Sea Turtle and Shark Tagging Expedition in Southern Nicoya Peninsula, Costa Rica
Sea Turtle and Shark Tagging Expedition in Southern Nicoya Peninsula, Costa Rica.
From February 10th to 17th, 2011 a team of 9 researchers from both PRETOMA and CIMAR, have embarked on the yacht Sirenus to investigate the southern coast of the Nicoya Peninsula. The a purpose of this expedition is to tag sharks and sea turtles, while monioring the coastline which includes the three marine protected areas of Camaronal and Caletas-Ario National Wildlife Refuges and the Cabo Blanco Absolute Natural Reserve.
During the expedition we intend to capture bull sharks (Charcarhinus leucas), using hooks, and Olive Ridley and Green sea turtles using gill nets. Once captured the animals will be fitted with acoustic and satellite tags which will help the researchers learn if their movements throughout the zone is continuous or seasonal, moving through cetain types of habitats such as feeding zones.
Submerge yourself in the cruise and become part of the virtual crew of this expedition by visiting this blog.
Day 1 (February 11): After a smooth 5 hour passage from the Los Suenos Marina in Playa Herradura last night and a peaceful rest aboard Sirenuse, which anchored one mile from Playa Bejuco in Nandyure, Guanacaste, the alarm clock rang at 5:00 in the morning for us to begin the preparations for our day. Configuring the tagging teams, preparing the bait for fishing and setting up the scuba diving equipment, which will be used to identify the locations for acoustic receivers and complete transects of the bottom composition, lasted until 9:00 am.
The team was strategically divided into 3 groups. The first group was in charge of setting 5 hooks baited with squid on a short longline at specific depths close to the Sirenus as well as chumming the water (using a mixture of skipjack tuna) to disperse the scent which attracts the sharks to the area. For 24 hours a day during the next week, the hooks will be checked at set intervals with hopes of having luck to catch the expected shark. A smaller boat left with another group to set the gill nets and continously monitor them. The final group departed for the first exploratory dives of the area.
Unfortunatley the day passed uneventfully. A spotted eagle ray was caught incedentally in the gill net, which was happily set free with no injuries. The lack of luck was also seen at the hooks, the sharks did not appear and did not seem to want to bite. Local fisherman suggested moving in closer to the shore and Sirenus moved hundreds of meters closer to the beach. After 6 exploratory dives throughout the day, some of which lasted no more than a few minutes, through unfavorable conditions including strong currents and extremely low visibility, the team of divers managed to collect some bottom composition data fom Punta Pilas, north of Playa Bejuco. From the information learned from these dives, it appears that Punto Bejuco is not the appropriate haitat for the Olive Ridley sea turtle as the the majority of this location appeared to have short ,steep, rocky reef area resulting in the majority of the sea floor to be purley sandy bottom.
Around 5:00pm, the dive team returned and the gill nets were collected. Fresh bait was added to the hooks which will be set out all night under continuous viligence, sacraficing valuable sleeping hours.
Tomorrow will be a new day and we hope to have more luck with the captures of sharks and sea turtles as well as setting an acoustic transmitter in the zone. Dinner awaits, salad and delicious pasta with tomato sauce. Good night and until tomorrow!!!
Day 2 (February 12): For some of the expedition members, last night wasn long enough, as they had to prepare bait, repair fishing gear, and even work on this blog. Early morning tasks start again slightly before 6:00 am.
Chumming is very important to attract sharks. 4 skipjack tunas are cut and chopped up, together with fish guts that were given to us early morning by the artisinal fishermen of Bejuco who had been fishing all not long. The bait on the hooks was changed for fresh bait, hoping we would have mor luck than yesterday. 3 additional hooks were set close to the wave break and in front of the Bejuco estuary, hoping to have more chances of catching bull sharks in one of their favorite habitats, river mouths. The divers on board the Pearl and the turtle netting team on the Dolphen head towards Punta Pilas, ton continue with the transect counting and capture of sea turtles.
The dive team continued to experience some trouble due to the oceanic conditions, such as bad visibility and strong current, in spite of which fortunately the morning is easy and incident free. Every now and then dolphins surprise my playfully jumping in front of the bow of the boat. No sharks nor turtles were caught, but several cow nosed rays swam close to the boat, attracted by the chum.
After lunch, finally some action. One of the buoys moved rapidly, sinking up and down repeately. Suddely, the buoy stopped moving. The line was checked, and the bait had evidently been bitten. Could it have been a shark? We can’t be sure, but the event encourages us to continue. The turtle catching team discovers that the current has dragged the turtle net dangerously close to the rocky outcrops. After a lot of work, the net is untangled from the rocks, but still, the net ends up tangled and ripped. The rest of the day, the turtle team aborts operations and dedicates to repairing the net in deeper and calmer waters. Some section of the net suffer sever damate, and will have to be repaired early tomorrow morning.
As of yet, we still haven’t caught any turtles or sharks, although we have already counted 20 quadrants in Punta Pilas. The Sirenuse has now moved a few miles south, to Punta Coyote, where we will be working for the next two days. We have already tagged 14 hawksbill sea turtles, 1 green turtle, and two olive ridelys since June of 2009, and the presence of bull sharks in the Coyote Estuary and Caletas beach is well known and documentes. We hope the dive during the next two days will be easier and more relaexed.
We can feel the good vibes surrouding us. Good night for right now, from the Sirenuse.http://www.pretoma.org/expedition-day-by-day/News