Europe is consuming far more fish than its waters can now provide, leaving it reliant on fish caught elsewhere in the world, a report said.
According to the study by think-tank NEF and campaigners Ocean2012, July 9 is the point at which the EU blows its annual "budget" for fish, with consumption exceeding the amount sourced from depleted European stocks this year.
If the EU were only to consume fish from its own waters it would run out 189 days into the year, the report said, showing that almost half the continent's fish consumption depends on produce from non-EU waters.
The organisations are calling for reform of the Common Fisheries Policy (CFP), which governs fishing in the EU, to make fish stocks in Europe's waters more sustainable.
The report also warns dependence on fish from outside Europe could damage stocks in other parts of the world, where they are also overfished and on which local communities may rely.
Since 2000, the date of the year at which the EU effectively starts depending on other parts of the world for its fish supplies has moved a month earlier, the report said.
The date at which the UK becomes dependent on fish from outside European waters is a little later than the overall EU date, and falls on August 4.
Fish farming has helped to marginally offset the over-exploitation of wild fish stocks, but has not stopped the EU being increasingly reliant on fish from outside the union, the report said.
Aniol Esteban, head of environmental economics at NEF and co-founder of Ocean2012, said: "Safeguarding the marine environment is vital if we want to make efficient use of EU resources, and protect livelihoods and economies.
"The EU has some of the largest and richest fishing grounds in the world, but at the moment we're not managing them properly. The upcoming reform of the EU's Common Fisheries Policy presents a unique opportunity to ensure that these ecosystems are protected for future generations."