Exploring the Northwestern Hawaiian Islands
October 2, 2014
By Dr. Richard Pyle
September 27, 2014: Back to French Frigate Shoals
After leaving Pearl and Hermes, we had scheduled two and a half transit days to get back to French Frigate Shoals, which would have allowed us one and a half days of diving. However, the crew of the Hi’ialakai made better-than-expected headway in transit, arriving early enough at French Frigate Shoals that we were able to get in two full days of diving. Even before the bubbles cleared after plunging into the clear blue water for my first deep dive yesterday, I was startled when I turned around and saw a Galapagos Shark bearing down on me. I managed to turn my video camera on just in time to capture its closest pass, and from that point onward, we were obviously the subject of much interest among about seven or eight larger-than-usual Galapagos Sharks.
On the bottom, the ledge was small and mostly featureless. However, there was one small ledge near where we hit the bottom that had a few fish under it, including the smallest Sunrise Basslet (Liopropoma aurora) I’ve ever seen. It was no greater than 2 inches (5 cm) long, and kept swimming back and forth from one end of the small undercut ledge to the other. Most of the individuals of this species I’ve seen have been between 6 and 10 inches (15-25 cm), so it was a treat to see and film such a cute little fella!
After Jason and Dan completed their transects, we continued down the reef until we found a small “grotto” in the ledge with lots of fishes of various species. Some of the fishes in the grotto were species that our colleagues back home needed for population genetics research, so Dan began spearing the appropriate species and placing them in his bag. With each speared fish, the group of Giant Trevally (Caranx ignobilis) surrounding us grew in number and “intensity” (for lack of a better word). And, of course, the same was true for the sharks. Towards the end of the dive, the Trevally (we refer to them by their Hawaiian name, Ulua) were too fast for Dan: as soon as he speared a fish, the Ulua would pounce and the speared fish would disappear before Dan could get it into his bag.
Although not as aggressive as the Ulua, the Galapagos Sharks were also coming in closer and closer, obviously attracted by the “action.” I was slightly concerned at first about how aggressive the sharks might be once they caught a whiff of blood from the speared fish. Although they did make some very close passes, they were much more timid than the Ulua, and generally didn’t show any signs of aggression towards us.
After our bottom time was over, Jason sent the bag of speared fish to the surface along with the “Happy Bag.” This is always a prudent thing to do when we owe significant amounts of decompression in open water. As the bag of speared fish rose to the surface, it left a scent trail that the Ulua and sharks followed up towards the surface. Unsurprisingly, the sharks stayed with us for most of the decompression (as they have for most of our dives up here). Indeed, decompression was anything but boring, as members from the morning deep dive team joined us and our safety divers (Keo Lopes and Senifa Annandale) as shallow free divers to help shuttle gear from us up to the boats.
Encouraged by our earlier experiences with sharks and Ulua being attracted to dangling shiny things, Rob has been bringing out a GoPro camera to dangle in front of whatever animals join us for decompression. Today he hit paydirt. I watched in amusement as a Galapagos Shark approached his camera and nuzzled it with its snout. Rob masterfully kept the camera pointed in the right direction, and the view both from the outside, and from the GoPro camera itself, was definitely worth the risk of losing the camera into the belly of a shark. For what was originally supposed to be only a half-day of diving, our first day at French Frigate Shoals was very productive.
Today’s dives were not expected to be as dramatic as yesterday’s. Dan Wagner had identified two small ledges at moderate depth (165-200 feet; 50-60 meters), and we were going to investigate. The morning dive team (Randy, Brian and Rob) found a small ledge with pure white sand on top and bottom, and huge aggregations of tiny Blueline Snapper (Lutjanus kasmira) and Earle’s Splitfin Anthias (Luzonichthys earlei). Earle’s Splitfin Anthias is endemic to the Hawaiian Islands, and is named after its discoverer, my long-time dive partner John Earle. It’s an unusual species that is somewhat ephemeral, either swarming a deep ledge by the thousands, or completely absent from the reef; and it’s always a joy to see them. The Snapper, however (known locally by its Tahitian name, Ta’ape) is another story altogether. It was intentionally introduced to Hawai’i in the 1950′s as a food fish, but for various reasons it’s never been highly sought after for that purpose. Instead, it appears to be competing with native species of snapper (and other fishes), which are much more valuable. One of our standing missions on these cruises into the Papahānaumokuākea Marine National Monument is to monitor the populations of this species as we move up the chain. Seeing such an enormous population of juveniles here at French Frigate Shoals is somewhat disheartening.
As Dan, Jason and I descended for our afternoon deep dive, we were completely surrounded by a large school of Amberjack (Seriola dumerili), with a few scattered Grey Snapper (Aprion virescens) nearby. These fish were much smaller than I usually see for schools of this species, and they were also very “twitchy”. It soon became apparent why when a somewhat agitated Grey Reef Shark (Carcharhinus amblyrhinchos) came charging through the school.
