From Page and Screen to Personal Encounters by Lewis Shedden

From a young age, I have always wanted to be a marine biologist and have a career in which I worked close  with sharks, with most interactions with sharks occurring on tv screens and in books prior to this internship, other than a few occasions during scuba diving. What fascinated me about sharks from books and in tv is how many interesting and unique species there were. Some that could walk on land, some who could breathe whilst not moving (unlike most) and that they were so much more than these “dangerous apex predators that eat people” as the media and films made them out to be, not that I believed that stance anyway! This internship at the Bimini Shark Lab provided fellow interns and me a first-hand experience with a variety of species. During the beginning of this internship, we went to the Florida Keys for a research trip. During this trip we worked with multiple species of sharks. Through this blog, I wanted to highlight why sharks are special and my experiences of working with a few of these charismatic, cartilaginous creatures. Overall, sharks are misunderstood animals that contribute to the functioning of ecosystems in numerous ways. Some examples are clearing diseased or unhealthy fish from the system, controlling populations and preventing reefs from being overconsumed. Some of the species I have read about in literature and seen on tv are the blacknose, great hammerhead and lemon sharks and now I have had in-person interactions with each of the three species. 

Blacknose sharks (Carcharhinus acronotus) are a smaller species in the Carcharhinidae family, reaching just over two meters in length when fully grown. Distinctive characteristics include a black nose, as well as darkened patches on multiple fins. Their diet consists of small fish. For me the really interesting aspect about blacknose sharks is, like larger species, they exhibit philopatry. Working with this shark was really interesting, as I was able to perform an ultrasound on a pregnant female! We identified at least 4 pups that were being carried by the female. This is an average litter size for this species, and it was amazing to have that experience, the first time I encountered this species outside of books and tv. Being able to see the pups in the womb was interesting to see how they developed and identifying features to look for on the ultrasound scanner in order to spot pups in future ultrasounds on a variety of species.

Here the interns were getting guided through an ultrasound on a blacknose by Matt Smukall, the CEO of Bimini Shark Lab. This occurred on the Florida Keys Research trip (Photo Credit: Alina Hussey, 2023).

Great hammerheads (Sphyrna mokarran) are a species I have always wanted to work with in my career. These charismatic animals are part of the family Sphyrnidae. They have a unique characteristic, a cephalofoil, which gives them their hammerhead name. This allows them to have a broad field of vision and allows them to turn quickly at steep angles to catch their prey. They are one of the larger species of shark found in the Bahamas, with the largest observed in Bimini measuring at around 400cm total length. Their diet mostly consists of rays, and they may also consume bony fish. I have always dreamt of working with great hammerheads, and in the Florida Keys, we saw 3 of them! I had the privilege of tagging one of these larger sharks, at about 3 meters long. We had to be as quick as possible, due to their increased stress levels when being caught, and we worked up the shark in under 3 minutes! This encounter felt like a lifetime, the experience was unlike any other and I was just in awe of the beautiful shark I had waited 19 years to work with!  From seeing them on tv to learning about them from a young age and now finally being able to have worked with them during a research trip and being lucky enough to swim with Gaia and Selene, during the rest of my internship is difficult to comprehend. Nothing prepares you for how quick they can turn on their cephalofoil, seeing that up close made me appreciate just how agile and incredible these animals are!

Lewis helping to Dart tag a great hammerhead (Photo credit: Ally Draime, 2023).

Lemon sharks (Negaprion brevirostris) are one of the most researched species at the Bimini Shark Lab as made possible by the late founder of Bimini Shark Lab, Dr. Samuel Gruber. They are called lemon sharks due to their yellow coloration. Two dorsal fins of similar size, a flattened head, and smooth angular teeth also make characteristic features. Mangroves are utilised as nursery habitats, providing shelter to the young until the sharks are big enough to venture out on their own. Their maximum size can be up to 340 cm long! They have a varied diet, including fish (preferred prey is the yellowfin mojarra), crustaceans and molluscs. Working with these species is an honour, as the species which the shark research in Bimini was pioneered, what is cool about these species is their use of natal philopatry and their relationships with other individuals. They come back to where they are born to give birth, and the pups will socialise with individuals of similar, or larger size, learning from each other. They, like other species, can use buccal muscles to pump water over their gills, so can breathe whilst stationary. What is also interesting, based on stable isotope analysis, is that lemon sharks are not always the typical “apex predator” that sharks are determined as in media and film. They fill functions in ecosystems by hunting at a variety of trophic levels and prove that sharks are more complex than perceived to be. Being able to work with them and knowing that data collected will contribute to research such as this is really special. 

Lewis holding a lemon shark in order for it to be worked up (Wyatt Albert, 2023) .

To be where I've always wanted to be and doing what I've always wanted to do is an honour and a privilege. Being able to work with and interact with these species of sharks has been a really great experience. Both scenarios (research and interacting in the wild) have allowed me to really get to learn about species I have wanted to see since childhood, in different contexts. The research has provided a more scientific context to these species, whilst the interactions in the wild allowed me to see individual traits, characteristics and personalities shine through.  

Research activities occurred within the FKNMS and under permit FKNMS-2022-083 issued to Bimini Biological Field Station Foundation. To learn more about the research projects being conducted in the Florida Keys by BBFSF, check out www.thesharklab.com.