In a study published in the journal Frontiers in Marine Science, researchers at Okinawa’s Churashima Research Center said they have developed an artificial womb designed specifically for elasmobranchs, a subspecies of fish that includes several species of sharks, rays, rays and sawfish.

Researchers have begun an experiment to find the best methods for breeding this species of sharks in captivity. More than 80% of representatives of this species are listed in the Red Book as endangered. In the study, the scientists said the technology was needed to rescue live embryos found in dead females.

The experiment was carried out using live embryos found in a pregnant slender-tailed lantern shark, also known as Moller’s lantern shark, caught by fishermen in Japan. An ultrasound of the shark showed that there were six live embryos in the uterus. The scientists removed the embryos and placed two of them inside an artificial uterus.

The slender-tailed lantern shark is a rare and poorly understood species of deep-sea shark that lives off the coast of New Zealand and Australia in the southwestern Pacific Ocean. It lives at a depth of 250 to 850 meters below the ocean surface and grows up to about 50 cm in length.

The artificial uterus was designed using three main elements; main chamber, reservoir and filtration system. To get inside, scientists have developed an artificial uterine fluid that mimics the state of the uterus of a female shark.

Embryos were in the uterus for five months. During the first month, the embryos appeared inactive, but gradually they showed signs of “strong swimming movement”. During the incubation period, they grew from about three inches in length to five inches. After an incubation period, the scientists placed the embryos in a tank of seawater, signaling an “artificial birth” of the embryos.

However, according to the researchers, the sharks died just a few days after birth. Scientists attribute this to the inability to adapt a suitable marine environment for the postpartum period.

The 160-day incubation achieved in the study is the longest in the history of observations not only for the species, but also for elasmobranchs in general. Despite the fact that both embryos died after birth, it turned out that the artificial uterine fluid played a “key role” in keeping the embryos alive during the incubation period.

After the study, the scientists said the “remaining technical problem” is how to safely raise the babies after artificial birth.

“We attempted to accomplish this process by periodically exposing the samples to sea water prior to ‘artificial birth’. Although this approach was ultimately unsuccessful, animal conservation technologies will become increasingly important in the context of the design of future zoos and aquariums,” the scientists said.