The UK is set to become an independent coastal state post-Brexit under proposed new laws put before the Lords.
Foreign fishing boats will be barred from fishing in UK waters unless licensed to do so, peers have been told.
But details on access have still to be thrashed out during negotiations with the EU before the end of the transition period in December.
Environment minister Lord Gardiner of Kimble said: “The Government’s vision is to build a sustainable fishing industry, with healthy seas and a fair deal for UK fishing interests.”
“Any decision about giving vessels from the EU and other coastal states access to our waters will be a matter for negotiation.
“This Bill provides the framework to enable us to implement whatever is agreed internationally,” he said.
“From 2021 the UK will be an independent coastal state, able to control who can fish in our waters.
“We will be responsible for setting annual total allowable catches of fish species in our waters.”
By leaving the Common Fisheries Policy (CFP) at the end of the transition period, the automatic rights for EU vessels to fish in British waters will stop for the first time since 1973.
For the Opposition, Lord Grantchester welcomed changes made to the legislation, which had “mysteriously stalled” in the Commons before the election.
But he said there were still aspects which did not meet Labour’s aspirations and called for further amendments in the Bill’s later stages.
Former diplomat and independent crossbencher Lord Hannay of Chiswick said the “detailed shape of Britain’s new post-Brexit fisheries policy remains as shrouded in mystery as ever”.
Lord Hannay called for ministers to be realistic in negotiations with the EU, rather than relying on “slogans and mantras”, and warned against linking fishing to other sectors in the talks.