Lionfish in the Caribbean hit with ulcers
Mystery sores afflicting invasive lionfish in the US and Caribbean have not been found on fish in Bermuda waters, environmental experts said yesterday.
A spokeswoman for the Department of Environment and Natural Resources added that it was not expected the sores, which were first spotted in Florida two years ago, would affect lionfish in the seas around the island.
She said: “While lionfish larvae can drift on ocean currents, adult lionfish are not able to swim large distances across the open ocean and so the chances are slim to none that an ulcerated lionfish could swim here from Florida.”
She was speaking after lionfish were found in the Gulf of Mexico with ulcers deep enough to expose muscle tissue.
Scientists have as yet been unable to find a cause for the sores to check if they could spread to fish native to the affected areas.
Lionfish is native to the Indo-Pacific Ocean region and considered an invasive species in the Atlantic, where it preys on native fish.
Efforts to kill off the fish in Bermudian waters started in 2008 and they have also been identified as a good food source.
Sightings of ulcerated lionfish were first reported in waters off northwestern Florida in August 2017.
Later tests on affected fish did not show “parasites, water moulds or other potential infections or diseases”.
Some lionfish found with the ulcers also had scar tissue, an indication the sores were healing.
Lionfish with the sores have since been found in the Gulf of Mexico, the Caribbean Sea and off the coast of South Carolina.
The DENR spokeswoman said ulcers in fish were not uncommon.
She added that the ulcers found in fish in other areas could be due to contaminants in the water.
She said: “If these ulcers are related to contaminants specific to the water where the fish are found, then the phenomenon is not likely to appear in Bermuda.”
The spokeswoman said that water temperature could also be a factor.
She explained: “The first instances of ulceration were observed in the month of August in 2017, when water temperatures are at their highest.
“This can be a very stressful time of year for fish, and is often a time when diseases or other stress responses manifest.”
The spokeswoman added that could explain why lionfish were seen with healed or healing ulcers the following spring.
She said that “the likelihood of the phenomenon occurring in Bermuda is really dependent on what is causing it”.
She said: “Even if a causative pathogen is identified, it is likely that it is something that is present in the marine environment already and that fish species native to the region are less susceptible to it.
“Invasive lionfish may not have a very robust immune system because of their limited gene pool and thus may react differently or be more susceptible to western Atlantic pathogens than native fish.”
Members of the public who find fish of any kind that appear to be sick should contact the Marine Resources Section of DENR at 293-5600.
The spokeswoman added that photographs of sick fish, samples of seawater from the area it was found and specimens preserved on ice were also helpful to department experts.
She said that people should not eat diseased fish.
The spokeswoman added that fish that appeared sick should be handled with care and people should avoid contact with any open wounds.