Boris Johnson has been accused of sacrificed the fishing industry in a drive to secure a trade deal with the EU.
It comes as the Prime Minister said the deal brought "glad tidings of great joy" to the UK.
The deal was agreed on Christmas Eve following months of negotiations with the European Union and comes just a week before the current trading arrangements expire with the UK leaving the single market and customs union without the prospect of tariffs and quotas.
Mr Johnson later posted a video on Twitter in which he brandished the document, which has not been released in full yet, and at one point punched the air with enthusiasm at its contents.
Mr Johnson said: "Tonight, on Christmas Eve, I have a small present for anyone who may be looking for something to read in that sleepy post-Christmas lunch moment, and here it is, tidings, glad tidings of great joy because this is a deal.
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"A deal to give certainty to business, travellers, and all investors in our country from January 1. A deal with our friends and partners in the EU.
"You remember the oven ready deal by which we came out on January 31, that oven ready deal was just the start - this is the feast, full of fish, by the way.
"And I believe it will be the basis of a happy and successful and stable partnership with our friends in the EU for years to come.
"So, that's it, that's the good news from Brussels, now for the sprouts, and a happy Christmas to you all."
But the deal has already come in for criticism with Barrie Deas, chief executive of the National Federation of Fishermen's Organisations, saying there will be "frustration and anger" across the industry about the outcome of the negotiations.
Sporting a fish-themed tie, Mr Johnson told the Government press conference: "For the first time since 1973 we will be an independent coastal state with full control of our waters."
But Mr Deas told the PA news agency: "In the end it was clear that Boris Johnson wanted an overall trade deal and was willing to sacrifice fishing."
He said: "The broad feeling is that the UK has made significant concessions on fish in order to secure a trade deal.
"I think the industry will be extremely disappointed.
"We have secured increases in quota from the EU but they don't come anywhere close to what our entitlement is in international law.
"So I think there will be frustration and anger across the industry about that."
Mr Deas said he thought the failure to secure a 12-mile exclusion zone to protect inshore fisheries for at least five years is "going to be particularly contentious".
He said it was "understandable" that "the EU wanted to hold on to the advantages it has held for 40 years".
The Prime Minister told the press conference that the UK's share of fish in home waters will rise "substantially" from roughly half to closer to two-thirds in five-and-a-half years' time "after which there is no theoretical limits beyond those placed by science or conservation on the quantity of our own fish that we can fish in our waters".
Mr Johnson accepted that the UK had given ground on access to fishing waters, saying that the EU began wanting a transition period of 14 years while the UK wanted three years.
The Prime Minister said the five-year transition was a key compromise.
He said: "I think that was a reasonable transition period and I can assure great fish fanatics in this country that we will as a result of this deal be able to catch and eat quite prodigious quantities of extra fish."
The seafood sector said it was relieved a tariff-free deal has been agreed.
Seafish - the public body which supports the industry - welcomed the Brexit deal if it makes trade flows easier but said uncertainty remains on fishing rights.
