Research Report
Survey of Finless Porpoises in Osaka Bay
Finless porpoises are a type of dolphin that live not only in Japan but also in the coastal areas of China and the Korean Peninsula.
It is an endangered species, designated as "endangered" on the IUCN (International Union for Conservation of Nature) Red List.
In fact, finless porpoises also live in Osaka Bay.
It is said that their numbers have decreased compared to the past due to environmental changes such as urban development, but there are few survey records, so no definite answer is known.
As a first step towards protecting the finless porpoises that live in Osaka Bay, Kaiyukan has been conducting research on finless porpoises since 2010, with the aim of letting as many people as possible know about them.
\ Looking for information /
If you see a finless porpoise in Osaka Bay, please let the Kaiyukan know!
What kind of creature is a finless porpoise?
It is a small dolphin with a body length of about 2m.
They are characterized by their grey body colour, lack of a dorsal fin and a row of sesame-seed-sized bumps on their neck and back. It is thought that they rub these bumps together to communicate with each other.
They feed on small fish, squid, octopus and other cephalopods. They can also find prey hiding in the mud using echolocation (ultrasound). Japan's finless porpoises are divided into five groups based on genetic differences, and the finless porpoises in Osaka Bay belong to the "Seto Inland Sea group."
Scientific name: Neophocaena asiaeorientalis
The key to finding finless porpoises is patience?!
Finless porpoises are actually very difficult creatures to find. Unlike other dolphins, they don't have a dorsal fin and don't jump, and their grey body coloring makes them easily mistaken for whitecaps, making them difficult to spot.
The trick to finding finless porpoises is to keep watching the ocean! Keep looking for them, aiming for the moment they come to the surface to breathe. It's a test of patience, so take a break every now and then to refresh your eyes and keep looking for them♪
There have been frequent reports of Finless Porpoise sightings
Research Methodology
Survey method 1: Visual survey by seawater carrier crew
At Kaiyukan, seawater for raising the creatures is transported by boat from off the coast of Hinomisaki in Wakayama Prefecture.
The waters northwest of Kansai International Airport, which is a route used by seawater carriers, are an area where finless porpoises are often spotted.
If we spot any finless porpoises while passing by, we record the date and time, weather, the number of porpoises, and their appearance.
Survey method 2: Visual survey using recreational fishing boats
The area around Kansai International Airport is a no-fishing zone, and many different creatures live there. There have been many sightings of finless porpoises, which may come to eat these creatures.
Visual surveys are conducted from recreational fishing boats from spring to autumn, and the more eyes there are on a survey, the more accurate it becomes. As part of the "Osaka Bay Living Creature Survey" (sponsored by the Osaka Bay Environmental Restoration Liaison Committee), we conduct joint surveys with the Osaka Eco Animal and Marine College, and sometimes we invite participants to conduct surveys with our customers.
Research method 3: Underwater sound recording research using A-tag
"A-tag" is a research device that can confirm the presence of living creatures by using sounds made in the sea. Since research from above the sea has the disadvantage of being easily affected by sea conditions, we are investigating the habitat of finless porpoises from below the sea.
Survey method 4: Interviews with people involved with the ocean
Because it is difficult for the aquarium keeper to go out to sea every day to conduct surveys, we ask fishermen, yacht owners, and other people who go out to sea every day to help us gather information on finless porpoise sightings. Thanks to this, we have been able to accumulate very valuable information.
Survey method 5: Survey of dead finless porpoises
When a living creature washes up on the beach, runs aground on a rocky area, or gets caught in a fishing net, it is called a "stranding." If it is alive, it may be returned to the sea or taken into care by an aquarium, but even if it is dead, a detailed examination of the carcass can provide valuable information that can lead to wildlife conservation.
When a finless porpoise is found, a aquarium keeper will head to the site, bring back the body, and perform a CT scan, tissue sampling, etc. By investigating the cause of death, what it was eating, and what stage of development it was at, we can learn about the environment in which the porpoise lived.
According to the Fisheries Protection Law, it is forbidden to capture or relocate finless porpoises or take their carcasses home, even for the purpose of conservation. At Kaiyukan, we always contact the relevant government agencies before taking any action.
If you see a finless porpoise in Osaka Bay, please let the Osaka Kaiyukan know!
At the Kaiyukan, we are researching finless porpoises in Osaka Kaiyukan. If you spot one, whether it's alive or dead, please let us know.
Contact: Kaiyukan Mammal Environment Exhibition Team TEL: 06-6576-5545
Please tell us, "I contacted you because I saw a finless porpoise."
Here's what the aquarium keeper have to say:
① Where did you see it? (Please be as detailed as possible)
②What is your current condition?
③ How many were there?