INVESTIGADORES
CRESPO Enrique Alberto
artículos
Título:
Abundance and distribution of endangeret Franciscana dolphins in Argentine waters and conservation implications
Autor/es:
CRESPO, E.A., S.N. PEDRAZA, M.F. GRANDI, S.L. DANS & G. GARAFFO
Revista:
MARINE MAMMAL SCIENCE
Editorial:
Wyley-Blackwell
Referencias:
Año: 2010 vol. 26 p. 17 - 35
ISSN:
0824-0469
Resumen:
This is the first study in Argentine waters on the abundance of the threatened Franciscana dolphin, Pontoporia blainvillei. During 2003-2004 we carried out 17 aerial surveys using line transect sampling methodology. 101 Franciscanas were observed in 71 sightings. In northern areas density was estimated in 0.106 ind km-2. Density was lower in southern areas (0.055 ind km-2) and declined with depth beyond 30 m isobaths (0.05 ind km-2). A correction factor for submerged dolphins was applied to density and then extrapolated to the strip between the coastline and the 30 m isobath. Abundance in the Northern Area was estimated in 8,279 (4,904-13,960) individuals while in the Southern Area it was estimated in 5,896 (1,928-17,999) individuals. Considering an annual mortality of about 500-800 individuals, around 3.5-5.6% of the stock may be removed each year by the fishery, over the 2% recommended by the IWC and may not be sustainable by the population. Higher densities in coastal areas make Franciscana more vulnerable to coastal fishing camps which increased mortality in recent years. A remarkable finding was that while density decreases to the south, values of CPUE increases, indicating different catchability of dolphins between areas.