The 36-hour crossing from Costa Rica’s port town of Puntarenas to Cocos Island had exceptionally calm seas, a beautiful sunset, and occasional pods of bottlenose dolphins riding the bow of the 115-foot SeaHunter, our home for the next ten days and 21 dives.

Some brown boobies accompanied us on part of the trip, flying around our vessel and picking off flying fish startled by the Sea Hunter (using the vessel much as cattle egrets use cows, riding along to catch the insects they stir up). The birds also used the vessel as a safe place to rest, landing on the railing unbothered by our close presence. One turtle, most likely an olive ridley, and a sea snake were spotted at the surface of the open sea.

Arriving at Cocos before sunrise, we awoke to greetings from boobies, white (fairy) terns, and one or both of the frigatebirds of Cocos, resembling miniature Archaeopteryx. The two species are hard to distinguish: the magnificent frigatebird is slightly larger, with a wingspan of 3 to 4 feet, while female great frigatebirds have a distinctive red eye ring. It was apparently mating season, as the males were regularly soaring the skies with their showy red gular sacs inflated.

While the two skiffs — one for the yellow team and one for the blue team, each with nine divers and two divemasters — were lifted off the mother ship by crane, we had an extensive safety briefing before plunging into the sea at Chatham Bay for our check-out dive, a chance to refine our buoyancy and test our equipment.

We were met with scores of colorful reef fish: blue and gold snappers, bright yellow juvenile hogfish cleaning, and Cortez rainbow wrasse cleaning red Pacific creolefish, known as sandía, or “watermelon” fish, in Spanish. Documenting fish-cleaning activity, a form of symbiosis, was one of our research objectives for the trip (more on that below).

Ever-present and abundant whitetip reef sharks were seen lying on the sand and swimming through the coral heads, and a beautiful marbled ray glided by to greet us.

It’s always great to be back “home” at Cocos Island, my favorite underwater place on the planet.

But I was alarmed by the water temperature — 84°F. The effects of an incipient El Niño were clearly felt in the overheated water and visible in coral bleaching, which I estimated to already be affecting 10–15% of the shallow coral in Chatham Bay.

Temperatures in the range of 82–86°F were felt throughout the trip, from the surface to depths of 100 feet, and coral bleaching was present at every dive site. El Niño was probably also responsible for a general reduced abundance of fish overall — schools seemed smaller, and fewer seabirds were seen diving on schools of small “bait” fish.

Oceanic Cleaning Stations

Oceanic cleaning stations — sometimes called the “spas (or car washes) of the sea” — are specific locations, often on coral reefs, where small animals remove wounded or dead skin and parasites from larger fish (and sometimes turtles), helping to maintain the health of their clients while getting an easy meal for themselves. This form of symbiosis is called mutualism, where both species benefit, and it’s critical to maintaining healthy marine communities. (When you don’t have hands, sometimes you need a little help from your friends.)

Documenting the various species of cleaner fish and their client fish is one measure of Cocos’s importance to both migratory and resident species — data collected on this trip, and others, will be compared with past and future regional studies at other oceanic island sites like Malpelo and the Galápagos in the Eastern Pacific.

A major draw for divers at Cocos is that several large sharks, especially scalloped hammerheads, use well-established cleaning stations, giving divers the chance to wait nearby for close encounters with a shark that normally keeps its distance from divers and their exhaled bubbles.

I believe these cleaning stations are especially important to female hammerheads following mating, which leaves them with open wounds from males aggressively biting and scraping the pectoral and gill region to align their bodies for copulation (again, fish don’t have hands). In fact, the vast majority of hammerheads at Cocos are females, and the cleaning stations seem most active when the wounds are recent.

Hammerheads swim into schools of yellow barberfish, and the less abundant king angels, slowing down and turning slightly sideways — probably signaling to the cleaner fish that they aren’t a threat and are ready for their “treatment.”

