The government has ordered offshore energy firms to avoid “noisy” detonations when disposing of unexploded bombs on the seabed.

Over 300,000 pieces of unexploded ordnance from the First and Second World Wars sit on the UK seabed and, if encountered, must be cleared during the construction of offshore wind projects.

Marine minister Emma Hardy said “high-order” detonations of the dormant weapons should be a last resort and the industry must adopt quieter alternatives instead. Large explosive blasts can kill off whales, dolphins and other sea creatures, and the noise can disrupt their behaviour.

As well as minimising the harmful effects of loud explosions and pile driving on vulnerable marine species and commercially valuable fish stocks, the measures will prevent construction delays caused by breaches in noise thresholds, accelerating the building of offshore wind projects planned for 2025 onwards.

Hardy said the rules will allow more offshore wind farms to be built while protecting vulnerable animals. “These new measures support the construction of offshore wind that the UK needs, while making sensible changes to stop needless harm to underwater life,” she added.

Stop Sea Blasts campaigner Joanna Lumley said she was “thrilled to the core” at the decision to protect the UK’s “unbelievably precious seas”.

“This is a magnificent example of government and industry coming together to embrace technology and challenge the old way of doing things,” she said.

“This announcement should ensure that high-order detonation, and the damage it wreaks, is consigned to the history books.”

The government has partnered with The Crown Estate’s Offshore Wind Evidence and Change programme and representatives from the explosives and offshore wind industries to test and develop new, quieter technologies for bomb clearance, and pilot proposed noise limits during offshore wind construction.

Marine Planning Officer at The Wildlife Trusts Christina Platt said:   “While many people are aware of the harmful impacts pollutants like plastic and sewage can have on marine wildlife, underwater noise tends to get a lot less airtime. But the reality is that human activities at sea can often emit noise at levels which can negatively impact wildlife, from causing changes in their behaviour, to injuries and even in some cases death.

As UK seas get busier, it’s only right that all efforts are taken to limit unnecessary harmful underwater noise pollution.”

Read more in the Joint Position Statement, ‘Marine environment: unexploded ordnance clearance’ by Defra, MMO, JNCC, Natural England and the Scottish Government.