Sharks in the Dutch Caribbean; the Most Misunderstood Fish in the Sea

Sharks in the Dutch Caribbean, and truly around the world, are some of the most misunderstood species in the world.

For generations, sharks have had an undeserved bad reputation, even here on Bonaire or in other parts of the Dutch Caribbean. People tended to see them as terrifying animals that pose a danger to everything that swims in the ocean, including humans. But we now know that is very far from the truth; these magnificent creatures are essential to healthy oceans and risks to humans are small. Humans should respect sharks, not fear them.

There are at least ten reef-associated shark species in the Dutch Caribbean

Wageningen Marine Research has reported ten reef-associated shark species in the Dutch Caribbean in a recently published study as part of Dutch Caribbean Nature Alliance’s (DCNA) Save Our Sharks Project. The most common species are the nurse shark and the Caribbean reef shark. Overall, more sharks were observed in conservation areas than in unprotected areas, highlighting the importance of these zones in shark conservation.

Why sharks are necessary for healthy oceans.

More than 100 million sharks are killed each year as a result of fishing and shark finning activities, twice the rate at which they can reproduce. The demand for fins and other shark products has driven a number of species close to extinction. Sharks are especially vulnerable to overfishing and habitat degradation as they are late to mature and produce few young. The main threats to sharks in our waters are accidental bycatch, habitat degradation, and the risk of a shark fin market developing, which would lead to targeted fishing of sharks.

Humans need healthy oceans and healthy oceans need sharks.

Sharks keep our oceans healthy. These top predators remove sick or weak members of their prey populations. A decrease in the number of sharks leads to a disturbed natural balance in the sea. This can affect the overall fish population, and good fish stocks are not only important for fishermen that depend on fishing but also for (dive) tourism and the local community.

Shark research establishes a baseline for the Dutch Caribbean.

A recently published study by Wageningen Marine Research, as part of the Dutch Caribbean Nature Alliance’s SOS Project, established a baseline for current shark diversity, distribution, abundance, spatial behavior, and population structure for inshore reefs around the Dutch Caribbean islands.

There were two methods used by the researchers to study sharks in the Dutch Caribbean waters. One method used Baited Remote Underwater Video (BRUV) which used a device consisting of two cameras set in front of a baited feed bag. The idea is that as sharks come near the bait bag to feed, video footage can be collected to identify and count local shark populations. The other method was acoustic telemetry to track sharks. In this method, a small acoustic tracking device is implanted within the shark. Acoustic receivers are installed at specific locations, and whenever sharks with these transmitters travel near the receiver (within a range of 450 to 850 meters) they are recorded. This method also helped researchers better understand the movements of sharks, habitat use, migration, and connectivity between islands. The telemetry study tracked two shark species, Caribbean reef shark (Carcharhinus perezi) and nurse shark (Ginglymostoma cirratum).

Research findings of sharks in the Dutch Caribbean waters.

In BRUVs deployed around Sint Maarten, Curaçao and Bonaire, the most common detected shark species were Caribbean reef sharks, with Sint Maarten also frequently showing nurse sharks. Overall, more sharks were observed in marine parks or areas of conservation than in unprotected areas, highlighting the importance of these zones in shark conservation.

Furthermore, when comparing the BRUV surveys from Sint Maarten, Curaçao and Bonaire to previous BRUV studies from Aruba, Saba, Sint Eustatius, and Saba Bank, it showed that the Aruba survey had the largest shark diversity (8 species) and the Bonaire survey the lowest (2 species). The Saba survey documented 5 shark species, Saba bank had 4 shark species with Curaçao, Sint Eustatius, and Sint Maarten each registering 3 shark species. There was an additional BRUV submarine test at 300 meters deep off Curaçao which found an additional shark species (Cuban dogfish). In total, at least 10 shark species were seen within the Dutch Caribbean in the different BRUV surveys.

The acoustic telemetry studies demonstrated that both the Caribbean reef shark and nurse shark have small home ranges and strong site fidelity. Large crossings between areas were rare.

The importance of protected areas, such as the Bonaire National Marine Park and Yarari Marine Mammal & Shark Sanctuary.

Both the BRUV and acoustic telemetry studies showed a higher presence of reef-associated sharks within the conservation zones in the Dutch Caribbean, along with high site fidelity and small home ranges. Furthermore, as some longer distance movements were also documented, interconnectivity between these areas is just beginning to be understood. The ongoing study on acoustic telemetry (funded by the Ministry of Agriculture, Nature and Food Quality (LNV)) will yield more data on this. Therefore, not only are local marine parks crucial for the conservation efforts of sharks and rays, but larger conservation networks, such as the Yarari Marine Mammal and Shark Sanctuary which comprises all the waters of Bonaire, Saba, and Sint Eustatius, are vital to protect entire populations.

(Source:  Dutch Caribbean Nature Alliance (DCNA, images courtesy of Melanie Meijer zu Schlochtern and Hans Leijnse (SHAPE/DCNA))