Over 500 reef and nurse sharks in local waters

| 19/10/2023 | 17 Comments

(CNS): Scientists from the Department of Environment have published the first estimates of population sizes and home ranges for Caribbean reef sharks and nurse sharks in Cayman Islands waters and the first estimate of the reef shark population globally. Footage from baited underwater video systems (BRUVS) and photo ID, used as a non-invasive alternative to tagging, revealed 180 Caribbean reef sharks and 336 nurse sharks.

Sightings of the other four coastal shark species — hammerheads, lemon, blacktip and tiger sharks — were too few to estimate population parameters. However, the study found numerous immature Caribbean reef and nurse sharks, suggesting both species are breeding in Cayman waters.

The study found that the home ranges of both species are relatively small at less than 20km², but the occasional long-distance movements of some individual sharks often extend to areas beyond any one marine park’s boundary, potentially exposing them to fishing activities.

According to the scientific paper, understanding the ecology of shark populations is critical for their effective conservation and management. Over the past decade, shark conservation has become a global priority due to the substantial decline in some shark populations, specifically in the Atlantic Ocean and the Caribbean Sea, as the result of intense over-exploitation and other human activities, such as habitat degradation.

Counting the sharks is challenging, the scientists explained, because of declining numbers, the complexity of their habitat and their highly mobile nature. Population models rely on sufficient sightings and the precision of population estimates increases with sample size. But sharks are typically elusive and difficult to capture because they tend to avoid areas where there are boats or snorkelers and SCUBA divers.

Reef sharks play a key role in maintaining healthy reef ecosystems, but a recent study found that they are much less abundant in the Caribbean than in the Pacific and Indian Oceans. Reef sharks in remote locations, such as the Cayman Islands, are considered ecologically vulnerable to local extinction as they are less likely to be repopulated from other regions.

Nurse sharks and Caribbean reef sharks are the two most abundant reef shark species in the region, including the Cayman Islands. All of these sharks are protected in Cayman waters, and the DoE said it appreciates the effort of fishermen to safely release any sharks they accidentally hook.

Source: Cayman Islands DoE (click to enlarge)

Learn more about shark research and protection in Cayman here.

Read the full scientific paper here.


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Category: Marine Environment, Science & Nature

Comments (17)

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  1. Anonymous says:

    It would be nice if the fishermen would be taught not to kill sharks.

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  2. Anonymous says:

    Interesting. From snorkeling along Seven Mile Beach and along the rest of the west side I’d say Rack’ems ship wreck is the best on the west side and has about a 50% chance of seeing a nurse shark. On Seven Mile Beach it’s extremely rare in my experience only saw one by Marriott and one baby one just off of Royal Palms. On the other hand Back in the day I’d say there was a number of cougars at Royal Palms particularly after sunset.

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  3. Anonymous says:

    Bring half a tuna in a mesh bag and you’ll see lots…just give it a minute.

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    • Anonymous says:

      Yeah.. except that’s illegal. It is against the law to bait or feed sea life in the Cayman Islands. It’s for our own good and the sharks. A fed shark often becomes a dead shark if it associates people with food.

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  4. shoota says:

    I’d love to snorkel with these and my camera.

    Where’s the best place that I shore dive from to see sharks, turtles, etc in Grand Cayman? Already dove Brac/Little.

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    • Anonymous says:

      Don’t waste your time on Grand go back and go under the dock at Carib Sands on the Brac. Snorkel away, that’s where all 500 of them live and breed.

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    • Anonymous says:

      there is nothing more thrilling than seeing these magnificent creatures underwater. On East End there are regulars that are named and loved by divers who come back year after year to see them. they are hugely important for our tourism industry as well as the environment.

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    • Michael Stephen Terrien says:

      Best places for sharks on GC are north wall and east end, at least in my experience. Don’t see so many of them on the heavily traveled west side.

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    • Anonymous says:

      Try diving/snorkeling in Breakers outside of the reef.

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    • Anonymous says:

      In Grand, the most likely dive site to see reef sharks is ‘Jack McKenney’s Wall’ in East End. Every time I’ve been on a dive there I’ve seen at least one. However, any wall sites near there will probably have them also.

      In Little Cayman, most sightings are on the North in Bloody Bay. ‘Mixing Bowl’ is your safest bet for Reef Sharks.

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    • Anonymous says:

      Divetech. Pretty much guaranteed a turtle or nurse shark there. Best shore dive site on Cayman.

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