Lionfish

Pterois is a genus of venomous marine fish found mostly in the Indo-Pacific, known collectively as the lionfish. Pterois is characterized by red, white and black stripes, showy pectoral fins and venomous spiky tentacles.[1] [2] Pterois are classified into fifteen different species, but Pterois radiata, Pterois volitans and Pterois miles are the most commonly studied. Pterois are popular aquarium fish and are readily utilized in the culinary world.[1]

In the mid 1990s, the species P. volitans and P. miles were unintentionally introduced into the Atlantic Ocean and have become an invasive species along the East Coast of the United States.[2]

Morphology and Behavior
Pterois range in size from 6.2 to 42.4 cm with typical adults measuring 38 cm and weighing an average of 480 g.[2] [3] [4] They are well known for their ornate beauty, venomous spines and unique tentacles. [5] [6] Juvenile lionfish have a unique tentacle located above their eye sockets that varies in phenotype between species. [5] It is suggested that the evolution of this tentacle serves to continually attract new prey; studies also suggest that it plays a role in sexual selection [5].

Hazard to humans
Lionfish are known for their venomous tentacles; a feature that is uncommon among marine fish in the East Coast coral reefs. The potency of their venom makes them excellent predators and dangerous to fishermen and divers. [2] Pterois venom produced negative inotropic and chronotropic effects when tested in both frog and clam hearts <sup class="reference" id="cite_ref-g_6-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[7] and has a depressing effect on rabbit blood pressure.<sup class="reference" id="cite_ref-h_7-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[8] These results are thought to be due to nitric oxide release. <sup class="reference" id="cite_ref-f_5-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[6] In humans, Pterois venom can cause systemic effects such as vomiting, fever and sweating and has been lethal in a few cases. <sup class="reference" id="cite_ref-f_5-2" style="line-height: 1em; font-weight: normal; font-style: normal;">[6]

Prey
<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">According to a study that involved the dissection of over 1,400 lionfish stomachs from Bahamian to North Carolinian waters, Pterois prey mostly on small fishes, invertebrates and mollusks in large amounts, with some specimens’ stomachs containing up to six different species of prey <sup class="reference" id="cite_ref-c_2-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[3]. The amount of prey in lionfish stomachs over the course of the day suggest that lionfish feed most actively from 7:00-11:00 A.M., with decreased feeding throughout the afternoon. Lionfish are skilled hunters, using specialized bilateral swim bladder muscles to provide exquisite control of location in the water column, allowing the fish to alter its center of gravity to better attack prey <sup class="reference" id="cite_ref-c_2-2" style="line-height: 1em; font-weight: normal; font-style: normal;">[3]. The lionfish then spreads its large pectoral fins and swallows its prey in a singe motion. <sup class="reference" id="cite_ref-m_8-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[9] Tiger grouper (Mycteroperca tigris) have been shown to occasionally prey on Pterois, but these findings have been few and far between <sup class="reference" id="cite_ref-j_9-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[10]

<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">Pterois can live from five to fifteen years and have complex courtship and mating behaviors.<sup class="reference" id="cite_ref-m_8-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[9] Females release two mucus-filled egg clusters frequently, which can contain as many as fifteen thousand eggs. <sup class="reference" id="cite_ref-k_10-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[11] <sup class="reference" id="cite_ref-m_8-2" style="line-height: 1em; font-weight: normal; font-style: normal;">[9] Studies on Pterois reproductive habits are have increased significantly in the past decade.<sup class="reference" id="cite_ref-k_10-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[11]

Native waters
Pterois radiata is endemic to the Indian Ocean and Western Pacific <p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">The lionfish is a predator native to the Indo-Pacific. It aggressively preys on small fish and invertebrates. They can be found around the seaward edge of reefs and coral, in lagoons, and on rocky surfaces to fifty meters. They show a preference for turbid inshore areas and in harbors.<sup class="reference" id="cite_ref-l_11-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[12] Lionfish have a generally hostile attitude and are territorial towards other reef fish.<sup class="reference" id="cite_ref-n_12-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[13] Many universities in the Indo-Pacific have documented reports of Pterois aggression towards divers and researchers.<sup class="reference" id="cite_ref-n_12-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[13]

P. volitans and P. miles as invasive species
See also: Pterois volitans and Pterois miles <p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">Two of the fifteen species of Pterois, P. volitans and P. miles, have established themselves as significant invasive species off the East Coast of the United States and in the Caribbean. About 93% of the invasive population is P. volitans, also known as the Red Lionfish.<sup class="reference" id="cite_ref-13" style="line-height: 1em; font-weight: normal; font-style: normal;">[14]

