Red Lionfish

June 23, 2014 - AL.Com - More Lionfish off Florida and Louisiana Than off Alabama, but There are Plenty Here, Alex Fogg was interviewed by Ben Raines regarding lionfish in the northern Gulf.

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Photo credit: Primofish.com

Note: Pterois volitans and Pterois miles, a closely related sister species, were once thought to be a single species. It is difficult to distinguish between the two without DNA analysis. Pterois volitans is the more common in Atlantic and Caribbean waters, accounting for approximately 93% of the invasive lionfish population.

Description

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Red Lionfish, photo credit: Brian Gratwicke

The red lionfish is a scorpionfish in the family Scorpaenidae. They are conspicuous for their elongated feathery fins, bold patterning, and behavior. Adults reach a length of about 18.5 inches (47 cm) and a weight of 2.6 lbs. (1.2 kg). Like other scorpionfish, the red lionfish has has large feathery fins that protrude from the body, suggesting the mane of a male lion. Spiny projections on the head and venomous spines in the dorsal, anal and pelvic fins make the fish less desirable to potential predators. Numerous fleshy tabs on the head may mimic algal growth to camouflage the fish, and its mouth, from its prey. Lionfish have numerous small teeth on their jaws and the roof of the mouth that are adapted for grasping and holding prey.

While coloration varies, red lionfish are characterized by bold narrow vertical bands of red, maroon,or red-brown alternating with broader white or yellowish bands. The fins are spotted.

Male and female red lionfish are similar in appearance and show distinct traits only during courtship and breeding.

Red lionfish are slow-moving and behave as if they are extremely confident or indifferent to threats. They rely on their coloration, camouflage, and poisonous spines to deter predators. Adults are solitary and tend to remain in one location for long periods. They will fiercely defend their home range against other lionfish and other species. They congregate in small groups only as juveniles and during breeding season.

Lionfish have not been widely exploited as a commercial species, but are very popular as aquarium fish. Releases of aquarium fish who have grown too large may account for the introduction of lionfish into new areas.

In popular culture, fictional red lionfish have appeared in the aquarium of Captain Jean-Luc Picard's ready room in Star Trek: The Next Generation and in the aquarium of the villain who challenges James Bond in The Spy Who Loved Me.

Occurrence

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Red Lionfish, photo credit: U.S. Geological Service

The native range of the red lionfish is the western Pacific Ocean and Eastern Indian Ocean. The similar Pterois miles occurs in area between the Red Sea and Sumatra. Typical red lionfish habitat is described as near and offshore coral and rocky reefs to depths of about 165 feet (50 meters). However, in their natural range they also appear in shallow coastal and estuarine waters, with the highest population densities being in shallower inshore waters. Large adults have also been observed at depths of 1000' (300 meters) in the open ocean.

Lionfish are said to be primarily nocturnal, preferring to shelter under ledges or crevices during the day. However, daylight activity and feeding are also common.

Life Cycle & Reproduction

Lionfish have a prodigious reproductive capacity. They reach sexual maturity is less than a year and spawn year-round in warmer waters. Females can spawn as often as every three to four days. Females produce 15 to 30 thousand eggs per batch, so that a single fish in warm waters can produce as many as two million eggs per year.

During breeding, one male may associate with several females. The coloration of the male darkens and its stripes become less distinct, while females become paler. Spawning occurs near the surface with males immediately fertilizing the released eggs. The eggs hatch in about 36 hours and may spend 30 days in a pelagic stage, allowing them to disperse widely on ocean currents. This characteristic has facilitated the rapid expansion of their range in the Altantic and Caribbean. Larval fish are good swimmers and begin feeding on small ciliate protozoa just four days after conception. Juvenile fish grow rapidly, as much as 1 mm/day.

The typical red lionfish is thought to live for around 10 years, though captive specimens have survivied for as long as 35 years.

Feeding

The red lionfish is one of the apex predators in the coral reef environment and they are described as robust generalists in their feeding.  They consume small fish, shrimp, crabs, and other invertebrates, typically smaller than 4 inches (10 cm) in length. Lionfish feed in a solitary manner, approaching their prey slowly, finally seizing it in a lightning quick lunge and snap of the jaws, and swallowing it whole.

Lionfish exhibit two interesting feeding behaviors. They spread their long feathery pectoral fins to form a visual barrier and herd small fish into a confined space so that they are easier to capture. Even more unusual is their use of water jets in capturing prey. The lionfish approaches the prey slowly and directs jets of water at the prey. There are two potential explanations for how this might benefit the lionfish. One is that the prey attempts to align itself with the moving water and is thus easier to capture and swallow head first. The other is that the turbulence of the water jet confuses the prey's sensory systems. A video of this behavior is available on the Inter-Research Science Center website.

