Lionfish in the Bay!
Late last month, an FWC officer observed a lionfish swimming off the Laishley Pier in Punta Gorda. This is the third documented lionfish sighting inside Charlotte Harbor, and it’s also the most up harbor. Laishley Pier is actually on the Peace River.
What’s not good about this beautiful fish? Well, for starters, it doesn’t belong here. Lionfish are native to the Indo-Pacific, but unfortunately they are well established throughout the Gulf of Mexico, the Atlantic to North Carolina, and the Caribbean.
The lionfish established here comprise two species, Pterois volitans, the red lionfish and P. miles, the devil firefish. The lions share, 93 percent of those established, are red lionfish. Genetic studies indicate that lionfish in the Atlantic are likely all descendants of a few individuals, which is consistent with the widely held belief that lionfish were introduced into the Atlantic as a result of accidental or deliberate release of aquarium pets. Isolated lionfish sightings were first documented in southeast Florida in the 1980s, and by the early 2000s they were established in that area. They then expanded to the Bermuda (2004), the Bahamas (2005), the Turks and Caicos (2008), the Cayman Islands and the Florida Keys (2009) and the Gulf of Mexico (2010). Today, they are a common sighting on any reef, in the listed areas — natural or manmade, including those off southwest Florida.
Lionfish species are members of the scorpionfish family. They have venomous spines on their dorsal, pelvic, and anal fins. When these spines penetrate an object, the sheath covering the spine rips, releasing the venom into the wound. And, unlike many types of fish, lionfish do not avoid people; while they will not attack divers, they usually do not move out of the way either.
One of the reasons lionfish were able to expand so rapidly is they breed like rabbits — actually, rabbits wish they could breed like lionfish! Lionfish become sexually mature at a small size. Male fish as small as 4 inches may be mature, while females mature at about 7 inches. They also spawn year-round, and may release eggs as frequently as every four days.
Without the natural predators that would normally control their population, lionfish are presently more successful in their introduced range than they are in their native range. In fact, researchers in the Bahamas have reported lionfish densities that are more than eight times higher than densities from the lionfish’s native range in the Red Sea.
But, there’s some encouraging news. Two recent studies have documented how Nassau grouper and Red grouper alter the feeding behavior of lionfish. In the most recent study published in 2016, researchers evaluated the predatory behavior of lionfish and red grouper in Florida Bay. In Florida Bay, red grouper are primarily associated with karst hard bottom features called solution holes, which are pockmarked pits in the limestone (commonly called Swiss cheese bottom). Red grouper excavate these by removing the sediment. Previous studies have shown that red grouper presence at solution holes positively affected the abundance and diversity other species, and in particular juvenile coral-reef fishes.
To determine the interactions between red grouper and lionfish, researchers experimentally altered the presence of these species in karst solution holes and then tracked subsequent changes in the juvenile reef fish and invertebrates. The experimental designed called for some study sites to have only lionfish on a solution hole, some with only red grouper, some with one of each, and some with neither.
What they found was that average juvenile reef fish abundance declined 83.7% in solution holes with a lionfish but increased by 154% in solution holes with a red grouper. Juvenile reef fish abundance was the same in solution holes with both lionfish and red grouper when compared to holes where both lionfish and red grouper were excluded.
Equally interesting, lionfish changed their diet when a red grouper was present. When they were alone, lionfish stomach contents were mostly fin fish; however; when they were in the presence of a red grouper, they ate mostly crustaceans. At the same time, the abundance of 2 species of cleaner shrimp decreased by 14.7% when lionfish were present, but increased by 56.2% at holes where lionfish were absent.
In neither the red grouper nor Nassau grouper study was a grouper observed feeding on lionfish directly, but the fact that its presence altered the predatory behavior of lionfish is good news. It also highlights the importance of maintaining healthy grouper populations — they appear to be front-line soldiers in the fight against lionfish.
McGuire Maia and Jeffrey HIll. 2014. Invasive Species of Florida’s Coastal Waters: The Red Lionfish (Pterois volitans) and Devil Firefish (P. miles), University of Florida IFAS Extension, EDIS SGEF 208.
Ellis Robert, D. and Meaghan E. Faletti. 2016. Native grouper indirectly ameliorates the negative effects of invasive lionfish, Mar Ecol Prog Ser, Vol. 558: 267–279.