Ocean Lover

Sharks of the Cayman Islands

The Cayman Islands are known for being a popular diving destination in the Caribbean with over 365 dive sites. Some of the main attractions of dive sites in the Cayman Islands include wreck diving at famous shipwrecks such as, the Kittiwake, the Balboa, the Oro Verde as well as our biodiverse reefs. In order to help maintain our status as a diving destination hotspot, the Cayman Islands for over 30 years, has been protecting its marine life and reefs with Marine Parks. In 2015, the Cayman Islands increased their ocean conservation as the National Conservation Law effectively put protection measures in place for sharks and rays. Sharks are an apex predator, at the top of the marine food chain, as a result they regulate the species at lower down the chain levels, helping to keep marine ecosystems such as reefs balanced. Sharks therefore are a considerable asset to our islands reefs and other marine ecosystems. Additionally, sharks are beneficial to ecotourism as many visiting snorkelers and divers are keen to see large charismatic marine life, and sharks tend to be one of the main attractions. According to a report by Marine Conservation International and the Cayman Islands Department of Environment (DOE) the added value to marine tourism of having sharks on the reef is about US$54 million per year. For divers and snorkelers, seeing a shark is both a privilege and a highlight. There are 8 species of sharks commonly found in the Cayman Islands, including: Great Hammerhead, Nurse shark, Lemon shark, Caribbean Reef shark, Blacktip, Tiger shark, Oceanic Whitetip and Silky shark. Amongst the variety of shark species found in the Cayman Islands, some species of sharks reside in Cayman waters all year long and inhabit coastal waters. Whereas, other species of sharks are pelagic and seasonally pass through Cayman while on migratory routes.

Coastal Sharks

There are four common species of coastal sharks that can be found in the Cayman Islands: Nurse sharks, Lemon sharks, Caribbean Reef sharks, and Blacktip sharks. They frequently inhabit areas including mangroves, turtle grass, sand beds and coral reefs. Coastal sharks tend to inhabit shallow, near shore regions.

Nurse Sharks (Ginglymostoma cirratum)

Nurse shark (Ginglymostoma cirratum) resting under a coral head on Grand Cayman. Photo Credit: Elly Wray

Nurse sharks tend to be known for their docile behavior. Some might even refer to them as the “puppies” of the ocean as some may demonstrate a friendly demeanor. Nurse sharks are creatures of habit. Once they find a favorite resting spot(s) they tend to frequently inhabit that area. In some instances, nurse sharks can be found “hiding” under coral or tucked away in shipwrecks as they rest during the day and are more active at night. An interesting fact about nurse sharks is that they are one species of sharks that is able to rest on the sea floor and actively pump water over their gills. Nurse sharks are typically found in tropical and subtropical waters at depths up to 240ft. Unfortunately, Nurse sharks often fall victim to a case of mistaken identity, as they are often mistaken for Lemon sharks. This is a result of Nurse sharks and Lemon sharks being similar in body shape and coloration. Nurse sharks vary from a dark grey to yellow brown in coloration and can grow up to 14ft in length.

Facts about Nurse sharks

• IUCN Conservation Status (Red List): *

Data Deficient (Globally)

Least Concern (Central America & Caribbean)

• Population Trend: Unknown

• Life Span: unknown but thought to be around 25 years

• Max Length: ~14ft (430cm)

• Reproduction: Ovoviviparous

• Gestation Period: 5-6 months

• Litter Size: 20-30

• Size at Birth: ~ 12 inches (31cm)

• Mating Cycle: Every 2 years

Below is a helpful chart showcasing similarities and differences between Nurse sharks and Lemon sharks.

Lemon Sharks (Negaprion brevirostris)

Juvenile Lemon shark (Negaprion brevirostris) near mangroves on Little Cayman. Photo Credit: Johanna Kohler

Lemon sharks, as their name suggests, are recognizable due to their yellow brown color. They grow up to 11ft in length. Lemon sharks are found in the tropical Western and Northeast Atlantic and East Pacific. Lemon sharks are quite adaptable to varying water conditions. They are among a few shark species that are tolerant of relatively high water temperatures. Due to living in shallow coastal waters, Lemon sharks can also adapt to water conditions with low salinity and low oxygen concentration levels. Lemon sharks have been known to be fairly gentle and non-aggressive, but – as with any wild animal one must always be careful and alert.

