Where When How Summer 2017 : Page 86
Reprinted with permission from Dive Training Photos provided by Dive Training 86 • • • • • SUMMER 2017 “Where When How -Turks & Caicos Islands”
Reprint - Dive Training 86 Killers On The Loose Lionfish
Reprinted with permission from Dive Training
The December 2007 issue of Dive Training contained an article, “Beauty and a Beast,” which was the first in any diving publication to delve closely into what was then seen only as an interesting but localized environmental concern. However, some said that it had much broader implications, and might bring on one of, if not the, most significant changes in Atlantic coral reefs since the die-off of black spiny sea urchins in the early 1980s. (For a closer look at the sea urchin die-off, see “Pin Cushions in Paradise” from the September 2004 issue of Dive Training.) Now, thirteen years later, the dire predictions could be well on their way to becoming a reality.
How did this happen?
Researchers point to several possible scenarios by which lionfish may have entered the western Atlantic. A popular theory blames the devastation wrought in 1992 by Hurricane Andrew. A home on Miami’s Biscayne Bay, containing an aquarium with six lionfish, was destroyed by the storm and shortly thereafter several of the survivors were spotted in the bay. But others maintain that lionfish were present long before Andrew. At least one reliable report documents a lionfish being caught from a fishing pier in Lake Worth, Florida, in 1983.
Aside from where it happened, it appears pretty certain that at least some lionfish weren’t accidentally introduced at all; their release was quite intentional. A scientific paper published in 2004 concluded that the most logical source of the lionfish was the release by hobbyists who either lost interest in their pets or had fish that grew too large for their aquarium.
The phenomenon that I’m referring to isn’t global warming, coral bleaching or even the more recently recognized problem of ocean acidification. This is the result of a type of fish that ended up where it didn’t belong. And unless you live someplace where TV and the Internet are illegal, you probably already know the culprit. Actually, there are two culprits, Pterois volitans and Pterois miles, known collectively and more familiarly as simply, lionfish.
Today there’s no doubt that this beautiful but venomous transplant from the Indo-Pacific has, in fact, become a permanent Atlantic resident — the first tropical marine fish ever to do so.
A Complete Circle
When we examined the lionfish problem back in 2007, most reports were coming from the Gulf Stream-influenced waters off North Carolina and the central Bahamas. Since then, with the exception of Barbados and a tiny portion of the southern Antilles, lionfish are now found residing throughout the Greater Caribbean and beyond. Thus, what was a relatively local issue now affects the entire region. (Though Brazil is not yet affected, the assumption is that their invasion is only a matter of time.) Lionfish have even spread into the Gulf of Mexico as far north as Bradenton, Florida, transforming the phenomenon from an invasion to a full-on takeover.
For a long time the hope was that lionfish would not complete their circular invasion of the entire Caribbean basin — that somehow natural barriers, such as opposing currents or long distances, would keep the invaders isolated in specific locales. For example, although lionfish have been routinely sighted along Florida’s Gold Coast (Miami to Palm Beach), they were absent from diving’s Mecca, the Florida Keys. The Keys were thought to be protected from the Bahamian epicenter by the fact that the Gulf Stream flows in the wrong direction — away from, rather than toward, the Keys. But all hopes were dashed in January 2009 when the first reports came in from Key Largo. By May they were spotted regularly off Key Largo, and by October lionfish were Keys-wide. Now reports are coming in at a rate of more than a dozen per day, with more than 500 having been reported and thousands more on their way. Still, the situation in the Keys isn’t yet as bad as the Bahamas (the Keys fish are still relatively small compared with their Bahamian brethren), but without a strong management response the Bahamian experience could be soon duplicated in the Keys.
What’s as concerning as the sheer number of reports is where the lionfish are being seen. In a word, everywhere. Lionfish are being spotted in the Keys, just as they are elsewhere, in every marine habitat, from off-shore reefs to the bridge pilings of U.S. Highway 1 (an especially popular habitat for them as of this writing). “They’re being found anywhere there’s water and structure,” says Lad Akins, special projects coordinator for the Reef Environmental Education Foundation (REEF), and one of the most knowledgeable people on the planet regarding the invasion. “In one day we took 30 beneath the Long Key bridge alone, and there’ve even been reports of fish in residential canals.”
The only good news is that none of the nearly meter-long specimens found in the Bahamas have been reported yet in the Keys. In the Bahamas commercial fishers targeting waters as deep as 600 feet (182 m) are bringing back lionfish. (Though not as deep, Keys lobstermen have reported juvenile lionfish in the bait wells of their traps retrieved from more than 200 feet [61 m].) The numbers in the Keys also pale in comparison with the Bahamas where a single one-day “lionfish derby” in the Abacos removed more than 1,400 fish. Not surprisingly, in a recent interview Lakeshia Anderson of the Bahamas Department of Fisheries said that the livelihoods of Bahamian fishers may depend on stopping, or at least slowing, the invasion. “With the quantities of lionfish that we’ve found in our waters,” Anderson says, “and the amount of food they consume, it has the potential of really collapsing our commercially important species — our fishing industry, in general.”
