Bonaire – Invasive Species

 

Pro-active Approach to Combat the Invasion of the Indo-Pacific Lionfish by the Bonaire National Marine Park

The Challenge
The invasive Indo-Pacific lionfish (Pterois volitans and Pterois miles) was first reported in Bonaire’s waters in 2009 and has since become firmly established. Nowadays, it is common for divers on Bonaire’s reefs to encounter this invasive species. This issue is far from being an isolated problem; in less than a decade, lionfish have become established along the Southeast U.S and the Caribbean and are now expanding into the Gulf of Mexico and South America. Lionfish are not only established, they are thriving, and have surpassed some native species in certain locations. The lionfish invasion, which many believe is to blame on aquarium enthusiasts releasing unwanted lionfish, is reported as one of the most rapid invasions in history. Several factors have contributed to the proliferation of lionfish: the lack of natural predators in their invasive range, their generalist diet, their ability to adapt to many habitats and their prolific rate of reproduction.

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Hunting lionfish at night. © Andre de Molenaar

By competing with native species for food or space, invasive species can cause important changes to the physical environment, as well as lead to the irreversible extinction of native species. Invasive species are especially an issue for island environments where native species have evolved in isolation and are more vulnerable to introduced predators. Lionfish are a major threat to reef ecosystems because they decrease the survival of a wide range of native reef animals via both predation and competition.  They can also trigger an increase in algal growth by preying on ecologically important herbivore species that keep seaweeds and macroalgae from overgrowing corals. This is of great concern for Bonaire’s reefs, which are some of the most diverse and healthiest in the Caribbean region. The presence of lionfish is also an important concern for Bonaire’s economy, as it has the potential to drastically reduce local fisheries as well as affect revenue from the tourism industry. Additionally, lionfish pose a risk to the health and safety of visitors, locals, and park staff, due to their venomous spines that can inflict a painful sting and result in serious health complications.

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Lionfish are caught by spearfishing. © Bas Tol

Actions Taken
Faced with the arrival and rapid population growth of the lionfish, the Stichting Nationale Parken Bonaire (STINAPA Bonaire), a nongovernmental organization that manages the Bonaire National Marine Park, quickly sprang into action to curb the invasion and protect native fish communities within the Bonaire National Marine Park. Because of the nature of the lionfish invasion, notably the mobility of the species and the high level of human resources required, the complete eradication of the species is a goal that cannot realistically be attained at present. The aim is therefore to actively control population numbers of the invasive species through periodic and repeated removal efforts, reducing the population of lionfish to a level where the impact on native reef fish communities is minimized and the spread of lionfish to previously unoccupied areas is diminished. The removal program is based on volunteers using spear guns, as the experience in the Bonaire National Marine Park has been that spear guns are the best technique to collect lionfish. While spearfishing is illegal in Bonaire, participating volunteers are provided with special permits allowing the spearing of lionfish using Eradicate Lion Fish (ELFs) by local authorities.

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Volunteer collecting lionfish. © Jan Veenendaal

So far, around 300 local volunteers have been trained and licensed by STINAPA Bonaire to hunt and kill lionfish. Marine Park rangers conduct lionfish workshops for volunteers or visitors who are interested in helping to remove the fish, focusing upon how to safely catch and remove them. A core group of about 30 hunters remove hundreds of fish every week. STINAPA’s Junior Rangers are also involved in the program. All Junior Rangers have received lionfish education while those over the age of 18 have received training on lionfish removal. These Junior Rangers are not only helping with the removal of lionfish but are also helping instill amongst the youth of Bonaire an understanding of the threat that lionfish pose and the need for a pro-active approach.

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Results of volunteer lionfish collecting. © Larry Holling

STINAPA Bonaire has also established a number of important partnerships. They collaborate with Bonaire’s Council on International Educational Exchange Research Station (CIEE ) to ensure that lionfish data are processed and analyzed. So far, more than 5,000 lionfish have been handed off to CIEE, with research focusing on vital statistics such as the size and weight of lionfish, sexual maturity, feeding preferences, and habitat and depth preferences. STINAPA also partners with the Dutch Caribbean Nature Alliance (DCNA) to hold workshops to educate dive operators as well as the general public on why and how to control lionfish. STINAPA and DCNA have jointly developed an innovative tool for lionfish control: a smart phone app whereby Bonaire’s lionfish hunters can add the location and details of lionfish caught, escaped, or seen during a dive, and this data can be viewed on a live map. The goal is to create a centralized location for all collected data in order to show the complete picture to anyone interested.  

How Successful Has it Been?
A study took place in 2011 to determine the effectiveness of lionfish removal efforts within the Bonaire National Marine Park. Differences in the density and biomass of lionfish were compared between areas in which lionfish were directly targeted during removal efforts and areas where they were not. Results showed that the local density and biomass of the invasive lionfish in fished locations on Bonaire is 2.76 times lower than in unfished areas. This study therefore shows that continued removal efforts are effective at reducing the local density and biomass of invasive lionfish. It also shows that using volunteer divers is an effective means in controlling lionfish populations, as large quantities of lionfish are being removed. However, these lionfish removal efforts can only target areas that can easily be accessed by divers, and a number of hard to access sites are not being controlled. In 2013, Bonaire’s deep reef was explored as part of the Bonaire Deep Reef Expedition; lionfish were observed as deep as 165 meters. Therefore, unless lionfish in these hard to access areas can be targeted, the effects of removal efforts will continue to be offset.

STINAPA Bonaire’s partnerships for this project have been a huge success. The thousands of lionfish that have been analyzed by the CIEE research station now represent one of the largest, in-depth and most long-term lionfish datasets in the Caribbean. Thanks to the research carried out on lionfish, managers of the Bonaire National Marine Park can better forecast the impact that lionfish will have on native fish populations and therefore develop more effective management plans. The research has also been a key asset in educating both Bonaire’s local population and visitors about the invasion. Research findings are shared via articles in newsletters and on social media, as well as through public lectures. They are also shared with Bonaire’s youth through lectures and hands-on workshops in local schools.

Lessons Learned and Recommendations
Lessons learned and key recommendations include:

  • Due to the nature of the lionfish invasion, a larger community effort is needed to increase the chances of more successful removal.
  • Setting up an efficient research program is crucial to the successful management of lionfish. Data on lionfish within the infested marine environment will help resource managers make informed decisions.
  • Extensive research on the subject at hand is also vital in explaining and gaining the trust of local stakeholders. If they see that research clearly supports community needs, they are more likely to comply with it.
  • Monitoring (pre- and post- infestation) is essential to assess the extent of the infestation so that management strategies can be adapted to respond to the level of threat.
  • A well-informed community is key in the fight against invasive species.
  • Due to the highly mobile nature of the lionfish invasion, complete eradication of the species is extremely difficult. Efforts should instead focus on actively managing lionfish in island waters, controlling abundance as much as possible.

Funding Summary
The program costs USD $7-10,000 per year.

Lead Organizations
Stichting Nationale Parken Bonaire
Council on International Educational Exchange Research Station
Dutch Caribbean Nature Alliance

Resources
Read the Honduras Lionfish Case Study in the Reef Resilience Toolkit
Effectiveness of Lionfish Removal Efforts in the Southern Caribbean (PDF)
Invasive Indo-Pacific Lionfish Reduce Recruitment of Atlantic Coral-reef Fishes (PDF)
The Role of Volunteer Divers in Lionfish Research and Control in the Caribbean (PDF)
Biology, Ecology, Control and Management of the Invasive Indo-Pacific Lionfish (PDF)
Lionfish Management Guide (PDF)

Written by: Florence Depondt

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