Lionfish

Abstract:

The Indo-Pacific lionfish, Pterois volitans, has invaded most of the Tropical Western Atlantic in the last few years. The degree to which populations of this invasive species can be controlled by native predatory fish (mostly grouper), is controversial with conflicting reports. Here, we review the evidence of two recent papers and point out some of the difficulties in inferring predator-limitation purely from observational data. A negative relationship has been found between large-bodied grouper and lionfish during early colonisation though the degree to which this is caused by direct predation versus behavioural mechanisms is unclear. Evidence to the contrary from a recent study suffers confounding effects of habitat quality, fishing, and dispersal and therefore remains equivocal. 

The invasion of lionfish (Pterois miles and P. volitans) may prove to be one of the greatest threats of this century to warm temperate and tropical Atlantic reefs and associated habitats. As the first marine reef fish invasive species to this region, lionfish are changing the culture of how reef managers view invasive species, the regional connectivity of marine reefs, and their vulnerability to marine invasions.

The term “lionfish” is now as notorious as the other major invaders of the last century, such as Asian carp, kudzu, zebra mussels, and sea lamprey. Originally imported into the United States as a popular aquarium fish, the lionfish is now one of the most abundant top-level predators of many reefs. Lionfish pose a threat to the integrity of the reef food web and are capable of impacting commercial fisher- ies, tourism, and overall coral reef health.

Viewed in context with other reef stressors — such as land-based pollution, climate change, and overfishing — the lionfish invasion is distinguished by two obvious characteristics.

A RAPID, WIDESPREAD INVASION

The first outstanding characteristic of the lionfish invasion is that it has occurred rapidly across a wide geographic area. The initial confirmed lionfish sighting in the United States occurred in 1985, off Dania Beach, Florida. Some 15 years later, in 2000–2001, lionfish were identified as an established invader in the offshore waters of North Carolina, United States. At the time of this writing in 2012, lionfish are fully established throughout the Southeast United States, the Caribbean Sea, and much of the Gulf of Mexico. Lionfish are expected to reach the warm temperate reefs of South America soon.

BROAD DIET AND GENERAL HABITAT

The second pronounced characteristic of lionfish is their broad diet and general habitat preferences. Because of these factors, lionfish have the potential to affect the structure and function of many Atlantic marine communities — from the sea surface to depths exceeding 300 meters, and across habitats ranging from coral and hardbottom to artificial reefs, mangroves, and seagrass beds. For example, the high densities of lionfish observed in locations such as the Bahamas may be causing an abrupt change to the biodiversity and community structure of reef fish communities, and could constitute the most significant change since the beginning of industrialized fishing (Albins and Hixon 2011). 

CASCADING IMPACTS

Alarmingly, lionfish may trigger cascading impacts through their disruption of the food web. For example, the lionfish consumption of herbivorous fishes could reduce the functional role of herbivores in keeping algae in check, a process known to be important for the health of coral reefs. Lionfish may also compete for resources — principally food and space — with economically important species, such as snapper (Lutjanids) and grouper (Epinephelids). It is uncertain if stock-rebuilding efforts will be able to return reef fish stocks to pre-lionfish abundance levels.

Lionfish could also affect the recovery of species of concern, such as the Nassau grouper (Epinephelus striatus), Warsaw grouper (E. nigritus), and speckled hind (E. drummondhayi). These species are critically low in abundance and might not recover quickly under the additional predation mortality imposed by lionfish.

Lastly, it is the interaction of the lionfish invasion with existing reef stressors that poses the greatest concern. Coral reefs of the Atlantic are already highly stressed from bleaching events, climate change, ocean acidification, overfishing, and pollution. The additional stress of this invasive species could accelerate and compound the degradation of coral reef ecosystem health in profound and unexpected ways.

LOCAL INTERVENTION IS CRITICAL

Local control efforts are critical for mitigating the effects of lionfish on key marine habitats. These efforts are invaluable for supporting other conservation initiatives, such as management of marine protected areas and fisheries stock rebuilding. The re-colonization of lionfish from remote and unmanaged habitats will continue to inflict constant stress on Atlantic marine communities. Until new technologies and approaches are developed for controlling lionfish populations, managers must be prepared for long-term intervention. 

The Indo-Pacific lionfishes (Pterois volitans [Linnaeus, 1758] and P. miles [Bennett, 1828]: Family Scorpaenidae) are the first nonnative marine fishes to establish in the Western North Atlantic/Caribbean region. The chronology of the invasion was reported last year (Schofield 2009) using records from the US Geological Survey’s Nonindigenous Aquatic Species database. This article provides an update of lionfish geographic spread (as of October 2010) and predictions of future range

Field and laboratory observations of feeding by invasive Pacific red lionfish Pterois volitans were conducted during June through August of 2008, 2009 and 2010 near Lee Stocking Island, Bahamas. Observations of this invasive marine predator revealed a previously undocumented piscivorous behavior. While slowly approaching prey fish, lionfish produce jets of water directed toward their prey. These jets may confuse or distract prey, and often result in prey fish facing the attacking lionfish, increasing the probability of head-first capture and swallowing. While a variety of fishes are re - ported to create directed water jets, to our knowledge, this is the first report of a fish that does so during the capture of fish prey. This behavior may confer a high degree of predatory efficiency, and thus contribute to the dramatic success of this Pacific invader of tropical Western Atlantic and Caribbean coral reefs

We recorded the first sighting and collection of the non-native, invasive red lionfish (Pterois volitans [Linnaeus, 1758]: Scorpaenidae) in the southern Gulf of Mexico, off the northern Yucatan Peninsula. In December 2009, two individuals were sighted (one of them speared) at 38 m depth over a reef formation, about 58 km northwest of the Alacranes Reef National Park, which is located 130 km off the northern coast of the Yucatan Peninsula, Mexico. More than 20 years after the introduction of P. volitans into the western Atlantic, specifically off the Florida and North Carolina coasts, the invasion circuit now appears to be closing in, since this new record was made about 800 km from the Dry Tortugas and Marquesas, Florida. This recording appears to be the first introgression of the P. volitans population into the Gulf of Mexico via larval transport. 

