Kushimoto Town, located at the southernmost tip of Honshu, is known for the coral colonies that have formed there due to the influence of the Kuroshio Current, one of the world’s largest warm currents. Among them, the Acropora hyacinthus, which forms the table coral that symbolizes Kushimoto, spawned en masse on the night of July 13^th 2025. This was reported by Nanki Seaman’s Club, a long-established and popular diving center in Kushimoto.

The spawning was reported by Toshiya Iwasaki, an experienced dive guide from Nanki Seaman’s Club. “First sight of coral spawning was confirmed during a night dive on July 10^th . The location was the boat pier at Kushimoto Marine Park. There was a slight swell on the day, so the newly laid eggs moved from side to side. Soon, the number of eggs increased rapidly. I think that more than half of the colony of Acropora hyacinthus was spawning at the same time”.

The mass spawning took place two days after the full moon, on a spring tide day. High tide was at 8:37pm, and the spawning began at 9:08pm. The spawning continued until 9:45pm, and since the water was shallow, divers were able to observe it closely. The Kushimoto coastal waters, home to precious coral communities such as Acropora hyacinthus, were registered as a Ramsar Convention wetland in November 2005

Images and information provided ≫Nanki Seaman’s Club

Text by Yukari Goto, Marine Diving Web

Please also see Marine Diving Web’s special feature on Kushimoto and the series on corals.

≫Diving at Nanki Seaman’s Club! Coral Heaven Kushimoto

≫Facts divers should know about corals Part 4: Seas with coral reef