Mission Blog: August 19, 2009
Pearl and Hermes Atoll
By Yannis Papastamatiou, PhD, Scientist, Diver
New species of deepwater butterfly fish caught at 200ft off Pearl and Hermes Atoll by Rich Pyle.
(Photo:Yannis Papastamatiou/NOAA) Click on the thumbnail for a larger image.
We arrived early in the morning at Pearl and Hermes atoll. Pearl and Hermes has always been my favorite atoll of the island chain, mainly because it has the highest density of apex predators (sharks and jacks). Today I am in the morning technical dive team which consists of Ray and I. Using the multi beam sonar on the Hi'ialakai; we had found what looked like a good ledge off the SW tip of the atoll. Unlike the previous days at Necker and Nihoa, we have lucked out with the weather-the water is pretty much flat.
We roll over the side and start our descent to the top of the ledge. On the way down I look up and see about 60 giant trevally (Caranx ignobilis, Hawaiian name Ulua) heading towards us. We reach the top of the ledge at about 160ft and drop down to the bottom of the canyon at around 210ft. A lone Galapagos shark swims down with us, followed by the marauding gang of ulua. Ray starts his transect to get an idea of which fish are down there, and that takes us a little deeper to about 220ft. There are masses of black coral growing down here, and I take some samples for Dan Wagner who is doing his PhD on the reproductive ecology and taxonomy of black corals.
We head back up the ledge and swim at 200ft for about 10 min. Along the way we run into a Hawaiian grouper (Epinephelus quernus). These grouper are found in the main Hawaiian Islands below 300ft, but at Midway and Kure they are found in water as shallow as 30ft. However, this is the first time I have seen one at Pearl and Hermes. After 20min on the bottom, we now have 60 minutes of required decompression, so we start the long ascent up. We are soon joined by our expert safety team, who will keep an eye on us during the ascent to make sure everything is going well. The ulua stay with us for the whole decompression, keeping things interesting.
Ray Boland decompressing while surrounded by Ulua at Pearl and Hermes atoll. (Photo:Yannis Papastamatiou/NOAA)
The afternoon dive team consists of Rich, Randy, and Greg. They dive on a different ledge, at about 210ft, and come up looking pretty ecstatic. Rich has 3 specimens of a previously un-described species of deepwater butterfly fish. He has seen these fish before in much deeper water off Oahu (400ft). Based on these fish observation, it's starting to appear that the deepwater fish community is moving shallower as we move up the island chain. At Pearl and Hermes and Laysan, we find fish at 200ft, which can only be found at 400ft in the main Hawaiian Islands. We know that some fish found at 300ft off of Oahu can be found in 30ft of water off of Midway and Kure. The obvious question is: what will we find at 200ft off of Kure and Midway?? We hit Kure tomorrow.