Note: Pterois volitans and Pterois miles, a closely related sister species, were once thought to be a single species. It is difficult to distinguish between the two species without DNA analysis. Pterois volitans is the more common in Atlantic waters, accounting for approximately 93% of the invasive lionfish population in the Atlantic cost of the U.S. and the Caribbean.
Animated map of red lionfish report from 1985 through 2013.
Source: USGS, REEF, and NOAA via Gulf and Caribbean Fisheries Institute. Animated version from the REEF website.

The Lionfish Invasion

Dr. Mark Albins, who conducted a seminar on red lionfish at GCRL on October 10, 2013, described the red lionfish as "the perfect super-invader." Red lionfish reproduce rapidly, grow rapidly, disperse readily on ocean currents, tolerate a variety of habitats, and have few natural controls. Many species of fish and invertebrates that are preyed upon by invasive lionfish do not recognize the odd-looking newcomers as threats.

See the progress of the lionfish invasion from 1985 through 2013 in the animated map on the right.

Lionfish are thriving in their new range. They grow about one quarter larger than in their native range and their population densities can be five times greater.

It is thought that red lionfish arrived in the U.S. waters either by releases from hobbyist aquariums or in the ballast water of ships. The earliest reported sighting occurred in south Florida in 1985. They have spread at an astonishing rate along the U.S. east and Gulf coasts and throughout the Caribbean. The map of reported red lionfish captures on the right shows the rapid expansion of their invasive range from 1985 through 2013. Invasive lionfish populations have grown about 67% per year. Field experiments have shown that lionfish can quickly displace 80% of the native fish populations on coral reefs. The projected range includes all of the Gulf of Mexico, the Caribbean Sea, and the western Atlantic coast from North Carolina to Uruguay.

The red lionfish's sister species Pterois miles comprises about 7% of the invasive population. To date, Pterois miles occurs as an invasive primarily on the eastern seaboard of the U.S. Lionfish populations are established as far north as Cape Hatteras, and juvenile fish have been found in New York and Rhode Island. Low water temperatures during winter probably prevent the fish from overwintering in northern regions.

This lionfish invasion is raising major concerns about the impacts of red lionfish on native hard-bottom, mangrove, seagrass, and coral reef communities, and even on estuarine habitats. The concern is not only the direct predation of the lionfish on native fishes and competition with native fish for food sources, but cascading effects throughout the entire ecosystem. For example, what effect might a significant reduction in the number of cleaner fish have on fish populations who depend on them? How will corals fare if lionfish remove a significant portion of the herbivorous fish whose feeding helps keep seaweeds and algas from overgrowing the corals?

Predators and Natural Controls

Few natural predators of red lionfish have been documented, even in their natural range. It is not well understood how lionfish populations in their native range are kept in check. They appear to be less affected by external parasites than other fish, both in their native range and their invasive range. Within their invasive range, it is likely that sharks and other larger piscivorous (fish eating) fish have not yet recognized lionfish as prey. However, it is encouraging that lionfish have been found in the stomachs of groupers in the Bahamas.

Human control of invasive lionfish is not likely to provide an overall or long-term eradication or control option. However, it may be possible to control the population of lionfish in limited selected areas by regular removal efforts.

Defense Mechanisms & Danger to Humans

Scorpionfishes, including the red lionfish, earn their common name with their ability to defend themselves with a sting or stab from venom delivered via spines in their fins. Lionfish are among the most venomous of all fishes. The red lionfish have venomous spines in their dorsal, anal and pelvic fins. Lionfish should be handled carefully; an envenomation is a serious medical issue.

In humans, the venom causes intense pain and inflammation. Serious systemic symptoms such as respiratory distress, abdominal pain, seizures, and loss of consciousness may also occur. A lionfish “sting” is rarely fatal, though some people are more susceptible to the venom than others. One source suggests that scorpionfishes as a group rank second only to stingrays in total number of envenomations, with 40,000 - 50,000 instances per year.

NOAA recommends treating a puncture wound by immersing the wound area in hot water (Other sources suggest 113° F or 45° C.) for 30 to 90 minutes as first aid, followed by prompt attention from a medical professional. The Poison Help Hotline at 800.222.1222 may provide further information.

Details on recognizing, collecting, and handling lionfish are provided in this flyer.

Resources, References, Photos, and Videos

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GCRL is conducting a Bounty Program to obtain research specimens of red lionfish. The link offers details.