Biology Reference
In-Depth Information
Yáñez, (1999) worked in Noel Kempf Mercado National Park, on the Itenez and Paragua
Rivers, in the Santa Cruz area. His descriptive study included distribution patterns, dolphin
sounds, and possible interactions with the giant otter (
Pteronura brasiliensis
) as well as
incorporated legends and myths related to bufeos in the area.
The studies conducted by Aliaga-Rossel, (2000, 2002) evaluated the distribution and
abundance of river dolphins during four heavy precipitation seasons across three different
water types (white, black and mixed waters) in the Tijamuchi River. Aliaga-Rossel
documented one of the highest population densities relative to other areas surveyed. This
work constituted the first study in Bolivia using standardized methodology.
Aliaga-Rossel et al., (2006) reported distribution and abundance survey results collected
during the dry season in the central Mamore River and four of its tributaries: the Tijamuchi,
Apere, Yacuma and its tributary, the Rapulo (Table 1). More recently, Aliaga-Rossel &
Quevedo, (in prep) surveyed the Tijamuchi and Ibare Rivers and compared their findings with
earlier surveys of the same areas (Aliaga-Rossel 2002; Pilleri 1977). They concluded that the
abundance of river dolphins varied temporally with the lowest values for both rivers in the
most recent surveys. Although both rivers possessed similar water characteristics, the authors
noted a decreased abundance of river dolphins in the Ibare River compared to Pilleri & Gihr,
(1977) and the Tijamuchi River. The authors also suggested that this spatial variation may
reflect increased human activities in the Ibare River. This work was conducted during the
rainy season of a Niña year, when garbage accumulates along the shores and sewage
overflows into the river. Salinas (2007) worked in the Blanco and San Martin Rivers of the
Itenez sub-basin, covering an area of 56 km with a single observer in a boat (non standardized
method). This constituted the first study of relative abundance in this area.
In 2007, Omacha-Faunagua (unpublished data), initiated a long survey project titled
―First evaluation of the abundance of the three River dolphin species (
Inia geoffrensis, I.
boliviensis
, and
Sotalia fluviatilis
) in the Orinoco and Amazon River Basins, South America‖.
This extensive survey was carried out during the dry season in Bolivia, travelling more than
500 km along the Mamore River, and 598 km along the Itenez River.
Several expeditions were carried out to capture samples for different genetic studies
(Banguera
et al.,
2002; Hamilton et al., 2001; Ruiz-García et al., 2006, 2007, 2008a, b; Ruiz-
García, 2010), all of them supporting the status of the Bolivian bufeo as a separate species. In
the genetic expedition carried out by Ruiz-García and collaborators in 2003, more than 1.300
km of the Mamoré, Yacumo, Iruyañez, Yata, Itenez
and Beni rivers were traveled.
Many other completed studies simply provide lists or distribution data, but these reports
are not directly related to bufeos. Other less reliable or non standardized reports such as grey
literature, casual observation and posters in scientific conferences also exist (Aramayo, 2008;
Tapia, 1995; Tello, 1986). They are considered questionable sources because the methods
and/or results were poorly presented and unclear. A common problem that easily leads to the
collection of inaccurate data is the use of non-standard methods.
C
ONSERVATION
S
TATUS AND
T
HREATS
The conservation status of the bufeo in Bolivia is incompletely known and laws that
explicitly protect the bufeo do not currently exist in Bolivia. Some protection is afforded by
Search WWH ::
Custom Search