Hammerhead cleaning stations are found at several Cocos dive sites, with Manuelita Outside, Dirty Rock, and Alcyone being the most active.

This trip was timed to coincide with post-mating activity and the increased hammerhead numbers usually present in June and July, but cleaning activity was low this time. Plenty of hammerheads were seen, but in small schools, usually numbering 5–20 animals. Interestingly, no recent wounds were noted on the females, suggesting the mating season may have shifted this year — possibly due to El Niño. It’s also possible the hammerheads spent more time at depths below where we could dive, seeking cooler water.

Interestingly, the dive site at Little Dos Amigos, a cleaning station for Galápagos and hammerhead sharks, was quite active, with the big sharks being cleaned by yellow barberfish. Oceanic blacktips were also present and being cleaned, but I observed very few hammerheads, and none being cleaned.

The Giant Fish of Cocos Island

The highlight of this trip was seeing three of the five largest fish in the ocean — whale sharks, giant mantas, and tiger sharks — though these riches weren’t evenly distributed between the two skiffs, with the yellow team hitting the jackpot: three whale shark sightings, plus several giant mantas and tiger sharks!

Whale sharks were sighted on different dives: one at Alcyone, and twice at Little Dos Amigos.

These 30-foot behemoths, the largest fish in the sea, make their living filter-feeding on plankton. The whale sharks also provided passage for numerous remoras (suckerfish), which use a modified first dorsal fin — evolved into an oval, sucker-like organ — to hitch rides on sharks, mantas, other fish, turtles, and even whales and dolphins.

The relationship between remoras and their hosts can take various forms of symbiosis. It’s sometimes considered mutualistic, since remoras move around their hosts and feed on skin parasites while hitching a free ride. But it can also be viewed as parasitic: large numbers of remoras, each 1–3 feet long, can create significant drag, forcing even a whale shark to expend more energy to swim.

Another interesting observation, captured on video during this trip, was a Galápagos shark circling a whale shark and seemingly trying to eat the remoras off its body. Is this cleaning behavior a form of commensalism, where only one organism benefits (the Galápagos shark gets an easy meal, with no real benefit to the whale shark), or mutualism (the Galápagos shark gets a meal, and the whale shark benefits from reduced drag)?

Giant mantas are also filter feeders, with wingspans that can reach 22 feet. One encounter with a manta at Punta Maria lasted nearly 20 minutes, the animal moving back and forth and seemingly making eye contact with each diver. Remoras were seen on the giant mantas as well.

Cocos Island’s marine life is so diverse and dynamic, always in flux due to shifting weather and currents that deliver different water temperatures and nutrients. After 30 trips and more than 600 dives, I am always amazed, and never disappointed.

Help Turtle Island protect Cocos Island’s biodiversity and its highly migratory sharks and turtles. Take action to encourage its completion and support the Cocos-Galápagos Swimway Campaign with a donation.

Photo and video credits: Fish photos by Avi Klapfer, Hammerhead photo by Edwar Herreno. Whale shark video by Dr. Jason E. Farley and Mr. David Dial from Middle River, MD, Hammerhead shark and manta videos by Oscar Steiner.

For Immediate Release, February 5, 2026

Contact: Todd Steiner, Founder & Special Projects, TSteiner@seaturtles.org  

Laurel Irvine, Communications Manager, LIrvine@seaturtles.org

Turtle Island Restoration Network Invites Divers and Ocean Enthusiasts to Join 2026 Cocos Island Expedition: A rare opportunity to explore one of the world’s greatest shark diving destinations, while supporting and conducting marine conservation.

COCOS ISLAND, COSTA RICA – Turtle Island Restoration Network (TIRN) is seeking ocean enthusiasts and experienced divers to join a 10-day scuba diving and research expedition to Cocos Island National Park, a UNESCO World Heritage Site, from June 25th to July 5th, and one of the most remote dive sites on Earth.

