Skip to content

The Lionfish Menace

1 February 2016

Red Lionfish are not indigenous to Caribbean waters, but began making an appearance here in the last few years.  It is not clear how they made their way to the Caribbean from their native Indo-Pacific waters, with theories including accidental or deliberate escape from home aquariums to travelling in the bilge water of large cargo ships.  I first came across these exotic looking fish in Thailand, and recall that they were pointed out in excitement.  They are called Lionfish because they have spines that radiate out like the mane of a Lion.

These spines are sharp, and most are venomous.  18 venomous spines across the back, dorsal, pelvic and anal fins contain a protein-based combination of a neuromuscular toxin and a neurotransmitter called acetylcholine, and necrotise flesh of swimmers or divers who accidentally encounter them.  The toxin can be rendered inert by applying heat or freezing although will otherwise remain a risk for several hours after the Lionfish’s death.

They have no natural predators in the Caribbean.  They, in turn, are voracious carnivores that feed on small crustaceans and fish that are essential for the ecosystem of the reef.  Female Lionfish can release between 10,000 and 30,000 unfertilized eggs every 4 days year round, from age 12 months and upwards.  Lionfish will eat any prey up to just over half of their own body size and can expand their stomach to up to 30 times its normal volume.  Dead Lionfish have been found with dozens of small reef fish in their stomachs, which ultimately affects the ecosystem of the reef.  With no predators to keep their numbers in check and breeding more prolifically than rabbits, they have spread throughout the Caribbean and represent a real threat to the health of the Reefs.

As there are no natural predators, the various Environment Departments  have investigated various methods to try to eradicate the Lionfish from Cayman waters, or at least cull their numbers.  This first involved training divers to catch the Lionfish in nets and encouraging snappers, groupers and sharks to eat them.  The most successful culling method so far has seen the Cayman DOE licensing scuba divers to spear Lionfish whilst diving (any other form of spearfishing is illegal in Cayman in many other Caribbean jurisdictions).  Most dive centres in Cayman run regular “culls” and as a result few Lionfish are seen on the more commonly dived dive sites.  However, when the culls venture into less popular dive sites, it is not unusual for a culling trip to clear 200-300 fish from the reef in 2-3 dives.  The spears we are issued with a Bahamian Pole Spears, basically a three pronged spear with a rubber sling that is propelled from one hand.  Whilst we were initially encouraged to feed dead fish to the local predator fish to encourage hunting, this is now discouraged and we collect the bodies in home-made containers.


My friend, modelling the container (don’t worry, we didn’t spear the turtle!)


Unfortunately, whilst these predator fish have been known to eat injured lionfish, there are few reports of them actively hunting them.  Instead, the Snappers and Groupers, and Moray Eels and sharks, have learned that divers may provide them with food.  Snappers and Groupers now follow divers, acting like bloodhounds to identify Lionfish, but not realising that they can kill the fish themselves.  Interestingly, the venomous spines do not appear to affect the ability of the larger fish to prey upon them, the defence mechanism appears only to affect divers!  It may sound a strange claim that the larger fish will act at this, but watch the below video of a Nurse Shark that trailed us on a dive (when we weren’t even spearing), investigating any overhangs we showed an interest in and eventually rooting out three Lionfish from a crevice, with several snapper watching on with interest.

Concerned with the change to the behaviour of the local undersea life in response to Lionfish culling, the DOE have stopped importing new spears, although they continue to encourage us to cull the Lionfish.  In fairness, we have seen a marked change in underwater behaviour.  In addition to the snappers highlighted in the video above, we see more Eels out during the day and sharks are more inquisitive about divers and hang around for longer.  Whilst these are generally nurse or small reef sharks, there are several dive sites on which the dive shops no longer allow culling, because the sharks were getting too inquisitive.

Lionfish, once caught and safely returned to the surface are remarkably tasty (coming from someone who struggles to like fish).  They take careful filleting (and it is advisable to clip off the spines before filleting them although after a certain period of time this is just painful, not too dangerous as the venom loses its efficacy).  One fish will not produce much flesh, but the produce of an afternoon’s dive can result in a large and tasty ceviche (I will steal and post my friend’s recipe soon).  Whilst the flesh is most commonly used in ceviche, we have fried and baked it and several restaurants on the island are developing recipes, the theory being that if man gets a taste for a species, it can’t last long!

Read more posts about diving


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: