[3-part series] Collaboration with Ogasawara Village 2025 Report: "Baby green sea turtles have arrived again this year!"

Following on from last time, this time we will continue to report on Sumida Aquarium's efforts related to Ogasawara. In this second installment, we will introduce two new baby green sea turtles that will be arriving at Sumida Aquarium in September 2025.
Author: Fujiwara, Exhibition and Breeding Team

■ From Ogasawara to Sumida Aquarium
Since 2016, Sumida Aquarium has participated in the Joint Breeding Loan Program run by the certified NPO Everlasting Nature. Under this program, Sumida Aquarium has been taking care of two baby green sea turtles born in the Ogasawara Islands. We have been raising them carefully for a year so that they can live healthily in the natural ocean, and then we are continuing our efforts to return them to their natural ocean home.

The baby green sea turtles that come to Sumida Aquarium are selected from those born that year that are protected in the aquariums at the Ogasawara Marine Center.

The selection criteria are based on the first impression of the staff in charge of raising the animals, such as which ones make eye contact or which ones seem to have a strong splashing appeal.

One of the babies that arrived in September 2025 was notable for its strength as it pushed its way forward, pushing aside the other babies around it.

The other one was a little smaller than the others around it, but I noticed it swimming at its own pace and was also impressed by the fact that its face, chin, and underbelly were very black, so I decided on these two (the black chin and underbelly change as it grows).

Aquarium at Ogasawara Marine Center

Baby turtles come over when you look into the tank

I'm thinking about which one to choose

I decided on these two

■ "Sunrise" and "Sunset"
The names of the two babies have been decided as "Asahi" and "Yuhi."

This name was thought up by fifth graders at Ogasawara Village Ogasawara Elementary School.

The sunrise and sunset seen from the Ogasawara Islands rise from the sea and sink back into the sea.

This is a sight that can only be seen on an island surrounded by the sea, and it is so beautiful that we sympathize with the desire to share it with as many people as possible!

Sunrise over the sea (Chichijima/Kasayama)

Sunset over the sea (Chichijima/Weather Station)

After that, we had them look at the faces of the two babies up close and named them together, saying, "This one's Asahi, and this one's Yuhi."

We actually went to the viewing spots recommended by the fifth graders, and the sunrise rising from the sea and the sunset sinking into the ocean were so beautiful, with the light reflecting off the water, that we were impressed, saying, "I've never had the opportunity to see the sunrise and sunset so clearly before."

Thank you to the fifth graders at Ogasawara Elementary School for not only giving us a wonderful name, but also teaching us about the charms of the island that I didn't know about.

A fifth grader from Ogasawara School holding a baby and deciding which one to name "Asahi" or "Yuhi."

■Moving to Sumida Aquarium
The baby green sea turtles come to Sumida Aquarium with us on a boat called the Ogasawara Maru, which takes 24 hours.

The ship has a pet room where pets such as dogs and cats can be left, and the baby green sea turtles are also left there.

Pet room on board the Ogasawara Maru

Sea turtles can be transported without being put into water as long as their bodies and shells are wet, so we carry them by placing a wet towel inside the case.

While they are traveling, we check on them every 2-3 hours and take care of them by keeping their bodies and shells wet to prevent them from drying out.

Sometimes my neighbors have dogs, and I have to take care of them while feeling their eyes on me.

Care on board

■ Life at Sumida Aquarium begins
After a long 24-hour journey, Asahi and Yuhi arrive at Sumida Aquarium, where they are checked by the aquarium's veterinarians for any injuries or illnesses, and their size is measured before they are sent to the back yard to rest for the night.

The next day, an unveiling ceremony was held, and the fish was placed in the aquarium at Ogasawara Base, watched by many people.

This is where Asahi and Yuhi begin their lives at Sumida Aquarium, and every year we are thrilled to see the babies' reactions when they are fed for the first time.

In many cases, perhaps due to fatigue from the long journey or because it is their first time in the aquarium or seeing the sights, they barely eat anything and only nibble.

As for this year's babies, Asahi and Yuhi, Asahi was indifferent to the food, while Yuhi only started eating after nibbling a few bites.

So when Asahi showed Yuhi eating, Asahi also became interested in the rice and began to take bites.

That alone was enough for us, and we were relieved that they recognized what we had prepared as food.

At Sumida Aquarium, we feed the sea turtles artificial food and seaweed, but this is different from what they ate when they were at the Ogasawara Marine Center, so it is important that they first get used to this food and find it delicious.

The next day, both dogs noticed the food and started eating it, and now they quickly finish any food we prepare for them.

Sea turtle food (artificial food and seaweed)

Asahi's rice

Every Sunday morning, we measure their weight and shell size to monitor their growth.

"Asahi" has grown steadily, from 69g to 151g in weight and from 7.3cm to 9.7cm in shell size, while "Yuhi" has grown steadily, from 56g to 138g and from 6.6cm to 9.0cm (as of October 26, 2025).

At this stage, babies often float on the surface of the water, resting by securing their bodies to gaps in the tank to avoid being swept away by the water current.

When floating to rest, they float with both front legs resting on their shell.

Asahi rests with its front legs on its shell

"Yuhi" rests in a unique position, wedged between the gaps in the tank

It is said that this pose makes them look like floating leaves, preventing them from being spotted by predators such as birds, and is a behavior that can only be seen in babies.

The two babies are growing day by day, and can now be seen diving to the bottom of the tank.

We will continue to introduce the growth of the two cubs and their activities at the aquarium, so please come and see Asahi and Yuhi and watch them grow together.

Asahi

"Sunset"