BEHAVIORAL RESPONSES OF FREE RANGING BOTTLENOSE

BEHAVIORAL RESPONSES OF FREE RANGING BOTTLENOSE DOLPHINS,
Tursiops truncatus, TO BIOPSY SAMPLING IN SOUTHERN BRAZIL.
Fruet, Pedro F. 1,3 , Dalla Rosa, L. 1,2 & Freitas, T.R.O 3
1 - Laboratório de Mamíferos Marinhos, Museu Oceanográfico de Rio Grande, RS, Brazil.
2 - Marine Mammal Research Unit, University of British Columbia, Canada.
3 – Departamento de Genética, Universidade Federal do Rio Grande do Sul, RS, Brazil
[email protected]
In this work we present a preliminary analysis on the reactions of bottlenose dolphin
to biopsy sampling in the Patos Lagoon estuary, southern Brazil. Biopsying was conducted
from a motorboat, using a crossbow and darts. To evaluate behavioral responses, we
collected data on behavior (traveling, feeding, socializing and resting) and group size
before each attempt. We defined four reaction categories: no reaction, low-level reaction
(slight change in behavior, for a few seconds), moderate (more forceful reaction, like a tail
slap, but not prolonged) and strong reaction (dolphins modified its behavior in a forceful
and prolonged manner). Seventy-six attempts were made during 2003-2004. Fifty-seven
attempts were miss and nineteen hit the dolphins. No strong reactions were observed in the
present study. Low-level reactions were the most observed response in both hits or misses,
representing 68.42% and 63.15%, respectively. Moderate reactions were observed in
26.3% (n=5) of the hits and 10.5% (n=6) of the misses, while 26.3% (n=15) and 5.2%
(n=1) represented no reaction to misses and hits, respectively. Prior behavior state seems to
be related with the dolphins reactions, as feeding behavior represented 72.7% of the
moderate reactions, followed by 27.3% of socializing. We did not observe moderate
reaction in dolphins that were traveling, just low-level reaction in the hits (n=5) and no
reaction (n=5) and low-level reaction (n=8) to misses. The type of reaction and prior
behavior to biopsying attempts (independent of hit or miss) was significantly different
(G=7.94, P=0,01). When we tested group size versus behavior reaction, there was no
significant difference (G=6.60, P=0,16). These results show that biopsy sampling of
bottlenose dolphins at the Patos Lagoon estuary may be conducted without long lasting
behavioral changes to the dolphins.