Disappointing findings on lionfish proliferation
Two studies on lionfish reveal they are here to stay. The first reports lionfish establishing deepwater refuges and the second concludes that natural predators won't stem the proliferation. That said, it doesn't appear these studies specifically looked at the impact of lionfish on other reef fish. Looks like hunting them intensely can have some local impact, but I imagine the impact of this deepwater refuge angle will take some time to manifest more fully.
(From the Christian Science Monitor)Predatory lionfish now a confirmed invader in the deep Atlantic
Scientists have confirmed that the hardy, Indo-Pacific fish that has invaded waters off the US East Coast and the Caribbean is now living deep in the Atlantic, possibly imperiling smaller fish there.
By Elizabeth Barber, Contributor / July 12, 2013
An expedition down to the Atlantic depths has confirmed for the first time that the lionfish, an invasive species, is living there. The expedition verifies anecdotal evidence that the venomous animal is eluding eradication and imperiling native fish.
Last month, the first expedition to send a deep-diving submersible down to investigate the Atlantic Ocean lionfish invasion found at 300 feet deep large populations of the fish. Scientists believe that native fish are becoming lionfish prey, as the lionfish hunts any fish smaller than it, and are also losing out against the foreign fish in the competition for food.
“This data has confirmed for us that we have a problem there,” said Stephanie Green, lead scientist on the project and a postdoctoral associate at Oregon State University’s Hixon Lab, noting that researchers are still investigating the exact scale of the issue. “This is the first time we’ve had a look at what the problem is in deep depths – it’s the next frontier in this study.”
Scientists have traced the lionfish, native to the Indo-Pacific and the first exotic fish to invade the Caribbean, to the aquarium trade between oceans in the 1980s. The fish were likely released into the ocean near southern Florida.
“Genetic work has showed that the whole invasion began from a few releases,” said Dr. Green.
Divers have been relatively successful at removing lionfish from Florida’s shallow coral reefs, and there have been various efforts in the region to drive up dinner-table demand for the fish. The Reef Environmental Education Foundation Fund sells a cookbook devoted to lionfish recipes, as well as a list of local restaurants that serve lionfish. Conferences on the invasive species have ended with tastings of lionfish cuisine.
But deep-sea dives to the depths that the lionfish has now claimed are not possible, and humans have not been able to remove them. That raises concern that the fish might use the deep sea as a base from which to retake the shallower water.
“There’s some concern that the lionfish might be using a deep-sea refuge,” said Green, noting that further study is needed to confirm that hypothesis.
The effect of the lionfish, a venomous fish that plumes like a Japanese fan, is well known in the shallower Atlantic, but its impact on the deep sea is less well understood. The animal is what is known as a gape-limited predator, which means that the fish is limited in food consumption by the size of its mouths. The fish, growing up to 47 cm in length, can consume prey up to half its size, which puts about 70 percent of the fish population within their gulp. Studies have shown that at least 40 species of fish have dropped in number since the lionfish was introduced to their Atlantic environment, Green said.
“There is strong evidence that the lionfish is having negative effects on the native population,” she said. “We don’t see any signal that anything is controlling lionfish population.”
As big fish tend to live longer, the lionfish also reproduce more efficiently than do smaller fish: One female lionfish can spawn some 2 million eggs per year; the eggs are bundled in gelatinous blobs of some 12,000 to 15,000 eggs and distributed throughout the ocean. That means that the invasive lionfish population has grown in a disproportionate number relative to native fish deep in the Atlantic.
And a separate study released this week from the University of North Carolina at Chapel Hill also suggested that a lack of native predators in the Atlantic has further boosted the lionfish’s disproportionate growth: Nothing is down there to eat them.
Researchers are now investigating possible solutions to the lionfish problem, including creating deep-sea traps that could nab the large fish, said Green. Scientists are also hoping to catch one of the fish – using mounted suction cups – in the deep environment to better understand the changing ecosystem there.
(From Science Direct, portions deleted for brevity, link to full article below)
Caribbean's Native Predators Unable to Stop Aggressive Lionfish Population Growth
"Lionfish are here to stay, and it appears that the only way to control them is by fishing them," said John Bruno, professor of biology in UNC's College of Arts and Sciences and lead investigator of the study. The research has important implications not just for Caribbean reefs, but for the North Carolina coast, where growing numbers of lionfish now threaten local fish populations.
Lionfish, native to the Indo-Pacific region, have long been popular aquarium occupants, with their striking stripes and soft, waving fins. They also have venomous spines, making them unpleasant fare for predators, including humans -- though once the spines are carefully removed, lionfish are generally considered safe to eat, Bruno said.
They have become big marine news as the latest invasive species to threaten existing wildlife populations. Bruno likened their extraordinary success to that of ball pythons, now eating their way through Florida Everglades fauna, with few predators other than alligators and humans.
The international research team looked at whether native reef predators such as sharks and groupers could help control the population growth of red lionfish in the Caribbean, either by eating them or out-competing them for prey. They also wanted to evaluate scientifically whether, as some speculate, that overfishing of reef predators had allowed the lionfish population to grow unchecked.
The team surveyed 71 reefs, in three different regions of the Caribbean, over three years. Their results indicate there is no relationship between the density of lionfish and that of native predators, suggesting that, "interactions with native predators do not influence" the number of lionfish in those areas, the study said.
The researchers did find that lionfish populations were lower in protected reefs, attributing that to targeted removal by reef managers, rather than consumption by large fishes in the protected areas. Hackerott noted that during 2013 reef surveys, there appeared to be fewer lionfish on popular dive sites in Belize, where divers and reef managers remove lionfish daily.
The researchers support restoration of large-reef predators as a way to achieve better balance and biodiversity, but they are not optimistic that this would affect the burgeoning lionfish population.
"Active and direct management, perhaps in the form of sustained culling, appears to be essential to curbing local lionfish abundance and efforts to promote such activities should be encouraged," the study concluded.
We noticed a real reduction in the number of lionfish in Bonaire last May. Many restaurants have incorporated them in their menus. I rarely dive below 80' anymore, so cannot speak to greater depths. I did see two that were tucked under ledges that were by far the largest I've ever seen.
People don't have a clue, just try to remember how it was because it is and will be different everywhere. Some people say the reefs will prosper because the lionfish eat the fish that graze on the beneficial algae. I say I liked it the way it was. Check out this photo from a small wreck in 250' of water off the west coast of Florida 100's. I know they are here to stay.
Maybe if there was an international ban on harvesting them the Japanese would kill 90% of them for use in "scientific studies".
And if that photo is not enough, look at THIS!
Good grief!!! There must be a kajillion of 'em.
Sad part of it is, I have it on good authority that lionfish are actual alien beings sent here to save the earth.
So in our inimitable way we kill them to satisfy our blood lust.
That is a way cool video. I bet your hand was getting tired.
Great stuff, OWS. Thanks.
Lionfish Animated Distribution Map, for those that have not seen this yet.