The invasion by Indo-Pacific lionfish (Pterois volitans and P. miles) of the western Atlantic, Caribbean and Gulf of Mexico is emerging as a major threat to coral reef communities across the region. Comparing native and introduced populations of invasive species can reveal shifts in ecology and behaviour that can accompany successful invasions. Using standardized field surveys replicated at multiple sites in Kenya and the Bahamas, we present the first direct comparisons of lionfish density, body size, biomass and behaviour between native and invaded coral reefs. We found that lionfish occur at higher densities with larger body sizes and total biomass on invaded Bahamian coral reefs than the ecologically equivalent species (P. miles) does on native Kenyan reefs. However, the combined average density of the five lionfish species (Pterois miles, P. antennata, P. radiata, Dendrochirus brachypterus and D. zebra) on Kenyan reefs was similar to the density of invasive lionfish in the Bahamas. Understanding the ecological processes that drive these differences can help inform the management and control of invasive lionfish.

This document serves as a reference for the controlling and management of the invasive Indo-Pacific lionfish (Pterois miles and P. volitans complex). Lionfish are expected in St. Maarten waters in the near future and can have serious detrimental affects to the island’s marine environment, particularly to the populations of both ecologically and economically important fish species. Coral reef ecosystems can also experience degradation due to predatory stress caused by lionfish on coral reef grazers such as parrotfish (Scaridae).

The invasive lionfish also poses a threat to public health; the species has fourteen venomous spines over the length of its body which can inflict a painful sting. Particularly vulnerable to lionfish envenomations are those stakeholders of the Marine Park who have the potential of coming in close contact with the species such as fishers and divers. Recreational beach goers also face the potential of being envenomated. Envenomations can be particularly dangerous to infants, the elderly, individuals with a compromised immune system and those sensitive to the venom.

Due to the nature of the invasion of aquatic species in general and lionfish more specifically, it must be realized that a complete eradication of the species is impossible, therefore this plan will seek to actively manage lionfish in St. Maarten territorial waters. The goals and objectives of this management plan are to adequately control the impact the species will have on the ecosystem level and with regards to the risk it poses to the community and to the local economy. Management goals and objectives are coordinated and communicated with different agencies to ensure local and regional cooperation, education of and outreach to stakeholders, research and management option development on the nature of the infestation, and a species control mechanism which will seek to limit the effects of species arrival.

Management actions should be clear in both the management of the species on a local level and contributing species information on a regional and international level. Management actions in this plan are divided into two stages; pre species arrival and post species arrival actions. Actions within the two stages can belong to phase one management actions, which are the first actions to be implemented, or phase two actions, which follow phase 1 actions and are continuous. Some management actions belong to both phase one and phase two management actions. The proposed management actions for the controlling of lionfish in St. Maarten waters include education and outreach on the nature and threats of the invasion, coordination with other agencies and organizations on management options, infestation research and development such as stomach content analysis and genetic sampling, planning and assessment in the form of lionfish action protocols and lionfish sweeps, and specimen control mechanisms such as species collection and eventual culling.

Appreciation is expressed to all those who assisted with technical support regarding this Response Plan, particularly the insight gained from the St. Eustatius Lionfish Action Plan (Bervoets 2009), on which this document is based, during the Lionfish Workshop hosted by the Bonaire National Marine Park in cooperation with the Reef Environmental Education Foundation and funded by the Dutch Caribbean Nature Alliance, and various workshops given by Chris Flook of the Bermuda Museum and Zoo. 

The Indo-Pacific lionfish species [Pterois volitans (Linnaeus, 1758) and P. miles (Bennett, 1828): Family Scorpaenidae] are the first nonnative marine fishes to establish in the Western North Atlantic and Caribbean Sea. Despite the continued documentation of its range expansion and highly publicized invasion (including public-driven removal efforts) there remains a paucity of basic information on lionfish ecology. This knowledge gap limits effective long-term management. In this study we conducted a multi-scale investigation of habitat occupancy of a newly established population of lionfish in Roatan, Honduras. Based on field surveys and citizen sightings in Roatan Marine Park we found that lionfish occurred more frequently on aggregate coral reef habitats (54% of sightings) compared to patch reef habitats (30%) and sea grass lagoons (16%). In general, these aggregate and patch reef habitats contained adults (mean total length =118.9 mm and 114.7mm, respectively) whereas sea grass habitats contained juveniles (mean total length=89.5 mm). At the micro-habitat scale lionfish occupied areas dominated by hard coral and overhanging structure; the same microhabitats containing native fishes of concern – grouper (Nassau grouper, Epinephelus striatus; yellow fin grouper, Mycteroperca venenosa) and snapper (dog snapper, Lutjanus jocu; mutton snapper, Lutjanus analis). Results from this study contribute information on basic habitat requirements of lionfish and inform current management removal efforts focused on containing spread and mitigating their impacts on native species