Nassau grouper goes for the kill with invasive lionfish

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The Nassau grouper herds the lionfish toward open water.

NASSAU, Bahamas, Monday August 31, 2015 – A recent Lionfish University video, documenting a Nassau grouper stalking and ultimately devouring a lionfish in the Caribbean, is thought to be the first-ever footage showing this type of event without the assistance of humans, and may indicate that divers’ attempts to “teach” groupers to eat the invasive species is finally bearing fruit.

In the video, the grouper appears to herd the lionfish away from the safety of the reef into open water, where it can investigate and prod from various angles, being careful to avoid the armour of poisonous spines, before lunging for the kill.

The resulting meal for the grouper represents a big step forward for biologists and conservationists, given that lionfish, which are native to the Indo-Pacific, have the potential to disrupt ecosystems in the Caribbean and Atlantic.

The continuing infestation of these prickly pests throughout the region is cause for alarm because the venomous lionfish have no known natural predators in this part of the world and their rapid proliferation is going largely unchecked.

While it remains unclear exactly how devastating their presence–believed to be the result of people dumping their unwanted aquarium pets into the sea–may turn out to be, the outlook is bleak.

The concern is so genuine that fisheries agencies and scuba divers the likes of the Lionfish University group – who are dedicated to the preservation of coral reefs and native fish populations – have, for the past several years, conducted large-scale culling events in the hope of minimizing the threat.

Researchers have discovered that a single lionfish residing on a coral reef can reduce recruitment of native reef fishes by 79 per cent, according to the National Oceanic and Atmospheric Administration (NOAA).

Because lionfish feed on prey normally consumed by snappers, groupers, and other commercially important native species, their presence could negatively affect the well-being of valuable commercial and recreational fisheries.

As lionfish populations grow, moreover, they put additional stress on coral reefs already struggling from the effects of climate change, pollution, disease, overfishing, sedimentation, and other stressors.

For example, lionfish eat herbivores and herbivores eat algae from coral reefs. Without herbivores, algal growth goes unchecked, which can be detrimental to the health of coral reefs.

Measures currently in place to counter the threat include culling, as well as harvesting the invasive species for food and the curio and aquarium trade.

With any luck, the larger groupers, such as the expert hunter in the video, may unwittingly contribute to the effort.

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