Sea Hunter May 23-June 03, 2023 | Cocos Island Trip Report

This was our first research trip back at Cocos Island for 2023!  The goal? To study the migratory movements of sea turtles and elasmobranchs (sharks)  in Cocos Island National Park and Bicentennial Marine Management Area. The Sea Hunter had aboard representatives from CREMA, Turtle Island Restoration Network (TIRN), Sea Change Agency, Marine Watch International, MigraMar, and Ocean Blue Tree.

By the end of the week the researchers had placed 7 acoustic tags on hammerheads, 4 internal tags on Galapagos and silvertip sharks, and performed some much-needed maintenance to the acoustic receivers around the island. External acoustic tags emit acoustic signals every 1.5 minutes, and can function for up to two years. Internal tags emit acoustic signals every 4-5 min, and can last between 6 and 10 years.

All-in-all, this was a super successful expedition!! We are so thrilled to be back at Cocos Island and honored to be able to help protect what we love most – the ocean and its sharks.

Now for the trip report:

Our first two days at the island were relatively quiet, and we saw hammerheads coming into the cleaning stations plus schools of bigeye jacks and bluefin trevallies hunting. At Punta Maria we saw a Galapagos, two silvertips, a couple of hammerheads and two big wahoos. We encountered blacktip and whitetip reef sharks during afternoon dives at Viking Rock.

By Day 3 the action really started picking up, and we decided to visit Alcyone so the scientists could perform some routine maintenance on their acoustic receiver there. There was a strong surge in the deeper waters, but they nonetheless succeeded in their task! Later, Manuelita Outside was fantastic with many hammerheads streaming into the cleaning stations. On our afternoon dive at Pajara, we saw a big tiger shark.

On Day 4, rough conditions made it impossible to visit Dos Amigos, so we returned to Dirty Rock and Manuelita where we enjoyed excellent hammerhead cleaning station activity. At Dirty Rock, the research team tagged a hammerhead with an acoustic tag, and out in the blue saw yellowfin tunas and mobula rays.

For Day 5 we once again found ourselves back at Dirty Rock, where the hammerheads were busy using the deep cleaning station. We also saw two marble rays and a huge school of jacks at the pinnacle. Diving Punta Maria was a challenge, and strong currents there definitely added an element of adventure! Later, in the afternoon, we went for a walk topside in Wafer Bay where researchers gave a presentation to the park rangers.

Day 6 Manuelita Channel was hot, and so many hammerheads were using the cleaning station and swimming close to the sandy bottom. We also observed two frogfish in the middle of the channel. Alcyone was quiet, with no current and few sharks — but we did find ourselves inside of a massive school of bigeye jacks followed by mullet snapper schooling above the rock. It was just magical. Then our afternoon dive at Manuelita Outside we saw a Galapagos and a couple of dolphins.

The resolution number pertaining to this expedition is: R- 009 PI-DR-ACMC-2022, granted by SINAC-MINAE-ACMC.