Often called “the most beautiful island in the world” by Jacques Cousteau, Cocos Island lies in the Eastern Tropical Pacific and is the only island in the region with a tropical rainforest. Its remote waters are globally recognized as one of the best places on Earth to dive with sharks and experience large marine wildlife.

Participants will explore dramatic underwater seamounts and reefs that are home to massive schools of scalloped hammerhead sharks, as well as whitetip reef sharks, Galápagos sharks, eagle rays, green sea turtles and an extraordinary diversity of endemic fish species found nowhere else on the planet.

“Cocos Island is one of the most extraordinary dive sites on Earth. After more than 30 trips and 600 dives, I am still humbled by its grandeur and the vitality of its underwater world. Each visit feels like traveling 200 years back in time – before our oceans were overfished and polluted. This is what healthy oceans once looked like – and what they can look like again if we choose to protect them, said Todd Steiner, founder of Turtle Island Restoration Network. “We are especially seeking underwater photographers for this trip to help capture this living time capsule – images that can help our research, protection and global action efforts.”

Dive and Travel with a Purpose

Beyond being a world-class dive adventure, the expedition directly supports TIRN’s ongoing conservation work in the region. For nearly a decade, Turtle Island Restoration Network has conducted shark and sea turtle research at Cocos Island, helping document illegal fishing threats and strengthen the scientific case for expanded protections.

Research conducted during past expeditions has contributed to the foundation for stronger conservation measures at Cocos Island and along the Cocos–Galápagos Swimway (one of the world’s first bi-national marine protected areas to save the marine species that migrate between Galapagos Marine Reserve and Cocos Island National Park).

Participants will have the opportunity to learn about marine research and conservation challenges facing the Eastern Tropical Pacific while experiencing one of the planet’s most iconic marine ecosystems.

Expedition Details

What: 10-day liveaboard scuba diving and research expedition

When: June 25 – July 5, 2026

Where: Cocos Island National Park, Costa Rica

Vessel: Undersea Hunter Group’s 115-foot (35m) liveaboard vessel, Sea Hunter

 For more information on the Cocos Island Dive Expedition and how to book, visit www.seaturtles.org/our-work/our-programs/cocos-island. To protect the Cocos-Galapagos Swimway, visit www.seaturtles.org/the-cocos-galapagos-swimway.

Turtle Island Restoration Network is a global ocean conservation nonprofit with offices in California and Texas, whose mission is to inspire and mobilize people around the world to protect marine biodiversity, the oceans and watersheds that sustain all life on Earth.

We are extremely excited to share that we will be headed back to Cocos Island National Park and World Heritage Site this coming June 2026, and you have the opportunity to join us on a 10-day scuba and research expedition!

Cocos Island is the only island in the Eastern Tropical Pacific with a tropical rainforest, and is home to large populations of scalloped hammerhead sharks, white tip reef sharks and a number of endemic fish that occur nowhere else on the planet. Cocos is also the location of much of our scientific research to gather critical data for the success of the Cocos-Galapagos Swimway campaign.

What: A 10-day liveaboard adventure to experience, view and photograph the incredible marine biodiversity of Cocos Island, as well as participate in crucial shark and sea turtle migration research.

When: June 25th through July 5th, 2026

Where: The expedition will be supported by the Undersea Hunter Group, which has been operating expeditions to Cocos Island since 1990 or Aggressor Adventures. They are committed to top-notch dive experiences, vessels and service and has operated expeditions for National Geographic, Sylvia Earle and many other world-renowned ocean explorers and conservationists!

Why: Your participation will not only help fund this important research trip, but also give you the opportunity to participate in over 20 dives with sharks, rays and massive schools of fish! A trip to explore the tropical Cocos Island and visit the Ranger Station can also be arranged.

Please email Todd Steiner at tsteiner@seaturtles.org to book or inquire about the trip, more details are also included on our trip’s page here.

