Cocos Island trip report (shark tagging expedition)

[NTSilver]

We were fortunate enough to take our second trip this year to Cocos Island, Costa Rica. We went as part of a Costa Rican NGO, PRETOMA, research expedition to tag hammerheads with radio transmitters and collect white tip samples for the University of Hawaii. It was a fantastic trip and all for a very good cause – to collect data to learn more about sharks and hopefully preclude their extinction. It is estimated that as much as 90 percent of the populations of the world’s top predator fish species have been destroyed by longline fishing in the past 50 years.

We were aboard the Undersea Hunter (the smaller of the Hunter boats) which accommodates 14 divers and 6-8 crew members.

This trip was totally different than the trip in May. In May we saw tons of hammerheads on every dive, so many so that by the end of the week I was looking for other things as the hammerheads swam by. On this trip the thermocline had risen to around 60 feet and it was cold (in some places 70 degrees or less – normal water temp in 78 degrees) and very few hammerheads until later in the week with thermocline descended. Definitely required a 5mm with hood. Also something that we didn’t really experience the last trip was the currents. I cannot even describe the current on one particular dive. It was so bad that I could not pull myself down the line. My mask filled with water and when I tried to clear it, the mask came off. Luckily I was able to hold onto it and proceeded down the line. Finally someone grabbed me which enabled me to put my mask back on and continue down the anchor line. 1000 pounds later I finally reached the bottom and was able to calm down. Unfortunately no hammerhead action that day. On the other dives, the current was very strong as well, and a reef hook would have some in handy.

There were several highlights: a dive with a giant manta on our second dive, several spotted eagle rays on every dive, green turtles on every dive, Galapagos and Black Tips hunting, a kamikaze turtle biting the tailfin of a Galapagos, and my favorite – swimming alone with six mobulas at the surface.

We also learned more about the current situation in Costa Rica regarding the illegal shark finning trade from Randall Arauz, Director of PRETOMA, expedition leader. We learned, as they reported in the movie Sharkwater, the real illegal activity is happening at the private docks at the north end of Puntarenas. We learned upon our return that the docks had been shut down and were no longer allowed to accept boats. Evidently Sharwater is currently playing in Costa Rica and the government is under some pressure to save one of its most beautiful natural resources. We also witnessed firsthand the miles and miles of long lines that had accumulated at one of the dive sites. Our group brought up as much as we could but there was still so much left behind.

It was great to be part of this expedition and we hope to be fortunate enough to assist in the future.

[pakman]

Nice NTSilver! Gotta love Cocos...

BTW, how do you guys tag hammerheads?

[NTSilver]

Well Pakman, we left the the hammerhead tagging to the professionals. They have spearguns and tag them with radio transmitters which are tracked by receivers at about 4-5 dive sites. The thermocline definitely played a part in the lack of HH activity the first few days, so they were really getting a little nervous that they would not get to tag any. However, the thermocline calmed down and they were able to tag 9 HHs. We were able to assist with setting up a new receiver and locating older receivers that had been set back in May to gather the data.

Us non-professionals actually helped a doctoral candidate from Univ Hawaii snip the tailfins of whitetips. This involved a little paper punch looking item where you snipped the tailfin and the shark swam away. We were able to get 38 samples which I transported back to the US and then on to Hawaii.

It was very fun and very educational at the same time.