LIONFISH: FURTHER RESEARCH INTO THE CARIBBEAN POPULATION EXPLOSION


LIONFISH – MARMITE DENIZENS OF THE OCEAN

A short time ago I posted in some detail about the poisonous LIONFISH. I included material about the rapid increase of this Pacific species in Caribbean and Floridian waters following accidental / deliberate releases in recent years. I also included videos from Grand Bahama scuba-expert FRED RIGER to balance the anti-lionfish orthodoxy, showing that the fish in fact do some good on the reefs. The post provoked a few comments, and had a surprising number of hits. Here is some further research courtesy of the excellent SEA MONSTER which adds a dimension to the debate and concludes with a very good point… Incidentally, in a recent morning snorkelling at Fowl Cay Marine Preserve, Abaco, I did not encounter a single one of these creatures (Mrs RH was unluckily stung by a jellyfish, though…). But I guess the Preserve is well policed against such intrusive species, which are otherwise found in large numbers in the area.

Why are lionfish populations exploding across the Caribbean?

Author: John Bruno on June 6, 2012

Lionfish are an exotic fish now found throughout the Greater Caribbean and eastern Atlantic that have become incredibly abundant on many reefs, especially in the Bahamas and off North Carolina. Lionfish are piscivores (fish that eat other fish) and were introduced from the Indo-Pacific by the aquarium trade in the late 1990s off Florida. Mostly likely, someone got tired of their fish and released them purposefully.

One hypothesis explaining their great success is the absence of natural enemies; predators, parasites and competitors.  This is probably compounded by the fact that few Caribbean reefs have any predators left that could eat them (thanks to overfishing).

Another – and I think much more likely explanation – is because there is so much to eat in the Caribbean! Not because there are more fish, but because it is so much easier to catch them. Unlike fish in the Indo-Pacific, native Caribbean fishes do not appear to recognize lionfish as a potential threat.  So the lionfish gobble them up, grow faster, make more babies, spread to new islands, etc.

Case in point: My lab group was working in Belize last week on the lionfish invasion. One of the things we were doing was collecting the otoliths and gonads from lionfish that we speared on a number of reefs to compare their fitness across the Caribbean (e.g., on reefs with and without native predators, etc).  We also looked at stomach contents and many of them had parrotfishes in their tummies or still in their throats!  The photo above is of the eggs from one lionfish we caught near Glovers Reef Atoll and the partial contents of it’s stomach (a juvenile striped parrotfish)!

Lionfish appear to be little more than machines that convert parrotfishes to baby lionfishes. Which is pretty much the purpose of all animals (consuming others and transforming them into your own genotype and species).  But jeez, couldn’t those aquarium hobbyists have released a herbivore that could be converting macroalgae to fish biomass? That would have been much more useful.

LIONFISH: FACTS, VENOM & CRISIS CONTROL IN THE BAHAMAS – & A COUNTER-VIEW


LIONFISH: UNINVITED GUESTS IN THE BAHAMAS

I recently put some lionfish details and images on my MARINE LIFE page. I wrote: “…their existence and rapid increase in the waters of the Bahamas is a cause of great concern, and they are keenly hunted. Last year’s inaugural Lionfish Derby on Green Turtle Cay brought in more than 1400 of these creatures in the day, ranging in size from  a 57mm juvenile to a 349mm fish. Here, from THE ABACO SCIENTIST is where in the world the 2 species of Lionfish ought by rights to be. Well away from the Caribbean, that’s where!

