Meghan Pearson
May 1, 2019
The presence of the lionfish, any species of a tropical fish belonging to the genus Pterois, is a major ecological problem that plagues the Caribbean today. An invasive species, lionfish have adapted fairly well to the Western Hemisphere, and are more abundant in the Caribbean than in their native Indo-Pacific Ocean.[1] They are a relatively recent threat. Some have cited that they arrived in 1992 after Hurricane Andrew caused boats transporting them to capsize.[2] In 2012, Trinidad and Tobago was the last country in the Caribbean to be invaded by the lionfish, and today they are found as far north as North Carolina and as far south as Brazil. [3]
Lionfish have few natural predators, mature and reproduce relatively quickly, and have a broad diet, all factors that have led to their proliferation. If they are not predators to a native fish species, they will outcompete them for food. In fact, through the food web, the lionfish’s depletion of select native species exerts an indirect effect on the populations of other marine species. Lionfish proliferation thus threatens the survival of endangered species but also threatens reef health since it depletes fish that are essential to maintaining the health of reef ecosystems. Lionfish also compete for food with larger fauna such as sharks and rays. [4] In the same manner, the lionfish is also a threat to fisheries in the Caribbean, as well as to tourism because fishing is a common activity for tourists in some areas.[5]
Since the scale of the lionfish proliferation is unprecedented for an invasive species in the Caribbean, the process to remove them has been extraordinarily difficult. Lionfish have been observed in the stomachs of large grouper, suggesting that they might be one its few predators. The problem is that even though groupers are likely to make the overall effect of lionfish less damaging, their populations are also depleting due to overfishing.[6] Thus governments have to monitor overfishing in addition to the lionfish threat. This interplay of overfishing and the destruction of marine ecosystems by lionfish is all the more reason for groups in the Caribbean to make a more conscious effort to stop lionfish proliferation.
Fishing derbies and culling have been implemented in various countries in the Caribbean in the last five years to combat the lionfish threat.[7] Culling is the intentional removal of individuals from a population, and in practice has historically been applied to invasive species.[8] They are selective in nature and avoid the problem of catching other endangered fish through bycatch. Derbies are essentially incentivized culling competitions. They take place in a single day and invite members of the general public to catch and remove as many lionfish as possible. These fish are measured and winners are awarded monetary prizes for the largest fish, the most fish or some other metric. These prizes are an incentive for people to attend derbies, which help garner the public participation that is essential for these efforts to be successful.[9] Efforts to remove lionfish from the waters of the Caribbean as soon as possible are necessary as Green et. al. found that reductions in lionfish density anywhere from 25 to 95 percent will be needed to bring lionfish down to levels where they would not overconsume other species of fish.[10]
Current areas in the Caribbean where lionfish derbies are common include South Florida, where derbies are hosted year-round by Reef Environmental Education Foundation.[11] Jahson B. Alemu writes that lionfish derbies have also been implemented in Trinidad and Tobago.[12] A map included by Malpica-Cruz et. al, shows that between 2010 and 2015, lionfish derbies have occurred in the Yucatán Peninsula, Belize, Costa Rica, Panama, and Venezuela. Their study also indicates that derbies have also occurred on the island nations of the Dominican Republic, Barbados, the Virgin Islands and the Bahamas during this time.[13] Efforts should be made to expand lionfish derbies beyond mainland nations and into island nations more.
These derbies are also important because they can provide data for research on lionfish population levels and densities, and improve public awareness of the lionfish problem.[14] These competitions can also serve as an opportunity to educate local communities about the lionfish threat. For example, some derbies make participants attend mandatory meetings on lionfish ecology and collecting and handling techniques. Attendees can taste samples of cooked lionfish, and ask questions about the animal.[15] Organizers see these methods as a way to dispel popular myths, one being that lionfish are not edible.
