Fisheries chiefs and campaigners say current catch quotas will continue until the UK leaves the EU, and new arrangements may not be more generous

British fishermen have been warned that, despite the promises made by the leave campaign, they cannot expect to be granted greater catches after the UK leaves the European Union, and they may face increased economic turmoil.

Fishermen will have to remain within their current catch quotas while the UK is still a member, and even if new arrangements are negotiated after a Brexit, they will not necessarily be more generous, fisheries chiefs and campaigners have warned.

British fishing fleets will still be bound by international agreements on fish stocks that must now be worked out, and which may not be to their benefit.

“Promises have been made and expectations raised during the referendum campaign and it is now time to examine if and how they can be delivered,” said the National Federation of Fishermen’s Organisations.

“Unfortunately, perhaps, the UK’s geopolitical position means that it is not politically or legally possible just to ringfence most of our fish resources, in the way that, for example, Iceland can. The reality is that most of our stocks are shared with other countries to some degree or other.

“We can certainly seek to renegotiate quota shares, as well as access arrangements, but it is realistic to expect that there will be a price. Who will pay that price is a critical question.”

The cost could, in theory, be subsidised by the government, or it could be borne by consumers, though this would depend on the price of fish to be imported, if UK fisheries are to remain competitive. The effects on fishing fleets are likely to vary across the UK. Many fishermen currently benefit from EU subsidies to help them buy better boats with new nets that help to preserve fish stocks, for instance by allowing juvenile fish to swim clear.

A spokesman for the European commission told the Guardian: “It is far too early to speculate on this question [of what will happen to fisheries]. That will be addressed in due course, once negotiations with the UK begin on its withdrawal agreement as well as on the agreement concerning its future relationship with the EU. For the time being, nothing changes.”

Although there are only about 11,000 people directly employed in fishing in the UK, nearly half of them in Scotland, which voted to stay in Europe. The industry was made a touchstone by Leave campaigners.

Nigel Farage, of Ukip, led a small flotilla of fishermen up the Thames days before the vote, to be greeted by rival boats led by Bob Geldof, leading to a charged encounter. The murdered Labour MP, Jo Cox, sailed to the Houses of Parliament in a dinghy on the same day, with her husband and two young children, bearing a Remain flag.

Scottish political leaders have been adamant that they should not bear the brunt of any disadvantage arising from renewed negotiations on fishing after a Brexit. Angus MacNeil, the Scottish National party MP, tweeted: “Met a young fisherman last night livid about Brexit - he has just bought a fishing boat with EU grant help!”

The New Economics Foundation, which closely follows EU fishing policy, warned that fishermen should not bargain on any quick change. “Those communities and fishers hoping for an immediate end to EU quotas will be sorely disappointed. In reality, there will be years of renegotiations, and given the small size of fishing compared to other industries, there is little chance it will be seen as a priority,” said economist Griffin Carpenter.

Other green campaigners called for ministers to draw up a plan for sustainable fishing following the UK’s departure from the EU. Trevor Hutchings of WWF-UK said: “The government must deliver a coherent plan for maintaining and conserving the marine environment as a whole. This must recognise that fish stocks do not respect national boundaries. Effective management will rely on international cooperation.”

Will McCallum, head of oceans at Greenpeace UK, pointed out that the Westminster government, rather than Brussels, was in charge of allocating the EU-agreed fishing quota, and had chosen for years to give most of it to a handful of large corporations rather than to the smaller fishermen who have most to lose.

He said: “Leaving the EU has often been held up as a magic pill for the UK’s fishing industry. But now we’ve voted to leave, it is far from plain sailing. One thing is clear: the UK government cannot settle back into its old habit of privileging a handful of large companies to the detriment of the UK’s small-scale fishermen. It wasn’t the EU that gave almost two-thirds of the entire fishing quota of England and Wales to just three companies - it was the British government.”

Scotland’s fishermen are likely to face further uncertainty, as calls for a new referendum on independence have raised the prospect that it could remain a member of the EU. Bertie Armstrong, chief executive of the Scottish Fishermen’s Federation, said: “The result of the [EU] referendum brings both opportunities and challenges. It is vital that we have clarity from the UK and Scottish governments on their future intentions for fishing.”

Vote Leave declined to comment.