Greetings from Pohnpei State in Micronesia. We are finishing up three weeks of deep dives around Pohnpei island and neighboring Ant Atoll, documenting fish biodiversity for the Bishop Museum and collecting specimens for DNA analysis for the Hawaii Institute of Marine Biology. This is the final expedition sponsored by the Seaver Institute to characterize mesophotic coral reefs across the Pacific.
Pohnpei is a high volcanic island in the middle of Micronesia (Caroline Islands), and is the home to the capital of the Federated States of Micronesia. Our dives have been along the outer wall of a barrier reef that encircles almost the entire island, creating a protected lagoon, similar to our diving a few years ago in Moorea, French Polynesia. The lagoon allows us to travel fast on protected waters, and then exit through one of the many passes and search for interesting sites based on vertical terrain.
Pohnpei is a rainy place, with very consistently high humidity and air temperature, which is almost the same as the water temperature (mid to high 80’s Fahrenheit). We get cold zipping along in the sometimes heavy rain in a speedboat, and then hop in the water which feels like a warm bath. There are several noticeable thermoclines around 200 and then again at 300 feet. These temperature changes usually indicate a shift in fauna for us, as certain deep fishes prefer cooler water. After 20 minutes or more below the thermocline, moving back up the wall feels like switching to warm baths, which means that the three plus hours spent on decompression are very comfortable.
I have been switching between capturing video clips of mesophotic reef fish and spearing or hand netting fish for DNA sampling. I occasionally try to do both filming and collecting at the same time, with typically less than stellar results. One lesson in deep fish collecting is to never count a fish as collected until it is back in the lab – I have lost fish this trip from net to bucket, bucket to hand (for needling to relieve expanding gasses in the swim bladder), bucket to boat, hand to mangrove channel (don’t ask), and even fish bag to photo station. I wouldn’t make a very good jailer – everyone would escape.
As usual, we are making a fish list for the island and neighboring atolls, and are over 320 species for about 10 dive days. John Earle has joined the expedition for a week, and has been a machine, recognizing and recording hundreds of reef fish. Richard and Brian tend to focus on the deep reef fish, and also on collecting. John’s expertise is to record the totality of species, not only the charismatic, rare and valuable beauties.
We have had exceptionally calm seas and winds the last few days, and took the advantage to cross the 10 miles or so from Pohnpei proper to the west side of Ant Atoll. The commute ran a bit long – 90 minutes or so, but the ride was worthwhile, as the vertical drop was probably over 1000 feet from the reef top. We had great visibility, and lots of interesting cuts, caves and undercuts. Richard is one of the leading Angelfish experts in the world, and was delighted to find Centropyge aurantia – Golden Angelfish during decompression. This was a new fish for me – famous for it’s cryptic nature. 30+ minutes of watching and waiting and I have a few clips of the little fella. We may return Tuesday to revisit the deep caves, and also see if we can record more of this little known angelfish.