An increasingly popular usage for the lionfish that is connected to the derby is to serve it as a food. This is an attractive option because, as mentioned previously, the lionfish preys on native fish species that are caught by Caribbean fisherman and sold to people on their islands for food. However, lionfish have venomous spines, which is scary to many people who believe that if they ate a lionfish they would be ingesting the venom as well. The venom is only dangerous if injected, and cooking the fish can deactivate the venom. Another issue around creating a lionfish fishery is that lionfish meat available for consumption is currently available seasonally and is generally hard to find.[16]
One factor that matters in efforts to remove lionfish is location, more specifically, depth. Lionfish are more likely to be culled in shallow reefs than on deeper reefs, because derbies rely on recreational divers, and divers are not allowed to go deeper than 30m in most cases.[17] Shallow water culling efforts are important because settlement of eggs and larva are thought to occur in mangroves, seagrass beds, and shallow reef environments.[18] However, lionfish can still be found in Mesophotic Coral Ecosystems, which are reefs 30-150 m in depth.[19] In fact, Andradi-Brown et al shows that lionfish abundance does not portray an overall difference between shallow and mesophotic depths at invaded sites, so there is essentially an entire population of lionfish that has the potential to be removed, but is not targeted in removal efforts.
Time since invasion is another factor researchers have been investigating in the lionfish epidemic, and this intertwines with the variables of location and lionfish size. Andradi-Brown et al found that as time since invasion increases in an area, larger fish can be found at deeper depths and smaller fish can be found in the shallows.[20] Thus, the largest fish, and perhaps the most vociferous, are to be found in deeper depths of waters for areas that were invaded longer ago.
However, Andradi-Brown et al also suggests that larger lionfish can be found in shallow areas if a short amount of time following the original invasion has passed. For example, they said that in Puerto Rico, the largest lionfish were found in the shallow waters, which makes sense as only two years had passed in between the time in which the study was conducted and the time of invasion. They said that, “We found a negative correlation between time since invasion and the SMD (Standardized Mean Difference) in lionfish body length, suggesting this short time since invasion explains why we did not find larger lionfish at mesophotic depths in Puerto Rico.”[21] This again emphasized that time since invasion is an important factor. It points out that culling at shallow depths can be more acceptable and effective in areas that were recently invaded, rather than in areas that were invaded longer ago.
However, Malpica-Cruz et al found that, when it comes to holding culling derbies in areas that were invaded earlier rather than in areas that were invaded more recently, it would be more efficient to focus culling efforts on areas that were invaded earlier. Lionfish catch is higher in areas that were invaded a longer time ago rather than in areas that were invaded more recently because the lionfish density is lower in the areas that were invaded recently.[22] Malpica-Cruz et. al points out that these results may indicate that lionfish derbies in areas where they have recently arrived are less efficient because they give lower yields. Derbies may not be an efficient usage of time and resources in areas that were invaded more recently, but it is worth it to hold derbies in areas where the lionfish problem is more pressing.
The methods used by participants in culling derbies, as well as their backgrounds have been shown to affect culling efforts. Malpica-Cruz et. al performed a case study on lionfish derbies and the methodologies used and found that regular culling, through spear-fishing or hand-netting is effective, but time consuming.[23] These methods also appear to be more selective and effort intensive.
Andradi-Brown et al suggests that to deal with the lionfish problem, a syncretic approach is warranted. They write:
With increased interest from technical divers combined with technological development in lionfish traps, it is becoming possible to incorporate deeper culling depths into lionfish management programs. In addition, if mesophotic lionfish populations are dependent on lionfish recruitment in shallow marine habitats for new individuals, then infrequent deep reef culling combined with intense regular shallow culling could be sufficient to reduce the overall population and maximize the chances of complete localized eradication where culling intensity is sufficient.[24]
Technology needs to be developed that allows culling to happen at deeper depths where there are still large populations of lionfish. They also point out that lionfish populations at deep depths and shallow depths do interact, and can switch locations. This should serve as a reminder that lionfish derbies should continue to maintain shallow lionfish culling operations and deeper culling operations simultaneously. When these two processes are used together, in the degree that is most effective for the area that they are applied in, resources can be used efficiently and lionfish can be culled.
