Lionfish: the perfect invader?
Fadilah Ali is an ecologist with a specialty in invasive species biology, control and management. She has a Masters degree in Environmental Science with a focus on Biodiversity and Conservation and is currently completing her PhD in Ocean and Earth Sciences at the University of Southampton in England where she researched the lionfish invasion in the Southern Caribbean.
As it glides past with its large, ornate, feathery pectoral fins, lionfish give the impression of a harmless beauty, simply floating by peacefully. Introduced to the Caribbean region more than two decades ago, lionfish have been deemed as one of the worst marine invasive species of all time, with potential to cause harm to local ecosystems, both ecologically and economically.
Native to the Indo-Pacific region, lionfish are a prime commodity within the aquarium trade owing to their beautiful, ornate patterns and majestic attributes. This popularity brought them to the Caribbean as a prized pet and unfortunately resulted in their unintentional introduction to Florida via aquaria releases. Once released, lionfish established reproducing populations and their gelatinous egg masses spread via ocean currents from Florida to further along the US coast and also to Bahamas and Bermuda and eventually the rest of the Caribbean. The confirmed introduction of lionfish to Trinidad and Tobago in 2012 represented the completion of their invasion loop and lionfish are now currently established within North, South and Central America, the Gulf of Mexico and all the islands of the Caribbean.
Lionfish, like many other invasive species are generalists meaning that they can survive in a variety of habitats (coral reef, mangrove, seagrass), at a vast depth range (<1m to >300m), have exceptional thermal and salinity tolerance and consume a wide variety of prey items. Lionfish cause their impact based on how they feed, and are successful because they possess multiple feeding strategies. Renowned for being principally piscivorous (consuming only fish), crustaceans (shrimps, crabs, lobsters) and also juvenile octopus and stingrays have been found in lionfish stomachs. By consuming the juveniles of economically important species such as snappers, groupers or lobster, lionfish can have a direct impact on future economies. Furthermore, lionfish consume ecologically important species such as herbivores which help to remove excess algae (e.g. parrotfish or damselfish) and cleaner species (e.g. cleaner wrasses, shrimps or gobies) which help to keep local predators free from disease. As a result lionfish feeding behaviours can indirectly affect the health of local ecosystems.
By relying on multiple feeding strategies, lionfish can capitalise on a variety of prey, but also outcompete native predators. They can use suction feeding and ambush predation, or use their large pectoral fins to herd prey or fan sand away from burrowed prey. They were recently discovered to blow jets of water at prey to disorient them and increase the chances of head-first capture, a successful feeding method. They also have the ability to endure bouts of starvation lasting as much as three months, owing to their ability to stretch their stomachs up to thirty times its original size, allowing them to consume prey two-thirds their own body size. The voraciousness of lionfish diets and their prey preferences appear to be related to native prey assemblages as well as the health of local ecoystems. Thus healthier, less disturbed environments may be more resilient to the threat of invasive species.
Lionfish learn from every failed removal attempt and in areas where hunting is predominant, lionfish have a higher flight time. Furthermore, they are increasingly being reported at high densities at depths exceeding recreational dive limits, making complete removal very difficult. Within their invaded region, lionfish have no natural predators meaning that their populations can grow unabated. Lionfish are prolific breeders and when they reproduce they can release ~10,000 eggs and this feat can be repeated every four days. This gelatinous egg mass then lies at the mercy of ocean circulation, highlighting the real difficulty of lionfish control. Management is only as successful as its weakest point of control, therefore there needs to be a dedicated and concerted effort from all those involved. No matter how well one country may control lionfish populations, if another country’s lionfish populations grow unabated, lionfish eggs will continue to be circulated.
Armed with venomous dorsal, ventral and anal spines, there is often the misconception that lionfish are poisonous and consumption of their meat can be fatal. However important differences exist between venom and poison. Venom has to do with injection (i.e. venom is injected when spines make contact with another object), whereas poison has to do with ingestion (i.e. consumption of food or drink). Furthermore the venom of lionfish is protein based; therefore the application of heat (e.g. through cooking) will denature the protein and render it harmless. Thus, since lionfish are venomous, their meat is perfectly safe for consumption and throughout the invaded region a market is being developed for lionfish as a food fish. Once their spines are removed, lionfish meat is similar to any other fish and is delicate, taking well to seasoning and can be manipulated into various cuisines, whether filleted, eaten whole or in tiny pieces. The possibilities are endless: lionfish pizza, sushi, sausages, burgers, tacos etc. There are multiple benefits of encouraging lionfish as a food fish. Firstly, overfished local species such as groupers, snappers or lobsters are bequeathed an opportunity to replenish their stocks when lionfish are used as an alternative. Furthermore, ecologically lionfish are more sustainable because of their fast generation time and growth.
|Lionfish sushi: E Sushi Shop, Aruba|
Lionfish jewellery L-R:
Oceana.org, Kaj Expressions Belize, Frapper Jewellery
Additionally, their spines and fins have been manipulated into beautiful works of art as well as various forms of jewellery such as lionfish earrings, necklaces, pendants, rings and even cufflinks. Utilising their spines in this way helps to raise the commercial value of landed fish by as much as 61% and in many countries throughout the invaded region, locals have been able to benefit financially from lionfish.
If you happen to see lionfish, please inform the Department of Marine Resources and Fisheries in Tobago at 639-4446; 639-4354 or dial 211 for the Contact Centre. If spotted in Trinidad, then contact the Institute of Marine Affairs at 634-4291/4, Ext 2406.
|Lionfish distribution: USGS|