Summer of the Shark

Between August 20th and 30th, Pretoma and Turtle Island Restoration Network (www.tirn.net) will jointly lead a Cocos Island Shark and Sea Turtle Tagging Expedition, a historic expedition that will investigate declines in Eastern Pacific shark populations, migratory movements of hammerhead sharks and green turtles, and the effect of man's activities on these endangered species. Pretoma, a Costa Rican non government organization led by Randall Arauz, is also a member of Migramar (www.migramar.org), a network of non government organizations that work in the Eastern Pacific to study the migratory paths of these creatures, and provide advice for their regional conservation and management.

There are 88 shark species recorded throughout the Eastern Tropical Pacific, and although they are not targets for most fisheries, sharks tend to become hooked on open water long lines that catch tuna, mahi-mahi, and a variety of billfish. Some estimates are that 50% of world's shark catches are classified as by-catch, and do not even appear in official statistics. Ruthless and efficient killers in their own environment, sharks have driven the ocean's natural selection processes for millions of years and are the best indicators of overall marine ecosystem health. Yet they are extremely vulnerable to man because of their relatively slow growth, late onset of sexual maturity, and low birth rate. Over the past decade, there has been growing concern that shark populations around the globe are in rapid decline and on the verge of extinction.

Pretoma and TIRN will be working aboard the Argo, a spacious work boat perfect for scientific endeavors. Our goal is to place 10 acoustic tags on targeted Hammerhead and Silky Sharks. We will also attempt to tag a Galapagos Shark, something that has never been done yet at Cocos. The team will recover 4 acoustic receivers placed underwater at strategic locations around the island, and download data which will detail movements of the previously tagged sharks, 54 in total over the last 4 years. We are interested in their behavior in places where sharks school and there is an apparent residency. How far do they forage? Do groups remain cohesive over time? Do they display diel patterns? Furthermore, we are interested to know if these sharks follow defined migratory corridors when traveling to other Islands of the Eastern Pacific. Preliminary results show sharks migrating from Galapagos Islands to Cocos, over 700 km, in just fourteen days. Movements have also been confirmed between Malpelo and Cocos.

This project is aimed at developing a baseline of shark distribution and abundance at dive sites in Cocos Island National Park.  Many pelagic and coastal-pelagic species in the Eastern Tropical Pacific migrate throughout the region at different times of the year, so a comprehensive regional management plan must include adequate protection for key species at particular sites when they are vulnerable. Many shark species appear to display a high degree of fidelity to very specific sites. Through the Migramar network, it will be possible to determine residency and fidelity at these sites, as well as the degree of connectivity between them. In this way, we can build up a model of spatial utilization for the different populations, and contribute to the management of protected areas.

Another major goal of this project is to implant satellite tags on 4 Eastern Pacific Green Turtles, catalogued as endangered species by the International Union for the Conservation of Nature.  Habitat destruction, pollution, long-line fishing and poaching are the biggest challenges to the green turtle's survival. Turtle populations once numbering in the hundreds of thousands have been depleted so badly that only a few thousand exist today. No one knows where the Cocos Island green turtles are coming from or going to as of yet, nor if they follow defined migratory patterns, which will be revealed by tracking them with satellite tags. We need to know where these turtles forage and how to protect them throughout their range.

The Cocos Island Shark and Sea Turtle Tagging Expedition is supported by BBC Wildlife Fund and sponsored by the Whitley Fund for Nature, PRETOMA's corporate membership, and by expedition participants, most of whom are avid shark and sea turtle conservationists.  The Catch Conservation Fund (www.catchconservation.com) is a new partner who will be filming the expedition to support and promote Pretoma's future work to protect sea turtles and sharks in the Eastern Pacific.

For more information:

Pretoma
Tel (506) 2241 5227
Fax (506) 2236 6017
email
website: www.pretoma.org