Regarding the influence of background on culling efforts, one surprising result Malpica-Cruz et al found in their study was that derbies that consisted mostly of artisanal fishers had the lowest catches. This ran counter to their expectations that they would have the highest catches. Derbies dominated by the general public and recreational divers, by contrast were more effective in catching lionfish.[25] They suggest that this was the case because artisanal fishers prefer to catch lionfish by free-diving, and recreational fishers prefer to SCUBA dive. This means that artisanal fishers are not able to go to the depths that recreational fishers who have the SCUBA equipment are able to dive to, and are also not able to stay underwater as long as SCUBA divers are able to.
The efficiency that recreational SCUBA divers are able to put forth makes sense as Andradi-Brown et. al found that lionfish tend to be larger on mesophotic reefs than on shallow reefs. Even though recreational divers are unable to dive to the depths of mesophotic reefs, lionfish probably increase in size at deeper levels. They theorize that this is because lionfish tend to move to the deeper reefs as they mature. It is also possible for lionfish eggs and larva can move to deeper areas below culling limits.[26] Thus, while participation is important, so it the ability for participants to go to great depths and to stay underwater for longer periods of time so that greater amounts of larger lionfish can be caught.
Andradi-Brown et. al points out that culling as a form of environmental management relies on volunteer recreational divers and that they can only go to shallow depths. However, even though it is established that volunteers who can SCUBA and go to greater depths would be the most effective divers, most volunteers would probably not fit this criteria. This makes sense as many people in the Caribbean are probably not able to afford SCUBA certification, much less the equipment. Some may not be interested in learning how to SCUBA. A solution would be to encourage programs where locals could learn swimming, water safety skills and how to SCUBA dive so that they could participate in lionfish management efforts. It would also be effective to get tourists who are already SCUBA certified to come to the islands and participate in culling derbies. Today, the Barbados tourism industry markets deep sea fishing tours and coastal tours where tourists can catch barracuda, tuna, wahoo, dolphin and blue and white marlin.[27] Assuming that other islands in the Caribbean have similar tourism programs, it would be a reasonable transition to promote and market recreational lionfish culling to vacationers, especially if they are already SCUBA certified.
To combat the growing ecological threat that lionfish pose to the Caribbean environment and possibly to tourism, a few suggestions are laid out for existing culling derbies and programs. Culling efforts should be concentrated in areas that were invaded earlier, because population densities of lionfish tend to be higher in those areas, so more individuals should be caught. However, it is important to introduce culling derbies to the areas that were invaded recently to curve lionfish populations before they proliferate to levels seen in the more dense areas. These efforts need not be as intense as the efforts in areas that were invaded earlier. In these recently invaded areas, culling at shallow depths should be emphasized as opposed to in areas that were invaded earlier. The technology and expertise needed to remove lionfish at deeper depths should be explored and invested in. Regarding the methodology used to cull lionfish, it is advisable not just to rely upon artisanal and professional fishers but to invest in the general public as well. SCUBA divers are useful because they can swim to deep depths and stay underwater for longer periods on time than free divers can. SCUBA diving should be marketed to people who live in areas bordering the Caribbean, as well as to tourists to increase the manpower and interest that exists in recreational lionfish fishing. Lionfish meat should also continue to be marketed to the public and could possibly become an export product, so that there is another incentive beyond monetary prizes for people to hunt lionfish.
All hands on deck are needed to combat the lionfish threat as it involves the sea, the one element that connects the diverse peoples and animals of the Caribbean together. All of the islands of the Caribbean are connected in that they face this common problem, so they should not hesitate in assisting each other.
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Bibliography:
“2019 Lionfish Derby Series.” REEF. Accessed 3 May 2019. https://www.reef.org/2019-lionfish-derby-series
Alemu I., Jahson B. “The status and management of the lionfish, Pterosis sp. In Trinidad and Tobago.” Marine Pollution Bulletin, 109. (2016): 402-408.