Florida’s two-day lobster mini-season, which occurred in July, provided another useful insight into the status of the lionfish invasion in the Sunshine State. This year the Florida Fish and Wildlife Conservation Commission conducted a telephone survey of lobster license holders, asking them if they saw any lionfish while lobstering. On average, one-third of lobster hunters from southeast Florida and the Keys who were interviewed reported seeing them. (Lobster hunters were thought to be a good source of information because lionfish like to hide in the same habitats as lobster, which is something to remember the next time you eagerly reach into a hole to grab a lobster.)
Why All the Concern?
While lionfish have gotten all the publicity, they are not the first Indo-Pacific fish to visit the Atlantic. In fact, species from the other side of the world have been so prevalent that the U.S. Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA) and REEF have released a new publication, “Field Guide to the Nonindigenous Marine Fishes of Florida.” It contains 30 different species. But the difference between lionfish and the other marine species is their firm foothold and proliferation, which begs the question, why? What has made them succeed where no other marine fish has?
Be Careful Out There
Except in places where fishing is prohibited, lionfish are unregulated, so they can and should be removed whenever possible. But dealing with a fish that has the potential to deliver a very serious, though not fatal, injection of venom is not something to take lightly. Pole spears can be very effective on adult lionfish. Hand nets are best for smaller specimens, but learning exactly how to net and handle the fish afterward requires some training and a few specialized equipment items, like puncture-proof gloves. (Most divers are stung when handling the fish after it’s netted or speared.) It’s also important to get the collected specimens into the hands of researchers so your efforts do more than just eliminate a fish from the population. You can learn more about these and other issues, as well as how you can contribute to fighting the invasion in other ways, by logging on to REEF’s Lionfish Research Program website at www.reef.org/programs/ exotic/lionfish.
Reasons for their stellar success have yet to be confirmed but there are a number of theories, one or all of which may provide an answer. The first involves the fish’s omnivorous appetite and hunting strategy. As confirmed by stomach content analysis, lionfish eat just about anything that occurs in their habitat — up to half the size of their own body — and that includes both fish and invertebrates.
Since our first article appeared, there has been some serious scientific research going on regarding the eating habits of lionfish. While they eat virtually any critter that will fit into their mouths, including sea urchins, brittle stars, crabs, shrimp and a variety of other mollusks, lionfish are primary fish eaters. In fact, what Oregon State scientist Mark Albin and his adviser and esteemed reef fish ecologist, Dr. Mark Hixon, have found can only be described as alarming. Working at the Caribbean Marine Research Center in the Bahamian Exumas, the team has shown that these voracious piscivores can eliminate 80 percent of the juvenile fish population on a reef in as little as five weeks. In turn, they not only eliminate the next generation of fish, but also take away the food source from other important commercial species such as adult grouper and snapper. (Research has yet to find a Caribbean fish, including sharks, that will eat a live lionfish, though many species will consume them once they’re dead.) Lionfish also eat the ecologically important algae eaters of the reef like parrotfishes, damselfishes and surgeonfishes.
Aside from what they eat, the way they catch their prey is quite unique for a reef fish in the Atlantic. Lionfish, like many other reef residents such as grouper, are described as ambush predators because of their lie-in-wait hunting technique. But that, in and of itself, is nothing new, as many predatory reef fish in the Caribbean use this same strategy. So the thousands of other fish swimming around the reef trying to avoid becoming lunch are used to it. What is novel about lionfish is their use of those signature-long, brightly colored fins to maneuver their targets into striking range. Of course, prey in lionfish’s native range has coevolved to recognize this, but not their prey here in the Atlantic. Like hunting deer at night with spotlights, Caribbean reef fish have no experience with this fin strategy and become easy prey. Will fish on this side of the international date line adapt to better avoid becoming a snack? Only time will tell.
Another theory for their continuing success involves, of all things, parasites. As mentioned in our original lionfish article back in 2007, work on the parasites that infect lionfish was first initiated by Dr. Ann Barse from Maryland’s Salisbury State University. She found that very few parasites were seen in the Atlantic population compared with what are found in native species. Her work is being continued by researchers in the Bahamas such as zoologist Paul Sikkel. Like Barse, Sikkel is finding the gills — a prime location for parasites — amazingly clear compared with other native fish. The parasites that normally swarm all over a local species apparently aren’t going near the lionfish. The significance of this finding Sikkel describes as avoiding a kind of “tax” that fish have to pay whereby much of their energy gets diverted from growth and reproduction into fighting the parasites. Not having to do that may well explain the abnormally large size of some of the captured lionfish and, though it is yet unknown, a suspected higher reproductive success rate than in their home range.
