Fig1. Shinsei-Maru, in the Port of Hakodate
M2のLさんが新青丸調査について報告を書いてくれました！
From April 11th to May 1st, me and another doctoral student boarded on Shinsei-Maru and joined the KS-21-6 research cruise. I had been looking forward to this cruise since finished the survey in December in Hakuho-Maru. This time the survey was also conducted by the Hokkaido University, with an aim to explore oceanographic features in the southern Okhotsk Sea after sea ice retreat. Spring bloom induced by the sea ice could create a favourable environment for the stimulation of biological production. Continuously, a great number of lower trophic levels attract higher predators, which may include whales, dolphins, and other marine mammals. For us, the marine mammal observation team, we were so curious and excited about what could be encountered during the cruise.
Our cruise started from the Port of Hakodate heading to the north part of Hokkaido, into the Sea of Okhotsk. A sighting survey of marine mammals was conducted at the compass deck. With the help of Matsui-san, Mitani-sensei, and other lab members we made a windbreaker to protect us from the chilly wind (it worked very well! Thanks a lot!).
We met Dall’s porpoises and northern fur seal in the Sea of Japan on the first day of our survey. When it was almost at the end of our survey, we were informed by the officer on the bridge that he saw an animal that looked like a killer whale. Although we tried very hard to search for it, unfortunately, we didn’t see it. However, that observation gave us hope, a hope for finding whales in this season.
From April 13th to 20th, we did the survey in the Sea of Okhotsk. Before April 20th, we were around Kitami Yamato Tai (Bank). The happiest thing was that we observed a vertical, high blow twice when we arrive in the Okhotsk Sea. As the vessel were so far from the blows that we could only speculate they were from baleen whales but couldn’t verify the species. In the next few days, other observations started at some stations constantly. Exclude the time when the vessel stopped, we observed a group of Baird’s beaked whales (ツチクジラ).
Weather turned to be terrible on April 19th that forced us to do the survey inside the bridge. After lunchtime sea states became much worse that made both me and my colleague felt uncomfortable. When we were struggling with the seasick a high, unusual black dorsal fin caught my eyes. Officers helped us to confirm that observation, and for sure we saw about six or seven killer whales! It was an exciting observation that immediately cured our seasickness and gave us hope to continue our survey. At almost sunset time we saw two blows in front of our vessel and there were two baleen whales.
Fig2. Blows observed inside the bridge under terrible sea state
On the next day, we had a sighting survey day! No stations and we did the sighting survey for the whole day. Shinsei-Maru went across the cape of Shiretoko peninsular and sailed to the offshore waters of Rausu-city. Groups of Baird’s beaked whales were observed. In the afternoon, we observed killer whales again. At first sight, we thought there were only two killer whales but when we tried to get more closer, a minke whale was also there. It seemed that minke whale was trying to get rid of those two killer whales. While we following the killer whales and minke whale, another two Baird’s beaked whales were suddenly been observed.
Our vessel briefly stopped in the Port of Monbetsu on April 21st and 22nd. We visited the seal rescue centre, the Okhotsk Tower, and other places. Although it was almost the decline period of the spring bloom, through the undersea windows in the Okhotsk Tower the water was still turbid, colored in a yellow-green.
Fig3. Spotted seal, in the Okhotsk Tokkari Centre
On April 24th, when our vessel sailed to the deep waters in the north part of Shiretoko peninsular we met a group of killer whales again. This group of killer whales composed of eight individuals. One calf and three males were confirmed, and we observed spy-hopping behaviour by one of those animals. It was likely that they might be the same killer whales we met on April 19th, as the observed locations were very close and the high dorsal fin were so similar.
Fig4. We saw a group of killer whales!
Fig5. Spy-hopping behaviour, it was looking around and went back to the water
Another amazing observation happened on April 26th, when we were out of the Nemuro Strait heading to the offshore waters near the Abashiri city. At about 14 o’clock we observed baleen whales several times. From 15:30, high and vertical blows were constantly observed surrounding our vessels. There were more than 15 individuals, some of them were alone while others were in a small group.
Fig6. Unbelievable observation day! A number of baleen whales were observed.
From April 27th we left the Sea of Okhotsk, sailing to the Sea of Japan via the Soya Strait. Before we passed the cape of Soya, we observed Dall’s porpoises and minke whales in the waters of the Okhotsk Sea. The sea state was so nice that we were able to take photos of minke whales.
Fig7. The bodies of minke whales, we could see the blowhole.
We found Dall’s porpoise and northern fur seals when we move to the south part of Hokkaido. Northern fur seals were highly been observed off the Matsumae. On the last day, we started the survey nearby the cape of Erimo. We could see rubbishes sometimes in the coastal waters.
Because the sea state would turn to be bad, thus our voyage ended earlier than scheduled and arrived at the port of Kushiro on April 29th. I really had a good time through the whole voyage. The ocean always gives me surprise whenever I sailing on it. I joked that whale power cured my seasickness and learned that no matter how terrible the sea state is we should be responsible for the survey in our tolerable range. This might be the last onboard survey for me during my master’s degree, I really enjoyed it. In fact, I cherished every time’s surveys and I made some friends during the cruise. I am also looking forward to joining more surveys in the coming future!
