Marine Life
Hachijō’s Marine Life
Hachijō waters feature an interesting mix of tropical and temperate fishes, including endemic species, and others making seasonal appearances.
Fish found all year round in Hachijō include common yet colourful reef-fish and the usual warm-water suspects, such as schools of damselfish, anthias, butterflyfish, soldierfish (including the yellowfin soldierfish, found at much shallower depth than elsewhere), sergeant majors, Moorish idols, porcupinefish, lionfish, scorpionfish wrasses, needlefish, mullets, chubs, scads and more…
Large schools of batfish are also spotted seasonally, as are schools of small sized obtuse barracuda (Sphyraena obtusata) in the shallows.
https://www.youtube.com/watch?v=EPzy-y8uXRg
Bigger fish commonly observed around the island include amberjacks (Seriola rivoliana), emperors such as the spangled emperor (Lethrinus nebulosus), and more seasonal encounters with trevallies such as island trevallies (Carangoides orthogrammus), black jacks (Caranx lugubris), various schooling fish such as rainbow runners. Tunas, skipjack and dogtooth tunas, mackerels and other game fish abound in the area, but are mostly found off-shore, in areas reserved for fishing or too remote/difficult to access for diving purposes – individuals and schools do occasionaly show up seasonally on more exposed dive sites.
Endemic species and/or fish more specific to Hachijō include the famous wrought iron butterflyfish or Yūzen, (Chaetodon daedalma), the redtail triggerfish (Xanthichthys mento), the spottedtail morgon (Goniistius zonatus) and the redlip morgon (Goniistius zebra), the stripped Japanese boarfish or banded boarhead (Evistias acutirostris), Hubbard’s hawkfish (Cirrhitops hubbardi) or the blunt-headed wrasse (Thalassoma amblycephalum), as well as subtropical surgeonfish such as the scalpel sawtail (Prionurus scalprum).
The island is also famous for its seasonal Yūzen tama, large clusters of wrought-iron butterflyfish.
Beautifully coloured angelfish, damselfish and anthias, sometimes in larges aggregations, are found all year round on Hachijō dive sites, including the Japanese Gregory (Stegastes altus ), the Japanese swallow angelfish (Genicanthus semifasciatus), the Japanese angelfish (Centropyge interrupta), the neon damselfish (Pomacentrus coelestis), the purplemask angelfish (Centropyge venusta), amethyst anthias (Pseudanthias pascalus) and scalefin anthias (Pseudanthias squamivinnis).
On the macro and critters front, Hachijō Island is famous in Japan for its many beautiful nudibranchs, including Spanish dancers and rare endemic species, as well as its gobies such as the Helcogramma nesion triple fin blenny, or beautiful species such as the gorgeous prawn goby (Amblyeleotris wheeleri), fire goby dartfish (Nemateleotris magnifica) and more that will delights gobies-blennie fanatics.
Other macro/critter highlights include the odd harlequin shrimp (Hymenocera picta), boxer crab (Lybia), slipper lobster or frogfish (Antennariinae), not to mention a high diversity moray eels including the beautiful dragon moray (Enchelycore pardalis), and rays including round ribbontail rays (Taeniura meyeni) and other types of stingrays.
However the real star of the island is the elusive Japanese pigmy seahorse (Hippocampus japapigu), officially recorded in 2018.
Occasional encounters, especially on early morning dives on sites exposed to currents such as Nazumado or Hachijō Kojima dive sites include thresher sharks (Alopias vulpinus) and scalloped hammerhead sharks (Sphyrna lewini), along with spotted eagle ray (Aetobatus narinari) or dolphins.
https://www.youtube.com/watch?v=ZNaoPO8Mvb8&list=PLa2IcuBEFbutH2OH3kgdcfeB7jsh9MKHD&index=2
Seasonal highlights included various schooling events (rainbow runners, mackerel scads, redtail triggerfish, banded boarhead, dogtooth tunas, greater amberjacks), and also bigfin reef squid (Sepioteuthis lessoniana) spawning events, usually around May.
https://www.youtube.com/watch?v=Vc4f0ltiHfc&list=PLa2IcuBEFbutH2OH3kgdcfeB7jsh9MKHD&index=9
Hachijō is also very famous for its resident green sea turtles (Chelonia mydas) which are commonly seen on all dive sites of the island, with a high concentration around the Sokodo reef.
Finally, a small pod of dolphins is regularly spotted around the island, having presumably moved from neighbouring Miyake Island.
And in more recent years, humpback whales, orcas, false killer whales and other cetaceans have been regularly spotted around the island in the winter months – it is rare to see them underwater but very common to hear them calling out to each other during dives.