Int. Whal. Commn., v. 15, p. 241-250, 1994.
• SOYKAN, C.U.; MOORE, J.E.; NAS ÎYDELIS, R.; CROWDER, L.B.; SAFINA, C.; LEWISON, R.L. Why study bycatch? An introduction to the Theme Section on fisheries bycatch. Endang. Species Res., v. 5, p. 91-102, 2008.
• SZTEREN, D.; PAEZ, E. Predation by southern sea lions (Otaria flavescens) on artisanal fishing catches in Uruguay. Mar. Fresh. Res., v. 53, n. 8, p. 1161-1167, 2002.
• TREGENZA, N. J. C.; BERROW, S. D.; HAMMOND, P. S.; LEAPER, R. Harbour porpoise (Phocoena phocoena L.) by-catch in set gillnets in the Celtic Sea. ICES J. Mar. Sci., v. 54, p. 896-904, 1997.
• ZAR, J. H. (ed.) Biostatistical Analysis New Jersey: Prentice-Hall Inc., 1996.662 p.

Publication Dates

• Publication in this collection
  18 July 2012
• Date of issue
  June 2012

History

• Received
  28 Feb 2011
• Accepted
  18 Apr 2012
• Reviewed
  05 Apr 2012