Facts about Lemon Sharks

• IUCN Conservation Status (Red List): * Near Threatened (Globally)

• Population Trend: Unknown

• Life Span: ~ 25 years

• Max Length: ~11ft (340cm)

• Reproduction: Viviparous

• Gestation Period: 12 months

• Litter Size: 4-17

• Size at Birth: ~ 20 inches (31cm)

• Mating Cycle: Every 2 years

Caribbean Reef Shark (Carcharhinus perezi)

Male Caribbean reef shark (Carcharhinus perezi) on Grand Cayman. Photo Credit: Johanna Kohler

As the name suggests, Caribbean Reef sharks are typically found in the Caribbean as well as Gulf of Mexico and Western Atlantic Ocean. Due to their preference to inhabit Caribbean waters, these sharks are inclined to stay near to a shallow coral reef habitat. They particularly like reef drop offs and outer reef walls. Caribbean Reef sharks are known as one of the apex predators in the coral reef system and they prey on a variety of reef fish and squid. As a result, their presence is important to help maintain a balance of reef fish. Caribbean Reef sharks have been known to be mistaken for a Blacktip sharks due to their similar body shape and coloration.

Facts about Caribbean Reef sharks

• IUCN Conservation Status (Red List):* Near Threatened (Globally)

• Population Trend: Decreasing

• Life Span: 25 years

• Max Length: historically up to ~9ft (2.8m), but now ~7ft (2.2m) due to fishing pressure.

• Reproduction: Viviparous

• Gestation Period: 12 months

• Litter Size: 4-6

• Size at Birth: ~ 29 inches / 74cm

• Mating Cycle: Every 2 years

Below is a helpful table indicating the differences between Caribbean Reef sharks and Blacktip sharks

Blacktip Sharks (Carcharhinus limbatus)

Blacktip shark (Carcharhinus limbatus) captured on BRUV survery, Dept. of Environment. Photo Credit: Johanna Kohler.

As the name suggests, Blacktip sharks get their name due to the black tips or edges found on their pectoral, pelvic and dorsal fins. Blacktip sharks are considered to be very timid and as a result they tend to be skittish and try to avoid divers. This makes it rather difficult to encounter Blacktip sharks as they are very shy and swim fast. Blacktip sharks can be found in tropical and subtropical coastal waters in depths up to 100ft.

Facts about Blacktip Sharks

• IUCN Conservation Status (Red List): * Near Threatened (Globally)

• Population Trend: Unknown

• Max Length: ~5.5ft (1.7m)

• Life Span: at least 12 years

• Reproduction: Viviparous

• Gestation Period: 11-12 months

• Litter Size: 1-10

• Size at Birth: 22-24 inches / 56-61cm

• Mating Cycle: Every 2 years

Pelagic Sharks

Pelagic sharks, also known as oceanic sharks, love open waters. They inhabit open waters of the oceans and seas. Various species of pelagic sharks are known to visit Cayman waters on their migratory route. During their voyage through our region they can typically be found in deep waters just offshore, yet may come for a visit to our reefs.

Great Hammerhead Shark (Sphyma mokarran)

Great Hammerhead shark (Sphyrna mokarran) on Grand Cayman. Photo Credit: Living the dream divers, North Wall

Great Hammerhead sharks are the largest of the hammerhead species, reaching up to 18-20ft long. They are found in tropical coastal and open waters worldwide. Great Hammerhead sharks have a tendency to be lone travelers and seldom travel in groups. A cool fact about Hammerhead sharks is that their “hammer” shaped head combined with electro-pores allows them to use the Earth’s magnetic field to navigate throughout the oceans. Hammerhead sharks famous for their “hammer” shaped heads, are an endangered species. Populations of this species of shark have declined by more than 80% in the last 25 years.

Facts about Great Hammerhead sharks

IUCN Conservation Status (Red List): * Endangered (Globally).