Read more and see amazing photographs published in our 2012 Earth Island Journal piece here. This once-in-a-lifetime expedition makes an impact for highly migratory species, we hope to sea you there to make an impact with us! If you can’t make it, you can support our work to protect the Cocos-Galapagos Swimway here.

Photo by Kaylam-Pratt on a TIRN Cocos Island Expedition trip.

For Immediate Release, July 23, 2025

Contact: Todd Steiner, Founder & Special Projects, TSteiner@seaturtles.org   

This Shark Week, Turtle Island Restoration Network Calls for Action to Protect the Ocean’s True Stars: As Shark Populations Plummet Worldwide, Advocates Urge Costa Rica to Protect Critical Migration Corridor

UNITED STATES – As millions of viewers celebrate the awe and mystery of sharks during Discovery Channel’s iconic summer series, Shark Week, Turtle Island Restoration Network (TIRN) — a leading ocean and watershed conservation nonprofit — is calling on the global citizens and policymakers alike to take meaningful action to protect these magnificent predators before it’s too late.

Every year, more than 100 million sharks are killed in commercial fisheries*, driving many endangered species — like scalloped hammerhead sharks, whale sharks, silky sharks, and tiger sharks — toward extinction. Yet these same species keep entire marine ecosystems healthy by maintaining the balance of ocean food webs.

“The public’s understanding of the ecologically important role sharks play in maintaining healthy oceans has grown tremendously in recent years, but this has not yet translated to a decrease in fishing mortality. While shark finning is down, shark meat consumption is up according to a recent study*. This Shark Week, we urge everyone who loves these animals on screen to take real-world action to protect them in the wild.” said Todd Steiner, ecologist and founder of the international environmental organization, Turtle Island Restoration Network.

Many shark species are highly migratory and travel outside the territorial waters of any single nation. One of the most urgent opportunities for action to protect sharks is the completion of the Cocos–Galápagos Swimway, a proposed marine protected migration corridor linking Ecuador’s Galápagos Islands with Costa Rica’s Cocos Island National Park. This 396-mile underwater “blue highway” is a lifeline for countless charismatic marine species, including hammerheads, whale sharks, tiger sharks and silky sharks that travel between these UNESCO World Heritage sites.

While Ecuador has protected its portion of the Swimway with a no-take marine reserve, Costa Rica has yet to secure its share, leaving migrating sharks vulnerable to industrial fishing and illegal poaching as they travel the open ocean.

“The science is clear: protecting small islands alone isn’t enough for highly migratory species… If we want to keep seeing hammerheads and whales sharks on our screens, and in our oceans, we need bold action now to protect their entire migratory routes,” Steiner concluded.

Turtle Island Restoration Network has championed this ‘swimway’ approach for decades. Early campaigns in the Gulf of Mexico helped safeguard migration routes for the critically endangered Kemp’s ridley sea turtle, aiding the species’ recovery. Now, the same proven strategy can protect some of the ocean’s most perfectly evolved predators… the real stars of Shark Week.

How Anyone Can Help Conservation This Shark Week:

• Individuals use their voices here
• Scientists sign on in support here
• Organizations join the coalition here

For more information on the Cocos-Galapagos Swimway campaign and to take action with us, visit www.seaturtles.org/the-cocos-galapagos-swimway. Access media for a Cocos-Galapagos press story here.

*Worm et al., Global shark fishing mortality still rising despite widespread regulatory change. Science 383, 225–230 (2024) 12 January 2024.  

Turtle Island Restoration Network is a global ocean conservation nonprofit with offices in California and Texas, whose mission is to inspire and mobilize people around the world to protect marine biodiversity, the oceans and watersheds that sustain all life on Earth.

The United Nations Ocean Conference was co-sponsored by Costa Rica and France took place in Nice in 9-13 April 2025 and TIRN was there to turn up the pressure on Costa Rica to complete the Cocos-Galapagos Swimway.

