| Sumario: |
Invasive species alter ecosystem integrity and functioning and are considered one of the major threats
to biodiversity on a global scale. The indopacific lionfish (Pterois volitans [Linnaeus, 1758] / miles [Bennet,
1882] complex) is the first non-native marine fish that has established itself in the Western Atlantic. It was first
reported in Florida in the 1980s and then spread across the entire Caribbean in subsequent years. In Costa Rica,
lionfish were first sighted by the end of 2008 and are now present in all South Caribbean reefs. Lionfish are
a major problem for local fisherman by displacing native fish species. The aim of this study was to determine
population density, size and diet of lionfish populations at four study sites along the Southern Caribbean coast
of Costa Rica. Two of the sites were located inside the National Park Cahuita where regular lionfish removal
occurs, whereas the other two study sides do not experiment this kind of management. Total length and wet
weight of >450 lionfish individuals were determined between March and June 2011. Three relative metrics
of prey quantity (percent number, percent frequency, and percent weight) were compared from ~300 lionfish
caught with the polespear in shallow waters (<7m depth). Population density was assessed weekly through visual
transect surveys. Our results showed that lionfish preyed mostly upon teleosts and crustaceans. Teleosts domi nated lionfish diet in percent frequency (71%) and percent weight (85%), whereas crustaceans had the highest
percent number (58%). The top five teleost families of dietary importance were Pomacentridae, Acanthuridae,
Blennidae, Labridae and Serranidae. The average total length (±SD) of lionfish was 18.7(±5.7)cm and varied
significantly between sites (p<0.001). Mean density of lionfish was 92fish/ha with no significant differences
between sites. Smallest fish and lowest densities were found at the two sites inside the National Park Cahuita.
Despite management efforts on a regional scale, nationwide efforts are ineffective and lionfish control activities
are poorly implemented. We conclude that there is an urgent need to develop an improved institutional frame work for local lionfish control that promotes effective coordination among the relevant stakeholders in order to
deal with invasive lionfish in Costa Rica. Rev. Biol. Trop. 63 (1): 213-221. Epub 2015 March 01.
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