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The return of old friends

It’s been an exciting time for the shark team at the Cape Eleuthera Institute with 2 tagged sharks recaptured over the past few weeks. The team has been conducting frequent long line surveys to collect information about the species, sex and size of the sharks that inhabit the waters around Eleuthera. DNA, blood and muscle samples are also collected from each shark to build up a wealth of biological data which can be used for more in depth studies in the future. Research technician Maggie Winchester inserts a dart tag into the dorsal fin of a Caribbean reef shark with the help of Dr. Heather Marshall

CEI tags all of the sharks that are caught on their longlines with 2 different kinds of tags, a dart tag and cattle tag, which assign an individual tag number to each shark. This not only allows the shark to be easily recognized by the shark team, but also shows other people that these sharks have been caught and sampled by CEI. The tags provide the CEI contact details to allow other research stations or fisherman that may catch the shark to report its location. This recapture data allows the team to analyze distribution behaviors and track the movement of the sharks around Eleuthera.

The most recent recapture was of a female Caribbean reef shark (Carcharhinus perezi) which was caught on the 31st of October, only 300m away from where it was first caught in April 2010. Over the past 6 years this shark has grown by nearly half a meter and now measures a total length of 178cm. A few weeks earlier, on the 12th of October, the team caught a large female nurse shark (Ginglymostoma cirratum) that had not been seen since it was first tagged nearly 8 years ago. This shark had only grown by 3cm over this time but was recaptured nearly 6km away from where it was originally caught and tagged.

A Google Earth satellite image showing where and when the 2 sharks were originally caught and recaptured

Using species-specific size at maturity data, the team can use the total length measurements of these 2 recaptured sharks to estimate that both sharks have recently reached sexual maturity. This is particularly important information when considering the local populations of these sharks as they are now thought to be of reproductive age. These resident sharks will remain around the Cape and contribute to local populations by giving birth to several pups in the mangrove creeks surrounding Eleuthera.

CEI shark team pulls in rare catch!

On Wednesday, August 31, 2016, the CEI Shark Research and Conservation Team caught and sampled a huge 258 cm male lemon shark (Negaprion brevirostris). This thrilling capture was made while conducting a longline survey off of Cape Eleuthera, Bahamas to establish a dataset about the abundance and size of different coastal shark species in south Eleuthera.  Although a wide variety of sharks can be found around the Bahamas, and there are many known lemon shark nurseries, mature lemon sharks are not commonly seen near south Eleuthera. The information collected from this rare catch can be used to trace the lineage of lemon shark populations found throughout the Bahamas, which can ultimately help influence future shark conservation and management initiatives.

Research Tech Maggie Winchester holds a 258cm long lemon shark in tonic immobility.  This allows the team to take measurements and samples, as well as tag the animal in a manner that is safe for both the shark and the researchers

Lemon sharks are a large species of coastal shark that can reach up to 3.5 m in length. They can be identified by their pale brown or olive coloring, and their two equally sized dorsal fins.  Lemon sharks are listed as Near Threatened and their position at the top of the food chain makes them a valuable species for the local ecosystems. However, there is a limited amount of data on these adult sharks in this area which makes this catch all the more exciting. The Bimini Biological Field Station fills this knowledge gap by reconstructing adult male genetic information using the samples from the more abundant juveniles. Now we can include the data collected from this individual to create a more complete understanding of the local lemon shark population.

The team holds the lemon shark in tonic immobility so Dr. Heather Marshall can take a blood sample

During the workup procedure, the lemon shark was measured to obtain information about its size, age, and sex, which can then be added to the data collected by CEI to show the dynamics of the local populations of sharks. The size of the shark was recorded by taking three specific measurements of its body. The team also collected a tissue sample, which will be used to build up a long term genetic record of the shark populations around Eleuthera. After all measurements and samples were collected, the lemon shark was tagged using a dart tag and a dorsal tag. These tags are used for identification purposes, allowing the research team to recognize a recapture. Following the workup procedure, the lemon shark was released in great condition and everybody was left in awe as it swam away.

The team is preparing to release the lemon shark by removing the hook so the researchers can effectively release the shark quickly and safely

The team watches the lemon shark swim away after a successful capture and release

Newcastle University Summer Research Update

Globally, sharks are among the most threatened group of species, facing some of the greatest population declines in modern history. This is exacerbated by conservative life history characteristics such as slow growth rates, late maturity ages and low number of offspring, which in turn increase their vulnerability to extinction. Turtles also exhibit similar life history characteristics, therefore assessing their importance as a food source and the significance predation has on their population can help us to further conservation efforts. This summer, Newcastle University student Massimo Casali in collaboration with the Cape Eleuthera Institute’s Shark Research and Conservation Program has been conducting a study to elucidate the importance of habitat complexity and coastal shark species on turtle abundance in different creek systems. The Bahamas offers unique opportunities to study turtles and sharks on account of a total ban being enforced since 2009 and 2011 respectively, and so this project will take advantage of the relatively untouched environment of south Eleuthera, The Bahamas. Newcastle University undergraduate student Massimo Casali holding a nurse shark prior to release

Through the use of experimental longlines, sharks are caught in close proximity to creek systems before being sampled, including the taking of morphometric data (measurements), tissue harvest for stable isotope analysis and tagging, allowing for mark-recapture assessment. So far the team has caught a total of 21 sharks represented by 5 species; nurse shark (Ginglymostoma cirratum), Caribbean reef shark (Carcharhinus perezi), blacknose shark (C. acronotus), blacktip reef shark (C. limbatus) and tiger shark (Galeocerdo cuvier). This research has also included a range of educational programmes and Island School classes enabling us to reach a broad range of budding young shark scientists.


