Intrusive Lionfish Putting Our Ecosystem at Risk

Environmental crises are often extremely newsworthy events. Think Deepwater Horizon, Exxon-Valdez, the Love Canal, or even global warming. All of these were (and are) major headline-makers.

However, there is another brand of environmental crisis that is much harder to fit into a metonymic one-liner.

They are slow and insidious, and do not have a singular monolithic culprit like an energy company or industrial waste facility. These are the crises of ecological imbalance, and particularly, of invasive species introduction.

In the United States there are several keystone examples: zebra mussels in the great lakes, kudzu in the southeast, Burmese pythons in the Everglades. Most of these are representative examples of the law of unintended consequence. Zebra mussels were likely introduced via the ballast of ships traveling up the St. Lawrence [1]. Kudzu was shown at the 1876 Centennial Exposition in Philadelphia [2]. Burmese pythons (and several other large snake species) have been released by irresponsible collectors and have flourished and out-competed indigenous snake species.

Yet another ecological crisis knocks at Florida’s door, this time threatening the balance of the entire marine coastal ecosystem. This is the crisis of a tiny venomous kraken known as Pterois. You might better recognize it as the Lionfish.

What is Pterois?

Lionfish are most recognizable to Floridians for their inclusion in saltwater aquaria. They are an exotically beautiful relative of the rockfish, and have highly venomous spines pointing from their center in every direction. These spines result in few natural predators in their indigenous indo-Pacific distribution, and none in their developing home on the East Coast of the United States[3]. There are approximately ten to fifteen different species of Pterois in the world, but two are of particular concern as invasive species: P. volitans (Red Lionfish) and P. miles (the devil firefish).

Lionfish are relatively small reef fishes that belong to a venomous order known as “scorpaeniformes” or scorpionfish. They grow to about 15-20 inches and live up to ten years. The fact that they reproduce each month and have clutches of approximately 15,000 offspring make them incredibly effective at populating new areas. Animals that reproduce in such large quantities are known as r-strategists[4], and generally have a very low rate of offspring survival. However, the low known predation rate of lionfish could mean that (relative to other marine r-strategists) their populations grow at an incredibly high rate outside of their native range[5].

Lionfish are highly intelligent hunters that employ tactics such as distraction and shooting jets of water at prey in order to disorient them during predation. They are aggressive, and have even been observed displaying territorial behavior and defensiveness toward human divers. Their diet is highly varied and includes everything from small fishes to mollusks, making their potential impact on food webs particularly significant[6].

Their venom is usually deadly to other potential marine predators in the coral zone such as grouper and snapper, but it also poses serious risks to humans. Lionfish stings can cause extreme pain, nausea, vomiting, fever, convulsions, vertigo, paresthesia and even heart failure or death (most common among the elderly or very young) in human victims[7].

 

How and Why are they Invading Florida?

The precise vector by which lionfish were introduced to Florida and the east coast is in dispute, but there are a number of likely possibilities. As noted, lionfish are a common feature in saltwater aquaria, so it is speculated that they were introduced either by destruction of such aquaria during natural disasters, or by release from them by owners who no longer wished to care for the fish[8]. They are also potentially being introduced in ships’ ballast from indo-Asian cargo liners.

Regardless of how the lionfish were introduced, now that they are here their populations are exploding. In one four-year span (2004-2008), their population in some areas of the Floridian-Caribbean region grew up to 700%[9]. The fact that lionfish have few natural predators, combined with the fact that they reproduce at such a high rate has made them ideally suited for a hostile takeover of our coastal ecosystem.

In addition, their feeding habits stand to impact a number of different fisheries in a fashion that is difficult to numerically estimate. Lionfish diets are highly diverse meaning their presence will affect multiple areas of the existing coastal food web.

This could result in a huge trophic cascade that could fundamentally rewrite the operation of the coastal ecosystem of the Caribbean and eastern US. Given the importance of this ecosystem to a number of commercial fisheries such as red snapper, grouper, sponges, corals, swordfish and several other pelagic fish, the presence of the lionfish stands to impact the livelihood of many people in the eastern seaboard. The seriousness of the Pterois invasion cannot be overstated.

 

What Can be Done?

A few years ago a mathematical model was developed to help understand the significance of the Pterois invasion and what measures might be appropriate for controlling and/or mitigating it. The study determined that in order to instigate a decline in the lionfish’s presence there would need to be a removal of 27% of the extant invasive population – per month[10]. Further, the study suggested that the short reproductive cycle (essentially monthly) demanded that this effort be upheld indefinitely.

These numbers mean that population control purely via hunting and removal is unlikely. However, efforts from sportsmen exist and are supported by a number of different government and nonprofit agencies. Underscoring the significance of the danger posed by the lionfish, the Florida Keys National Marine Sanctuary issued permits to enter the sanctuary and kill lionfish, regardless of whether or not the hunter has a state-issued fishing license.

