Blue whales in Sri Lankan waters were observed ‘fluking up’ 55% of the time.
This contrasts with blue whales in the north Atlantic, where fluking up is exhibited only by specific individuals and is observed only 15–20% of the time (COSEWIC, 2002).
Within Sri Lankan waters, this behaviour was not individual specific and showed no obvious pattern.
Ilangakoon and Sathasivam (2012) state that the blue whales on the south coast of Sri Lanka fluked up on “approximately 70%” of the dives while dives without fluking were associated with hurried behaviours resulting from disturbances caused by whale watching boats.
This implies that non-fluke up diving occurred 30% of the time and only resulted from vessel related disturbances.
We did not find this to be the case in our study as nonfluke up dives occurred 45% of the time and were not significantly associated with the presence of other vessels within 300 m.
A fluke up dive was always followed by a deep dive but not necessarily one of longer duration. This suggests that individuals were not diving deeper following a ‘fluke up’ dive as is also supported by our model results.