The Invasion of the Lionfish

The Invasion of the Lionfish

                                                                      (Photo: Florida Sea Grant)

It is a song that has been played in our state time and time again. An exotic pet or plant is
brought across our borders and either intentionally or accidentally it is released into the
environment and a problem ensues. Ornamental plants for our yards that spread seeds, exotic
reptiles that become to large to care for, tropical mammals that are used in movie productions that
manage to escape their “full-proof” enclosures and the next thing you know you see them
wandering the streets of your community.

In many cases these non-natives are just another part of the landscape but in some they begin to
cause economic or environmental problems and they become invasive species. There are many
examples of invasive creatures in Florida; iguanas, red fire ants, Chinese tallow, Japanese
climbing fern, and most recently – Burmese pythons. The states of Florida and Hawaii have the
largest problems with these creatures because of their tropical/sub-tropical climates; thus they
have some of the toughest laws dealing with them. There is a $1000 fine for releasing a
nonnative in Florida. These plants and animals find plenty of food, few predators, and warm
temperatures year round. It is no different in the Gulf of Mexico. Many tropical fish released
into our waters do not survive the cold winters or the high salinities, but things could not be better
for the red lionfish.

Also known as the Turkeyfish and Zebrafish, the Red Lionfish (Pterois volitans) is one of 500
species in the family Scorpaenidae; 6 of these are native to the Gulf of Mexico. Many members
of this family are venomous and the red lionfish is no exception. They are small fish ranging in
from 6 to 12 inches in length; however in 2004 a 17 inch lionfish was caught of the coast of North
Carolina. The lionfish is from the western Pacific Ocean and range from the Micronesia area to
Australia and north to the southern shores of Japan. They have a close cousin, the Devil Firefish
(Pterois miles) that is found in the Indian Ocean and Red Sea. Both of these fish are very cryptic
and are more nocturnal in habit so detection is not always easy when looking for them. They are
found primarily on offshore reefs ranging depths between 35 and 600 feet, and in their native
region they have been found in the turbid areas of estuaries.

They feed on a variety of small reef fishes, shrimps, crabs, and they have few natural predators.
Lionfish are ambush hunters preferring to blend into the environment and wait for the prey to
cross the “magic line” where they by corral them using their large pectoral fins and engulf them.
It is believed they hunt mostly at night and hide within the reef during the daylight. There are
records of cannibalism in this species.

They spend most of their adult lives as solitary individuals but during breeding season (which can
occur year round) they congregate in groups from 8 to 12 and begin a complex courtship behavior
that involves flaring fins, and a “waltz-like” dance. To fertilize the eggs, females will release a
buoyant mucous ball and the male will release between 10,000 and 30,000 sperm on this egg
mass. Microbiological activity will dissolve the mucus ball and the fertilized eggs are released.
These eggs drift far and wide and in 2 days hatch to become benthic juveniles. They reach sexual
maturity in about 2 years.

So the questions are… how did they get here? And are they truly invasive?

It is believed that the lionfish issue began with the aquarium trade. Currently there are a reported
8,000 fish delivered to the Tampa Bay area alone each year. Some want these fish because of
their beauty (they are neat looking fish), others are attracted by the fact they are venomous. They
are relatively easy to maintain and can command a large price; lionfish are good business. The
most popular explanation as to how they were released in our local waters is the destruction of
homes and pet stores during the heavy hurricane seasons of past years. The earliest record of a
lionfish in Florida was in 1985 in the town of Dania. The question now was would they
reproduce and can they survive the colder winters here.

They breed year round and mature quickly. More fish were found in southeast Florida by 1992
and records were occurring in North Carolina and as far north as Long Island, New York.
Coldwater temperatures should be a barrier to their distribution. Studies show that they stop
eating when water temperatures reach 60˚F and death occurs at 50˚F. By 2000 there were records
of this fish in the Bahamas and through out the Caribbean region. The first records in the
northern Gulf of Mexico were 2010 when lionfish were seen in Apalachicola and Pensacola.
Between 2004 and 2008 there was a tenfold increase in their population in Bahamian waters.
Recent records of this animal can be seen on the figure below.

( Courtsey: USGS Nonnative Aquatic Species )

So now they are here… are they invasive?

