On the surface, the decision of the United Kingdom to withdraw from the so-called London Fisheries Convention (LFC), an agreement that allowed European nations to fish in each other's waters, was an inevitable part of the Brexit process.

Nonetheless, the 10,000 metric tons of fish that foreign fleets catch annually in British coastal waters is only a fraction to the 708,000 tonnes of fish that UK fisheries collected in the same waters in 2015.

UK Environment Secretary Michael Gove said the decision to exit the 53-year-old fishing agreement was about "taking back control" of UK waters. He also called common fisheries policy "an environmental disaster," saying the decision to withdraw was made to "ensure that we can have sustainable fish stocks for the future."

"I think it's important that we recognize that leaving the European Union is going to help the environment," Gove added.

In May, the UK also committed to leaving the Common Fisheries Policy (CFP), a set of rules for managing European fishing fleets and for conserving fish stocks, when Brexit is carried through in two years.

Yet environmentalists are sounding the alarm over concern for marine ecosystems.

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"I was quite surprised," Will McCallum, Greenpeace UK head of oceans, told DW in response to Gove's statement. "Leaving the London Convention provides no guarantee of sustainability at all."

He points to the fact that fish stocks have "generally improved" since these agreements came into effect. "To blame [the LFC and CFP] for having a negative environmental impact on fish stocks is a first for me," McCallum said, adding that the agreements regulated an industry that had seen "major fish stock collapses."

"It's important that we don't roll back on any of the progress that has been made over the last 30 years," he said.

McCallum also insists that the UK must continue to cooperate with neighboring countries in order to insure sustainability of stock. "Fish don't stay in our waters," he pointed out. "They move across borders. They're migratory."

This French fishing trawler working off the Welsh coast will be banned under Brexit

Protecting marine waters post-Brexit

Environmental advocates are also concerned that withdrawal from this and many other EU marine water agreements will threaten broader marine biodiversity.

Tom West, an associate researcher at London-based ClientEarth, says that Gove's talk about regaining control of fisheries must also include laws to protect UK marine protected areas, which have conservation under EU law.

"Withdrawing from the LFC and the CFP without any sign so far of what will replace them is risking rowing back on hard-won environmental protections over the last 40 years," he said in a statement after Gove's announcement on Sunday.

Beyond specific fisheries agreements, ClientEarth is concerned about protecting broader marine biodiversity, especially when the UK is no longer subject to the EU Marine Strategy framework directive, implemented in 2008.

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The marine directive is currently working toward its goal of achieving Good Environmental Status (GES), which translates into maintaining biodiversity in the EU's marine waters by 2020 - and "to protect the resource base upon which marine-related economic and social activities depend."

UK waters also contain marine protected areas that are among the more than 3,000 "Natura 2000" EU directive sites.

West stressed the importance of clearly deciding how the law will protect these, and how they will be managed post-Brexit. "We want to make sure we don't go back on those 40 years of protections that we gained," he told DW.

Oversight and accountability

West is among numerous environmental lawyers and activists who believe that ecological protections could be significantly weaker outside the EU legal framework.

"The loss of the oversight provided by European Union bodies - the commission, the courts, et cetera - is going to be a threat to the vital protections that we've achieved in the last 40 years," said West.

McCallum agrees that the onus is on the UK government to ensure that checks and balances are put in place, and "to ensure accountability and proper cooperation with neighboring countries."

Removing a fundamental layer of accountability may make empty words of Michael Gove's promise that leaving the EU will be better for the marine environment.

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West said it would be possible improve protections. But much more plausible, he thinks, is "that there are threats and risks to the standard of our environmental protection and to the oversight and enforcement of it."

The other fear is timing: There are only two years to create new legal protections before an inevitable period of legal limbo sets in.

"It's hard to see how those cooperative processes will be replaced withing this really, really, really short timeframe we've got," said West.

Carrying sustainability forward

Meanwhile, other groups applauded the move.

The Scottish Fishermen's Federation (SFF), which supports Brexit and the general withdrawal from EU agreements, echoed the claim that the decision would be good for the environment.

"Fishermen have to be pleased with this first step to taking back control of our own waters," tweeted the SFF.



Greenpeace agrees that fishing rights need to be prioritized to those who are fishing more sustainably. But it argues these can both be foreign and local fleets.

"If boats are proven to be fishing in a sustainable way, if they're shown to be providing local employment, there's no reason why, in Greenpeace's opinion, they shouldn't be fishing in our waters," said McCallum.