In the days leading up to the conference, TIRN founder Todd Steiner wrote and co-authored two opinion editorials (op-eds) with scientists in Ecuador and Costa Rica published in two of Costa Rica’s leading newspapers, Delfino (in Spanish) and Tico Times (in English).

TIRN also attempted to deliver more than 11,000 open letters from citizens around the world, 53 non-governmental organizations and more than 348 from 41 different nations, but Costa Rican Consul Generals in Los Angeles and Houston refused to meet with TIRN representatives.

While Costa Rica President Rodrigo Chaves Robles basked in the limelight of the gathering of over 15,000 attendees, as the co-chair of the UN Conference, and spoke in platitudes about how great Costa Rica’s ocean protection actions are, in reality his administration has stalled, stymied and rolled back protections for sharks, sea turtles and other marine species found in its jurisdictional waters.

President Chavez took credit for the 2021 Costa Rica expansion of Cocos Island National Park and the Bicentennial Marine Management Area (BMMA), which together has allowed Costa Rica to falsely misrepresent that it has met its 30-30 ocean protection goal, a a global initiative to conserve at least 30% of the Earth’s land and ocean areas by 2030, agreed to by over 100 countries.

In reality under Chavez, policies to protect the 38,600 square mile BMMA has stalled, as he ignores a multitude of scientific studies indicating the importance of protecting the Swimway.  More than three years into his presidency, the area remains a marine ‘protected’ area (MPA) in name only– with no regulations in place to restrict fishing or other harmful activities that are driving critically endangered leatherback turtles and sharks toward extinction.

Chavez rhetoric at the  UN Ocean Conference was slammed as hypocritical by legislators, environmentalists and Costa Rican civil society. To tamp down dissent, his administration even obstructed renowned Costa Rican marine scientists UN accreditations, having them withdrawn to thwart democratic political discourse (read more here). Some have compared Chavez anti-democratic actions to tendencies now occurring in the US, referring to him as a “mini-Trump.” 

Former long-time TIRN staffer Randall Arauz, now with Marine Watch International, also criticized the Chavez administration for its failure to protect marine wildlife.

“How can the Costa Rican government claim to be protecting our oceans, when they ignore a Supreme Court order to end the fishing of endangered hammerhead sharks and continue to allow commercialization of marine wildlife for the profit of a few and at the expensive of healthy marine ecosystems? Hypocrisy in an understatement. They are in the pockets of the industrial fishing industry,” said Aaruz

Chaves term as President is coming to an end this year, and if he fails to act, TIRN has vowed to make completion of the Swimway an issue in the 2026 Presidential elections.

“Without strict regulations to eliminate fishing along the Swimway, sea turtles and sharks will continue to die on longline hooks,” said Todd Steiner and founder of TIRN.

He continued, “Ecuador enacted protections of its portion of the Swimway in 2021, but to date, Costa Rica has failed to take the necessary actions to ensure the protections necessary to ensure the long-term survival of these interconnected marine ecosystem of these UN Biosphere Reserves. We call on Costa Rica to take immediate action!”

In the meantime, TIRN will continue to increase the scientific foundation underlying the need for the Swimway , while expanding the coalition of scientists, NGOs and citizens around the world demanding Costa Rica take action to protect endangered turtles, sharks and the two of the world’s premiere UN Biosphere Reserves diversity hotspots.

As of 6/25/25

Alert: 11,338

Scientists: 348 from 41 different countries

NGOs: 53

Statement of Todd Steiner, founder of Turtle Island Restoration Network and Mission Blue’s Hope Spot Champion for Cocos-Galapagos Swimway from United Nations Ocean Conference in Nice, France:

We are disappointed that Costa Rican President Rodrigo Chaves failed to announce strict protection for the Cocos-Galapagos Swimway today at his speech at the United Nations Ocean Conference in Nice, France, one of the world’s most important biological hotspots which is under Costa Rica’s jurisdiction.