The reproductive mode is also another factor that makes lionfish particularly good baby-making machines. Like most reef fish, they are broadcast spawners. Males engage in elaborate posturing designed both to intimidate rivals and impress potential mates. This can go on for three or four days. If impressed by the display, a willing female joins her suitor. The pair then begins a spawning dance where they circle each other face to face while slowly ascending. The actual deed happens just before reaching the surface, when the female expels a mucus ball containing thousands of eggs. As this “egg ball” floats to the surface, the male turns belly up and releases a cloud of sperm into it. Soonafter — in some cases after only a day — the eggs hatch into larvae, and the young eventually settle to hideouts along the seafloor. Just three months later the young are diminutive versions of their parents. And unlike other fish that mate only seasonally, lionfish mate year-round, ensuring a continuous supply.
The combination of numbers and appetite are enough to make reef scientists and managers break out in a cold sweat. Just a back-of-the-envelope calculation is quite astonishing. For example, in the central Bahamas, studies have documented lionfish densities at about 200 per acre, and each lionfish eats from 30 to 40 fish per day. Multiply that by 365 days, and you soon come up with some mind-numbingly large, if not disastrous, numbers of fish being removed each year. What’s even scarier is that in some of the hardest-hit regions, lionfish densities can be as much as 1,000 per acre.
Yet another alarming fact is their growth rate and maximum size. Studies have shown a growth rate of up to a halfmillimeter per day, or 10 inches a year, and numerous specimens have been caught in excess of a meter in length. This is a faster growth rate and larger size than in their native Indo-Pacific range. Lionfish obviously love their new home.
Kill ’em and Grill ’em
Every scientist that I’ve spoken to about the lionfish invasion has told me that these critters are, like thousands of other exotic species, probably here to stay. Some have even expressed grave doubt that’s there’s much that we can do about it, and believe that local eradication efforts are a waste of time and resources. But recently there has been some reason for hope.
Along with studies focusing on what lionfish eat and how they manage to make their way around the vast Caribbean Basin, some are looking at whether human removal of the invaders is working. And so far, the research says it may be having an effect. Experimental reefs in the Bahamas that had high concentrations only last year, have this year shown far lower numbers after removal efforts. “What that tells us is that our removals took,” says Dr. Mark Hixon, “and lasted a whole year.”
According to REEF’s Lad Akins, the key is to intercede early and consistently. “While we may not be able to completely eliminate them,” he says, “with a focused and consistent eradication effort, it appears that we may be able to keep their numbers low and reduce their ecological impact.” Research so far indicates that about 27 percent of mature lionfish will have to be removed monthly for one year to reduce its population growth rate to zero.
Clearly, one way of controlling lionfish is to create a commercial market for them. At a recent meeting of Florida Keys National Marine Sanctuary (FKNMS) officials, I had my first opportunity to eat “lionfish bites,” and indeed they were quite good. In fact, had I not been told what was on the menu I would have guessed hogfish. To this end, NOAA is now sponsoring the “Eat Lionfish” campaign (See “‘Eat Lionfish’ Campaign Among Strategies to Combat Invasive Species,” Dive Training, October 2010) and is encouraging not only individual fishers to fire up the barbie, but restaurants to put the spiny invaders on their menu. While many have expressed a willingness to try, the problem is supply. There is not yet a fishery for lionfish, and many fishers have been understandably reluctant to target a species that’s so difficult to handle. Current efforts are concentrating on programs where fishers could take preorders from suppliers, ensuring a sale before leaving dock.
Another innovative approach has been the lionfish derbies, as mentioned previously. With the rousing success in the Bahamas, FKNMS managers have organized three such derbies in the Florida Keys. In each location teams of up to four divers will compete for more than $3,000 in prize money, and winners will be awarded in three categories: most fish, biggest fish and smallest fish.
On site for each derby will be researchers who will immediately perform dissection and stomach content analysis. In addition, chefs will also be on hand to maintain a continual supply of ceviche and lionfish bites. This is clearly a unique opportunity for a nexus of competition, science and culinary delight.
As the invasion is now a regional problem, it calls for a regional solution. This has inspired a regional workshop that will be concluded by the time this article appears. Convened by the International Coral Reef Initiative (ICRI), and sponsored by REEF and the governments of Mexico and France, the symposium has several ambitious objectives, such as identifying current control strategies; compiling existing information from throughout the region; developing a draft strategy for control; establishing the basis for generating information about the species; establishing regional policies to control traffic, import, export and marketing of exotic invasive species; and developing communication strategies.
For More Information
The Mote Marine Laboratory,
Tropical Research Station on
Summerland Key, is an excellent information resource on all aspects of lionfish and the status of both research and the invasion.
Log on to
Read the full article at http://onlineissues.wherewhenhow.com/article/Reprint+-+Dive+Training+86+Killers+On+The+Loose+Lionfish/2820013/419587/article.html.
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