The EU currently sets fishing catch limits in order to maintain fish stocks. The WWF is concerned that poor management post-Brexit could result in over-fishing

All of the UK’s fishing fleet should be fitted with electronic monitoring technology after Brexit in order to protect fish stocks from poor management and potentially illegal landings of fish, campaigners have urged.

Remote monitoring technology, including closed circuit television, is now widely available for fishing vessels, but is often not deployed. A study by WWF, the environmental group, has found numerous examples of fishermen obstructing physical monitoring by independent observers.

In extreme cases, this has involved practices including defiling measuring instruments, intimidating inspectors and refusing passage to women. While these are believed to be rare incidents, there is no comprehensive survey of their extent, obscuring the available data on whether fishing vessels are adhering to regulations on catch sizes.

One observer told WWF: “[After one particularly bad voyage] I refused to do another trip … It had been a frightening experience [because of poor conditions on the vessel] and on top of this I was threatened with violence ashore by one of the crew because losing the contract was going to cost the vessel and the crew lots of money.”

Without monitoring technology, the only ways of certifying catches are to rely on vessels’ own reporting, patchy satellite observations and occasional onshore monitoring of catches, nets and practices.

The position of the UK fishing fleet after Brexit, when the UK is expected to withdraw from the EU’s common fisheries policy governing acceptable catch limits, is still unknown and the subject of fierce debate. WWF argues that without adequate monitoring, there is a danger of poor practice and vessels under-reporting or misreporting catches and fishing activity.

Fish stocks have recovered in some areas under the CFP, including the North Sea where cod stocks have improved, but this is precarious and could be endangered if a new fisheries plan is put in place without sufficient regard to scientific advice.

WWF said that answers to parliamentary questions had shown that fewer than 1% of fishing trips undertaken by the English fishing fleet had been subjected to remote electronic monitoring between 2014 and 2016, with the figure for Scottish vessels somewhat higher at 3.7%.

WWF calculated that recording 100% of the activity on vessels and reviewing at least a tenth of this would cost about £5m, equivalent to about a quarter of the spend on traditional systems which record far less. Since 2015, costs per vessel over 10m in length for modern technology have come down by over a fifth to less than £4,000 a year.

Helen McLachlan, fisheries programme manager at the charity, said: “As the UK prepares to leave the EU, we must take the opportunity to become a world leader in sustainable fishing. At the moment, we simply do not know enough about what’s happening on our fishing boats or how many fish are being taken out of our seas, and that’s putting jobs, fish stocks and the UK’s precious seas at risk.”