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9/19/05 - Shark Tagging
by David Nichols, State of Hawaii, DLNR, HIHWNMS

Chief scientist, Randy Kosaki collects reef fish at Rapture
Reef, French Frigate Shoals while accompanied by a white-tip reef shark.

This was our last day of research activities at French Frigate Shoals before continuing along the island chain. First on the agenda this morning was to set a couple of short (10 hooks) bottom longlines. We were hoping to collect a few sharks in which to implant the acoustic transmitters. After these were set we needed to let them “soak” for a few hours in order to increase the likelihood of hooking a few sharks.

Next up was a quick dive on “Rapture Reef”. We intended to collect more fish specimens and the apex predator guys needed to retrieve the ultrasonic receiver that has been in the area since May. We have a checklist of reef fish species that are still needed for further research. The easiest to collect on this list have already been captured. Now we are down to those elusive species that require a high degree of skill (“fish sense”) to capture.

When we arrive at Rapture Reef (which was found using the GPS unit on the vessel) we notice that the floats marking our longlines were also nearby. Which means we were about to dive in an area that had scattered chunks of flesh around on hooks with the sole purpose of attracting sharks. The team starts discussing (half jokingly - half serious) about proper shark mitigation procedures for divers in the water.

Rapture reef was an amazing dive. It sits in about 80+ feet of water with such elaborate and healthy table coral that it creates layers upon layers of potential hiding areas for the heaps of fish that call this place home. I have never seen such a huge concentration of aquatic life. By the time I make it to the reef the white-tip reef sharks are awake and cruising around. They are a smaller shark and not particularly threatening. There was also a larger gray reef shark that (according to the shark guys back on the boat later) appeared to be quite agitated.

After the rapture reef dive it was necessary to retrieve the longline and tag any sharks that we happened to catch. Normally this would require a couple of boats - one to retrieve the line and another to use as the “implant station”. However, the weather had picked up considerably and made launching the second boat a little sketchy, therefore, all the work was done from the 8-meter HI-2. The first of the longlines was retrieved with no sharks. I was a little concerned but shouldn’t have been because we hit paydirt on the second line including a large (8’) Galapagos shark.

Randy Kosaki, Yannis Papastamatiou, and Carl Meyer orient a
shark alongside the HI-2 to implant an acoustic transmitter.

The sharks are brought alongside and tethered to the boat. The scientists take various measurements and then make a small incision in the abdomen. The acoustic transmitter is inserted and the incision is sewn back up. All this work is done with the shark still in the water alongside the vessel. These guys make it look easy even in the rough seas. The whole process takes less than 10 minutes. The longest part of the procedure (and looks to be the most dangerous) is the hook removal. Just imagine sticking your hand in a chipper machine. Dr. Carl Meyer has been doing this for years and as he pulls the hook out of the large Galapagos, I take a quick count and he seems to still have all of his fingers attached. Evidently he has the procedure for removing hooks from large apex predators pretty well ironed out.

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