Lionfish Invasion Update

Many Red lionfish swimming around Giant barrel sponge in RoatanIt has been 20 years since the first breeding populations of Lionfish were spotted off the coast of North Carolina in 2000. Since then they have rapidly spread in the Atlantic Ocean invading more than 4.3 million square miles (7.3M sq km) of water all the way down to South America passing through the Caribbean Sea and Gulf of Mexico. A lot has been done during these years, hundreds of studies and several strategies have been put in place in order to address and control this invasion which could potentially become the worst marine invasion in history. The Roatán Marine Park started its own Lionfish program in 2010 with great results. Below is an update about the Lionfish situation in the Caribbean and Atlantic ocean.

Even though the Lionfish invasion was first studied off the coast of North Carolina in 2000, scientists agree the the invasive species way before. There are a few theories about how and  when the lionfish invasion began. Perhaps it was due to a hurricane that broke a beachside aquarium in Florida in the early 1990s. Or it may have been before this as some specimens were spotted in the water off Florida in 1985 leading to the idea that Lioonfish could have been released in the water by people that used them as pets in private aquariums. How and when it began is unsure but the fact is that lionfish have spread all over from North Carolina to South America. Lionfish have been described by scientists as the rats of the sea. They can reproduce very quickly and are extremely voracious. As a non native species they don't have predators in the Atlantic and at the same time their prey don't recognize them as predators making it even easier for them to hunt and eat everything that comes across their path. For all these reasons lionfish have the potential to become the most disastrous marine invasion in history and a serious threat for the Caribbean marine ecosystem and its inhabitants.

A single female can lay 2 million eggs a year. 
The eggs can travel with the current for almost a month sometimes covering long distance and invading far away reefs.

In Europe, The International Union on the Conservation of Nature (IUCN), has confirmed that lionfish have also been present in the Mediterranean since 2015. They spread through the Suez Canal from the Red Sea, probably due to the increase  of sea temperatures in the last few years.  However it is likely it will be harder for the lionfish to colonize in the Mediterranean like they have in the Caribbean, as the water temperature, is still too cold.


Red lionfish (Pterois volitans)THE INVADER

Red lionfish (Pterois volitans)
is a predatory scorpionfish that lives and hunts on coral reefs. Native to the Indo-Pacific it is characterized by red and white warning stripes along its body and venom-filled spines on its fins. This particular species is the largest of his family and it can reach 18.5 in (47 cm ). Lionfish can live up to 15 years, they become sexually mature after only one year and they can reproduce very quickly, apparently every 4 days, laying up to 15 thousand eggs every time. A single female can lay 2 million eggs a year which can travel with the current for miles for almost a month. They are extremely voracious. Lionfish can eat almost anything that fits in their mouth. Scientific studies show that lionfish can eat one to two fish per minute, and their stomachs can expand 30 times their size. A fairly large population of lionfish can potentially eat so much to bring the ecosystems to collapse. 

By eating juveniles and small reef fish the lionfish are compromising the food chain. They can take out entire populations and hence putting bigger fish such as grouper, snapper and any other kind of medium/large reef fish at risk and destroying the surrounding marine ecosystem. It’s hard to describe how a lionfish eats because it happens in a blink of an eye. Thanks to high definition slow-motion camera scientists observed that despite its slow movement lionfish can be very fast when catching prey. They move very slowly, almost floating and pretty much unobserved, waiting for the prey to get close and in the space of an instant they fire a disorienting jet of water from their mouth and then they just swallow the prey sucking it into it’s mouth and return to floating quietly like nothing happened. The attacks happen so quickly that nearby fish don’t seem to notice.

Lionfish are in fact venomous and not poisonous.
lionfish can be eaten and this is one of the strategies we can use to fight them.
The difference is the delivery method. Poisonous animals require their victim to ingest or absorb the toxin, basically they need to be eaten, like some frogs or salamanders. Venomous animals use specific apparatus to inject their toxin. Snakes use teeth for instance. Lionfish uses spines, they can potentially harm through their spine but their meat is good to eat and actually tastes delicious.

HOW TO FIGHT THEMdiver fishing lionfish 
The main point is how to manage the invasion. Many years from now, through a slow evolutionary process, lionfish will eventually become part of the invaded ecosystem and their population will be kept in balance from natural factors. Autochthonous Predators like groupers, barracuda and sharks will start to eat them, local parasites and pathogens will attack them and prey will start to recognize them and developing defense mechanisms that will make it more difficult for lionfish to hunt and hence less invasive, just like in their original habitat in the Indo-Pacific Ocean. Lionfish will probably become one of the many beautiful fish to just enjoy and photograph for scuba divers and we won't fear it anymore. But this will take time, lionfish will remain an invasive species for a long time and the chances are the marine environment will collapse under its pressure beforehand. Lionfish are not to be underestimated. Meanwhile marine biologists and ecologists along with marine parks and different other organisations all over the Caribbean are putting a lot of effort to try to stop and avoid a potential catastrophe for the marine ecosystem.

