Invasive fish in the Adriatic threaten local species

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STORY: Location: Molunat, Croatia

For decades, Croatian fisherman Marko Kristic has cast his net in the Adriatic Sea.

But climate change and increased maritime traffic have brought dozens of new species here, including the Mediterranean parrotfish.

Kristic says that’s threatening his traditional catch… and his bottom line.

"Another kind of problem is that when I catch it, I can't sell it to anyone, because the local people don't eat the new fish…”

Experts say the Adriatic is getting warmer.

Invasive species are moving in.

And it's putting the survival of hundreds of native fish species at risk.

The Mediterranean is becoming the fastest-warming sea on the planet, according to 2023 data from the Italian National Agency for new Technologies, Energy and Sustainable Economic Development.

The Adriatic is its northernmost arm.

"The Adriatic is changing, it is getting warmer. Because of that, new organisms appear. By that I mean fish and planktons and algae…”

Nenad Antolovic is a scientist at the Dubrovnik-based Institute for Marine and Coastal Research.

He says fish stocks in the Adriatic are slumping due to overfishing, climate change and the invasion of new species.

All in all, he says around 460 native fish species are in danger.

"Ten years ago, many would have said that nothing could kill you in the Adriatic. However, things have changed since then." //

"Currently, there is a risk because two different species of fish have the potential to be lethal. The toxic spines on lionfish can be fatal to a human experiencing an allergic reaction.”

In neighboring Montenegro, scientists from the Institute of Marine Biology in the coastal city of Kotor singled out the blue crab.

Researcher Olivera Markovic says it appeared about two decades ago.

“It is ranked among the top 100 worst invasive species in the Mediterranean.”

And fishermen and scientists say stocks of green crab have been cut back in some areas... and wiped out in others.

Scientist Ilija Cetkovic is especially worried about the lionfish.

“Other invasive fish species that have been documented thus far include dusky spinefoot, two varieties of pufferfish, and lionfish, which was first seen in October 2022. Because of its invasiveness, which is unique to that species in comparison to others, it is today a major problem in the Adriatic Sea and throughout the Mediterranean.”