Species Preservation
Artificial breeding of Southern rockhopper penguin
The Southern rockhopper penguin is a small penguin measuring about 50cm in length that lives on islands around Antarctica, such as the Falkland Islands (Malvinas).
It is an endangered species designated as "Vulnerable" on the IUCN (International Union for Conservation of Nature) Red List, and its population is also decreasing in captivity in Japan.
To solve these problems, in 2011, Kaiyukan began research into artificial breeding in collaboration with the Kobe University Graduate School of Agriculture.
What kind of creature is the Southern rockhopper penguin?
It is characterized by yellow ornamental feathers (crown) above its eyes, and its name comes from the fact that it moves by hopping across rocky areas.
They nest in pebbles and grass on coastal rocks, laying usually two eggs during the annual breeding season, and when the chicks are born, they raise them together as a pair.
Scientific name: Eudyptes chrysocome
The benefits of artificial breeding
There are three main reasons for the decline of captive Southern rockhopper penguin.
- Unbalanced sex ratio (more males)
- Difficult to breed (low fertility)
- Pedigree bias (closely related individuals cannot form breeding pairs)
Kaiyukan focused on the problem of [1. There are a lot of males]. By collecting sperm from a single male that is not paired with a female and injecting it into a female through "artificial insemination," it will be possible to solve both [2. Low fertility rate] and [3. Bloodline bias].
The road to a world first
First, we started by looking into how reproduction occurs.
- Video observation = mating season
- Blood test = Changes in blood components during female breeding season
- Ultrasound (echo) examination = When eggs are produced in the female's body
By examining and comparing each of them, we can predict the optimal timing for artificial insemination. The male whose semen we will use for artificial insemination is also important. The number and activity of sperm in the semen differ depending on the age, whether or not the individual has a mate, and whether or not the individual has nested, so we investigated the conditions of individuals that are suitable for collection.
The next task is to learn how to collect semen from males, known as "semen collection," and then how to inject the semen into females, known as "artificial insemination."
We used established methods for other birds as a reference to explore the most suitable sperm collection and fertilization methods for the Southern rockhopper penguin.
With the accumulation of this data and the collaboration that began in 2016 with Tokyo Rinkai Aquarium, the team succeeded in performing the world's first artificial insemination using liquid preserved semen on Southern rockhopper penguin in the same year.
Aiming for further development
In 2017, one year after achieving this world-first success, we signed a collaborative research agreement with Tokyo Rinkai Aquarium and began working on the "freezing and preserving" of semen. While liquid preserved semen can minimize the deterioration of sperm, it has drawbacks such as a short storage period and the fact that it cannot be used if the timing of artificial insemination and semen collection does not match. Therefore, we found the possibility of developing frozen preserved semen, which can be stored semi-permanently and can be used at the optimal timing for artificial insemination.
There are many obstacles to freezing and storing semen. The concentration of diluting fluid and cryoprotectant, freezing temperature, freezing speed, etc. affect the survival rate of sperm, so we established the freezing conditions while testing various cases. Then, in 2022, a chick born (hatched) at Kasai Rinkai Aquarium was successfully artificially inseminated using frozen-preserved semen for the first time in the world, and two years later, in 2024, the second successful case in the world was achieved at Kaiyukan.
In recognition of these research achievements, the aquarium was awarded the Koga Award, the first such award for Kaiyukan, at the general meeting of the Japanese Association of Zoos and Aquariums (JAZA) held on May 22, 2025.
(Blog) Behind the Scenes at Kaiyukan"Congratulations! Winning the Koga Award"
- Koga Award: The highest award given by the Japan Association of Zoos and Aquariums to zoos and aquariums that have made outstanding achievements in breeding rare species that are difficult to breed and are of global importance.
Using the techniques developed in this research, Kaiyukan hopes to contribute to the continued breeding of Southern rockhopper penguin in Japan through in-Aquarium breeding, and in the future to the conservation of penguins in the wild. We will continue our efforts to form a healthy population of this species in Japan and to develop breeding techniques.
[Past blog about artificial breeding]
Artificial breeding of Southern rockhopper penguin(May 7, 2018)
I tried it again this year (2021.08.08)
Achieved a world-first feat in collaboration with Kasai Rinkai Aquarium (August 16, 2022)
remarks
Kaiyukan and Hiroshi Kusunoki (Associate Professor) of the Graduate School of Agriculture, Kobe University conducted joint research with the aim of elucidating the reproductive physiology of the Southern rockhopper penguin and establishing techniques for artificial breeding. The research themes included "determining mating time through behavioral observation," "determining fertilization and egg-laying dates from female blood properties," "determining ovulation dates through ultrasound examinations," "developing a method for collecting semen," and "establishing a method for preserving semen."