President Rodrigo Chaves said nations must act today, not later, it is the only moral thing to do, yet his words ring hollow when he continues to fail to protect the most important part of the Ocean under its jurisdiction that connects Galapagos Islands with Costa Rica’s Cocos Island, two United Nations Biosphere Reserves.

While Ecuador moved to protect its part of the Swimway in 2022, Costa Rica has not lived up to its moral obligation to reciprocate…

Photo of Steiner and Randal Arauz (fellow Hope Spot champion, scientist, founded TIRN’s sister organization in Costa Rica PRETOMA and later CREMA, co-founder of MigraMar).

For Immediate Release, June 9, 2025

Contact: Todd Steiner, Founder & Special Projects, +1(415)488-7652 TSteiner@seaturtles.org  

Ken Bouley Executive Director, KBouley@seaturtles.org

Joanie Steinhaus, Ocean Program Director, Joanie@seaturtles.org

Scientists, Environmental Organizations and Thousands of Citizens Call on Costa Rica for Action to Protect Endangered Species and UN Biosphere Reserves: Costa Rica is a Co-Sponsor of the UN Ocean Conference Occurring This Week in Nice, France

NICE, FRANCE – As delegates from nations, non-governmental organizations, and scientists gather at the UN Oceans Conference this week in Nice, France, there is growing international pressure on Costa Rica to complete the Cocos–Galápagos Swimway – a critical no-take marine protected area (MPA) that safeguards endangered sharks and sea turtles migrating between the Galápagos Islands of Ecuador and Cocos Island National Park in Costa Rica.

Costa Rica is a co-sponsor of the week-long UN meeting, making this a pivotal moment for the nation to reaffirm its environmental leadership.

For several years, a coalition of environmental advocates and marine scientists has pushed for the creation of the Swimway to connect two UNESCO Biosphere Reserves through a protected migration corridor. Studies by MigraMar, a scientific research group working in the region, have tracked at least six species of sharks and sea turtles – including endangered hammerheads and leatherbacks – moving between these biodiversity hotspots, which are geologically linked by an underwater mountain range. The two parks are separated by 396 miles, so that the entire swath falls within the two nations economic exclusive zone, the 200-mile distance each nation controls from its shores.

“This is one of the most important actions necessary to protect migrating endangered sea turtles and sharks in the Eastern Pacific,” said Todd Steiner, ecologist and founder of Turtle Island Restoration Network, an international ocean advocacy organization. “While usual Park boundary protections work for ‘stay at home’ species, they ignore the needs of highly migratory species like hammerhead sharks and leatherback sea turtles that face extinction due to commercial fishing operations.”

In 2022, Ecuador stepped up and expanded its no-take MPA to the edge of its national waters, fully protecting its portion of the Swimway. This bold action followed an international advocacy campaign led by Turtle Island Restoration Network, which included a prominent advertisement in The New York Times calling for regional marine protection. Now, the campaign has landed in Nice with the same strategy – using public pressure and media visibility to urge Costa Rica to fulfill its part of the promise.

In a show of growing national awareness, one of the Swimway campaign’s champions published an Op-Ed in Delfino.cr, a major Costa Rican publication, earlier this week. The piece, titled “La Migravía Cocos-Galápagos: Un legado para Costa Rica y el mundo,” highlights how the proposed marine corridor would serve as a lasting legacy for both global biodiversity and Costa Rican conservation. Read the Op-Ed here.

“The concept of protecting migration route swimways was first proposed by TIRN to protect the Kemp’s ridley sea turtle along the U.S. Gulf Coast more than 20 years ago,” said Joanie Steinhaus, TIRN’s Ocean Program Director. “That early work helped reduce fishing impacts and contributed to the species’ ongoing recovery. We know this approach works.”

“We need Costa Rica to act to protect these internationally important biological hotspots,” said Bouley. “That can only be accomplished by ensuring iconic and keystone species survive not just within park borders, but throughout their entire migratory route.”

