The Aegean is getting gate crashed

The Aegean is getting gate crashed.

Over 1,000 non-native marine species have now been recorded in the Mediterranean. Around 240–250 are already living in Greek waters.

Why?

Our sea is heating faster than almost any other on Earth.

• Since 1982, Mediterranean surface waters have warmed 1.3°C (vs. 0.6ºC for the global ocean).

• July 2025 hit a basin average of 26.9°C, the warmest month ever recorded here.

And as warm-water species move in, native ones lose ground – a process known as ‘tropicalisation’.

To see where this leads, look east. Israel's shallow shelf sits in the warmest corner of the Mediterranean, which makes it the furthest along: just 5–12% of the native species once found there remain. Researchers call it the largest climate-driven biodiversity loss recorded in any ocean to date.

That's the trajectory. Greece is earlier on the same curve.

So who are the gate crashers?

Yes… the infamous silver-cheeked toadfish (Lagocephalus)... but we believe other species tell this story better.

The Atlantic blue crab (Callinectes sapidus)

Native to the US east coast, it reached the Mediterranean in ship ballast water. First recorded: Gulf of Venice, 1949. Warmer winter waters meant more crabs survived the cold months, and from 2016 it swept through the Adriatic and Ionian.

• 79% of Greek fishermen surveyed report shredded nets and economic loss

• In Papapouli Lagoon, it displaced Greece's native crab (Carcinus aestuarii) in just 6 years

• In Italy, ~€200M in shellfish farm damage, threatening 3,000+ businesses

The lionfish (Pterois miles)

Arrived through the Suez Canal. No predators here, venomous spines, and a breeding rate fast enough to take over a reef within a few seasons.

Greece launched a nationwide cull on 20 June 2026. Bounties are now past €4.73/kg.

And others

• Rabbitfish: Strip reefs bare, cost Crete and Rhodes fishermen ~€8,500/year each, now also under a bounty scheme.

• Nomad jellyfish: Up to a metre wide, officially ranked among Europe's worst marine invaders, clears beaches and clogs nets on sight.

The turnaround

Lionfish, rabbitfish, and soon blue crab all have a bounty on their heads. Restaurants from Rhodes to Piraeus are starting to put them on the menu (except, of course, the inedible Lagocephalus). So support our fishermen by ordering one in a taverna this summer!

An important takeaway (pun intended) is that species – including humans – have always moved. What's new is the speed and the methods.

Sources

• To Vima – how foreign species are taking over Greek seas

• ScienceDirect – blue crab Mediterranean distribution and impact

• Royal Society – native biodiversity collapse on the Israeli shelf

• Podcaster Capital – Mediterranean warming faster than the planet

• NCBI (PMC) – pufferfish human health impact assessment

• Athens Times – rabbitfish management programme

• Athens Times – Greece launches nationwide lionfish cull