In August-October 2017, the first successful captive reproduction of the black turtle occurred at the Ocean Expo Park in Okinawa. The black turtle, a rare species in Japan, hatched at the park’s sea turtle pool.

Sequence of events of leading to the hatching of black turtle.

• 1999 - Began caring for male turtle in captivity.
• 2009 - Began caring for female turtle in captivity.
• 2015 - March – Introduction of male and female black turtles into the same tank.
• 2017 - March - First confirmation of female sexual maturity through ultrasound imaging diagnosis.
• 2017 - 24th May - Confirmed mating.
• 2017 - 25th June - First egg laying recorded.

The black turtle continued to lay eggs 5 times throughout July and August 2017 laying a total of 262 eggs. The first hatching was confirmed on 27th of August 2017 and fourteen eggs had hatched by the 7th of October. Through this successful reproduction, we could confirm the size of the female at sexually maturation and the length of oogenesis between mating and first nesting. Knowledge of the reproductive ecology of this species is limited. Through continuing to care for the turtles in captivity we can learn and acquire new information.

Black turtle Chelonia agassizii

Mainly distributed in the East Pacific Ocean from Baja California Mexico to southern Peru, particularly around the Galapagos Islands. The upper shell (carapace) and lower shell (plastron) is grayish black. The oval carapace narrows to a point at the rear. In Japan, they can be seen around Nansei Islands, but is rarely seen near mainland Okinawa.