On Lionfish and Jaguars
Can we stall one of the most devastating marine invasions in history? More importantly, should we?
By Joe Curtis. Photographs by Kara Wall.
“One hundred feet!” yells the captain, speaking clearly over the hum of the boat engines. Spray from the waves splashes my back as I perch on the side of the research vessel Bullkitty, a 26 foot powerboat loaded down with scuba gear and research equipment. I check myself for the third time, making sure I have everything I need to swim, breathe, and collect data underwater. Once I take the plunge there’s no going back. So much as a pencil left behind on the boat can lead to an aborted dive, wasting precious time and money. As many times as I’ve been through this process, my heart always beats a little faster as we approach our drop zone. “Seventy five… fifty… thirty… Neutral, Dive!” As gracefully as possible, I fall backwards off of the boat into the turquoise water and, taking my first breath, begin to descend.
Out of the watery gloom emerges the seafloor of Biscayne National Park, a hidden gem sandwiched between the Florida Keys and Miami. Almost immediately, I spot a familiar shape drifting across the sand: a spiky cannonball, brilliantly striped with shades of red and orange. It’s a red lionfish (Pterois volitans) an invasive species that has spread like wildfire across the East Coast of the US and Western Atlantic. It only takes a quick YouTube search to see firsthand the overwhelming force of the lionfish invasion. Many recent videos show hundreds of individuals coating the sea floor, clinging to scraps of habitat in the middle of a barren reef. Lionfish are known for their voracious appetite, and research has repeatedly shown their potential to wreak havoc on native fish populations. For my master’s thesis with University of South Florida’s Fish Ecology Lab, I am counting fish on Biscayne’s reefs to help figure out how lionfish have affected the area’s sea life, and what it might take to stop them.
Fishermen and scientists alike are interested in slowing the lionfish invasion, however possible. Fortunately, lionfish don’t fear divers. They hang motionless when approached and presenting easy targets for a trained spearfisherman. Removal derbies have cropped up all over the Florida coast, encouraging divers to catch as many lionfish as possible to win cash prizes and bragging rights. Although spearing lionfish is certainly emotionally satisfying for frustrated conservationists, scientists are still unsure if culling (systematic removal) can effectively limit the spread of these environmental grenades.
In their Indo-Pacific homeland, lionfish do not reach such devastating densities. Ecological checks and balances, evolved over thousands of years of coexistence with other Indo-Pacific species, hold the populations of the spiny species to lower levels. In the Atlantic, however, predators haven’t gotten the memo that lionfish are tasty. They don't recognize the lionfish as food, and so are failing to control the invasion. Many prey species also don’t recognize lionfish as a threat, and might as well offer themselves up with a lemon wedge and side of butter. Unfortunately, until animal instinct kicks in, human intervention is the only viable option for lionfish population control.
To study the effectiveness of lionfish removals, our lab has set up a field experiment along Biscayne’s reefs. On eight of our twenty study sites, lionfish are left to roam unhindered; divers are actively culling lionfish from the other twelve. We hope to learn whether hunting lionfish reduces disruption on invaded reefs by counting native fish on sites with and without ongoing removal. Our goal is to provide resource managers with a concrete recommendation for how much to remove, an ecologically grounded suggestion to either ramp up control efforts or to lay down their spears.
As glamorous as it may seem to scuba dive for a living, our work does carry its challenges. For instance, many of the prey species we are trying to census live in the same cracks and crevices as the lionfish themselves. And lionfish are venomous; their backs are lined in long, hollow spines, each full of a powerful toxin. An accidental poke leaves a wound that throbs for hours. So far I have yet to be stung, and I’m probably more likely to be bitten by an eel than accidentally impale myself on a lurking lionfish, but the threat of pain is always there, in the back of my mind, as I reach into crevasse after crevasse. The damselfish I’m trying to flush out of those crevices–native species I'm counting in addition to the lionfish–are vicious little creatures too, and will attack anything that enters their territory. Luckily their tiny mouths are no match for my layers of wetsuit.
Tedium is another inescapable aspect of our project. For every hour beneath the waves (approximately 5 days worth spread over 100 dives ), my field work includes at least two hours of idle boat time. Staring over the water, watching my colleague’s bubbles lazily breach the surface, I use the time to reflect on the nature of our project and the coral reef environment.
One of the questions I find myself dwelling on most during these moments is whether we should simply accept lionfish as a new player in Biscayne’s seascape, despite their anthropogenic introduction. After all, predatory mammals were once invaders into South America, crossing over a newly formed land bridge and wiping out countless bird species and other native fauna. Yet nobody resents the presence of jaguars, or sponsors hunts to restore the Amazon to its prehistoric ecological state. Aside from the intellectual matter of origin, the only major difference between natural and anthropogenic invasions is speed and scale. Whereas new species previously met on a geologic timeline, as continents churned and crashed their way across the globe over millions of years, humans introduce new species every year to all corners of the planet.
Eradication is not on the table for lionfish: the invasion has taken too strong of a hold. Even with the hardiest removal efforts, lionfish now lurk at depths beyond the reach of human divers, reproducing frequently enough to resupply their fallen comrades. Eventually, lionfish will almost certainly reach some form of balance with their surroundings. Prey will learn to avoid them, predators will learn to eat them, and the reign of the lionfish will fade into the annals of ecological history. Given how beautiful and charismatic they are, lionfish could even come to draw in divers and tourists as they do on their native Pacific reefs. A day will come when nobody remembers a Florida without lionfish. While that may seem awful today, I often approach it with a forced-ambivalence, feeling powerless against the inevitability of the species' establishment.
Underwater though, my ambivalence fades. Thoughts of ecology, conservation and jaguars fade away into a background of swirling parrotfish and wrasses. As I swim along our site, I recognize a school of native fish I have seen on many of my other dives. They’ve grown a little over the last few months, and I find myself relieved that they've managed to avoid the gulp of a hungry lionfish. My familiarity with Biscayne’s reefs always steels my resolve to help protect the environment I’ve spent the last year exploring. Lionfish are still relatively new, and pose a very real danger to the health and resilience of America’s coral reefs. After counting a final flurry of fish with renewed vigor, I spot the end of our site. Every native fish I record is another piece of critical information, data which will help managers postpone the effects of this anthropogenic threat. Tucking my pencil into my wetsuit sleeve, I look to the surface, take a breath, and begin to ascend.
Joseph Curtis is pursuing a Master’s degree from the University of South Florida in the Fish Ecology Lab, focusing on the effects of invasive lionfish. He is an avid SCUBA diver and has traveled around the world exploring marine habitats. He can be reached at Jcurtis@mail.usf.edu.