Invasive introduction and range
<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">The red lionfish is found off the East Coast of the United States and the Caribbean Sea, and was likely first introduced off theFlorida coast in the early to mid- 1990s.<sup class="reference" id="cite_ref-14" style="line-height: 1em; font-weight: normal; font-style: normal;">[15] It has been speculated that this introduction may have been cause when Hurricane Andrew destroyed an aquarium in southern Florida,<sup class="reference" id="cite_ref-15" style="line-height: 1em; font-weight: normal; font-style: normal;">[16] It is also believed that six lionfish were accidentally released in Biscayne Bay, Florida after Hurricane Andrew in 1992. <sup class="reference" id="cite_ref-o_16-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[17] However, a more recent report states NOAA ecologist James Morris Jr. has discovered that a lionfish was discovered off the coast of south Florida prior to Hurricane Andrew in 1985.<sup class="reference" id="cite_ref-17" style="line-height: 1em; font-weight: normal; font-style: normal;">[18] <sup class="reference" id="cite_ref-18" style="line-height: 1em; font-weight: normal; font-style: normal;">[19] It is also believed that the lionfish were purposefully discarded by unsatisfied aquarium enthusiasts.<sup class="reference" id="cite_ref-o_16-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[17] The first documented capture of lionfish in the Atlantic occurred in Dania Beach, Florida.<sup class="reference" id="cite_ref-c_2-3" style="line-height: 1em; font-weight: normal; font-style: normal;">[3] In 2001, NOAA documented multiple sightings of lionfish off the coast of Florida, Georgia, South Carolina, North Carolina, and Bermuda, and were first detected in the Bahamas in 2004.<sup class="reference" id="cite_ref-19" style="line-height: 1em; font-weight: normal; font-style: normal;">[20] t is believed that Pteroiswere first introduced off the Florida coast by accident.

P. volitans comprises the largest part of the invasive lionfish population in the Atlantic and Caribbean <p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">Pterois volitans and Pterois miles are native to sub-tropical and tropical regions from southern Japan and southern Korea to the east coast of Australia, Indonesia,Micronesia, French Polynesia and in the South Pacific Ocean.<sup class="reference" id="cite_ref-l_11-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[12] Adult lionfish specimens are now found along the United States East Coast from Cape Hatteras, North Carolina, to Florida, and in Bermuda, the Bahamas, and throughout the Caribbean, including the Turks and Caicos, Haiti, Cuba, Dominican Republic, Puerto Rico, St. Croix,Belize, Honduras and Mexico.<sup class="reference" id="cite_ref-a_1-4" style="line-height: 1em; font-weight: normal; font-style: normal;">[2] Population densities continue to increase in the invaded areas, resulting in a population boom of up to 700% in some areas between 2004 and 2008.<sup class="reference" id="cite_ref-20" style="line-height: 1em; font-weight: normal; font-style: normal;">[21] Population densities have reached levels that are orders of magnitude greater than their native ranges.<sup class="reference" id="cite_ref-Williams_21-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[22]

<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">Pterois are known for devouring many other aquarium fishes.<sup class="reference" id="cite_ref-o_16-2" style="line-height: 1em; font-weight: normal; font-style: normal;">[17] Pterois are unusual in that they are among the few fish species to successfully establish populations in open marine systems.<sup class="reference" id="cite_ref-p_22-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[23]

<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">Pelagic larval dispersion is assumed to occur through oceanic currents, including theGulf Stream and the Caribbean Current. It is projected that currents could eventually result in new populations along the Gulf Coast.<sup class="reference" id="cite_ref-23" style="line-height: 1em; font-weight: normal; font-style: normal;">[24] Ballast water can also be attributed to the dispersal.<sup class="reference" id="cite_ref-24" style="line-height: 1em; font-weight: normal; font-style: normal;">[25]

<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">Extreme temperatures present geographical constraints in the distribution of aquatic species<sup class="reference" id="cite_ref-v_25-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[26], indicating that temperature tolerance plays a role in the lionfish’s survival, reproduction and range of distribution.<sup class="reference" id="cite_ref-u_26-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[27] Observational studies have shown that the abrupt differences in water temperatures north and south of Cape Hatteras directly correlate with the abundance and distribution ofPterois.<sup class="reference" id="cite_ref-v_25-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[26] Pterois expanded along the entire eastern coast of the United States and occupied thermal-appropriate zones within ten years.<sup class="reference" id="cite_ref-v_25-2" style="line-height: 1em; font-weight: normal; font-style: normal;">[26] Although the timeline of observations points to the east coast of Florida as the initial source of the western Atlantic invasion, the relationship of the United States East Coast and Bahamian lionfish invasion is uncertain. <sup class="reference" id="cite_ref-q_27-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[28]

Control and eradication efforts
P. miles makes up about seven percent of the invasive lionfish population in the Atlantic and Caribbean <p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">As the population densities of the invasive lionfish are increasing at drastic rates, attention has been called to the problem to at least keep the populations at bay. To completely eradicate the lionfish from its new habitats seems unlikely. A study from 2010 using population modeling used data collected about the known life history of the lionfish inhabiting the Caribbean coral reefs to figure out the best means of eradication. The study showed that the most effective way to even maintain current lionfish population densities, at least 27% of the invasive adult populations would have to be killed monthly. The fact that lionfish are able to reproduce monthly throughout the entire year means that this is an effort that must be maintained monthly for the maintenance of current population densities.<sup class="reference" id="cite_ref-Morris.2C_J.A._2011_28-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[29]