The answer is yes. These fish are voracious feeders. When they are smaller they feed on a
variety of tropical reef fish, shrimps, crabs, and some accounts show them feeding on small spiny
lobsters. As they increase in size they move to a more fish diet. Studies show that they feed on
over 50 species of reef fishes and some of them are economically important to us. They do
consume small species of herbivorous fish that control the algal growth on the coral reefs. Reefs
covered with algae will not last long and we all know how important reefs are to the economy of
south Florida. A study conducted in the Bahamas looked at whether these reef fish could
reproduce fast enough to balance out the attacks being made by the lionfish. The results showed
that the recruitment of the reef fish declined by 80% when lionfish were in the area. Another
study shows that their population density in the Bahamas is eight times greater than that of the
native waters; indicating whatever population control mechanisms there are in the Indo-Pacific
are not at play here. A third study compared reef populations in two reef systems where the
lionfish was the predator in one and a natural predator (the Coney Grouper, Cephalopholis fulva)
was the predator in the other. The decline of the reef fish populations in the area with the lionfish
was 2.5 times faster than that of the grouper. They reproduce often, have few predators, and
consume a great variety of local species including commercially valuable ones. These results
suggest yes, lionfish are invasive.

So what do we do about it?

The method of choice at the moment is removal by humans. Lionfish do not typically bite a hook
and line so the most effective method to date is spearfishing. Many areas are hosting “Lionfish
Rodeos” which reward divers for returning as many lionfish as possible. A rodeo was held in
Destin, Florida in July 2012. During this one day event 81 lionfish were landed. It is difficult to
find these fish diving because of their cryptic and nocturnal behavior so there is a challenge to

this. Until recently all divers who speared lionfish had to have a saltwater license and could not
bag more than 100 lbs. of fish. The question was “why would there be restrictions on harvesting
this invasive species?” The response from the Florida Fish and Wildlife Conservation
Commission (FWC) was that the lionfish is an unregulated species in Florida waters. Under their
regulations the harvest of 100 lbs. of an unregulated fish labels you a commercial fisherman and
thus you would need a commercial fishing license. To avoid this problem they set a bag limit of
100 lbs. On August 3, 2012 the state of Florida issued an executive order that will allow spear
fishermen to capture lionfish without a saltwater license and there will be no bag limit; anglers
will still need the license. This executive order will be for one year.

Some communities consume lionfish and their rating is very good. However the FDA reported in
2012 some cases of ciguatera in the tissue of the lionfish. Ciguatera toxin is something that has
been with Floridians for awhile. Small fish feed on small organisms on the reef. Many of these
contain defensive toxins that accumulate in the fatty tissues of the animal. As you move up the
food chain, and consume more prey, the levels of ciguatera toxin increase. In some cases they
increase to hazardous levels for human consumption. This appears to have happen in some
lionfish and so consuming these animals does pose a risk.

The state of the lionfish at the moment may be beyond eradicating the species from our waters
and they will become part of landscape just as the Chinese Tallow and Golden Orb Spider have.
We continue to try and remove these invasive plants and animals from our ecosystems and we
will continue to remove the lionfish. The concern here is the continued importing of nonnative
species. We encourage Floridians to landscape with native plants and not purchase exotic pets.
The University of Florida Extension recommends that if you no longer want your exotic pet there
are few things you can try.
    1) Find it a new home – another family, rescue centers, maybe schools or nature centers will
        take it.
    2) Return it to the pet store – many will take it back but will probably not refund your
        money.
    3) Contact wildlife agencies – FWC holds an “Amnesty Day” each year where they will
        take your unwanted pets.
    4) Euthanize it – this may not be want you want for your pet, but it is better than releasing it
        into the wild.

References:

Florida Fish and Wildlife Conservation Commission – nonnative marine species
        http://myfwc.com/wildlifehabitats/nonnatives/marine-species/lionfish

Florida Sea Grant
        http://www.flseagrant.org/component/content/article/2-uncategorized/92-lionfish

Green S., I. Cote (2009), Consumption Potential of Invasive Lionfish (Pterois volitans) On
       Caribbean Reefs, Proceedings of the 62nd Gulf and Caribbean Fisheries Institute,
       November 2-6, Cumnana Venezula, pp. 358-359.

Hoese, H.D., R.H. Moore (1977), Fishes of the Gulf of Mexico, Texas A&M Press, College
       Station TX, pp. 327.

Smithsonian Marine Station at Ft. Pierce Florida
       http://www.sms.si.edu/irlspec/Pterois_volitans.htm

Unites States Geological Survey – Nonindigenous Aquatic Species
        http://nas.er.usgs.gov/queries/FactSheet.apex?speciesID=963

University of Florida IFAS Extension, EDIS Document #WEC308 – Options for Unwanted
       Exotic Pets, http://edis.ifas.ufl.edu/uw353

University of Wisconsin-Lacrosse
       http://bioweb.uwlax.edu/bio203/s2008/ouvard_mich/nutrition.html
       http://bioweb.uwlax.edu/bio203/s2008/ouvard_mich/reproduction.html