MARINE NUISANCES – The lionfish are coming!


Before the battles of Lexington and Concord during the American War of Independence, the blacksmith Paul Revere famously called out to the towns folk of Boston “The British are coming!”. This alerted the Americans to the incoming British forces before the battles which ensued. I would respond in kind by saying “The lionfish are coming!”.

Lionfish (Pterois miles) are venomous predators which are native to the Pacific Ocean. Members of the scorpionfish family, they have the worst sting of all. Often sought after by tropical marine aquarists for their beautiful colours and elaborate fins designs, they quickly grow too large and consume all other residents in the same tank.

Only having one large hungry fish in a marine tank loses its appeal. Add to that the fact that cleaning the tank can become very hard because lionfish do not scare easily and can give you a nasty sting; the tendency has been to do the ‘humane’ thing and return them to the sea. This is thought to be the reason they now exist off the coast of Florida in the USA, where six individuals were released in the 1980’s after a disastrous hurricane.

Not native to the Atlantic, lion fish have now spread their territory from the coast of Florida, where they were originally released, across the Caribbean and down to the North coast of Brazil with millions of individuals having been spotted. As coastal dwellers, they have been limited to spreading east across the deep Atlantic Ocean, until now.

Off the coast of Cyprus, Lionfish were found in relatively small numbers around the 1990’s. The scientific study, led by researcher Demetris Kletou from the Cyprus Environmental research lab, determined that the sightings were sparse and it was unlikely that a viable population had established itself. No-one really knew how the fish got there as it was expected that the high levels of salinity in the Mediterranean would form a natural barrier to their habitational range. One theory is that the creation of the Suez Canal has opened the door for water exchange between the Red sea and Mediterranean which might have brought lionfish eggs through. They might simply have swum through the canal. Either way, they are here and here to stay, as recent observations by Kletou and his team have found increasing numbers of breeding pairs.

Lionfish are prolific reproducers; they can spawn once every four days and it is estimated that they produce over two million eggs per year. That’s a lot of babies! Further, it has been reported that lionfish eggs contain a chemical which deters other fish from eating them. Finally, unlike other species, lionfish can form reproductive groups which really helps to ramp up their numbers.

Recent work by Kletou in 2015, has found that the lionfish have already established these reproductive groups around Cyprus and have extended their range to Turkey and Greece. Following the Florida example, we can expect them to become a dominant species in the Mediterranean within the next decade or so. They won’t just remain here either as they will also extend their range west past Gibraltar and possibly out into the eastern Atlantic coast.

Ok, so we have some Lionfish. Why is this a problem? In any healthy marine ecosystem, you have the algae and the herbivorous algae eaters. Predatory fish eat the herbivores and the whole system remains in balance. Lionfish are predators and hungry ones at that! Some recent research suggests that they can expand their stomach up to 30 times its original volume. The Florida environment has seen a huge increase in algal growth because the Lionfish are eating all the algal grazers. In Gibraltar terms that would mean more seaweed!

Lionfish are also an invasive species and have no natural predators in the Mediterranean because they are covered in nasty spines. This only compounds the reproduction problem outlined earlier as there is no top down control on their numbers.

But there is good news and it comes in few parts. Firstly, lionfish are extremely tasty. They are also slow moving which makes them easy to catch! Historically, we have been exceptionally good at targeting particular species and catching them until the stocks collapse; this is one example where our type of efficiency would be welcome. Florida seafood menus now include these fish as part of the staple diet and there is no need to feel guilty whilst eating them either; in fact, it’s all for a good cause.

The second part to the good news is that the invasion has only just started making it easier to control. It is important that scientists work with governments to implement policies to prevent further invasion of the Mediterranean. Awareness needs to be spread for the arrival of the incoming predators and measures taken to preserve our coastlines equilibrium. I, for one, have my grill and lemon ready to do my part.

words | Lewis Stagnetto, The Nautilus Project