For some months now, sick or injured lionfish have been found off the coast of Klein Bonaire. The injuries are all the same. The animals are found floating on the surface, with superficial skin injuries. Lionfish Hunters posted it on Facebook, with a stream of responses from people having observed the phenomenon. A researcher, who also reacted, mentioned the same phenomenon in Florida.
Completed research is still lacking and so the phenomenon raises a lot of questions. Do the animals attack each other because of the increasing numbers at great depths? Is it a disease? What else is ill in the reef? Is it pollution? Are they being hunted down ineffectively by humans? Meanwhile, observations of Facebook users continue to come in. The animals are observed floating on the surface in small numbers or washed up on the beach, usually on Klein Bonaire and occasionally at Kralendijk and Lac.
A researcher at the University of Florida reacts to the post as follows. "We've been studying the occurrence and spread of skin ulcers presenting in lionfish. The first documented report of lionfish presenting skin ulceration was August 5, 2017 from lionfish harvested from artificial reefs near Destin, where 40% of 503 lionfish presented ulcers. We've additionally received reports of ulcerated lionfish from the West Florida Shelf, East Florida Shelf, Florida Keys, Bahamans, Cayman Islands, and U.S. Virgin Islands. We're still very early in our work and at this point there's a lot more questions than answers."
The researcher then shares some preliminary results: "(1) Reports have varied with respect to the percentage of fish presenting with skin ulcers, with the highest percentage of affected fish being reported from the Florida Panhandle. (2) The proportion of lionfish with active ulcers in the Gulf of Mexico greatly declined in winter and early spring from either of these Florida Gulf Coast regions, but several fish displayed what appeared to be healing lesions. (3) Diseased fish collected in the gulf had a lower relative condition factor than apparently healthy fish. They are significantly 'skinnier' however, the lethal and sublethal effects of skin ulcers are still unknown. (4) To our knowledge, there has never been a reported case of human illness due to ingesting healthy lionfish or ulcerated lionfish. However, we cannot make any definitive statements regarding human health."
Researchers from FWC and UF plan to continue monitoring observations and begin molecular studies on disease etiology, which will focus on a potential viral origin or association. Determining the causative agent will also provide insight into the likelihood of epizootic transmission to other species. Concurrently, the researchers will continue monitoring lionfish densities and reef fish communities and attempt to track population and community-level effects.