<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">Even to accomplish these numbers seems unlikely, but as populations of lionfish continue to grow throughout the Caribbean and Western Atlantic, actions are being taken to attempt to control the quickly growing numbers. In November 2010, the Florida Keys National Marine Sanctuary began to give out licenses to divers to kill lionfish inside of the sanctuary. This is the first time this has ever been done for any species in the sanctuary, in a desperate attempt to eradicate the fish. Rigorous and repeated removal of lionfish from invaded waters will be necessary to establish control on the exponentially expanding population.<sup class="reference" id="cite_ref-a_1-5" style="line-height: 1em; font-weight: normal; font-style: normal;">[2] Many conservation groups across the Eastern United States are organizing hunting expeditions for Pterois. The Environment Education Foundation recently hosted its third ‘lionfish derby’ in Florida, offering more than $3,000 in prize money for dive teams catching the most lionfish.<sup class="reference" id="cite_ref-s_29-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[30] Community organizations are forming across the country in hopes of halting the ever expanding lionfish population.<sup class="reference" id="cite_ref-s_29-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[30] Divemasters from Cozumel to the Honduran Bay Islands routinely spear Lionfish during dives, sometimes killing as many as eight in an hour. Based on average kills per dive, a professional diver could easily kill 3000 to 4000 Lionfish per year (3 dives per day, 6 days per week, averaging 4+ kills per dive).<sup class="Template-Fact" style="line-height: 1em; white-space: nowrap;" title="This claim needs references to reliable sources from May 2011">[citation needed]

<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">Other interest groups, such as NOAA, are setting up events and campaigns that encourage the killing and eating of the fish.<sup class="reference" id="cite_ref-Williams_21-1" style="line-height: 1em; font-weight: normal; font-style: normal;">[22] Many people are wary of the idea of eating a venomous fish, but when properly filleted the fish is perfectly healthy to eat. Encouraging the consumption of lionfish could not only help to maintain a reasonable population density, but also provide an alternative fishing source to other overfished populations, such as grouper and snapper. The Reef Environmental Education Foundation has even prepared a cookbook to help educate restaurant chefs on how they can incorporate the fish into their menu. The National Oceanic and Atmospheric Administration calls the lionfish a “delicious, delicately flavored fish” similar in texture to grouper.<sup class="reference" id="cite_ref-s_29-2" style="line-height: 1em; font-weight: normal; font-style: normal;">[30] Many recipes for lionfish can be found in coastal cookbooks, some including fried lionfish, lionfish ceviche, lionfish jerky and grilled lionfish.<sup class="reference" id="cite_ref-t_30-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[31]

<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">The invasiveness of the red lionfish is an extreme problem, and relatively little information is still known about the animal. The NOAA has research foci in place to better understand the fish and the implications surround its invasive nature. Some of these include investigating biotechnical solutions for control of the population, and understanding how the larvae are dispersed. Another important area of study is how the population is controlled in its native area. If we find out why it is not out of control in the Indo-Pacific, we may be able to implement a similar concept into the invasive populations, without causing unintended results such as another invasive species. NOAA also plans to further its “Lionfish as Food” campaign, as human hunting of the fish is the only known current form of control. The NOAA also encourages people to report lionfish sightings to help keep a better record of dispersal.<sup class="reference" id="cite_ref-NOAA_31-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[32]

Long term effects of invasion
<p style="margin: 0.4em 0px 0.5em; line-height: 1.5em;">Lionfish have successfully pioneered the coastal waters of the Atlantic in less than a decade and pose a major threat to reef ecological systems in these areas. They have become the second most abundant species of fish from the Bahamas to North Carolina, second only to the native scamp grouper.<sup class="reference" id="cite_ref-a_1-6" style="line-height: 1em; font-weight: normal; font-style: normal;">[2] This could be due to a surplus of resource availability resulting from the over-fishing of lionfish predators like grouper.<sup class="reference" id="cite_ref-r_32-0" style="line-height: 1em; font-weight: normal; font-style: normal;">[33] Although the lionfish has not expanded to a population size that is currently causing major ecological problems, their invasion in the United States coastal waters could lead to serious problems in the future. One likely ecological impact caused by Pterois could be their impact on prey population numbers by directly affecting food webrelationships. This could ultimately lead to reef deterioration and could negatively influence Atlantic trophic cascade.<sup class="reference" id="cite_ref-m_8-3" style="line-height: 1em; font-weight: normal; font-style: normal;">[9] It has already been shown that lionfish overpopulate reef areas and display aggressive tendencies; forcing native species to move to waters where conditions might be less than desirable.<sup class="reference" id="cite_ref-a_1-7" style="line-height: 1em; font-weight: normal; font-style: normal;">[2] Studies show that lionfish could be decreasing Atlantic reef diversity by up to 80%.<sup class="reference" id="cite_ref-n_12-2" style="line-height: 1em; font-weight: normal; font-style: normal;">[13]