Study will fill data gap on endangered local sharks

(CNS): The Department of Environment (DoE) has secured UK funding for pop-off satellite archival tags to study the movements of Caribbean reef sharks (Carcharhinus perezi) in the ocean around the Cayman Islands. Due to their ecological and socio-economic significance to Cayman, all sharks are protected species and are now considered endangered.

Until recently, local DoE studies looked at shark ecology near the shore. This new research will go deeper and further into the ocean to determine whether these important marine predators need more protection, officials have said.

The project, which began in March, is funded by a Darwin Plus Local grant of just over $52,000, which comes from the Biodiversity Challenge Fund UK Government. It is also supported by sales of White Tip Lager from the Cayman Islands Brewery.

In a press release, the DoE explained that the previous study revealed the wide-ranging nature of Cayman’s Caribbean reef sharks for the first time. But while these sharks are protected up to 45m down, deep-water fishing is unregulated, which means sharks using deeper waters off the edge of the drop-off could be vulnerable to fishermen.

It is unknown to what extent this species may travel outside of local marine protected areas and become vulnerable to accidental catch at depth and exploitation elsewhere.

Caribbean reef sharks are recognised as one of the top predators on coral reefs throughout the Caribbean and are pivotal to the health of, and subsequent resources provided by, these ecosystems.

So far, eight out of ten tags have been fitted on reef and black tip sharks. The tags are programmed to record data of the sharks’ movements, pop off at timed intervals, float to the surface and wash back to shore. Anyone who finds a tag can contact the DoE to return it.

DoE Shark Project Officer Dr Johanna Kohler said the main aim of the one-year study is to collect essential ecological information to improve our understanding of Caribbean reef sharks so we can better protect them and potentially other shark species in Cayman.

“So far, three tags have released from the animals, and we have received some preliminary data. If we retrieve the actual tag, we will be able to download even more data,” she said.

This project will provide meaningful results, benefiting the islands in the long term by providing the government with information for the sustainable management of marine resources close to shore, at depth and during national maritime boundary negotiations with neighbouring nations.

The data will help the DoE understand the ecological criteria needed to sustain the effective long-term survival of Caribbean reef sharks locally while being subject to the effects of climate change and anthropogenic activities.

“It will give insight into the role that Caribbean reef sharks play in connecting the shallow and deep-water habitats and highlight the potential importance of Cayman’s deep-sea to the overall survival of this ecologically important apex predator,” Dr Kohler added.

DoE Deputy Director Tim Austin explained the significance of this research locally and for the region. “These kinds of data sets are not currently available in Cayman or even within the UKOTs. The results would not only benefit the effective long-term conservation of Caribbean reef sharks locally but also in other UKOTs as well as within the Caribbean and beyond,” he said.

The new spatial information will enable the DoE to assess the overlap between Marine Protected Areas and key habitats of the endangered Caribbean reef shark population in the Cayman Islands.

If it is found that these sharks regularly use additional marine habitats, especially if offshore and deeper waters are found to be critical to the survival and recovery of this endangered species in Cayman waters, additional protections will need to be sought under the National Conservation Act (NCA).

John Bothwell, DoE Legislation Implementation and Coordination Unit Manager, said that scientific research was very important when it comes to informing environmental policy.

“These possibilities are a priority for the DoE, and any additional necessary protections recommended by the research will be brought to the National Conservation Council and then to Cabinet in order to effectively protect and manage marine resources throughout all of Cayman’s waters,” he said.

In 2015, the Cayman Islands became the tenth nation to completely protect all shark species within national waters. Previous studies have revealed that reef sharks move long distances between our three islands with records of sharks travelling almost 100 miles across deep open ocean and as deep as 200 metres.

But there is still very little data on the distance they move, the deep diving behaviour, temperature ranges, and changes in vertical habitat use or long-distance horizontal movements by Caribbean reef sharks in our area. This project aims to fill that data gap with robust new scientific data.

The knowledge gap on shark ecology, paired with continued reports of dead sharks despite proactive conservation efforts in Cayman, has raised concerns about the effective protection of this species locally. As a result, this project will prove critical to the future survival of our sharks.

See more details of the project here.

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