A day of shark tagging

The goal was to place SPOT tags on three large male gray reef sharks.  Eight had already been attached to sharks during a previous trip. The eight were split with 4 going on female sharks and 4 on male sharks. The tags send a signal to a satellite giving the sharks position when they come to the surface. What was interesting is they got signals from the male tagged sharks, but not the females. This is why we were looking to tag only make sharks this time.

On the way out we were fishing for food. As I think I mentioned earlier, the station is under a strict quota of fish that can be taken each week. They have to be Ono (Acanthocybium solandri), Ahi (Thunnus albacares), or Mahi mahi (Coryphaena hippurus). These are large pelagic fish that are just visitor's to the reef and not residents. They do not use fishing reels, but rather just tow a line with a lure on the end with a couple of bungee cords inserted to shorten the line. When the bungee stretches and the rope goes straight, you have a fish on the line and you have to pull it in fast or it will be eaten by sharks. Below is a photo of what the set up looks like being towed behind the boat.

Once at the site, we chummed for sharks.  Here is Francesco getting ready to put some Ono fish heads out into the water to attract the sharks.

We then put baited hooks into the water.  Here is Doug getting ready to start fishing for sharks with some nice Ono meat on the hook.

We caught a total of 11 gray reef sharks.  Six were male and 5 were females.  Of the 6 males, 2 were re-captures.  They had "spaghetti" tags on them. These are inexpensive tags about the diameter of a piece of spaghetti that have a number and some other information about where to return the tag if you find it. One of the males caught was one of the original 8 that were tagged with the infinitely more expensive SPOT tags. It was a very successful trip with the three new SPOT tags attached to large male gray reef sharks.

The information these tags provide will help with management of the shark population. For example, it is known that the smaller blacktip reef sharks are residents on the Palmyra reef. The SPOT tags have already shown that the gray reef sharks travel much further off shore from the reef than was expected.  Could they go as far as one of the neighboring islands like Fanning or Christmas? While the sharks are totally protected here on Palmyra Atoll, they could be taken by fishing that is permitted on the other Northern Line Islands.