After leaving Midway and making our way back towards home, our next stop is a return visit to Pearl and Hermes Atoll. We had three days of very successful diving here, and made some of the most exciting finds of the cruise! The most exciting of these were on a series of deep ledges at 280-290 feet (84-87 meters) along the north side of the Atoll. On our first dive to these ledges two days ago, we found an assortment of really cool fish, some of which I’ve never seen before, and possibly some that no diver has ever encountered or photographed before!
As we approached the ledge, there was a large cloud of fish hovering over what appeared to be a small cave. At first I assumed they were a common species, such as Thompson’s Anthias (Pseudanthias thompsoni) or Threespot Damselfish (Chromis verater). However, as I got closer it was clear they were actually Elegant Anthias (Caprodon unicolor). There were dozens of the smaller, dark females, and several of the much larger males with bright blue bars on their sides. I had seen this species a few times before up here in the Northwestern Hawaiian Islands, but I’d never seen a school this large before.
Once we reached the bottom, we were investigated by an unusual color form of the Hawaiian Grouper (Epinephelus quernus) that came up to check us out. Normally this species is very dark with a series of white spots, but this one was pale grey with dark margins on the fins. At first I thought it might have been a completely different species of grouper, but then I saw another one near by, which seemed a lot darker with faint white spots. As the two seemed to be hanging out together, I assumed this grey one is just an unusual color form.
The grouper wasn’t the only unusually colored fish I saw. Further down the reef I spotted a flash of red and saw what was clearly a wrasse of some sort, but not one I immediately recognized. At first my heart skipped a beat, as I thought it might be a Russell’s Wrasse (Polylepion russelli) — one of the few species of deep-dwelling Hawaiian coral-reef fishes that I have not yet seen in person. On closer inspection, however, it was clear that the fish was a Sunrise Wrasse (Bodianus sanguineus) with a highly aberrant color pattern.
Normally this species has bright yellow stripes on the head and body, as shown in the photo below from a depth of 200 feet (60 m) off Lisianski. This species is generally confined to depths of 300 feet (90 meters) or more off the Main Hawaiian Islands, but we often find them in the right habitat as shallow as 50 meters here in the Northwestern Hawaiian Islands. Throughout this cruise (and during cruises in previous years), I have seen hundreds of individuals of this species, but I’ve never seen one without the yellow stripes!
Although the mysterious red wrasse turned out to be just an unusual color form of the Sunrise Wrasse (Bodianus sanguineus), a much more exciting encounter (for me) on that same dive was what may well be the first time a diver has ever seen and photographed, the Hawaiian Pigfish (Bodianus bathycapros). There were three large individuals, two of which had the female color form, and one of them (the largest) had what is almost certainly the terminal-phase male color form.
As exciting as these fishes were, by far the most exciting for me was what I saw next. As soon as I saw it, I knew immediately what it was: Struhsaker’s Damselfish (Chromis struhsakeri). Until a few days ago, this fish had never been encountered by a diver before. It is relatively common below a depth of 500 feet (150 meters) in the Main Hawaiian Islands, and I’ve seen it through the port hole of the Hawaii Undersea Research Laboratory’s (HURL) deep-see submersible, Pisces V. But after years of searching for it on deep dives, I still had never seen it. I wish I could claim credit for being the first diver to see one underwater, or even the first to photograph it, but those honors go to Randall Kosaki and Brian Hauk (respectively), who had seen one on their last dive at Midway Atoll, the day before I had seen it off Pearl and Hermes.
Even still, seeing this fish with my own eyes (other than through the port hole of a submersible) was a tremendous thrill! I collected one specimen after getting some fleeting video of it. On later dives to the same area, Rob managed to get some excellent video footage of the species — clearly the best photos ever taken in its natural habitat. I suppose only a true fish nerd can appreciate how excited we are all about this encounter; but trust me, this is the stuff of high adventure for weirdos like us!
While the morning team (Randall Kosaki, Brian Hauk and Rob Whitton) continued to survey this same deep ledge system for the next two days, the afternoon team (myself, Jason Leonard and Dan Wagner) began exploring a shallower ledge system at a depth of about 165-200 feet (50-60 meters). This ledge system — which runs for miles — is what used to be the shoreline many thousands of years ago, when sea level was lower. The pattern (as seen in the bathymetry data shown above) is very characteristic of a “spur and groove” habitat that is typical of the shallow seaward edge of coral atolls.
Indeed, in all my years of diving these ancient-shoreline rocky ledges at this depth, I have never seen any as dramatic and impressive as this series of ledges. There were large rock outcrops in the sand off the ledge, huge overhangs and arches, caves, valleys, pinnacles, and peninsulas. On the top were very thin over-hanging ledges only about 1-2 feet (0.5m) high. And these ledges were covered with all sorts of fishes, both large and small. While Jason ran his standard visual fish survey along the ledge, and Dan took photographs of the benthic habitat with his pvc quadrat apparatus, I had a few minutes to soak in the fish life.
I was immediately surrounded by a school of Thicklipped Jacks (Pseudocaranx cheilio) — a species that is more commonly encountered in the Northwestern Hawaiian Islands than in the Main Hawaiian Islands. I also saw many of my “old friends” hanging out in the ledge — Masked Angelfish (Genicanthus personatus), Sunrise Basslets (Liopropoma aurora), Sunrise wrasses (Bodianus sanguineus — all with the normal yellow stripes), and many, many adult and juvenile Deep Hawaiian Anthias (Odontanthias fuscipinnis).
As previously mentioned, many of these species are encountered at much shallower depths here in the Northwestern Hawaiian Islands, than they are in the Main Hawaiian Islands. But one fish in particular is just startling to see at these depths: the Orangemargin Butterflyfish (Prognathodes n. sp.). This species was first discovered in Hawaii many years ago from video taken by the aforementioned HURL submersible. Deetsie Chave and I published an article describing its presence, and years later I collected the first specimens off the Big Island of Hawai’i, and later off Oahu.
Although I’ve collected many of these over the years, I’ve kept them all alive (mostly donated to the Waikiki Aquarium), I never had enough properly preserved specimens to describe the species. Now, however, we finally have enough specimens (including tissue for DNA sequences), so I will be giving it a formal scientific name later this year (it will be named in honor of Peter Basabe, who assisted me in the collection of the very first specimens off Kona, many years ago). One interesting aspect of this species which is different from most other species of reef-associated fishes, is that it is almost always found in groups of three individuals. Why this is, is anyone’s guess!
So, after three very successful dives off Pearl and Hermes, we now make our way back to French Frigate Shoals. We have a projected two and a half days of transit time to get there. We’ve been diving now for ten consecutive days (the most allowed aboard this ship), so needless to say we’re all looking forward to some “down” time.