By Corey Eddy and Jana M. del Favero
Edited by Katyanne M. Shoemaker
Two lionfish have been sighted in Brazil, both in the southeastern area of Arraial do Cabo (Rio de Janeiro). The first one was in 2014 and another more recently in March 2015. But with only two individuals spotted, why should we care?
Brazilian experts are still debating how these lionfish ended up in the Brazilian waters and if there may be more individuals in deeper waters, not observable by divers (details here).
While there is no consensus, I asked a colleague, Corey Eddy, to write about the invasive population of lionfish in Bermuda; I wanted to know what is being done there and what measures could be adopted in Brazil. Below it is the text he wrote:
"Since the discovery of lionfish in Florida in 1985, their population expanded rapidly to stretch from Venezuela to Rhode Island (US). It was thought their range of invasion could eventually stretch as far south as Uruguay. As lionfish are recognized and avoided by prey in their native territory, they have evolved into opportunistic predators with broad diets. However, due to prey naivety in their invasive range, lionfish are able to consume large quantities of invertebrates, juvenile fish, and small-bodied adult fish, many of which play important ecological or economic roles. Consequently, research shows that lionfish can reduce juvenile reef fish populations by nearly 80% in as little as five weeks. Bolstered by the lack of any natural predator, lionfish populations in the Atlantic have reached densities far greater than in their native range, with the potential to affect community structure, biodiversity, and the health of coral reef ecosystems. Fortunately, they are delicious and it only takes one minute to remove their dangerous spines, making them perfectly safe to handle. If we can create a fishery for them, we can save the ocean. We have to eat them to beat them."
Representation of the worldwide lionfish distribution. Diagram by Naira Silva. Lionfish illustration's Source.
My doctoral work is part of a larger project, funded through the UK’s Department of Environment, Food and Rural Affairs, that is investigating the biological and ecological characteristics of the lionfish population around Bermuda and the potential impact lionfish may have upon the structure and function of Bermuda’s coral reef ecosystem. For my first chapter, I will be using the data we collect on lionfish abundance and distribution to estimate the population size. Our team is assessing lionfish abundance via underwater visual surveys at 15 sites in each of five depth zones across the Bermuda platform (10, 20, 30, 45, and 60m) using SCUBA or appropriate technical diving equipment (i.e. trimix diving with multiple tanks). Using a roving search protocol that encompasses cryptic habitats, divers record all lionfish seen and attempt to capture each individual using a pole-spear. Following capture, all lionfish are measured, weighed, dissected, and processed for further analyses. Belt-transect surveys of reef fish, focusing upon small and cryptic species, are conducted concurrently to determine the abundance and distribution of potential prey. A number of these sites are being resurveyed after one year to assess re-colonization rates. This data will also facilitate the development of a distribution map that aids removal activities targeting lionfish at key locations and times that account for seasonal population fluctuations and movement patterns.
My next two chapters will document the life history characteristics of this species to estimate population growth as it pertains to their potential ecological impact. In chapter two, I will examine the demographics of the lionfish population as well as growth rates and longevity of lionfish in Bermuda. This work utilizes standard otolith (“fish ear bone”) aging techniques applied to specimens captured during our underwater surveys and opportunistically from other divers, commercial fishermen, and permitted lionfish hunters. Following this, my third chapter will examine the reproductive condition and quantify the fecundity of lionfish. Gonads will be weighed, sectioned, and analyzed by traditional histological methods to determine overall fecundity, reproductive seasonality, and the developmental stage of fish, thus providing an estimate of the reproductive potential driving the overall population growth.
In my final chapter, we are investigating the feeding ecology of lionfish to explore the impact they may have on the native fish and invertebrate communities, as well as the entire local ecosystem, and to identify factors driving the population’s distribution. This research involves conventional stomach content analysis (SCA) complemented with more advanced stable isotope analysis (SIA) that reveals details not detectable through traditional methods. Because the stable isotope ratios of carbon (13C/12C) and nitrogen (15N/14N) in the tissues of predators are directly related to the ratios found in their prey, the change in these ratios relative to a standard, δ13C and δ15N, are used to indicate the primary carbon sources for a consumer and an estimate of trophic position, respectively. To further indicate the potential impact of lionfish on Bermuda’s reef ecosystem, we will also perform this analysis on prey species (i.e. those identified by the SCA) and others we know are competing with lionfish for these same resources. By plotting δ13C and δ15N of lionfish and these various species, we can see the extent to which lionfish are utilizing resources needed by native species.
When completed, this project will estimate the extent to which invasive lionfish could impact Bermuda’s coral reef ecosystem and help mitigate that impact by providing data on lionfish abundance and distribution to assist the Bermuda Lionfish Task Force and the Department of Environmental Protection (http://www.lionfish.bm) in developing a comprehensive plan that facilitates large-scale, long-term removal of this species from local waters. Controlling and reducing the continued growth of the lionfish population is a crucial part of any effort to minimize negative impacts on native fish species and coral reef ecosystems, and avoid secondary impacts on fisheries and tourism.
In addition to my doctoral research, I am heavily involved in public education and one of the projects I work on may be very useful to implement in Brazil. As a volunteer for the Ocean Support Foundation (http://www.oceansupport.org), I run the Bermuda Lionfish Culling Program on behalf of the Department of Environmental Protection. This program allows any Bermudian resident, over 16 years of age, to receive the proper training and a special permit to hunt lionfish. This is different from a traditional spearfishing license because permitted lionfish hunters are allowed to hunt lionfish while using SCUBA, within one mile of shore, and on shipwrecks and other protected sites, situations normally forbidden by Bermuda law. To date, we have certified over 500 hunters, all of whom are a major help in removing lionfish and keeping Bermuda’s reefs clean and healthy. As Brazil has only recently been invaded, these early days are the perfect opportunity to mobilize SCUBA and free divers, fishermen, and environmentalists to get into the water and start hunting. Every lionfish that is removed greatly helps to preserve and protect Brazil’s marine environment, especially at this early point, when there may be very few lionfish around.
Corey Eddy biography:
Corey Eddy is a PhD candidate at the University of Massachusetts Dartmouth. He received his bachelor’s degree from the University of Rhode Island, whose study abroad program first brought him to Bermuda for a semester at the Bermuda Institute of Ocean Sciences. He is also a Fellow through the National Science Foundation’s Graduate Research Program and a member of the Bermuda Lionfish Task Force. As a volunteer for the Ocean Support Foundation, he developed and currently manages the Bermuda Lionfish Culling Program on behalf of the Department of Environmental Protection. His research interests focus on studying the life history characteristics, habitat use, and feeding ecology of ecologically important predators.