After a slightly delayed start and completing our successful “shake-down” dives in the Main Hawaiian Islands, the Hi’ialakai began its two-day transit towards our first stop within the Papahānaumokuākea Marine National Monument: French Frigate Shoals. Transit days aboard the ship are a stark contrast to diving days. We can sleep in as long as we want, because there is no morning briefing at 7:30 am, and there is no need to prepare our rebreathers and other dive gear for a day of diving. We also eat a delicious hot-cooked lunch aboard the ship (rather than the sandwiches, crackers and cheese we scarf down between dives out on the water). Later on in the cruise, transit days are very-much appreciated to give us needed “down time” to repair our gear and rest our bodies. But this early on in the trip, there’s very little work to be done, so we often just kick back and relax, and possibly read a book (I read The Rosie Project, by Graeme Simsion, which was recommended by both Bill Gates and my wife Lisa, and which I thoroughly enjoyed).
The ship arrived at French Frigate Shoals yesterday (September 11th) in the wee hours of the morning, and we got an early start preparing out gear and making sure our first day of diving in the Monument would be a success. After the safety briefing, we loaded up Metal Shark and headed to the first of two dive sites. The dive sites are selected the night before based on high-resolution bathymetry data we have for this area, which has been gathered by both the Hi’ialakai multibeam system on this and earlier cruises, and also from earlier cruises of this ship as well as others, including the R/V Falkor, operated by the Schmidt Ocean Institute. The morning team included Randy Kosaki, Brian Hauk, and Rob Whitton, and their target was a ledge at a depth of 280 feet (84 meters), and the afternoon team included myself, Jason Leonard, and Dan Wagner. Each of the three divers on each team has a specific role. One diver conducts a visual transect along a straight line, following a 25-meter (70-foot) measuring tape, counting fish species, sizes, and abundances. Another diver follows the same transect line with a photo “quadrat” unit — a PVC pipe frame with lights and a camera that is used to capture standardized digital images of the bottom to characterize the benthic habitat. The third diver functions as a safety diver, and his job is to keep an eye on the other two divers, each of whom is focused on his respective science task.
One of the specific species that Rob had hoped to see on this cruise was Steindachner’s Moray Eel (Gymnothorax steindachneri), a species found in very deep water in the Main Hawaiian Islands, but is known from somewhat shallower depths up here in the Northwestern Hawaiian Islands (this pattern applies to many different species). As luck would have it, on his first dive of the cruise he practically landed right on top of one! They saw many other fish on the deep ledge (including the ubiquitous Galapagos Sharks, Carcharhinus galapagensis), and completed their decompression in the company of sharks, as well as a passing Wahoo (or Ono in Hawaii; Acanthocybium solandri).
Our deep dive (the afternoon team) was somewhat less exciting. We hit a fairly barren sandy area, with hardly any fishes. I did see a female Wood’s Razor Wrasse (Xyrichtys woodi), but unfortunately I was still having trouble with my camera’s autofocus, so I failed to get any good video footage. Jason completed his fish transect, and Dan followed up with the photo quadrats, so the dive was successful, if not spectacular. Our decompression was unremarkable, and we finished the dive early enough that Rob and I had time to get in a quick dive to a nearby shallow reef. Our main purpose for being here is to explore and survey the deep (“mesophotic”) reefs, but we also want to capture images of as many species of fishes as we can (both shallow and deep) in preparation for a comprehensive checklist of fishes of this area that we plan to publish later this year. Although the shallow dive was pleasant and interesting (a very large Galapagos shark periodically visited us, and several large Giant Trevally, Caranx ignobilis, stayed near us), it was otherwise unremarkable.
Today included another pair of successful dives. I was again on the afternoon team, which included the same three divers as yesterday’s afternoon dive (myself, along with Jason Leonard and Dan Wagner). I spent some time on this dive capturing video of various fishes (including a particularly cooperative Longnose Hawkfish (Oxycirrhites typus).
But the highlight of the dive for me was actually an invertebrate: a spectacular purplish red long-spined urchin in the genus Diadema. I’m not a specialist in marine invertebrates, but I know enough to know that I’ve never seen anything like this before in Hawaii. Unfortunately, I didn’t have any way to collect the specimen, so I hope to find another one when we stop by French Frigate Shoals again on our way back home, on the second half of the cruise.
Tomorrow we begin a 48-hour transit to Lisianski Islands. With luck and cooperative weather, we’ll arrive there early enough on Sunday to get an afternoon dive in.