• Population Trend: Decreasing

• Max Length: ~18-20ft (6.0m)

• Life Span: 20-30 years

• Reproduction: Viviparous

• Gestation Period: 11 months

• Litter Size: up to ~50 pups

• Size at Birth: 23-27 inches / 58-69cm

• Mating Cycle: Every 2 years

Tiger Sharks (Gladeocerdo cuvier)

Juvenile Tiger shark (Galeocerdo cuvier) captured on BRUV survey by the Dept. of Environment. Photo Credit: Johanna Kohler

Tiger sharks get their name from their visually striking striped pattern that resembles that of a tiger. Their name might give the impression that they are fast swimmers, however, they are actually relatively slow. Tiger sharks can be found in tropical and subtropical oceans in both coastal and open waters. Tiger sharks prey mainly on rays and turtles. The deepest known sighting of a Tiger shark in the Cayman Islands was seen at the Cayman trench at just shy of 900ft.

Facts about Tiger Sharks

• IUCN Conservation Status (Red List): * Near Threatened (Globally)

• Population Trend: Unknown

• Max Length: ~18-20ft (5.5->6.0m)

• Life Span: 20-50 years

• Reproduction: Ovoviviparous

• Gestation Period: 16 months

• Litter Size: 10-80

• Size at Birth: 20-35 inches / 50-89cm

• Mating Cycle: Every 2 years

Oceanic Whitetip Sharks

Oceanic Whitetip sharks have distinctive white marks on the tips of their fins. They are epipelagic and as such live predominantly in the upper 660ft of the ocean water column and can often be found near the surface of water. They are active both day and night and move at a slow pace. In the past 50 years, world fisheries have drastically reduced their populations. Specifically, in the Gulf of Mexico, their populations have dramatically declined by 99.3%.

Facts about Oceanic Whitetip

• IUCN Conservation Status (Red List): * Vulnerable (globally) Critically Endangered (Gulf of Mexico)

• Population Trend: Decreasing

• Max Length: ~13ft (4.0m)

• Life Span: unknown but thought to be around 25 years

• Reproduction: Viviparous

• Gestation Period: 10-12 months

• Litter Size: 1-15

• Size at Birth: 23-25 inches / 58-64cm

• Mating Cycle: Every 2 years

Silky Shark (Carcharhinus falcifromis)

Silky sharks are known to be largely pelagic, inhabiting the open ocean. However, on occasion immature sharks can be found in coastal reef systems. Silky sharks are known to have smooth skin, silk like, and hence their name. They are relatively small sharks, but have distinctly large eyes and are swift swimmers.

Facts about Silky sharks

IUCN Conservation Status (Red List): * Near Threatened (globally)

• Max Length: ~5.5ft (1.7m)

• Life Span: at least 12 years

• Reproduction: Viviparous

• Gestation Period: 6 months

• Litter Size: 1-10

• Size at Birth: 22-24 inches / 56-61cm

• Mating Cycle: Every 2 years

What to do with a hooked shark?

Male Nurse shark (Ginglymostoma cirratum) with hook and line remains on Grand Cayman Photo Credit: Indigo Divers

Despite protection measures, sharks are still threatened by local fishing in Cayman. Fishing and fishing charters are popular among Caymanians, residents and visitors. Although fishermen don’t target sharks, no fishing methods is 100% selective. This is why sharks may bite the bait or get caught by going for the snapper or grouper struggling on the line. The accidental catch or by catch of sharks is still a significant threat to our local populations. If these sharks die, it will have a massive negative impact on our shark populations. Compared to other fish, sharks grow rather slowly, mature late (some sharks mature when they are 8 – 20 years of age), have long gestation periods ((they are pregnant for up to 1.5 – 2 years) and produce relative few young. These life characteristics limit the reproduction rate of a shark population and its ability to replenish itself quickly. Additionally if immature sharks are killed before they are able to reproduce they miss their chance to contribute their genes to the next generation.

The DOE recommends the following for the release of sharks in case of accidental shark catch:

Using extreme caution attempt to:

• Cut the hook and remove hook from shark OR Cut the line as close to the hook as comfortable

• Use non stainless steel hooks

• Use Circle Hooks

• Keep fight/handle time short to reduce stress and trauma on the shark

• Report the incident to DOE

Sharks have incredible self-healing powers and a strong immune system. Once the hook is out (either cut or rusted away) the hook wound will heal quickly.

Caribbean Reef Shark (Carcharhinus perezi) with hook on Grand Cayman

Resources

Johanna Kohler

Cayman Islands Department of Environment (DOE)

* The International Union for Conservation of Nature (IUCN) “Red List” summarizes the conservational status for each species (http://www.iucnredlist.org/).

Authors

Johanna Kohler and Laura Butz

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