The Lionfish

Lionfish are amazingly beautiful animals.  Their dorsal fins are like multi-colored striped pennants waving in the current and they are flanked by feather like pectoral fins that give it an appearance of a tropical parrot.  They move gracefully and slowly in the water, like a peacock that flairs out its feathers to show off its beauty.  But under this mesmerizing facade is a dangerous predator that is wrecking havoc on the ecosystem in this part of the world.

Lionfish are an invasive species that are taking over reefs in this part of the world.   Lionfish live in depths between 1 foot to over 1000 feet.

Where did the come from?

Lionfish are endemic to the Indo-Pacific area and where they co-exist with other members of the eco-system .  The current invasion is made up of two species of lionfish, Red Lionfish (Pterois volitans) and Devil Firefish (Pterois miles). Only through DNA testing in the lab, can scientists distinguish the two.  Visually, they seem to be identical.  Pterois volitans accounts for 93% of the lionfish in the Western hemisphere. Since then, lionfish have spread to all parts of the Atlantic coast, Gulf of Mexico, and throughout the Caribbean!  Genetic testing traced the entire invasion  back to 5-7 breeding females from the waters of Florida.  Now, Lionfish are found as far north as Rhode Island and as far south as Brazil. Colder ocean temperatures in the winter seem to limit their range,  as it is believed that lionfish are unable to survive water temperatures below approximately 50 degrees Fahrenheit or 10 degrees Celsius.

The Problem

Their appetite has been described as “voracious” and “insatiable” by experts, having witnessed lionfish eat 30-40 juvenile reef fish in an hour. Lionfish are known to eat just about evey fish and invertebrate within its living range – over 60 different species, including ecologically signifigant fish such as parrotfish that keep the algae in check on reefs, and commercially important species such as snapper, grouper, flounder, mahi mahi,  and amberjack. They also snack on diver’s favorite friends on the reef including, octopus, sea horses, lobsters, crabs, etc.

Lionfish are gape-limited predators. This means that mouth size is the only factor limiting an individual lionfish’s choice of prey! Lionfish’s stomach can expand up to 30 times it’s normal volume, and can swallow prey up to 2/3 the size of their own bodies.  Lionfish primarily hunt during dawn and dusk, and have been described as active hunters during periods of dim ambient light such as on cloudy or overcast days.There has been a measurable decline in reef fish – as much as 80% in parts of the Bahamas.

After one year, A female lionfish reaches sexual maturity and can produce 30,000 eggs every 4 days.That’s around 2.74 million eggs per female per year!  Once spawning occurs, the ocean currents distribute the eggs and larvae, and when the lionfish drop they will usually not travel far from their new home.

A Venomous Adversary

Lionfish have 18 venomous spines that are used for defense.  Spines are not hollow like snake fangs; Instead venomous glandular tissue is housed in grooves along the spine and can deliver a very painful sting if you get stuck.  There are 13 spines in the dorsal fin, one shirt spine in each of the pelvic fins, and 3 spines in the leading edge of the anal fin.The venom is made up of a neuromuscular toxin combined with a neurotransmitter called acetylcholine.  The best way found to relieve the effects of this toxin when stung is by using very hot, but not scalding water. This will denature and break down the protein based toxins. There have been no fatalities among humans as a result of a lionfish sting. As soon as lionfish leave their larval stage, they have formed all 18 of their venomous spines.

For more about first aid of lionfish stings, Click Here  Download DAN’s Pocket Sting Card HERE

 Natural Predators

In their natural environment, lionfish are preyed on by sharks, cornetfish, grouper, large eels, frogfish, and other types of scorpionfish. Large snapper and some species of trigger fish have been speculated to eat lionfish in their native ranges as well. In their invasive range, there have been no natural predators that have stepped up to help control the exponentinally increasing population.  Many have asked, and indeed tried, to “train” native fish and sharks to eat lionfish.  Most experts agree that it is not likely that we can train native fish to hunt and eat lionfish.

There are several problems with this approach:  Fish do not train their offspring to hunt like a mammal does. There is no “transfer of knowledge” and every new generation of would be predator would have to be trained. Also, ad hoc “training of predators” by well meaning divemasters and instructors only produces a situation in which the “trainers” teach large and potentially dangerous predators to equate lionfish hunters with food. In turn, these animals have become quite aggressive in some locations across the invaded area.

There are no known natural predators to keep them in check… until now!

It’s up to divers

That IS the current solution until we can find a better one. NOAA has determined that “Local control efforts are critical for mitigating the effects of lionfish on key marine habitats.”