Humpbacks and bottlenose dolphins interactions!

The whale watch trip on Ocean Intrigue on Wednesday morning started off very rough, the easterly winds were blowing about 20-25 knots, but we headed south and the wind speed started to drop as we were getting close to kihei area. Haleakala protects south Maui from eastern wind, creating perfect conditions with no wind and glassy waters.

In this calm water we encountered a mom and calf pair and they were in resting mode for few minutes and then mom started to display its pectoral fin for while, and then started to pectoral slap. The pectoral fin of a humpback whale it is a unique characteristic of the species, it can reach up to 15 feet long, it is 1/3 of its body and it is the longest pectoral fin among the cetaceans (whales, dolphins and porpoises). They were about 150 yards from the boat, and we could see details on mom’s pectoral fin; the knobby leading edge, black and white pigmentation, black round circle scars from barnacles that have dropped off, and also one barnacle growing on the tip of its fin. Barnacles grow in different body parts of the whales and they are sessile crustacean, shrimp-like animal that form a hard shell, and use the whales as a substrate from which they feed on plankton in passing water. Another interesting fact about their pectoral fin is that the knobs on the leading edge reduce drag over the fin, allowing the whale to lift like an airplane wing and this shape has inspired engineers to design wind turbines that mimic its contours, the blades are quieter, more efficient, and operate reliably at low wind speeds. Amazing! Well, While we were all watching the great whale pectoral fin show, one of the naturalists on board sighted bottlenose dolphins swimming towards the whales. Exciting! My first encounter with bottlenose dolphins on ROB program and more special witness interspecies interactions!

One of the goals of the ROB program is to collect data on cetacean interspecies interaction, when two different cetacean species are in close association or engaged interactive behavior. We want to get a better understands of these events and how often they occur here in Maui county waters, because it can provide insight into the behavior and ecology of the species involved. Two adult bottlenose dolphins and humpback mom/calf pair were involved in the interaction. we clearly noticed the humpbacks behavior changing with the dolphins approach, the pair started to swim slow in one direction and then increased speed and the dolphins started surfing the pressure wave produced in front of the traveling humpbacks. The majority of the interaction was between the dolphins and calf, most of the time the bottlenose dolphins were riding in front of the calf, mom was under the water for the most part. Bottlenose dolphins are well known for a variety of interspecies interactions, and interactions with humpback whales are common and researchers have been described them as associative, communal foraging, or involving bow-riding in front of whale's head as an energy-saving means of locomotion or a form of play. This encounter seemed to be a form of play; the calf did not seem to be bother by them, unlike it seemed to be engaged and enjoying the interaction.

Every day when we leave the harbor for our field work day we never know what to expect, each whale watch trip is different, and this is what makes our job so enjoyable and exciting. What I thought was going to be a rough work day turned out to be perfect conditions for whale watching with a remarkable encounter!

Mahalo nui loa to Captain Joe and Ocean Intrigue's naturalists/crew (Andrea, Meagan, Robin, Gabe, and Jess) for the awesome ROB season!

A hui hou!

Itana

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