 Photo credit: Brigitte Carey of Tilloo Cay

Two great lionfish photos from GRAND BAHAMA SCUBA  (thanks to Fred & Melinda Riger )

———————————————————

LIONFISH Pterois

1o UNCOMFORTABLE LIONFISH FACTS

  • A genus of  spiny venomous fish indigenous to the Indo-Pacific area, of which there are 9 species
  • In the mid 1990s 2 species were introduced to the US Atlantic coast and Caribbean (see below)
  • Unaccountably popular as aquarium fish; cooked and eaten by people (though not by me)
    For recipes see LIONFISH HUNTER
  • An adult can weigh 1/2 kilo and may live up to 15 years
  • They have ‘complex courtship and mating behaviour’, presumably to avoid each other’s spines
  • Females release two egg cluster bombs every month containing up to fifteen thousand eggs…
  • Lionfish prey voraciously on small fish, invertebrates and molluscs which they gooble up in one gulp
  • They have bilateral swim-bladder muscles to alter their centre of gravity to attack their prey better
  • Apart from a tendency to species cannibalism, they have very few predators. The spines work well…
  • Sharks are not affected by the venom, and attempts have been made to train them to feed on lionfish 

LIONFISH STINGS are painful and can take several days to resolve. Tests on frogs, clams and rabbits… well, you don’t want to hear about those. In humans the venom causes systemic symptoms ranging from nausea, vomiting, fever, breathing difficulties and dizziness to convulsions and paralysis. For the very young, the elderly, the allergic or those with immune system weakness the sting can be fatal. TREATMENT: If stung it is recommended that you remove the spine(s) if possible and immerse the wound in hot water for at least 15 minutes… and seek medical treatment as soon as possible

THE CARIBBEAN INVASION supposedly started in the mid-1990s, perhaps following hurricane damage to an aquarium in southern Florida. A few earlier sightings had been recorded, possibly the result of  deliberate aquarium releases. Two of the 9 species are involved: the red lionfish P. volitans (93%) and the common lionfish P. miles (7%). It’s a measure of their rapid breeding, habitat adaptability and near-immunity from predation that the first recorded lionfish in the Bahamas was as recent as 2004. A mere 8 years later they’ve spread throughout the region. 

POPULATION INCREASE AND CONTROL The population is increasing exponentially despite efforts at control. Their voraciousness and territorial aggression must certainly be affecting the indigenous populations of reef marine life. The problem is already extreme. It is now unlikely that lionfish can ever be eradicated. Even to confine the population to its current level would require more than a quarter of the adult population to be killed monthly. Lionfish are able to reproduce throughout the year, so there is no seasonal respite. In this conservation-minded era,  official encouragement of  organised hunting bucks the trend towards creature protection. Lionfish do have food value, if natural human reluctance to eat a venomous species can be overcome, and there are now many lionfish recipes. Whether killing lionfish for sport or for food, humans are their only effective predators. Below is an example, from Oceans Watch, of the sort of campaign that will surely become commonplace throughout the region. Time to reach for the speargun…

THE COUNTER-ARGUMENT

The above is the orthodox view, widely held throughout the region. Some will ask whether the arrival of the lionfish in the Caribbean has any positives; whether they actually make a contribution to the ecology of the area; whether there is a convincing case to put forward in favour of the species; whether there is evidence to back it up. So to redress the balance I commend these 4 short videos from the enormously experienced Grand Bahama diver Fred Riger, in which he cogently demonstrates the value of this imported species. In short, the videos reveal that the adverse effect on endemic fish populations is not merely overstated but wrong; that the spreading menace to the coral reefs of choking algal growth is actually reversed by lionfish; and that important grazing crab species are thriving as a result. 
I posted the bad lionfish stuff last night; by this morning Fred had rightly taken me to task for only giving one side of the story: “Far from being a pest, lionfish are solving a huge problem created by the mother of all invasive species HUMANS, who have over fished the ocean, wiped numerous species out of existence, killed most of the world’s coral, the very stuff we in the Bahamas live on. Targeting lionfish sets conservation efforts back thirty years or more and contributes to the decline of the coral reef”. So here are the videos giving the case in favour of lionfish, and they certainly provide a fresh perspective and plenty of food for thought…
 
“LIONFISH IMPACT: THEY ARE NOT SO EVIL AFTER ALL”