Marine protected areas to conserve highly migratory sharks in the Eastern Tropical Pacific

  • Sharks
Years funded
  • 2021
  • Active
Project types
  • Conservation
  • Education

Randall wants to help better protect migratory marine animals in the Eastern Tropical Pacific. He is interested in hammerhead sharks that aggregate around ocean islands (which are protected) and then migrate along the Las Gemelas and West Cocos seamounts (which are unprotected) between these islands. After deploying acoustic receivers, i.e. deep listening stations, at the summits of these underwater mounts, Randall and his team will track tagged hammerhead sharks in relation to these seamounts. The team will also deploy baited remote underwater video systems (BRUVs) to do ongoing monitoring at both sites.

Marine protected areas to conserve highly migratory sharks in the Eastern Tropical Pacific

Randall Arauz

Project leader
About the project leader

I was born and raised in Los Angeles, California, the son of Costa Rican immigrants. I lived only blocks away from the ocean and, like so many of my generation, was inspired at a very early age by The Undersea World of Jacques Cousteau television show. My family returned to Costa Rica when I was only 10 and so I ended up in one of the most biologically diverse places on earth! I studied biology at the University of Costa Rica, where I developed a strong interest in the biology and conservation of sea turtles. After graduating, I focused on...

PROJECT LOCATION : Costa Rica, Cocos Island
Project details

Marine protected areas to conserve highly migratory sharks in the Eastern Tropical Pacific - Cocos Island

Key objective

To impose the policy changes needed to halt the extinction trend of highly migratory endangered marine species in the Eastern Tropical Pacific and achieve the conditions for their recovery.

Why is this important

Hammerhead sharks are Critically Endangered. Policies are urgently required that severely limit fisheries-induced mortality. This project will strengthen the scientific evidence that justifies the expansion of a no-take policy in waters surrounding Cocos Island’s current 12-mile (20-kilometre) no-take radius (772 square miles; 2,000 square kilometres).


The unique behaviour of adult hammerhead sharks to aggregate at certain oceanic islands or ‘hotspots’ has led governments of the region to declare no-take zones around them. Seamounts that occur between these aggregation sites and along which adults migrate have also been identified as hotspots. Thus, the strict protection of known hotspots will not be efficient if fishing effort continues unabated at seamounts that occur between hotspots. Since 2015, acoustic receivers deployed at a depth of 590 feet (180 metres) at Las Gemelas Sea Mount, 40 nautical miles south-west of Cocos Island, have detected the movements of hammerhead and blacktip sharks that had been previously tagged at Cocos Island, as well an apparently resident thresher shark that remained at the seamount for over a year. Furthermore, in 2019 a scientific expedition led by the University of Costa Rica using Baited Remote Underwater Video monitoring (BRUVs) filmed aggregations of adult hammerhead sharks at the summit of West Cocos, an unexplored seamount 50 nautical miles west of Cocos Island.

Aims & objectives

We propose to extend our previous pioneering work studying the association of hammerhead sharks and other shark species to Las Gemelas and West Cocos seamounts.

We will deploy two deep receivers at the summits of Las Gemelas and West Cocos with the assistance of an unmanned submersible (Remotely Operated Vehicle or ROV). We will also invest time catching sharks and fitting them with acoustic tracking tags by means of simple surgery. We will also team up with the University of Costa Rica to perform BRUV monitoring at both sites.