Although the shark was gone almost as soon as it arrived, the Amberjack stayed with us for quite some time as we swam out over the sand in search of a ledge. After heading southwest for a while and finding nothing but sand and small rubble, we decided to change directions and move towards the east. We were searching for a small ledge that the bathymetry data suggested was nearby (and probably where the Grey Reef Shark both came from and retreated to), we were unsuccessful. Our swim over the flat bottom wasn’t completely uninteresting. Scattered across the bottom in all directions as far as I could see were dozens of Toenail Sea Stars (Asterodiscides tuberculosus) — a species I don’t recall ever having seen before (either in the Main Hawaiian Islands, or up here in the Northwestern Hawaiian Islands).
After about 20 minutes of seeing nothing but sand and small rubble, we decided to end the dive and head towards the surface. Because of our truncated bottom time, we finished decompression and were out of the water in just over an hour. It was a bit of a downer to end our deep diving within the Monument on such an “uneventful” dive, but as I passed my gear up to Metal Shark and climbed aboard the swim-step, I couldn’t help but smile as I thought back on all the great dives we’ve had so far on this cruise.
But there was a silver lining: because our dive ended nearly an hour sooner than planned, we had time for a shallow dive at one of the spectacular reefs surrounding French Frigate Shoals. We set our course for “Rapture Reef,” a beautiful reef dominated by large table Acropora corals. Because of the morning team/afternoon team schedule for deep diving, we had not yet had a chance to all dive together at the same time. But on this final dive in the Monument, both teams of deep divers and both safety divers (Keo and Senifa) plunged down to the reef together.
As I descended to the sandy bottom next to the reef, I was completely surrounded by massive schools of fishes, particularly Sleek Unicornfish (Naso hexacanthus) and Pennant Butterflyfish (Heniochus diphreutes). The table Acropora coral formations were amazing. This is what coral reefs are supposed to look like, and what they can look like if they are sufficiently protected as they are here in the Monument. After taking in the breathtaking splendor of so much life, I slowly made my way around towards the back side of the reef. In an amazingly weird coincidence, just after I thought to myself that we hadn’t seen any Flame Angelfish (Centropyge loriculus) on this trip; suddenly there were two of them; and they were the largest I have ever seen in Hawai’i!
Although it is rare in the Main Hawaiian Islands, and rarer still in the Northwestern Hawaiian Islands, the Hawaiian variant of this species is highly prized in the aquarium trade because they are much brighter red than individuals of the same species from elsewhere in the Pacific. After a while of filming the two fish, I called Rob over so he could film them with his camera as well. Shortly thereafter, I heard something that I didn’t quite understand. I heard the words just fine, but the context was all wrong. It sounded for all the world like Rob was saying “tinkeri!, tinkeri!” — which would imply the Tinker’s Butteflyfish (Chaetodon tinkeri). But that wouldn’t make any sense, because this was COMPLETELY the wrong habitat for that species. Tinker’s Butterflyfish typically live at depths of 200-400 feet (60-120 meters) in the Main Hawaiian Islands, especially off the Kona coast of the Island of Hawai’i. It is not commonly seen by divers due to its deep-dwelling habits, but the species is not rare in the environment where it occurs. It is extremely rare in the Northwestern Hawaiian Islands, however. Despite all of our years of deep exploration in exactly the right habitat (the same rocky undercut ledges that we have been frequenting on this trip), we’ve only seen it a couple of times. And as far as I know, no one has EVER seen it on a shallow Acropora reef like this! But sure enough, there it was!
This species has held a very special status for both Randy and I ever since we were young aquarists many years ago, so Rob and I called him over to see it for himself. This species is emblematic in many ways of what Randy and I both find so exciting about deep coral-reef exploration. In fact, a drawing that Randy made back when he was in graduate school of this species is on the T-shirt for this year’s cruise.
Tomorrow we head back to the Main Hawaiian Islands. We have one more day of deep diving, somewhere near the island of Ni’ihau. We’re hoping to get to a sea mount called “Five-Fathom Pinnacle”, but it depends on the weather, currents, and the timing of our arrival. In any case, we are definitely in the home stretch now!
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Originally published by Richard Pyle on his Bishop Museum Research Blog series about his NOAA Expedition to the Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands), aboard the NOAA ship Hi’ialakai; 6-29 September 2014.
Dr. Richard Pyle is Database Coordinator for Natural Sciences, Associate Zoologist in Ichthyology and Dive Safety Officer for the Department of Natural Sciences at the Bishop Museum in Honolulu, HI.
Featured image (top): A series of frames from the GoPro camera that was inspected by a Galapagos Shark (Carcharhinus galapagensis). Photos by Robert K. Whitton.