November 14, 2018
Lionfish invasion in the Gulf of Mexico expected to worsen as the climate changes
News Source: Houston Chronicle
Author(s): Alex Stuckey
Scientists battling coral reef deaths caused by warming ocean waters 100 miles off the coast of Galveston might now have another climate change problem to fight in coming decades: a proliferation of zebra-striped lionfish.
Lionfish — brought to the U.S. from their Indo-Pacific home to stock aquariums and later dumped by owners unable to care for the constantly hungry vertebrate — have no known North American predators to stop their spread. As a result, they’ve been decimating reef populations from New York to Florida since the 1980s, arriving at the Gulf of Mexico’s Flower Garden Banks National Marine Sanctuary in 2011.
And a recent study published in the Wilderness & Environmental Medicine journal suggests that venomous creatures like lionfish will become more prevalent as the oceans warm.
"They are the cockroaches of the sea,” said Michelle Johnston, a sanctuary research biologist. “They reproduce every four days and every four days they can release up to 50,000 eggs. Plus, nothing really eats them, they have venomous spines and the native fish are terrified of them."
Lionfish thrive in warmer temperatures, which is why sightings are more common in southern areas such as Florida. But as ocean temperatures continue to warm, scientists believe their population areas will continue to grow.
“Many aspects of lionfish life history and behavior are expected to be temperature-dependent,” the study states. “Without culling efforts, the spatial extent of suitable year-round lionfish habitat is expected to increase 45 percent on the southeast United States continental shelf during the 21st century, covering 90 percent of the region.”
This would cause problems all the way up the food chain and impacts not only the health of the reef but also the livelihood of the fishermen who depend on it, Johnston said.
Sanctuary officials at Flower Garden Banks are doing what they can to curb the lionfish invasion, conducting a number of reconnaissance missions to remove as many of these invasive fish as possible from the 56-square mile, federally protected sanctuary. Despite their efforts, the fish now number in the thousands — and scientists believe that count is low.
If they want to make a real impact, Johnston said, they’ll need to come up with better solutions — and fast.
“Ultimately, it’s our fault and we have to deal with these consequences,” Johnston said.
At one time, lionfish only could be found in the warm, tropical waters of the Indo-Pacific, their reddish-brown and white stripes easily recognizable on reefs dotting the coastlines of Australia, Malaysia, Japan and French Polynesia.
Recreational divers delighted at spotting the unusual fish in the briny water, but their allure led to something much more problematic: people started stocking home aquariums with them, especially in the United States.
Lionfish are great conversation starters behind an aquarium’s glass walls, but they are indiscriminate predators and will quickly decimate a fish population. They can eat up to 30 times their stomach volume and have a wide-ranging diet that includes more than 70 different species of fish, as well as invertebrates like shrimp and crab, according to the Ocean Support Foundation, a Bermuda-based organization founded in 2011 to manage the lionfish invasion.
“If you put a lionfish in a salt water aquarium — well, they like to eat,” Johnston said. “The lionfish start eating all the fish in the aquarium and people, instead of giving it back to the pet store, they just dump the fish.”
The first signs of this came in 1985, when a lionfish was spotted off the coast of southern Florida, according to the National Oceanic and Atmospheric Administration. By 2000, the numbers increased dramatically as lionfish found each other and mated.
It’s a problem because lionfish are such prolific reproducers. A single lionfish can produce up to 6 million eggs each year, according to NOAA, and live up to 30 years.
They made their way to the coasts of Alabama, Louisiana and Mississippi by 2010 and, a year later, the venomous fish arrived at Stetson Bank, one of the three coral reef systems that make up the federally protected sanctuary in the Gulf of Mexico, according to the sanctuary.
Between 2011 and 2017, researchers have recorded nearly 3,500 lionfish in the sanctuary, NOAA stated, though experts believe that number is low.
And just as the lionfish did in household aquariums, they started eating everything in sight. A single lionfish can eat up to 5,000 fish per year, Johnston said.
In the Indo-Pacific, lionfish predators include sharks, grouper, frogfish, large eels and scorpionfish, according to Lionfish Hunters, a group that promotes the removal of lionfish from the Western Atlantic Ocean, Caribbean Sea and Gulf.
