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Wednesday 11 november 2020

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

DCNA’s Save Our Sharks Project
There is a lack of knowledge concerning the
distribution and abundance of shark and ray
species throughout the Dutch Caribbean. To
combat this knowledge gap, from 2015-2018,
DCNA ran the “Save our Sharks” (SOS) project
for the Dutch Caribbean, funded by the Dutch
Postcode Lottery. In this project DCNA collabo-
rated with local fisherman and scientists and
aimed to build popular support for shark and
ray conservation amongst the local communi-
ty, as well as increasing knowledge about shark Caribbean reef shark in the Man of War Shoal Marine
and ray species within the region by conduct- Park , Sint Maarten.
ing a number of research projects. Photo credit: Melanie Meijer zu Schlochtern
in marine parks or areas of conservation than
Nurse shark on the Saba Bank which is part of the Shark Research in unprotected areas, highlighting the impor-
Yarari Marine Mammal and Shark Sanctuary. A recently published study by Wageningen Ma-
Photo credit: Hans Leijnse (SHAPE/DCNA rine Research as part of DCNA’s SOS Project es- tance of these zones in shark conservation. Fur-
thermore, when comparing the BRUV surveys
tablished a baseline for current shark diversity, from Sint Maarten, Curaçao and Bonaire to
WAGENINGEN, THE NETHERLANDS — Wagenin- distribution, abundance, spatial behaviour and previous BRUV studies from Aruba, Saba, Sint Eu-
gen Marine Research reported ten reef-associ- population structure for inshore reefs around statius and Saba Bank, it showed that the Aruba
ated shark species in the Dutch Caribbean in the Dutch Caribbean islands. survey had the largest shark diversity (8 species)
a recent published study as part of Dutch Ca- and the Bonaire survey the lowest (2 species).
ribbean Nature Alliance (DCNA)’s Save Our There were two methods used by the research- The Saba survey documented 5 shark species,
Sharks Project. The most common species are ers to study sharks. One method used Baited Saba bank had 4 shark species with Curaçao,
the nurse shark and the Caribbean reef shark. Remote Underwater Video (BRUV) which used Sint Eustatius and Sint Maarten each registering
Overall, more sharks were observed in conser- a device consisting of two cameras set in front 3 shark species. There was an additional BRUV
vation areas than in unprotected areas, high- of a baited feed bag. The idea is that as sharks submarine test at 300 metres deep off Curaçao
lighting the importance of these zones in shark come near the bait bag to feed, video foot- which found an additional shark species (Cu-
conservation. age can be collected to identify and count ban dogfish). In total, at least 10 shark species
local shark populations. The other method were seen within the Dutch Caribbean in the
More than 100 million sharks are killed each was acoustic telemetry to track sharks. In this different BRUV surveys.
year as a result of fishing and shark finning ac- method, a small acoustic tracking device is im- The acoustic telemetry studies demonstrated
tivities, twice the rate at which they can re- planted within the shark. Acoustic receivers are that both the Caribbean reef shark and nurse
produce. The demand for fins and other shark installed at specific locations, and whenever shark have small home ranges and strong site
products has driven a number of species close sharks with these transmitters travel near the re- fidelity. Large crossings between areas were
to extinction. Sharks are especially vulnerable ceiver (within a range of 450 to 850 metres) they rare, and found for two Caribbean reef sharks
to overfishing and habitat degradation as they are recorded. and one nurse shark which travelled between
are late to mature and produce few young. The first studies using BRUV were conducted Saba and Saba bank. The two Caribbean reef
The main threats to sharks in our waters are ac- on Saba, Saba Bank and St. Eustatius to better sharks made short directed journeys back and
cidental bycatch, habitat degradation and understand the local population of sharks and forth, whereas the nurse shark after two years
the risk of a shark fin market developing, which rays and their relative abundances, and were absence showed up at the Saba Bank before
would lead to targeted fishing of sharks. funded by the Dutch Government. Starting returning to Saba. One nurse shark from anoth-
in 2015, as part of the SOS project, additional er study on the US Virgin Islands was detected
We need healthy oceans and healthy oceans studies were conducted to include the waters in the network on the Saba Bank, a distance of
need sharks around Bonaire, Curaçao and Sint Maarten. at least 160 kilometres.
Sharks keep our oceans healthy. These top In 2017 a BRUV survey was done at Aruba, fi-
predators remove sick or weak members of nanced by Global Finprint. Importance of Protected Areas
their prey populations. A decrease in number Both the BRUV and acoustic telemetry studies
of sharks leads to a disturbed natural balance In addition, as part of the SOS project, acoustic showed higher presence of reef associated
in the sea. This can affect the overall fish popu- telemetry was also used to better understand sharks within the conservation zones, along
lation, and good fish stocks are not only impor- the movements of sharks, habitat use, migration with high site fidelity and small home ranges.
tant for fishermen that depend on fishing but and connectivity between islands. The telem- Furthermore, as some longer distance move-
also for (dive) tourism and the local community. etry study tracked two shark species, Caribbe- ments were also documented, interconnectiv-
an reef shark (Carcharhinus perezi) and nurse ity between these areas is just beginning to be
Respect, not fear, sharks shark (Ginglymostoma cirratum) around Saba understood. The ongoing study on acoustic te-
Sharks are some of the most misunderstood (from 2014) and then around Saba Bank, Sint lemetry (funded by the Ministry of Agriculture,
species. For generations sharks had an unde- Maarten and Sint Eustatius (from 2015). Nature and Food Quality (LNV)) will yield more
served bad reputation. People tend to see data on this. Therefore, not only are local ma-
them as terrifying animals that pose a danger Findings rine parks crucial for the conservation efforts
to everything that swims in the ocean, includ- In BRUVs deployed around Sint Maarten, Cura- of sharks and rays, but larger conservation net-
ing humans. But we now know that is very far çao and Bonaire the most common detected works, such as the Yarari Marine Mammal and
from the truth; these magnificent creatures are shark species were Caribbean reef shark, with Shark Sanctuary which compromises all the wa-
essential to healthy oceans and risks to humans Sint Maarten also frequently showing nurse ters of Bonaire, Saba and Sint Eustatius, are vital
are small. sharks. Overall, more sharks were observed to protect entire populations.q