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Lionfish Invasion - Unintended Consequences

by Terry Sovil

An unintended consequence is a result that was not intended and probably not expected. These are intentional or accidental. In nature the introduction of a non-native species into an area outside its native range is a good example. Accidental introduction is usually from human movement and not a motivation. Intentional introduction is intended to provide some benefit, often financial. Once a non-native species is introduced the consequences can be disastrous rather than beneficial.

Examples of introducing a species is often intended to provide a benefit to agriculture or aquaculture. Eurasian carp brought in as a food source. Foxes brought to Alaska for fur trade. The introduction of ornamental plants. A famous example is Eugene Schieffelin, a lover of Shakespeare, who wanted to introduce all of the birds in Shakespeare's plays into the USA. He deliberately released eighty starlings into Central Park in 1890.

LionfishIn 1992, Hurricane Andrew smashed open a public aquarium tank on the waterfront in Florida. Approximately 6 lionfish washed into the Atlantic Ocean and spawned an invasion that has rocked the Bahamas and is spreading. The first lionfish showed up in 2005. By 2007 there was a literal explosion of this fish that were eating the fish researchers had been studying. Lionfish are native to the reefs and rocky crevices of the Indian and Pacific oceans. Now they have spread up the Eastern seaboard of the USA and throughout the Caribbean and have reached Cancun. The Bahamas have taken the biggest hit and it appears Florida is next for an invasion. DNA testing suggests that the entire population is descended from just three separate females.

The lionfish is beautiful and deadly. They are a member of the Scorpion fish family. Their spines, up to 18 needle-like dorsal fins, are gorgeous but venomous. Most observations of lion fish in their traditional habitat is in depths of water 100 feet deep but in their new environments they have been observed much shallower. They tend to hunt among the rocks and coral during the night and hide under ledges and in crevices during the day. Though there are no reported fatalities their sting is extremely painful. Reports describe a sting that "feels like fire" and can last 15-20 minutes to several days. It can also cause sweating and respiratory distress. Some stings can send people to the hospital.

Lionfish have no natural predators in their new habitat and are voracious predators eating fish larger than themselves and 2-3 times their weight a day. Mark Hixon of Oregon State University reports that a single lionfish can deplete 79 percent of a reef in just five days! When that happens, coral ecology dies and algae take over. They grow to a length of 12" (30cm) but in the Caribbean are reaching lengths of 21" (55cm). They do not use their spines to hunt but for defense only. They will "herd" their prey with their fins but then swallow it whole.

Because these fish are prized in the aquarium trade the chances of their continued spread to other areas is almost guaranteed. The NOAA (National Oceanic and Atmospheric Research) reports that this spread has the potential to become "the most disastrous marine invasion in history by drastically reducing the abundance of coral reef fishes and leaving behind a devastated ecosystem." Many beginning aquarists purchase young lionfish with little knowledge of the fish. As it grows it begins to consume other fish in the aquarium and the owner may release it into the ocean for disposal. While many aquarists will deny responsibility for the hobby it is clear in this case that the marine aquarium hobby is to blame.

Controlling their growth is difficult. Scientists hope that a natural enemy such as a bacteria or virus will help control their population growth. Concerns grow as divers are seeing more Pacific lionfish in Atlantic waters. The reproductive cycle is fast, every 55 days, and in the warm waters of an area like Florida or Cancun an individual female may release thousands of eggs every week throughout a year. Young lionfish mature within a year. In an effort to help curb the spread divers are asked to kill them. There is also an effort to promote them as a food source as lionfish is being touted as a gourmet dish. Response has been positive. It is a great fish to work with--fillets are firm and mild, and take seasonings very well. Additionally it's rewarding to serve an invasive species fish dish rather than a threatened fish like snapper or grouper.

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