Thanks to a deep-diving submersible that explored the Atlantic last month, scientists now know that colonies of invasive, predatory lionfish are living in the ocean’s deep waters. This is bad news for the local wildlife population.
According to Stephanie Green, lead scientist for the project, the invasive fish are living 300 feet below the surface, where they are feeding on large quantities of native fish.
“This data has confirmed for us that we have a problem there,” said Green. “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.”
The animals are native to the Indo-Pacific, and their spread has been traced to the 1980s aquarium trade, where the animals were likely dumped in the Atlantic off the Florida coast. Lionfish have long been known to live in reefs in shallower waters, where divers have worked to remove them. Because of this, the popularity of lionfish cuisine has been on the rise.
However, the deep-sea lionfish have no natural predators (except humans), and their presence in the deep water could have dire consequences.
“There’s some concern that the lionfish might be using a deep-sea refuge,” said Green, although further study is needed. Part of the issue is the way the venomous fish feed. They are “gape-limited” feeders, meaning they can only eat what will fit in their mouths. However, the deep-sea lionfish are slightly larger than their shallow water counterparts. Because they can grow to 15-18 inches, and can take in prey about half their size, approximately 70 percent of the overall fish population is at risk. Not only that, but studies have confirmed that at least 40 species of native fish have experienced population drops since the lionfish were introduced.
Another problem is the lionfish’s ability to reproduce quickly. Big fish not only have a longer lifespan than smaller ones, but they also produce greater numbers. The Christian Science Monitor has done the math, and it’s bad news. “One female lionfish can spawn some two 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 disproportionate number relative to native fish deep in the Atlantic.”
Since the lionfish have no natural deep water predators, scientists believe it may be up to humans to handle the problem. In addition to continuing to study the deep Atlantic ecosystem, researchers are looking into creating deep sea traps to catch the fish.