Will lionfish cross the Panama Canal?
STRI/DICYT Coral reefs of the Caribbean already faced warming waters, disease and human-induced degradation. Then the lionfish came along. First introduced into the U.S. Atlantic in the 1980s, the lionfish has spread throughout the Caribbean in what has been described as one of the worst marine invasions ever recorded. Lionfish were not a problem in their native ranges in the Western Pacific, the Indian Ocean and the Red Sea, but in the Caribbean Sea and the Gulf of Mexico they out-breed, out-compete and out-live native fish species and are decimating coral reefs. It only takes a year for a lionfish to reach maturity and begin to reproduce.
Growing lionfish eat the larvae of game fish such as billfish and jacks as well as the fish that remove algae from the reefs. They also eat lobsters, octopus, sea horses and crabs, with serious consequences for coastal communities and the ecotourism business.Now there is concern that the voracious, virtually enemy-free fish could hop over the Isthmus of Panama and invade the Eastern Tropical Pacific (ETP).
Andrew Sellers, a doctoral student at McGill University who did his master's degree on lionfish in Panama's Caribbean, explained the likelihood of the scenario during a meeting of the Gulf and Caribbean Fisheries Institute (GCFI) held this week in Panama City.
Sellers outlined three possible scenarios for a lionfish (Pterois volitans) invasion: fish could swim across the 80-kilometer Panama Canal, cross the canal in the ballast water of a ship, or be introduced via the aquarium trade in Panama City.
Since opening in 1914, numerous organisms have crossed the Panama Canal but so far only one fish has successfully made the voyage under its own steam from the Atlantic to the Pacific. The Atlantic tarpon was first seen in the Miraflores locks, on Panama's Pacific side, in the 1920s, and later was seen in the Pacific.
Chances that the lionfish could do this are very low since it would have to rapidly adapt to the very low salinity of the canal's water. "We can assume that they will die in the fresh water of the canal," said Sellers, noting that salinity in the canal is even lower that the low-salinity conditions that lionfish have shown to survive experimentally.
Ballast water, which ships take on and release to control draft and stability, is another matter. At least 40 accidental introductions of fish species were attributed to ballast water in a 2000 study. Further research is required to determine if lionfish can survive in a ship's ballast.
Sellers believes the most dangerous possibility is the fish trade. Lionfish have become popular aquarium dwellers in Panama City, right on the Pacific Coast. Sellers thinks more stringent regulation of lionfish transportation and sales are paramount.
How the Caribbean copes
A GCFI workshop on lionfish held this week in Panama City brought experts from around the Americas together to share stories on management strategies, and to discuss scientific research and economic opportunities that linked to the lionfish invasion. Virtually every nation in the region has had its coastal marine ecosystems affected by the lionfish — which devour small reef fish and hammer native fish populations — but a variety of strategies have been successful in keeping the invader in check.
Control plans rely on local fishermen and recreational scuba divers to regularly cull the lionfish, which have become a popular — and profitable — dish in many places. Efforts were so successful on the Cayman Islands that restaurants had to import lionfish from Honduras at one point.
In Bonaire, "lionfish hunter" courses are taught by dive shops and there are strict controls on who can harvest the fish. In Guadeloupe, initial government funding to launch lionfish control programs launched a profitable industry. In 2013, lionfish meat was as valuable as snapper or grouper.
In Bermuda, most lionfish are caught at depths of 40m-80m, and researchers, inspired by accidental lionfish captures with lobster cages, are developing cages that can trap lionfish but not native fish species.
Belize stands out with a comprehensive, country-wide effort to integrate lionfish into local economies and to involve citizen scientists in data collection. The lionfish harvest supplements fishing communities’ income, and is especially valuable due to restrictions on local fish harvests. Belize has also established an artisanal jewelry industry to use lionfish fins and spikes, which increases the value of landed fish by up to 60 percent.