This move is unprecedented and marks a stark departure from previous wildlife management philosophy within the sanctuary[11]. On the First Coast, Brown’s Creek Fish Camp sponsors the North Florida Lionfish Blast, which has a $3250 purse. The tournament runs the month of April and has prize categories in most fish killed overall, as well as a two-day volume aggregate for the main contest.

While efforts to completely remove lionfish are probably an important component of managing this crisis, there may be some inherent dangers as well. Sarah Preston, a spokesperson from PETA, points out that any eradication efforts are a response to improper initial management of a resource (lionfish for the aquarium), and that humans should exercise compassion when dealing with living things. PETA recognizes the need for a robust response to the Pterois invasion, but advocates humane euthanasia.

There are concerns that the culture springing up around many eradication tournaments mischaracterizes the fish as evil parasites (the latter of which they are definitively not) rather than simply another byproduct of poor environmental stewardship on the part of coastal residents.

A biologist at the Army Corps of Engineers disagrees. He says that failing to engage the community of sportsmen in eradication efforts puts an unrealistic burden on state wildlife officials. Further, he argues, the PETA-advocated methods of live capture and immersion into a barbiturate require a great deal of time, likely making the necessary kill off quotas even more untenable. His position is that given the rate at which the fish proliferate, and the severely limited official personnel resources, a highly mandated and exclusively-professionally executed approach to euthanasia is unrealistic.

 

Out of the Frying Pan, Into the Firefish

The core of the issue is that because of human action and mismanagement we have the introduction of a highly effective invasive exotic colonist in Perois volitans and miles. These fish pose a major threat to the balance and structure of the coastal ecosystems of the American East, from the Caribbean up to North Carolina. It is imperative that we find a solution, but that is unlikely to be simply mechanically destroying the populations. We have to consider supplementary and alternate means of crisis management.

Of particular interest is the technique of integration. At the risk of repetition, ecosystems are all about balance. We have to consider that lionfish are now an unremovable part of the eastern coastal biome, and as such, it would be wise to seek ways to help the ecosystems rapidly adapt to the presence of the devil firefish.

In Nicaragua, several shark species in Roatan are being “trained” via controlled exposure to include lionfish in their predatory diet[12]. Lionfish are also showing up in an increasing number of culinary delicacy lists. Restaurants such as Haven in Houston, TX have partnered with environmentalists to create incredible Pteroic dishes and stimulate demand for the delicious, delicate flesh.

Creative efforts such as these might effectively offset both the environmental and economic dangers posed by lionfish to the Floridian plain and marine zone, but can also foster a culture of respect, rather than hatred of the animals.

Who knows? Maybe soon we’ll see a lionfish-shaped lure at C&H Lures and be able to order Lionfish Pad-Thai from a local seafood restaurant.

Written by Spencer Pitman


[1] Bossenbroek, Jonathan M., Clifford E. Kraft, and Jeffrey C. Nekola. 2001. PREDICTION OF LONG-DISTANCE DISPERSAL USING GRAVITY MODELS: ZEBRA MUSSEL INVASION OF INLAND LAKES. Ecological Applications 11:1778–1788.http://dx.doi.org/10.1890/1051-0761(2001)011[1778:POLDDU]2.0.CO;2

[2] Stewart, Doug. “Smithsonian.com.” Kudzu: Love It or Run. Smithsonian Institute, Oct. 2000. Web.

[3] Mark A. Albins & Mark A. Hixon (2008). “Invasive Indo-Pacific lionfish Pterois volitans reduce recruitment of Atlantic coral-reef fishes”. Marine Ecology Progress Series (Inter-Research) 367: 233–238. doi:10.3354/meps07620.

[4] Pianka, E.R. (1970). “On r and K selection”. American Naturalist 104 (940): 592–597. doi:10.1086/282697.

[5] Pterois DetailsEncyclopedia of Life. N.p., n.d. Web. <http://eol.org/pages/24659/details>.

[6] Cote, I.M., A. Maljkovie. 2010. Predation rates of Indo-Pacific lionfish on Bahamian coral reefs. Marine Ecology Progress Series 404:219-225.

[8] Schofield, P.J. 2009. geographic extent and chronology of the invasion of non-native lionfish (Pterois volitans and P. miles) in the Western North Atlantic and Caribbean Sea. Aquatic Invasions 4:473–479

[9] Whitfield, P.E., et al. 2007. Abundance estimates of the Indo-Pacific lionfish Pterois volitans/milescomplex in the Western North Atlantic. Biological Invasions 9:53–64.

[10] Morris, J.A., and Shertzer, K.A. 2011. A stage-based matrix population model of invasive lionfish with implications for control. Biological Invasions 13:7–12.

[11] “Lionfish Removal Permits.” Florida Keys National Marine Sanctuary. National Oceanic and Atmospheric Administration, n.d. Web. <http://floridakeys.noaa.gov/permits/lionfish.html>.

[12] Choi, Christy. “Taming the Lionfish: Can Predators Be Trained to Control Invasive Species?” Time 10 May 2011: n. pag. Time, Inc. Web. <http://www.time.com/time/health/article/0,8599,2070599,00.html>.