Resumen del producto

Approximately 300 blue whales from the Northeastern Pacific migrate to the Gulf of California during winter, were they feed, breed and nurse their calves, therefore this area offers an ideal scenario to study their behavior. In this study we used the focal animal sampling method to record the superficial and diving behavior of individual blue whales and their interactions with whale-watching boats (WWB) in the region of Loreto during February and March between 2009 and 2011. The focal animals were followed at a distance >100 m, they were identified and measured using the photo-sequence method and observations of their activities and diving time were recorded with a HP 95LX Palmtop computer connected to a GPS. We obtained a total of 63 focal animal samples from 41 different individuals (21 females, 9 lactating females, 10 males and 2 undetermined). Focal animals were tracked 122 h without WWB and 309 h with (treatment) and without (control: before and after the interactions with boats) WWB. Preliminary results demonstrate that males (362s ± 233s) dive for longer time periods than females (307s ± 196s), the latter could be related with the different energetic requirements of each sex. In both sexes a reduction in the diving time was recorded during the treatment (Males: 325s ± 219s, Females: 265s ± 164s), in contrast with the control (Males: 410.9s ± 219s, Females: 315.9 ± 190s). We preliminary conclude that diving time is a good indicator for monitoring the effects of WWB in blue whale behavior. Although it is necessary to continue monitoring these interactions to verify their effect, we suggest regulating the WWB activities to a maximum of two WWB per whale.

Palabras clave: Blue whale; whale watching; behavior

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