Overall, the research objectives of this study will form the basis for Massimo’s undergraduate research dissertation, that will specifically address the relationships between sea turtle and shark abundance in these biologically diverse ecosystems, considered fragile due to human induced disturbances. This will further allow conservation frameworks that will allow the management of sensitive coastal ecosystems throughout The Bahamas.

South Eleuthera offers the only mangrove creek systems on the Island - here shows Kemps Creek which borders the Grand Bahama Bank.

American Elasmobranch Society meets in New Orleans

The American Elasmobranch Society recently met in New Orleans for their annual meeting, attended by an international collective of shark and ray scientists to discuss current and ongoing work in this very eclectic field. The Cape Eleuthera Institute was represented by Oliver Shipley and Dr. Owen O’Shea of the Shark Research and Conservation Program, both giving oral presentations to a wide range of scientists from all over the world. Oliver’s presentation focused on novel methods for post-capture release of a small bodied deep-sea shark – the Cuban dogfish - and how novel approaches may increase survivorship during by-catch events. Owen spoke of the recently ‘re-discovered’ Caribbean whiptail stingray and discussed its contemporary distribution in The Bahamas and implications for management. Dr, Owen O'Shea during his presentation on Caribbean whiptail stingrays

The week spent in New Orleans was a huge success, with the convening of several meetings and discussions pertaining to the global fin print project and a whole day dedicated to a global sawfish research symposium. Among some of the other stand out talks were the very first satellite tracking of manta rays conducted in Sudan, juvenile white shark movement in California and challenges for management of large ranging sharks, such as the great hammerhead and oceanic whitetip. It was a fantastic week with many old relationships rejuvenated, and the fostering of new ones cemented, with collaborative studies already having been discussed.

Shark team tags and releases great hammerhead

On Wednesday, 3rd February, the Shark Research and Conservation Team captured and sampled only the fourth ever Great Hammerhead shark (Sphyrna mokarran) caught off of Eleuthera in the entirety of the program’s ten-year operation. During a shark ecology and handling class for the Cape Eleuthera Institute’s Gap Year Program, led by Research Assistant Oliver Shipley and Educational Assistant Cameron Raguse, the students were able partake in a rare experience in handling one of the most data-deficient sharks found in The Bahamas. Increasing our understanding of sharks in The Bahamas is important to ensure the most applicable and effective management of these keystone apex predators. The animal is safely secured prior to the workup

Hammerhead sharks (Sphyrnidae) are a morphologically distinct family of elasmobranchs comprising of nine species, and are found in temperate and tropical waters around the globe. They have evolved a unique dorso-ventrally compressed and laterally expanded cephalofoil that allows them to expand their field of sight and pin down prey items such as stingrays. Their common diet consists of molluscs, annelids, crustaceans, teleosts, and even other elasmobranchs. Great Hammerhead’s (Sphyrna mokarran) reach up to 3.5 m and weigh up to 230 kg. They are a highly migratory and solitary species that lives in coastal-pelagic waters near continental shelves. They are known to migrate from tropical to more temperate waters during the summer months to seek cooler water, and have been observed using offshore habitats including deep-water.

In The Bahamas, the biological and economic importance of sharks has been well recognized, leading to the 2011 amendment to the Fisheries Resources (Jurisdiction and Conservation) Act (Chapter 244), establishing The Bahamas as a National Shark Sanctuary. This declaration has provided thorough protection for a plethora of shark species, through the banning of commercial fishing and transport of shark related products into or outside of the approximately 630,000km2 that encompass The Bahamas.

The hammerhead shark is tagged with a dorsal identification tag.

This Great Hammerhead was captured during one of the shark team’s routine experimental longline surveys. The goal of this work is to gather tissue samples, such as muscle, fin and blood from a wide range of coastal elasmobranchs, to determine their diet, and subsequently the scale to which they perform important ecological controls. The experimental longline consists of a 500m mainline equipped with 40 gangions which terminate in baited hooks and are supported by flotation buoys. Lines are soaked for a total of 90 minutes before being retrieved.

The hammerhead shark is safely released in under 5 minutes

In addition to collecting tissue samples, the team also took measurements, a DNA sample, and attached two identification tags. This work-up procedure was completed in less than five minutes before the animal was safely released. A video of the release can be found on our Instagram page (@ceibahamas).