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The Marine Colonizers: Lionfish

December 3, 2025

Introduction:

As I scrolled through YouTube to look for something to watch, I came across a Short (the term for the vertical, short-form video format on YouTube). The short was of a free diver swimming through a kelp forest and using a tool to scoop up all the sea urchins into a gigantic net. For some reason, I was instantly mesmerized by the video. I think it’s because 1) I think the ocean is awesome, and 2) the sounds of the video felt almost like ASMR. I went down the rabbit hole that day and watched the rest of this user’s content (sea urchin harvesting). There was something so satisfying about watching him gather a netful of sea urchins and use his tool to crack one open for the nearby fish. It appears the diver and the native fish have developed a symbiotic relationship: the fish leads the diver to the sea urchins, and the diver opens sea urchins for the fish to feast on. Watching all these videos made me wonder, “Is this really the only way we can control sea urchin populations, and what happened that caused the situation to get this bad?”

I knew for a long time about the lionfish problem. Funnily enough, YouTube started recommending lionfish videos to me. The diver uses a harpoon to impale lionfish and then places them in a bin. So then that made me think, “Is gathering these invasive species the only method of managing their populations?” It doesn’t seem that effective to me.

How are lionfish so successful as invasive or non-native species?

Background

Lionfish, Pterois miles and P. volitans, are native to the warm waters of the Indian and Pacific Oceans, and were introduced to South Florida’s coastal waters about 30 years ago (Norton & Norton, 2021). These fish are actually the first non-native marine fish introduced to the US’s Atlantic Coast and the Caribbean (Morris and Akins, 2009). They were common reef predators in the Indian and Pacific Oceans, so, with no predators to keep their populations in check, South Florida’s Atlantic coast provided the perfect conditions for these lionfish to thrive (Norton & Norton, 2021). Climate change also plays a role in the rise of lionfish in the Atlantic Ocean: the increase in ocean temperatures extends the lionfish territories north and south (Norton & Norton, 2021). Another leading cause of the success of lionfish establishing their populations is believed to be their broad diet, making them ecological generalists (Côté and Smith, 2018). From 2004 to 2010, lionfish populations rose drastically, increasing from 23% to 40% of the total predator biomass in the ecosystem (Green et al., 2012). By studying lionfish stomach content, researchers have found that “90% of the prey consumed by lionfish were small-bodied reef fishes from 42 species. Between 2008 and 2010, the combined body mass of these 42 species declined by 65%” (Green et al., 2012).

Control Efforts

Lionfish’s venomous spines provide effective protection against predators, but lionfish control programs have started across the Caribbean, which may successfully reduce the effects of lionfish at local scales within high-priority areas, such as Marine Protected Areas and fish nursery habitats (Green et al., 2012). The most common form of lionfish control is culling by locals or during organized tournaments (Côté and Smith, 2018). Numerous studies have shown that regular culling at target sites could significantly reduce populations and promote the recovery of native prey populations (Côté and Smith, 2018). Lionfish sizes have decreased due to targeted culling in various regions (del Rio et al., 2023). Unfortunately, not only is culling costly and physically demanding, but for culling to be effective, the amount of lionfish removed must be high: e.g., “35-65% annually at large spatial scales” (Côté and Smith, 2018). Another mitigation strategy is found in gastronomy—we collect lionfish recreationally or commercially for human consumption (Côté and Smith, 2018). It turns out, lionfish are delicious and nutritious (Morris et al., 2011b). Unfortunately, relying on native predators, particularly big groupers, is insufficient in controlling lionfish populations (Côté and Smith, 2018). One reason is that native predators aren’t as abundant as they used to be, and so these populations don’t consume lionfish enough to be effective (Paddack et al., 2009; Sadovy de Mitcheson et al., 2013). Researchers have thought of training native predators to consume lionfish (Diller et al., 2014). However, further research has found that training predators is unrealistic, so low predation on lionfish isn’t due to native predators being unaware that they could consume lionfish, but because of lionfish’s defenses against predators (the venomous spines) (Côté and Smith, 2018).

