Abundance and distribution of endangered Franciscana dolphins in Argentine waters and conservation implications
| Autor: | Susana N. Pedraza, Silvana Laura Dans, Enrique A. Crespo, M. Florencia Grandi, Griselda Valeria Garaffo |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Platanistidae
ABUNDANCE ESTIMATIONS AERIAL SURVEYS WESTERN SOUTH ATLANTIC Ecology Otras Ciencias Biológicas CONSERVATION Endangered species Cetacea Aquatic Science Biology biology.organism_classification Aquatic organisms Fishery Ciencias Biológicas Abundance (ecology) FRANCISCANA (PONTOPORIA BLAINVILLEI) Ecology Evolution Behavior and Systematics CIENCIAS NATURALES Y EXACTAS |
| Popis: | 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. We observed 101 Franciscanas in 71 sightings. In northern areas density was estimated at 0.106 individual/km2. Density was lower in southern areas (0.055/km2) and declined with depth beyond 30-m isobaths (0.05/km2). 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 at 8,279 (4,904-13,960) individuals, while in the southern area it was estimated at 5,896 (1,928-17,999) individuals. Considering an annual mortality of about 500-800 individuals, about 3.5%-5.6% of the stock may be removed each year by the fishery and over the 2% recommended by the International Whaling Commission (IWC) and may not be sustainable by the population. Higher densities in coastal areas make Franciscanas 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 catch per unit effort (CPUE) increases, indicating different catchability of dolphins between areas. © 2009 by the Society for Marine Mammalogy. Fil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentina Fil: Pedraza, Susana Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentina Fil: Grandi, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina Fil: Dans, Silvana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentina Fil: Garaffo, Griselda Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentina |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|