Lionfish: a very spiny problem!

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For anyone who has been diving in the Caribbean in the last few years, you have probably heard of the lionfish problem. Having taught marine biology & conservation in the Caribbean for several years, it’s a question I get asked about a lot. This blog explains some of the facts about lionfish and what we can do to help our reefs:

  1. Where should they be?
  2. How did they get into the Caribbean?
  3. What is all the fuss about?
  4. What you can do to help the reefs?

Where should they be?

Lionfish are a beautiful predatory fish, native to the Indian and Pacific Oceans and the Red Sea.

In their native habitat the lionfish is great to observe and photograph. They are not very common as they have natural predators that keep population down and in balance with the other reef fish (Density/hectare in the Pacific is ~20).

How did they get into the Caribbean?

Unfortunately since 1992, two species of lionfish (Pterois volitans & Pterois miles) are now found in the Atlantic Ocean and the Caribbean Sea, where they are an invasive species. The theory is that captive lionfish were released or escaped off the coast of Florida and the population has spread. Lionfish established themselves in the Caribbean in less than 3 years and range from North Carolina to South America including the Gulf of Mexico. From a few individuals in 1992 the population has now spread out of control to become a major problem in the ecosystem (Density/hectare in Caribbean ~398 in 2012).

What is all the fuss about?

Why are lionfish an issue?

To understand the issue, we first need to know a bit about the fish.

Lionfish biology:

They have venomous tissue within their spines for protection and are generalist carnivores. Adults can grow up to 42cm and have a lifespan of 5-10 years. They become sexually mature in less than a year and spawn in pairs. Females can release 30,000 eggs at one time. Enclosed in a mucus layer, the eggs float to the surface. In a few days the mucus dissipates and the eggs are released to be dispersed by ocean currents.

Habitat & ecology

Lionfish inhabit all marine habitat types (reefs, lagoons, mangroves, sea grass beds, sand patches and artificial substrates) and can handle tropical temperatures all the way down to 10°C. They can also live at a huge range of depths (from shoreline to over 300m or 1000 feet), though they tend to be territorial, so may remain in the same area for up to 7 months. They appear to be attracted to cleaning stations.

So why are they a problem?

Lionfish have no natural predators in the Caribbean. The density per hectare of invasive lionfish is around 20x higher than in their native waters. They consume over 70 species of fish and many invertebrate species and can eat prey up to half their body length (basically they can eat pretty much anything!). This makes them top predators along with sharks, rays and groupers. By colonising mangroves and sea grass beds they pose a major threat to juvenile fish (this is where lots of baby fish live until they are big enough to survive out on the reef).

On heavily invaded sites, lionfish have reduced their fish prey population by up to 90% and continue to consume native fishes at unsustainable rates. Many reefs have been decimated of the native reef fish as the lionfish consume until supply of fish has run out. Once the food has run out, lionfish can survive for 12 weeks with no food, so can move on to other feeding grounds. Reefs without fish don’t function, so the coral also starts to suffer.

Invasive lionfish reproduction occurs throughout the year and as frequently as every 4 days (whereas native Indo-Pacific lionfish breed only once a year!). This means an invasive female lionfish can lay over 2 million eggs/year in the Caribbean. And unlike in the Indo-Pacific, many of these eggs will survive to adulthood. This means the populations are increasing at a phenomenal rate (700% in 4 years!).

Where lionfish containment programs operate, the deep dwelling fish can be very hard to get to in order to kill or capture. So lionfish pose a threat to the integrity of the reef food web and can have wide reaching impacts on commercial fisheries, tourism, and overall coral reef health.

What you can do to help the reefs?

Educate others and spread awareness of lionfish.

EAT THEM!! They are a delicious delicacy (see RECIPES below!).  Also eating this fish reduces pressure on fish stocks of native species.

Encourage local restaurants to serve Lionfish and promote consumption by community members.

We need to be the main predator and keep dive sites as free of Lionfish as possible. Though we cannot get all of them, reducing the numbers on the coral reef and shallow water can really help native fish species and coral health.

Lionfish removal:

Spearing lionfish is quick and safe if done properly (Hawaiian Slings can be used very effectively). A tube container is recommended to store captured fish.

Many marine park authorities and islands have licensed spearing lionfish as local removal efforts can significantly reduce lionfish densities and subsequent impacts. Efforts are invaluable for supporting other conservation initiatives like management of marine protected areas, pollution control and fish stock rebuilding in order to help our reefs.

Try our favourite Lionfish Recipes! To see them click here.

  • Island Lionfish Fry
  • Lionfish Ceviche
  • Lionfish Coconut Curry
  • Coconut Lionfish with Spicy Mango Dip
  • Marinara Lionfish Spaghetti
  • Lionfish Tacos with Street Corn and Salsa
  • Cajun Spiced Lionfish Fillets with Mango Salsa
  • White Wine Lionfish
  • Lionfish Sanganaki
  • BBQ Lionfish: Kebabs and Parcels

For more from CJ and Mike please click here.

CJ and Mike

CJ and Mike

CJ and Mike are dive instructors who have travelled all over the world pursuing their passion for the underwater world. CJ is a PADI MI and DSAT Trimix instructor with a degree in Conservation biology and ecology, who has been diving for 15 years. She loves looking for critters and pointing them out for Mike to photograph. Mike is a PADI MSDT who got back into diving in 2010. He enjoys practicing underwater photography and exploring new and exciting dive locales, occasionally with more than one tank. Follow more of their diving adventures at www.bimbleintheblue.com.

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