But fish native to the Flower Garden Banks don’t know lionfish are predators, Johnston said, which makes the venomous fish’s food gathering that much easier.
“The lionfish are virtually unchecked” in Flower Gardens, Johnston said. “The ones we’ve collected are extremely large, they’re obese, and some of them have fatty liver disease. They’re eating themselves into oblivion.”
Fishing industry concerns
Johnston believes the study’s predictions about a mass lionfish takeover is slightly alarmist, but she said it makes good points.
The only thing that limits a lionfish’s range is cold temperatures, she added, and if waters were warmer they’d likely spread out more, potentially traveling even deeper into the ocean.
“As far as climate change, if it’s going to get warmer, then yes their range could potentially broaden from where it is now, maybe going farther up the East Coast,” she said. “Lionfish do not like the cold.”
Lionfish have shown a preference to water temperatures around 73 degrees Fahrenheit, according to the peer-reviewed newsletter, Biodiversity Science.
If the study’s predictions are accurate, the lionfish would put an even bigger strain on the commercial fishing industry.
In Florida, for example, lionfish have been known to feed on snapper and grouper — major economic drivers in the state.
“The diversity of fish in Florida is being significantly altered by the lionfish, putting a strong economic engine at risk,” according to the Taxwatch Center for Competitive Florida in 2015. “One of the top species harvested in Florida is the red grouper (with a 2010-11 dockside value harvest of $15.1 million), which competes with the lionfish for prey, and is often prey itself.”
And the true threat of this invasive species still is being sorted out. In another study published last year, Matthew Johnston, a research scientist at Florida-based Nova Southeastern University, found that not much is known about the true economic impact. Data is needed quickly, he said, to help mitigate damage.
“We’re talking millions of dollars in the fishing industries — from catching and selling various fish to the hundreds of thousands of jobs and the recreational aspects of fishing,” he said. “If left unchecked, there is the real potential that lionfish will have a negative impact on the fishing industry. It’s likely that they are negatively impacting populations of the fish we like to eat, and at an alarming rate.”
Luckily those negative impacts haven’t reached Flower Garden Banks yet, said Buddy Guindon, a commercial fisherman who owns Katie’s Seafood Market in Galveston.
“We haven’t seen any noticeable changes, but there’s an abundance of lionfish on Flower Garden Banks,” Guindon said. “We’re thinking that the big snapper and grouper have started eating them.”
No real solutions — yet
This late into the lionfish invasion, there’s no real way to completely eradicate the species from the environment they were never meant to inhabit, Johnston said.
But scientists certainly are trying to mitigate the damage.
In the Flower Garden Banks specifically, sanctuary officials have conducted four separate volunteer dives to hunt the fish, pulling 1,200 from the reef system this past summer with pole-spears, Johnston added. But they know that isn’t enough.
“Removing lionfish through diving efforts is not the solution to the problem,” she said. But “it is definitely a tool to help mitigate the lionfish invasion and to help keep it from getting worse.”
At NOAA, scientists are developing special, clamshell-shaped traps to catch lionfish on the ocean floor.
Companies are also getting into the fray. Virginia-based R3 Digital Sciences is building a trap complete with a small camera that allows the device to identify lionfish. Only lionfish would be allowed to enter the trap, according to a May 2018 article published in Ocean Deeply, a digital media project that focuses on ocean health.
And in Massachusetts, Worcester Polytechnic Institute students are taking it one step further, building an underwater robot to hunt lionfish.
“The goal is to be able to toss the robot over the side of a boat and have it go down to the reef, plot out a course, and begin its search,” Craig Putnam, associate director of the institute’s Robotics Engineering Program, said in an August statement. “It needs to set up a search pattern and fly along the reef, and not run into it, while looking for the lionfish. The idea is that the robots could be part of the environmental solution.”
Johnston isn’t sure what the answer is for Flower Garden Banks, especially since the reef system is so deep. But technical divers, who can swim much deeper than recreational divers, will come to the sanctuary next summer to learn more about lionfish behavior in the depths of the Gulf.
For now, all sanctuary officials can do is manage the area by hunting the lionfish and removing as many as they can.
“It’s a process that’s never-ending. We remove them from the shallow areas and they come up from the depths. But that’s not a true solution,” she said. “The solution is for the system to naturally sort itself out.”