Behavioural response of southern right whales (Eubalaena australis) to anthropogenic approaches in Bahía San Antonio, Río Negro Argentina

The behavioural response of southern right whales (SRWs) to human approaches was
studied in Bahia San Antonio, Río Negro Argentina, to obtain essential information for
the evaluation of a recent authorized whale-based tourism and the implementation of
accurate regulations and conservation measurements.
A total of 50 SRW groups were approached with a small zodiac during the whale-seasons
(June-October) of 2008 and 2009, accounting for a total of 39h of behavioural
observations. The approaches occurred in a slow and controlled way up to a minimum
distance of 100m. A focal animal observation (instantaneous point sample) was used to
record three mutual exclusive behavioural states: rest, travel and socializing and/or aerial
activity. Groups (chosen ad random) consisted out of solitary animals (0.52), Surface
Active Groups (SAG; 0.32) and non-SAGs (0.13). Nevertheless, because of the low
amount of data, up to now all behavioural responses were analysed regardless group
composition.
Results indicated that whales continued travelling during an approach, but doubled their
time resting after an approach had finished (22% → 40%) and decreased drastically their
time socializing or aerially active (21% → 2%).
Although the probability that a whale remained in a social/aerially active behaviour when
affected by anthropogenic approaches decreased notably (-22%), no significant effect
could be found up to now (Z-test for 2 proportions, p>0.05), probably due to the relative
small dataset. Nevertheless, the apparent change in SRW social behaviour requires
urgently more detailed information to implement conservation strategies regulating
adequately the commercial whale-based tourism in the area.