Andradi-Brown, Dominic A., Mark J. A. Vermeij, Marc Slattery, Michael Lesser, Ivonne Bejarano, Richard Appeldoorn, Gretchen Goodbody-Gringley, Alex D. Chequer, Joanna M. Pitt, Corey Eddy, Struan R. Smith, Eran Brokovich, Hudson T. Pinheiro, M. Elliott Jessup, Bart Shepherd, Luiz A. Rocha, Jocelyn Curtis-Quick, Gal Eyal, Timothy J. Noyes, Alex D. Rogers and Dan A. Exton. “Large-scale invasion of western Atlantic mesophotic reefs by lionfish potentially undermines culling-based management.” Biological Invasions, 19. (2017): 939-954.
Arias-González, Jesùs Ernesto et. al. “Predicted Impact of the Invasive Lionfish Pteros volitans.” Environmental Research, 111. (2011): 917-925.
“Barbados Fishing Operators.” Go Barbados. https://barbados.org/fishing.htm#.XMx0HRNKi8U
Green, Stephanie J., Nicholas K Dulvy, Annabelle M. L. Brooks, John L. Atkins, Andrew B. Cooper, Skylar Miller and Isabelle M. Coté. “Linking Removal Targets to the Ecological Effects of Invaders: A Predictive Model and Field Test.” Ecological Society of America, 24. (2014).
“Lionfish Derbies.” https://www.reef.org/lionfish-derbies
Malpica-Cruz, Luis, Laís C.T. Chaves, Isabelle M. Côté. “Managing Marine Invasive Species Through Public Participation: Lionfish Derbies as a Case Study.” Marine Policy, 74. (2016): 158-164.
McDermott, Amy. “Invasive Lionfish are Delicious- But is it Safe to Eat Them?”Oceanea. Last modified 21 June 2017. https://oceana.org/blog/invasive-lionfish-are-delicious-%E2%80%94-it-safe-eat-them-6
Mumby, Peter J., Alastair H. Harborne and Daniel R. Brumbaugh. “Grouper as a Natural Biocontrol of Invasive Lionfish.” Plos One 6, no. 6 (2011): Accessed 3 May, 2019. https://journals.plos.org/plosone/article/file?id=10.1371/journ
[1] Andradi-Brown, Dominic A. et. al. “Large-scale invasion of western Atlantic mesophotic reefs by lionfish potentially undermines culling-based management.” Biological Invasions, 19. (2017): 949.
[2] “Invasion of the Lionfish,” Smithsonian.com
[3] Jahson B. Alemu, 402
[4] Arias-González et al 921.
[5] Ibid
[6] Peter J. Mumby et al. “Grouper as a Natural Biocontrol of Invasive Lionfish.” Plos One 6, no. 6 (2011): Accessed 3 May, 2019.
[7] Jahson B. Alemu I. “The status and management of the lionfish, Pterosis sp. In Trinidad and Tobago.” Marine Pollution Bulletin, 109. (2016): 402.
[8] Malpica-Cruz et al, “Managing Marine Invasive Species Through Public Participation: Lionfish Derbies as a Case Study.” Marine Policy, 74. (2016):160
[9] “Lionfish Derbies”
[10] Green et al. “Linking Removal Targets to the Ecological Effects of Invaders: A Predictive Model and Field Test.” Ecological Society of America, 24. (2014).
[11] “2019 Lionfish Derby Series.” REEF
[12] Alemu, 402.
[13] Malpica-Cruz et al, 161
[14] Malpica-Cruz et al, 159.
[15] “Lionfish Derbies”
[16] Amy McDermott. “Invasive Lionfish are Delicious- But is it Safe to Eat Them?””
[17] Andradi-Brown et al, 939
[18] Andradi-Brown, 950
[19] Ibid., 939
[20] Andradi-Brown et. al, 947
[21] Ibid.
[22] Malpica-Cruz et al., 161
[23] Luis Mapica-Cruz et al., 159
[24] Andradi-Brown, 951
[25] Luis Malpica-Cruz et al., 160
[26] Andradi-Brown, Dominic A. et. al. “Large-scale invasion of western Atlantic mesophotic reefs by lionfish potentially undermines culling-based management.” Biological Invasions, 19. (2017): 948.
[27] “Barbados Fishing Operators”