212
In the present work, the species occurred in depths of 10–150 m. Studies related
to the T. truncatus in Brazil, indicate the presence of the specie in areas of depths
varying between 15 and 300 m (Skaf and Secchi 1994; Baracho et al. 2005; Baracho
et al. 2008; Carvalho and Rossi-Santos 2011; Tardin et al. 2013), what does not
corroborate with the data found in the present work.
The Guiana dolphin, Sotalia guianensis, was the second more representative
species during the period of study. This species is so far the most studied dolphin
species in Brazil, mainly because it inhabits inside of bays and estuaries along all
the Brazilian coast (eg., de Oshima and de Santos 2016; Godoy 2011; Lima 2010;
Santos et al. 2010; de Santos et al. 2010; Araújo et al. 2007; Rossi-Santos 2006;
Spinola 2006; De Jesus 2004; Lodi 2003; Reis et al. 1993). Here we raise special
concern to the fact of the location of the sightings presented in this work are inside
an area considered as a gap of knowledge for the species (Hubner et al. in press).
There are some small rivers in the north coast of Bahia that could contribute for
occurrence of the species in this unstudied area. Rossi-Santos et al. (2006a, b),
studying distribution and use of the habitat of the small cetaceans in the Abrolhos
Bank, found that Sotalia guianensis was the most common species, followed by
Steno bredanensis and Tursiops truncatus.
In the present work, group size varied from 1 to 35 individuals. In Baía do Pontal,
Ilhéus, southern Bahia, the group size varied form 1–7 individuals (Santos 2010a).
In another study in the same area Imamura (2015) found groups raging 2–10
individuals.
Along the Brazilian coast, groups of 2–20 individuals are the most sighted number observed in Sepetiba Bay, Rio de Janeiro State, despite groups up to 280 were
recorded (Flach et al. 2008). For the Baía de Paraty, in this same State, group size
varied from 1 to 100 individuals (Lodi 2003). For the Norte Bay, Santa Catarina
State, and southern limit of distribution to the species, studies indicate an average
group size of 29 individuals (Daura-Jorge et al. 2005) and maximum group size
between 60 and 80 animals (Flores and Bazzalo 2004). In estuarine regions, such as
Cananéia, São Paulo State and Caravelas, Bahia State, small group sizes (1–14
animals) are reported as the most frequent category for the Guiana dolphin (Geise
et al. 1999; Rossi-Santos 2006; Godoy 2011).
Here, we reported the species occurring in depths of 4–60 m, and sightings of S.
guianensis in waters deeper than 30 m are quite rare to the species (see Borobia
et al. 1991). Innumerous works have reported for the species, its habitat use of shallow waters. For example, in Baía do Pontal, Ilhéus, southern Bahia, the highest
frequency of sightings occurred in deeper areas. Nearly half of the records (49.3%)
occurred in quadrants with 3–6.79 m depth (Santos et al. 2010).
In Caravelas, southern Bahia, another estuarine environment, S. guianensis
occurred more frequently in shallow water areas (0–6 m) (Rossi-Santos 2006), corroborating this preference of the species habitat use. In Cananéia, it was observed
Guiana dolphins in feeding behavior in depths varying between 1 and 15 m (Geise
et al. 1999; Godoy 2011). However, in the same study, the animals, when in traveling behavior, utilized areas with approximately 10 m. In the Baía de Guanabara, Rio
de Janeiro, it was also reported the species occurring in areas with depth of 10 m
M.S. de Carvalho et al.
In the present work, the species occurred in depths of 10–150 m. Studies related
to the T. truncatus in Brazil, indicate the presence of the specie in areas of depths
varying between 15 and 300 m (Skaf and Secchi 1994; Baracho et al. 2005; Baracho
et al. 2008; Carvalho and Rossi-Santos 2011; Tardin et al. 2013), what does not
corroborate with the data found in the present work.
The Guiana dolphin, Sotalia guianensis, was the second more representative
species during the period of study. This species is so far the most studied dolphin
species in Brazil, mainly because it inhabits inside of bays and estuaries along all
the Brazilian coast (eg., de Oshima and de Santos 2016; Godoy 2011; Lima 2010;
Santos et al. 2010; de Santos et al. 2010; Araújo et al. 2007; Rossi-Santos 2006;
Spinola 2006; De Jesus 2004; Lodi 2003; Reis et al. 1993). Here we raise special
concern to the fact of the location of the sightings presented in this work are inside
an area considered as a gap of knowledge for the species (Hubner et al. in press).
There are some small rivers in the north coast of Bahia that could contribute for
occurrence of the species in this unstudied area. Rossi-Santos et al. (2006a, b),
studying distribution and use of the habitat of the small cetaceans in the Abrolhos
Bank, found that Sotalia guianensis was the most common species, followed by
Steno bredanensis and Tursiops truncatus.
In the present work, group size varied from 1 to 35 individuals. In Baía do Pontal,
Ilhéus, southern Bahia, the group size varied form 1–7 individuals (Santos 2010a).
In another study in the same area Imamura (2015) found groups raging 2–10
individuals.
Along the Brazilian coast, groups of 2–20 individuals are the most sighted number observed in Sepetiba Bay, Rio de Janeiro State, despite groups up to 280 were
recorded (Flach et al. 2008). For the Baía de Paraty, in this same State, group size
varied from 1 to 100 individuals (Lodi 2003). For the Norte Bay, Santa Catarina
State, and southern limit of distribution to the species, studies indicate an average
group size of 29 individuals (Daura-Jorge et al. 2005) and maximum group size
between 60 and 80 animals (Flores and Bazzalo 2004). In estuarine regions, such as
Cananéia, São Paulo State and Caravelas, Bahia State, small group sizes (1–14
animals) are reported as the most frequent category for the Guiana dolphin (Geise
et al. 1999; Rossi-Santos 2006; Godoy 2011).
Here, we reported the species occurring in depths of 4–60 m, and sightings of S.
guianensis in waters deeper than 30 m are quite rare to the species (see Borobia
et al. 1991). Innumerous works have reported for the species, its habitat use of shallow waters. For example, in Baía do Pontal, Ilhéus, southern Bahia, the highest
frequency of sightings occurred in deeper areas. Nearly half of the records (49.3%)
occurred in quadrants with 3–6.79 m depth (Santos et al. 2010).
In Caravelas, southern Bahia, another estuarine environment, S. guianensis
occurred more frequently in shallow water areas (0–6 m) (Rossi-Santos 2006), corroborating this preference of the species habitat use. In Cananéia, it was observed
Guiana dolphins in feeding behavior in depths varying between 1 and 15 m (Geise
et al. 1999; Godoy 2011). However, in the same study, the animals, when in traveling behavior, utilized areas with approximately 10 m. In the Baía de Guanabara, Rio
de Janeiro, it was also reported the species occurring in areas with depth of 10 m
M.S. de Carvalho et al.