• Leanne Rosser

A new venture - Day One

Updated: Jun 4, 2020

Today was my first day as a dolphin researcher at Mutsu City Nature Centre and what a day it was! Waking up in a museum located in the beautiful coastal village of Kawauchi to the fresh breeze and calm waters of Mutsu Bay, right at the very tip of Honshu in Aomori prefecture. My husband and I moved here from Osaka only two days ago, ready to start a new adventure. After three years of studying the Mikura island bottlenose dolphins with the university, I was offered this wonderful new opportunity, my first paid dolphin research job. The day started with an educational boat tour for the local primary school kids to introduce them to Mutsu’s greatest treasure, the dolphins. Every year from May to June, Mutsu bay is filled with Pacific white-sided dolphins chasing the large shoals of sardines and mackerel that travel through its waters. They can only be spotted in the temperate zones of the North Pacific Ocean whereas their similarly striking looking relatives, Dusky dolphins, are found in Southern Pacific waters. Pacific white-sided dolphins are speedy, active, acrobatic members of the oceanic dolphin family and have striking, easily recognisable colour patterns. The school kids were treated to a pod of around 30 individuals, although they can often be found in much larger pods, sometimes superpods of hundreds or even thousands. Dolphins usually never fail to inspire awe and amazement in anyone who sees them, and even more so in children. The trip left them invigorated, chanting a cute chorus of “Iruka Daisuki!” (“We love dolphins!”)

After their trip had finished it was my turn for some inspiration! Our research boat left Wakinosawa port shortly after the kids had gone back to school. Our small team consisted of Igarashi-san (our new boss), Tanaka-san the captain, and my husband and I. Our first encounter was a relaxed group of around 20 individuals consisting of mainly females and young males, slowly surfacing around the boat. Mature males have a thick, uniquely curved hook of a dorsal fin, distinguishing them from the females' (and younger males') more pointed, slightly curved dorsal. The large, close-knit pods, typically including both sexes, are very social and cooperatively hunt fish as a group. After around 15 minutes of observing the group and taking videos, we headed further out into the bay guided by a commotion of splashing in the distance. As the boat sped up to check it out a constant stream of jumping dolphins came into view. It was a feeding frenzy! A huge group of dolphins were leaping in quick succession under a flock of screeching birds diving into a pool of bubbling commotion, with the hapless fish flying out of the splashing water in a panic. Pacific white-sided dolphins work together to herd fish into large bait balls.

A still shot from today's Go-Pro footage

Back in 2018 on my first research trip to the bay I had the privilege of hearing the cacophony of squeaks, whistles, clicks and dolphin chatter on a hydrophone as I watched their feeding behaviour from the boat. The dolphins were communicating with one another as they cooperatively closed in on a big bait ball of sardines. Today there was no hydrophone and not even a good camera (I forgot to charge it on my first day!...) but it was even better. We observed the group as more and more dolphins came to join the action. Suddenly our boat was surrounded by about 200 individuals. Some came swimming directly under our boat giving us a spectacularly close view of their black and white patterns, a couple of them even tilting on their side to get a closer look at us. Dorsal fins were speedily slicing through the water and sleek bodies were flung high in the air. The sounds of surfacing dolphins, splashes and frantic gulls was constant. We stayed with them for about an hour, mesmerized and captured the action on the go-pro camera. Even the captain joined in with our exclamations of amazement at the huge action-packed event before our eyes. We headed back to the port sunburnt but satisfied and finished the day back at the museum to make a record of what we had observed. After such a rewarding first day I am very excited to see what the rest of my time here in Mutsu has in store for me!

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