More than 150 studies have been published just in the last five years and many more are in progress. Some of these studies have showed two important things.

• Lionfish are not extremely destructive for the environment until their population grows to a certain density. Even if a single lionfish can eat a huge amount of fish compared to its size, it seems they can be assimilated by the environment without much damage if their number is kept low.

• After removing a considerable number of specimens from the reef they are slower to repopulate the same reef, much slower than scientists thought. Even though their reproduction rate is very high. Removing a certain number of individuals a couple times a year from a reef seems to keep the reef healthy and balanced. 

In some parts of the Gulf of Mexico the lionfish population has been tracked down for several years and the number of lionfish naturally declined. Scientists don't know why, probably parasitic skin lesions have affected this area's population. There is still a lot to learn about this invasion but this is an encouraging observation.

Along with the studies, different strategies have also been developed and implemented over the years trying to address the problem. Some have given good results, others need more time and investment to be proven right. 

Education and awareness about the issue. NGOs, marine parks and other kinds of environmental organisations are sharing studies, experiences and information about the lionfish invasion, promoting workshops and conferences and educating locals, visitors and divers about the problem.

Using tourism to bring down the lionfish population density. Dive shops organized and ruled by Marine parks and environmental NGOs are using scuba divers to remove lionfish from the reef allowing divers to spearfish with a special license often released by the local marine park. They also encourage lionfish tournaments. This strategy has proven to be valid but has an area limitation. It only works on reefs constantly visited by divers, however many lionfish populations also live beyond scuba divers reach. A statistic made in Roatán, by the Roatán Marine Park shows that 586 new lionfish fishing licenses have been issued to divers in 2019 alone. Proving that tourism is helping a lot to keep lionfish populations under control on Roatán reefs.

The Roatán Marine Park (RMP) has been training both locals and tourists how to hunt lionfish since 2010. Initially it was only open to Dive Masters and Instructors, however with the ever-increasing lionfish numbers and the need for the dive professionals to focus on their customers, the licensing program was opened to the general public. Licensing 3,344 snorkelers and divers since 2010, we have been able to apply a constant fishing pressure on this invasive species and with numbers nowhere like they were at the start of the decade, the program is certainly working.
(Read more about this program on RMP website and download the document attached for results and statistics during the last 10 years)

Putting lionfish on a plate. Many environmentalists think the best way to solve the lionfish problem is with commercial fishing. So far many local supermarkets and restaurants all over the Caribbean sell lionfish while in Florida the lionfish market is big enough to supply many restaurants and grocery stores with lionfish. But it is hard to keep statistics about this and lionfish are expensive to catch and not easy to fish with traditional methods. Research has shown that local independent fishermen in the Caribbean are able to make money from  fishing and selling lionfish to friends and local restaurants, while the commercial fishing industry is not interested in it since there are is not a huge profit margin.

shark eating lionfish

Training local predators. like groupers, barracudas and sharks to recognize them as prey and eventually including lionfish in their diet. Lionfish have no natural predators in the Atlantic and Caribbeans, but they are naturally eaten by bigger predators in the Indo-Pacific ocean. This has proven that local predators do eat lionfish once they have been offered to them but scientists still don't know when they will start to hunt them naturally. However some think that divers feeding bigger predators is not ideal as this may change the behavior of the bigger predators to expect a diver to provide food and decreasing the natural hunting behavior of the fish.

DNA manipulation. Some scientists think that it would be a possibility in a few years to lab-raise lionfish with a modified gene causing infertility in some female descendants. Once released these specimens with the new gene in the ocean they will affect the population causing infertile on a large scale and eventually have lionfish numbers fall drastically to the level of non danger for the environment. However this technology still needs research and we have to wait a few years before the first modified lionfish can be released in the ocean. 

As we saw a lot has been done in the last years trying to address this problem, however scientists cannot determine how the situation will evolve yet. Things are still uncertain and it is very hard to predict how nature will respond and how possible it could adapt to this invasion, but many points lead us to an optimistic scenario. Lionfish is indeed a beautiful fish to see floating underwater. Hopefully in a few years from now it will not represent a threat anymore but it will become part of the Atlantic Ocean and the Caribbean Barrier Reef’s environment. Just a beautiful addition to the already stunning underwater ecosystem. But for now it is important to be alert and keep the invasion under control. 

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