“We urge Costa Rica to complete the Cocos–Galápagos Swimway this week and build on its celebrated record of terrestrial conservation,” added Steiner. “It’s time to extend that legacy to the ocean, and to do so in a way that reflects modern science and the reality of migratory marine life.”

Media resources are available here https://seaturtles.org/scientists-environmental-organizations-and-thousands-of-citizens-call-on-costa-rica-for-action-to-protect-endangered-species-and-un-biosphere-reserves: For more information on the Cocos-Galapagos Swimway campaign and to take action with us, visit www.seaturtles.org/the-cocos-galapagos-swimway.

Turtle Island Restoration Network is a global ocean conservation nonprofit with offices in California and Texas, whose mission is to inspire and mobilize people around the world to protect marine biodiversity, the oceans and watersheds that sustain all life on Earth.

A new scientific paper (with a long name), Multidecadal underwater surveys reveal declines in marine turtles by a collaboration of scientists and institutions, including Turtle Island Restoration Network, shows a strong correlation with the decline of sea turtles and the appearance of tiger sharks at Cocos Island National Park, Costa Rica.

The research  published in Conservation and Science, utilized two datasets, including a long-term data collected by UnderSea Hunter from 1997 to 2019, which recorded 12,479 marine turtles and 3,194 tiger sharks across 35,706 dives, and a more recent data set by Turtle Island and CREMA from 2009-2014 in which 129 turtles were captured and tagged during approximately 400 dives.

The long-term data set found a 26% decrease in the relative abundance of turtles each year that was correlated with the occurrence of tiger sharks at Cocos. Tiger sharks were not regularly seen at Cocos until around 2010, their appearance corresponds to the significant decrease in turtle sightings.

Interestingly, the data showed that for each additional tiger shark present, there was a 43% decrease in the relative abundance of turtles and this is supported by data and observations from the more recent TIRN/CREMA dataset. A correlation with warmer water temperatures and a decrease in turtle sightings was also established, and may be a reflection of the larger climate changes facing  the Earth, a result of burning fossil fuels.

We know industrial fishing is devastating populations of sharks and sea turtles in the Eastern Tropical Pacific, with the largest impact affecting highly migratory species, because even if they are protected at one location like Cocos National Park, they face fishing threats during their migrations.

Turtle Island has spearheaded a movement to create the “Cocos-Galapagos Swimway”, to connect these two marine protected areas by a no-fishing zone along this multi-species migratory route. Data now indicates six species of sharks and turtles move along the proposed Swimway, including endangered scalloped hammerhead and whale sharks, and green and leatherback sea turtles. Ecuador has expanded the border of the Galapagos Marine Reserve to include part of its side of the Swimway, but to date Costa Rica has failed to protect its part of the Swimway.

You can help by signing an Action Alert to Costa Rica here!

Tiger sharks started being seen regularly at Cocos around 2010 and at the same time turtles sightings started to diminish.  We observed tiger sharks trying to consume turtles.  Turtles becoming prey can definitely impact populations.

Another phenomena called the “fear factor” has been recognized by scientists as playing a significant role in transforming landscapes, and in this case ocean-scapes as well.  It is the idea, now supported by data, that the presence of predators can alter the behavior of prey species by changing their behavior and the habitats they utilize.

So, the question becomes have the turtles left Cocos or have they just moved to sites we are not observing (i.e., away from the regular dives sites at Cocos)?

We expect both are partially true and we hope to refine our understanding by looking at the finer movements of turtles and tiger sharks using acoustic data we have been collecting, but not yet analyzed.  Another new technology we hope to employ is eDNA.  Collecting water samples from many different locations around Cocos, we can determine if turtles are still present, but in areas that we don’t dive.

You can learn more about our most recent Cocos Island research expedition here and learn more about participating by reaching out to me at TSteiner@tirn.net.

Photos by Elpis Joan.