We are well underway with our three and a half week cruise through the Northwestern Hawaiian Islands, arriving now at Lisianski after two full days at French Frigate Shoals. The deep team had two very good Mesophotic dives down to 280′ (85m) and conducted fish counts (transects), benthic surveys via photo quadrat, and general biodiversity surveys via high definition video, which is of course where I come in.
NOAA diving supported by the NOAA ship Hi’ialakai is probably some of the logistically best supported diving we ever do on expeditions. The ship has an onboard hyperbaric chamber, a physician with full sick bay, we have safety divers, a separate safety boat, the latest communications and navigation gear etc. We are running the deep team as two separate dive groups of three, so get double the data collection per day of diving.
One of the interesting biological aspects of the Northwestern or Leeward Islands is that there are certain species of fish that are rare or absent in the main Hawaiian islands, that are common up here. Steindachner’s Moray is a fish that I have encountered only twice on Oahu in about 20 years of diving, and I found one on both days at French Frigate Shoals. A cool eel, methinks.
Another neat aspect is the presence of apex predators on and around the reefs. We have sharks on every dive, and large jacks cruise the shallows. Sharks are rare to see when diving the main Hawaiian Islands – they are present, but in much fewer numbers, and more wary of inshore dangers. Here, they seem curious, and spend the entire 75-90 minutes of decompression with us. I saw my first Scalloped Hammerhead on deco two days ago, and we always have Galapagos Sharks around us as we dive, some quite large for the species.
Other large predators are common inshore, including Uku – Green Snapper (Aprion virescens), Kahala (Seriola dumerilli), and amazingly, three large Ono (Acanthocybium solandri). They were fearless, eyballing me as they circled and I filmed, very cool.
Another visible difference up here is the large numbers of sea birds. Without human habitation and the associated threats, the seabird numbers are much larger in the Northwestern Hawaiian Islands. Piles of Brown Noddies on fish bait balls, cruising Boobies, Frigate birds and terns are a constant presence topside.
We are just now arriving at Lisianski Island for two or three days of dive operations. A coral bleaching event was reported here, earlier this summer, and we are investigating, along with our normal Mesophotic (deep reef) biological surveys.