Two-way trade between Britain and the EU is worth eight hundred and eighty five billion dollars a year.
Fish make up less than half of one percent of that trade,
but disagreements over fishing rights could yet torpedo any trade deal.
Britain says it wants to take back control of its waters and restrict access to foreign boats,
that could devastate European fishing fleets.
If we cant fish in the English waters, there is no Belgian fishing anymore,
because eighty percent of the time, sometimes ninety percent of the time,we fish in English waters, all the Belgian ships.
It may appear Britain has the upper hand, but theres a big catch.
Most British-caught fish are exported to Europe,
and the EU could put tariffs on those imports, hitting British fisherman hard.
A trade deal is being held up by this fishing dispute,
but there are also disagreements on State aid and on the system of governance that will oversee any trade deal.
With the end of the transition period just six weeks away, talks are going to the wire.
Although the deadline is the end of the year, the 31st December, when the transition period ends.
You need a bit of time for ratification of any agreement.
So both sides see a breakthrough is needed in the coming days.
Even if a deal is struck, Britain will still leave the EUs Single Market and Customs Union.
Theres a lot of change on the 1st of January, deal or no deal.
The danger for the government is if the prime minister brings home a deal,
and says this is a great deal, then he owns any disruption.
Meanwhile, British prime minister Boris Johnson has been hit by domestic political turmoil as two political aides have departed.
Johnson is also having to self-isolate after meeting an MP who later tested positive for the coronavirus.
The EU is also disrupted by its own domestic agenda.
Hungary and Poland this week vetoed an agreement on the blocs annual budget,
and then eight hundred and eighty eight billion dollar COVID recovery fund
Analysts say theres a danger that Brexit deal could be sidelined at Thursdays summit,
as the EU deals with more pressing concerns.
Henry Ridgewell for VOA news London.