By Dr. Craig O’Connell, founder and director of O’Seas Conservation Foundation, Inc.
The phone rang. It was my uncle, asking to speak with me. I looked at my mom, waving my hands back and forth, obviously mouthing the word “NOOOOO.” I did not want to be disturbed as I anxiously sat in front of the TV, waiting to see what Shark Week was going to teach me next.
Several minutes later, an image passed across the screen that would heavily shape my passion and future. A shark was entangled in a net and drowning. This particular shark species lacked the ability to pump water over its gills (known as buccal pumping) and was suffocating to death. The fate of this shark looked grim and I was shocked—I had no idea that there were people actively killing sharks around the world. This inspired me to begin my research journey, and I quickly learned that humans kill approximately 100-273 million sharks on an annual basis. Even more shocking: by the time a one-minute commercial break during Shark Week was over, 190 sharks were killed.
What does this mean for sharks?
The real question should be “what does this mean for the environment?” Sharks are considered K-selected, meaning they are characterized by slow growth, late age at maturity (e.g. some take 10 or more years to reach sexual maturity), and produce relatively few young. Having such characteristics means that the likelihood of population rebound is unlikely if humans continue to kill them at such high rates. When I was younger, I didn’t quite understand this and always thought that the quantities of animals in the ocean were limitless. I quickly learned how wrong that assumption was.
It is important to understand the effects of shark loss on a broader scale. Losing sharks would essentially elicit a negative chain reaction all the way down the food chain. For example, in Shark Bay, Australia, a team of researchers illustrated that the absence of tiger sharks could have a cascading and negative influence on seagrass communities. In areas where these tiger sharks are absent, some of their prey species (e.g. sea cows and sea turtles) exhibit heavy foraging on seagrasses. Therefore, the results suggested that the loss of sharks can harm not only the marine environment, but the planet as well.
How can losing seagrass impact the planet? What the scientists revealed is that the loss of lush seagrass communities could cause an increase in atmospheric CO2 (that is normally stored and utilized by seagrasses) and theoretically further contribute to global warming. If you are having a hard time understanding what this means – think about the game “Jenga.” Jenga is a challenging game that requires players to remove one block from a tower constructed out of 54 blocks. When you remove the wrong one – the entire tower collapses. Thefore, our oceans are like a gigantic Jenga puzzle and if we remove the wrong piece of the puzzle, the entire environment may collapse and a vital natural resource will disappear.
What is leading to shark mortality?
Fisheries and beach nets are major contributors to the loss of our sharks, skates, and rays. In commercial fishing, these animals are often inadvertently captured. For example, pelagic longlines are fishing devices that can sometimes be composed of miles of fishing line and hundreds of baited hooks that aim to capture offshore species, such as tuna and swordfish. However, the large quantity of bait attracts sharks, leading to their eventual capture and oftentimes, their death. Fisheries rarely retain sharks (dead or alive) due to little market for shark meat, trip limits, and/or management plans, which prohibit the retention of certain species, and therefore, the capture and killing of these sharks is a waste as the shark sinks lifelessly down to the seafloor as discarded bycatch.
In other locations around the world, pelagic longlines are used to specifically capture sharks, as shark fins can be extremely lucrative. The unfortunate reality of this situation is that millions of sharks are captured and killed due to the shark fin trade. These sharks are captured, their fins are sliced off while the animal is still alive, and the struggling carcass is thrown overboard to drown and bleed to death.
Another contributor to shark mortality, and one that I have focused my conservation efforts on for approximately 10 years, is the use of beach nets as an attempt to maximize beachgoer safety. These nets are not shark-specific and catch and kill a wide variety of marine organisms, such as whales, dolphins, rays, and sea turtles. Ironically, most beach nets are designed to float a couple feet above the ocean floor. Therefore, many sharks can swim under the net into the “netted” off area, and become entangled and killed on their way back out to open ocean. Swimmer safety is important—but there are other more eco-friendly alternatives to nets.
What are scientists doing to save sharks?
In response to this, a variety of studies aiming to reduce shark capture have recently been conducted. These studies focus on an elasmobranch’s (sharks, skates and rays) unique electrosensory system, known as the ampullae of Lorenzini. This system gives these animals the ability to detect their prey even when they cannot see them and may also be capable of detecting geomagnetic fields (0.25-0.65 Gauss) to aid with navigation. Targeting this system, scientists are exploring the use of electropositive metals and magnets to deter sharks. More specifically, when I was completing my senior year at Boston University, an idea popped into my head that strong permanent magnets (~1000 Gauss) may be capable of overwhelming a shark’s electrosensory system due to the novelty and strength of the magnetic field. After completing my undergraduate degree, I started my scientific quest to understand whether this magnetic concept was plausible and if this technology could offer promise for future shark conservation efforts.
For several years I attached magnets to fishing hooks; however, I found this approach considerably challenging because attaching strong magnets to about 1000 hooks led to a huge tangled disaster on a commercial fishing boat. When this happens, this means the fishermen cannot fish and therefore, they were not very happy with me! With time, I did find out that simply touching a magnet to a fishing hook (termed contact magnetization), magnetized the hook and alleviated the need for magnet attachment. Although the hook had a weaker magnetic field, these hooks did deter several shark species (not all!) and did not stick to everything on the boat! Much more research is required on these to see if they offer any future promise in commercial fisheries.
Besides the fishing hook concept, I have been working on a way to utilize magnets to create an eco-friendly alternative to beach nets. After spending nearly 5 years testing the concept on a wide range of shark species and then subsequently teaming up with Mr. Michael Rutzen and Stellenbosch University, we constructed the Sharksafe Barrier – a promising barrier technology – that has thus far provided substantial evidence in being capable of deterring large and potentially dangerous sharks (e.g. tiger sharks, white sharks, great hammerhead sharks, and bull sharks). Using both a magnetic (i.e. permanent magnets) and a large visual stimulus (i.e. piping) that resembles and behaves like a kelp forest, the Sharksafe Barrier does not use any netting. Since the magnets target the ampullary system and the artificial kelp forest targets the visual system of our focal shark species, the barrier has been scientifically validated to effectively deter them.
What makes this technology even more exciting is species lacking this “sixth sense” that once fell victim to beach nets (e.g. dolphins and sea turtles), would conceivably be undeterred and could thus, swim through the barrier as they please. This technology is nearing the final phases of research and offers hope to the peaceful coexistence of humans and sharks along our shorelines.
The Future = Your Future
I hope all of you who made it this far have learned something—but don’t stop there. Go learn more! Put your phones and computers down and go outside and observe nature, even if you are afraid of it. Watching nature has the ability to change you because it makes you realize that you are part of something much larger than yourself.
When this realization “hits you,” you are going to share a similar mentality that I do, and you are going to want to save whatever wildlife and pristine places are left on this planet. When you get to that point of your life, don’t be afraid of what others think of you. Do what you think is right, and follow your passion. You only live once – so make it a good life, and make a difference. Leave this planet a better place than it was when you entered it.
About the Author
Dr. Craig O’Connell received his Ph.D. from the University of Massachusetts Dartmouth (2014) and is the founder and director of O’Seas Conservation Foundation, Inc. – a nonprofit focused on shark conservation research and youth education. Craig has authored over 20 scientific publications and hosted/presented episodes for the Smithsonian Channel, National Geographic, and Discovery Channel’s Shark Week. In addition, Craig has led scientific expeditions all over the world and has been a key inventor of a new conservation-based technology, known as the Sharksafe Barrier, a technology that may soon become an eco-friendly alternative to beach nets in areas such as South Africa and Australia.