More than 600 lionfish were speared last month as hunters dived into the fourth annual Winter Lionfish Derby.

Organiser Corey Eddy, who published a PhD thesis on lionfish in Bermuda, said that while the number of hunters doubled since last year, the number of fish caught tripled.

He said: “It’s amazing and scary. It really emphasises that lionfish are very abundant in shallow water during the winter. The average depth of capture was less than 20ft and many were caught in less than 10ft.

“We also saw far more small lionfish than ever before, which is also alarming as it may indicate a more successful reproductive period in 2017. The smallest lionfish was 3.75in, the smallest I’d seen before.”

Sixty hunters signed up for the derby, catching a total of 624 lionfish during January.

Lionfish, which are native to the Pacific Ocean and Indian Ocean, were introduced to the Atlantic in the 1990s. The fast-breeding species spread rapidly through the Caribbean and reached Bermudian waters by 2000.

Lionfish have no natural predators in the Atlantic and are not recognised as a threat by local fish.

Dr Eddy said culling events like the Winter Derby had been shown to help address lionfish in other areas.

Research by the Reef Environmental Education Foundation found that derbies can reduce the number of lionfish in an area by up to 52 per cent.

Dr Eddy said: “That is not to say the population will not experience a period of explosive growth, common in the majority of invasive species, which is exactly what we worry about with the record number of lionfish captured in this year’s winter derby.

“Our culling programme may give us an advantage in staying one step ahead of the invasion. We have an army of lionfish hunters and we need to keep them in the water. Tournaments such as the Winter Lionfish Derby and Groundswell’s annual summer tournament, are great opportunities to do that.

“In fact, we have tournaments of some sort every season and the spring tournament is right around the corner.”

Dr Eddy and his fellow lionfish hunters celebrated the close of the Winter Derby with a party and awards ceremony at the Bermuda Underwater Exploration Institute.

Free-diving team “We Dive at Five” caught the most lionfish, bringing ashore 133 of the invasive predators.

Meanwhile, team “LionSquish” took the prize for the Scuba-diving category, landing 49 lionfish.

Kweshon Hollis speared the largest fish, measuring 18in, while Chris Cabral caught the smallest.

Dr Eddy said: “Even though we had more people than ever before, we were fortunate to provide everyone who registered with some sort of prize thanks to Gorham’s, Makin Waves, BUEI, La Garza jewellers, Blue Hole Watersports, Dive Bermuda, Blue Water Divers, and Jessica Reiderer.

“The Bermuda Lionfish Task Force donated all the money for cash prizes, and BUEI provided the room free of charge.”