As we are still in the EU (just), then there is nothing to stop EU nations, or companies based in the EU buying British boats to access the UK quota. Some reading for you here.....

https://unearthed.greenpeace.org/201...-uk-fleetwood/

Particularly;

"The Spanish vessel owners in question were (and still are) known as “quota hoppers” – fishermen from other countries who had bought British boats and licences to gain access to the UK’s fishing quota.Quota hoppers have long been a source of deep resentment for British fishermen. They are held up as evidence for the widely-held view that European Union membership has been a raw deal for the UK’s fishing industry, and the origin of its decline. Their presence on the UK fishing register has been controversial from the eighties to the present day, and was one driver of the huge support for Brexit in coastal towns."