Journal of the Marine Biological Association of the United Kingdom

Research Article

Age and growth of franciscana dolphins, Pontoporia blainvillei (Cetacea: Pontoporiidae) incidentally caught off southern Brazil and northern Argentina

Silvina Bottaa1 c1, Eduardo R. Secchia1, Mônica M.C. Muelberta1, Daniel Danilewicza2, Maria Fernanda Negria3, Humberto Luis Cappozzoa3 and Aleta A. Hohna4

a1 Laboratório de Mamíferos Marinhos, Instituto de Oceanografia, Universidade Federal do Rio Grande-FURG, Cx.P. 474, Rio Grande, RS 96201-900, Brasil

a2 Grupo de Estudos de Mamíferos Aquáticos de Rio Grande do Sul-GEMARS, R. Felipe Neri, 382 s. 203, Porto Alegre, RS 90440-150 Brasil

a3 Laboratorio de Ecología, Comportamiento y Mamíferos Marinos (MACN-CONICET) Museo Argentino de Ciencias Naturales Avenida Angel Gallardo 470 C1405DJR Buenos Aires, Argentina

a4 National Marine Fisheries Service, National Oceanic and Atmospheric Administration Beaufort Laboratory, 101 Pivers Island Road, Beaufort, North Carolina 28516, US

Abstract

Age and length data of 291 franciscana dolphins (Pontoporia blainvillei) incidentally captured on the coast of Rio Grande do Sul State (RS), southern Brazil, were used to fit growth curves using Gompertz and Von Bertalanffy growth models. A small sample of franciscanas (N = 35) from Buenos Aires Province (BA), Argentina, were used to see if there are apparent growth differences between the populations. Male and female franciscana samples from both areas were primarily (78–85%) <4 years of age. The Von Bertalanffy growth model with a data set that excluded animals <1 year of age provided the best fit to data. Based on this model, dolphins from the RS population reached asymptotic length at 136.0 cm and 158.4 cm, for males and females, respectively. No remarkable differences were observed in the growth trajectories of males and females between the RS and BA populations.

(Received March 06 2010)

(Accepted May 10 2010)

(Online publication July 28 2010)

Correspondence:

c1 Correspondence should be addressed to: S. Botta, Laboratório de Mamíferos Marinhos, Instituto de Oceanografia, Universidade Federal do Rio Grande (FURG), Cx.P. 474, Rio Grande, RS 96201-900, Brasil email: silbotta@yahoo.com