Page 10 - aruba-today-20210116

Saturday 16 January 2021 LOCAL
A10

At least ten reef-associated shark species in the Dutch Caribbean

tablished a baseline for current shark diversity,
distribution, abundance, spatial behaviour and
population structure for inshore reefs around
the Dutch Caribbean islands.

There were two methods used by the research-
ers to study sharks. One method used Baited
Remote Underwater Video (BRUV) which used
WAGENINGEN, THE NETHERLANDS — Wagenin- a device consisting of two cameras set in front
gen Marine Research reported ten reef-associ- of a baited feed bag. The idea is that as sharks
ated shark species in the Dutch Caribbean in a come near the bait bag to feed, video foot- Caribbean reef shark in the Man of War Shoal Marine
published study as part of Dutch Caribbean Na- age can be collected to identify and count Park , Sint Maarten.
ture Alliance (DCNA)’s Save Our Sharks Project. local shark populations. The other method Photo credit: Melanie Meijer zu Schlochtern
The most common species are the nurse shark was acoustic telemetry to track sharks. In this
and the Caribbean reef shark. Overall, more method, a small acoustic tracking device is im- Findings
sharks were observed in conservation areas planted within the shark. Acoustic receivers are In BRUVs deployed around Sint Maarten, Cura-
than in unprotected areas, highlighting the im- installed at specific locations, and whenever çao and Bonaire the most common detected
portance of these zones in shark conservation. sharks with these transmitters travel near the re- shark species were Caribbean reef shark, with
ceiver (within a range of 450 to 850 metres) they Sint Maarten also frequently showing nurse
More than 100 million sharks are killed each are recorded. sharks. Overall, more sharks were observed in
year as a result of fishing and shark finning ac- marine parks or areas of conservation than in
tivities, twice the rate at which they can re- The first studies using BRUV were conducted unprotected areas, highlighting the importance
produce. The demand for fins and other shark on Saba, Saba Bank and St. Eustatius to better of these zones in shark conservation. Further-
products has driven a number of species close understand the local population of sharks and more, when comparing the BRUV surveys from
to extinction. Sharks are especially vulnerable rays and their relative abundances, and were Sint Maarten, Curaçao and Bonaire to previous
to overfishing and habitat degradation as they funded by the Dutch Government. Starting BRUV studies from Aruba, Saba, Sint Eustatius
are late to mature and produce few young. in 2015, as part of the SOS project, additional and Saba Bank, it showed that the Aruba sur-
The main threats to sharks in our waters are ac- studies were conducted to include the waters vey had the largest shark diversity (8 species)
cidental bycatch, habitat degradation and around Bonaire, Curaçao and Sint Maarten. and the Bonaire survey the lowest (2 species).
the risk of a shark fin market developing, which In 2017 a BRUV survey was done at Aruba, fi- The Saba survey documented 5 shark species,
would lead to targeted fishing of sharks. nanced by Global Finprint. Saba bank had 4 shark species with Curaçao,
Sint Eustatius and Sint Maarten each registering
We need healthy oceans and healthy oceans In addition, as part of the SOS project, acoustic 3 shark species. There was an additional BRUV
need sharks telemetry was also used to better understand submarine test at 300 metres deep off Curaçao
Sharks keep our oceans healthy. These top the movements of sharks, habitat use, migra- which found an additional shark species (Cu-
predators remove sick or weak members of tion and connectivity between islands. The te- ban dogfish). In total, at least 10 shark species
their prey populations. A decrease in number lemetry study tracked two shark species, Ca- were seen within the Dutch Caribbean in the
of sharks leads to a disturbed natural balance ribbean reef shark (Carcharhinus perezi) and different BRUV surveys.
in the sea. This can affect the overall fish popu- nurse shark (Ginglymostoma cirratum) around
lation, and good fish stocks are not only impor- Saba (from 2014) and then around Saba Bank, The acoustic telemetry studies demonstrated
tant for fishermen that depend on fishing but Sint Maarten and Sint Eustatius (from 2015). that both the Caribbean reef shark and nurse
also for (dive) tourism and the local community. shark have small home ranges and strong site
fidelity. Large crossings between areas were
Respect, not fear, sharks rare, and found for two Caribbean reef sharks
Sharks are some of the most misunderstood and one nurse shark which travelled between
species. For generations sharks had an unde- Saba and Saba bank. The two Caribbean reef
served bad reputation. People tend to see sharks made short directed journeys back and
them as terrifying animals that pose a danger forth, whereas the nurse shark after two years
to everything that swims in the ocean, includ- absence showed up at the Saba Bank before
ing humans. But we now know that is very far returning to Saba. One nurse shark from anoth-
from the truth; these magnificent creatures are er study on the US Virgin Islands was detected
essential to healthy oceans and risks to humans in the network on the Saba Bank, a distance of
are small. at least 160 kilometres.

DCNA’s Save Our Sharks Project Importance of Protected Areas
There is a lack of knowledge concerning the Both the BRUV and acoustic telemetry studies
distribution and abundance of shark and ray showed higher presence of reef associated
species throughout the Dutch Caribbean. To sharks within the conservation zones, along
combat this knowledge gap, from 2015-2018, with high site fidelity and small home ranges.
DCNA ran the “Save our Sharks” (SOS) project Furthermore, as some longer distance move-
for the Dutch Caribbean, funded by the Dutch ments were also documented, interconnectiv-
Postcode Lottery. In this project DCNA collab- ity between these areas is just beginning to be
orated with local fisherman and scientists and understood. The ongoing study on acoustic te-
aimed to build popular support for shark and lemetry (funded by the Ministry of Agriculture,
ray conservation amongst the local communi- Nature and Food Quality (LNV)) will yield more
ty, as well as increasing knowledge about shark data on this. Therefore, not only are local ma-
and ray species within the region by conduct- rine parks crucial for the conservation efforts of
ing a number of research projects. sharks and rays, but larger conservation net-
works, such as the Yarari Marine Mammal and
Shark Research Shark Sanctuary which compromises all the wa-
A recently published study by Wageningen Ma- Nurse shark on the Saba Bank which is part of the ters of Bonaire, Saba and Sint Eustatius, are vital
rine Research as part of DCNA’s SOS Project es- Yarari Marine Mammal and Shark Sanctuary. to protect entire populations.q
Photo credit: Hans Leijnse (SHAPE/DCNA)