Conclusion

Based on the existing research, I would argue that introducing or developing lionfish as a potential food source for humans could aid in controlling lionfish populations. I think it’s super important that we educate people about the environmental problems of non-native species inhabiting ecosystems, and the efforts we can make to restore balance. I would think that research in mitigating lionfish effects on ecosystems would help in further research of non-native or invasive species in other habitats too!

My attempt in drawing a lionfish! I’ve also labeled different parts of the fish.

 

Sources:

Côté, I. M., & Smith, N. S. (2018). The lionfish pterois sp. invasion: Has the worst‐case scenario come to pass? Journal of Fish Biology, 92(3), 660–689. https://doi.org/10.1111/jfb.13544

del Río, L., Navarro-Martínez, Z. M., Cobián-Rojas, D., Chevalier-Monteagudo, P. P., Angulo-Valdes, J. A., & Rodriguez-Viera, L. (2023). Biology and ecology of the lionfish                     pterois volitans/pterois miles as invasive alien species: A Review. PeerJ, 11. https://doi.org/10.7717/peerj.15728

Diller, J. L., Frazer, T. K. & Jacoby, C. A. (2014). Coping with the lionfish invasion: evidence that naïve, native predators can learn to help. Journal of Experimental Marine Biology and Ecology 455, 45–49.

Green, S. J., Akins, J. L., Maljković, A., & Côté, I. M. (2012). Invasive lionfish drive Atlantic coral reef fish declines. PLoS ONE, 7(3). https://doi.org/10.1371/journal.pone.0032596

Morris, J. A., & Akins, J. L. (2009). Feeding ecology of invasive lionfish (pterois volitans) in the Bahamian Archipelago. Environmental Biology of Fishes, 86(3), 389–398. https://doi.org/10.1007/s10641-009-9538-8

Morris, J. A. Jr., Thomas, A., Rhyne, A. L., Breen, N., Akins, L. & Nach, B. (2011b). Nutritional properties of the invasive lionfish: a delicious and nutritious approach for controlling the invasion. AACL Bioflux 4, 21–26.

Norton, B. B., & Norton, S. A. (2021). Lionfish envenomation in Caribbean and Atlantic Waters: Climate change and invasive species. International Journal of Women’s Dermatology, 7(1), 120–123. https://doi.org/10.1016/j.ijwd.2020.05.016

Paddack, M. J., Reynolds, J. D., Aguilar, C., Appeldoorn, R. S., Beets, J., Burkett, E. W., Chittaro, P. M., Clarke, K., Esteves, R., Fonseca, A. C., Forrester, G. E., Friedlander, A. M., García-Sais, J., González-Sansón, G., Jordan, L. K. B., McClellan, D. B., Miller, M. W., Molloy, P. P., Mumby, P. J., Nagelkerken, I., Nemeth, M., Navas-Camacho, R., Pitt, J., Polunin, N. V. C., Reyes-Nivia, M. C., Robertson, D. R., Rodríguez Ramírez, A., Salas, E., Smith, S. R., Spieler, R. E., Steele, M. A., Williams, I. D., Wormald, C., Watkinson, A. R. & Côté, I. M. (2009). Recent region-wide declines in Caribbean reef fish abundance. Current Biology 19, 590–595.

Sadovy de Mitcheson, Y., Craig, M. T., Bertoncini, A. A., Carpenter, K. E., Cheung, W. W. L., Choat, J. H., Cornish, A. S., Fennessy, S. T., Ferreira, B. P., Heemstra, P. C., Liu, M., Myers, R. F., Pollard, D. A., Rhodes, K. L., Rocha, L. A., Russell, B. C., Samoilys, M. A. & Sanciangco, J. (2013). Fishing groupers towards extinction: a global assessment of threats and extinction risks in a billion dollar fishery. Fish and Fisheries 14, 119–136.

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  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.