Guardian -- At 11.30pm, 10 nautical miles off Yemen’s western Red Sea coast, seven fishermen were near the end of the four hours it had taken to haul their nets bulging with the day’s catch into their fibreglass boat. Suddenly, away from the illumination of the vessel’s large spotlight, one of the men spotted a black silhouette coming towards them.

Moments later a helicopter began circling overhead. The fishermen assumed an approaching warship would call for them to show their registration documents and ID cards. They were well within the 30 nautical mile boundary they had been warned not to cross by leaflets airdropped on land by the Saudi-led coalition. But, without warning, gunfire suddenly erupted from the helicopter.

For the next five minutes, bullets sprayed the vessel without a pause. Osam Mouafa grabbed his friend, Abdullah, dragging him into a corner, curling himself into a protective ball as the bullets flew through the boat. Shot in both knees, with a third bullet having grazed his thigh, Osam began to feel water rising around him. “The boat became like a sieve,” he said, sitting next to the wooden stick he now needed to walk.

By the time the onslaught stopped, the captain – a father of eight – and Abdullah were dead. Another crew member, Hamdi, was deafened and paralysed down one side after being hit in the head by shrapnel. All bleeding heavily, the five survivors frantically began bailing water out of the sinking boat. The helicopter circled again.

Just when Osam thought the rest of them were about to die, the helicopter changed course, training its sights on another fishing boat a few hundred metres away. Osam watched in horror as a projectile fired from the helicopter sent the neighbouring boat into a ball of fire and fisherman diving into the water to escape the flames.

For the next three hours, the helicopter continued to circle. Osam used a piece of cloth as a makeshift tourniquet on his bleeding legs and played dead. The partially submerged vessel, with the fishermen’s clothes plugging the holes, drifted at sea for 15 hours until another boat rescued them, towing them ashore.

The attack on Osam’s boat by the Saudi-led coalition was not an isolated incident.

Since the Saudi kingdom launched its military intervention in Yemen in March 2015, more than 10,000 civilians have died. More than 250 fishing boats have been damaged or destroyed and 152 fishermen killed by coalition warships and helicopters in the Red Sea and on the small, scattered islands used by fishermen, according to Mohammed Hassani, the head of the fishermen’s union in Yemen’s western port of Hodeidah. Hundreds more, like Osam, have been injured and are no longer able to work.

“They have declared war on fishermen,” said Hassani, who has also documented accounts of further attacks on first responders attempting to rescue vessels that have come under fire. More than 100 miles further south in the port of Mocha, fishermen have been barred from going out to sea since the Houthi-Saleh forces, who the Saudi-led coalition have been fighting for more than two and half years, were pushed out by Yemeni fighters backed by a coalition partner, the United Arab Emirates, in February.

Yemen’s fishing industry has become an ever more vital lifeline for a country in the midst of the world’s worst humanitarian crisis. More than eight million Yemenis are now facing famine after Saudi Arabia tightened a blockade on the country on 6 November. Restrictions were slightly eased on 26 November, allowing some aid in for the 20 million Yemenis relying on humanitarian support. But aid agencies have predicted mass famine if key ports such as Hodeidah remain closed to commercial imports.

Yemen relies on maritime imports for more than 80% of its annual staple food supplies. Although staples remain available, the Saudi-imposed import restrictions, combined with a rapidly depreciating currency, mean food prices have sky-rocketed. Government salaries have gone unpaid since August 2016 and an estimated 55% of the workforce have been laid off due to the conflict. Millions of Yemenis can no longer afford to buy food, forcing them into the more than 75% of the population who are in need of humanitarian assistance.

Fishing is not the only domestic source of food supplies to be targeted by Saudi forces. In the district of al-Rawda in northern Sana’a, farmer Yahya Abdu Taleb stopped cultivating his land after a bomb from an airstrike landed in a field less than 50 metres from his house, where his wife and two daughters were sleeping. Fortunately for the family, the missile failed to explode.

Standing in the now fallow farmland, Yahya watches a team from Yemen’s national demining programme extract the missile buried some 10ft into the soil. He is desperate to start growing cucumbers again.

“I have three wells on my land. But now I don’t grow anything,” he said. When food prices started to rise, he went to rebuild the polytunnels needed to grow vegetables in the extreme mountain temperatures of Yemen’s arid northern highlands. But his neighbours begged him to stop. “The Saudis target them [the polytunnels]. They were afraid the planes would come back, bomb us and kill their families.”

Nine-year-old Zahara Taleb used a mobile phone to film the bomb being winched out of her father’s farmland next to their home. “I want to make sure it’s gone so I don’t have to be afraid anymore,” she said.

Ali al-Mowafa, heading the team from the NDP working to remove the unexploded ordinance in al-Rawda, said British, American and Italian-made bombs were identified among 12 missiles that failed to explode from one night when 52 bombs hit the district last August.

Research on the pattern of bombing, carried out by emeritus professor Martha Mundy at the London School of Economics, concluded that in the first 17 months of the Saudi-led bombing campaign there was “strong evidence that coalition strategy has aimed to destroy food production and distribution” in areas controlled by the Houthis and allied forces loyal to former president Ali Abdullah Saleh. Saleh was killed by Houthi forces in Sana’a on Monday, days after declaring he had switched allegiances.

Data on coalition airstrikes collected by the Yemen Data Project have recorded 356 air raids targeting farms, 174 targeting market places and 61 air raids targeting food storage sites from March 2015 to the end of September 2017.

Standing in for the UK prime minister, Theresa May, in parliament while she visited Saudi Arabia last week, her deputy Damian Green defended the British government’s continued support of weapons sales to the kingdom on the grounds that “our defence industry is an extremely important creator of jobs and prosperity”, while also highlighting Britain’s role as “the fourth largest humanitarian donor to Yemen”.

The government has approved more than £4.6bn in fighter jets and arms sales to Saudi Arabia since their Yemen bombing campaign began. British military officers are also providing targeting training to the Royal Saudi Airforce.

May said she would demand Saudi Arabia immediately end its blockade during her visit. It remains in place.

Attacking Yemenis’ ability to provide food for themselves, combined with the restrictions on imports, adds up to economic siege tactics that are resulting in the collective punishment of a population of 27 million people that has been described as a “blatant violation of international laws” by aid agencies.

Despite the prospect of imminent mass famine, this strategy is being used to put greater pressure on the Houthis in lieu of failed efforts by the Saudi coalition to bomb the opposition into submission over more than two years.

Yemen analysts also point to the policy as a more appealing option for the Saudi crown prince, Mohammed bin Salman, who also holds the role of minister of defence, than deploying thousands of loosely aligned, highly factional troops to attempt a precarious forced takeover of the capital.

Any ground offensive would most likely result in either failure or an even more bogged down conflict than the quagmire in Yemen that the Saudis and their coalition allies have found themselves in.

“There are voices in the coalition who view economic levers as a potential means of putting pressure on the Houthis and of pressuring people living under the Houthis into rebelling or expressing greater discontent against them as conditions worsen,” said Adam Baron, a Yemen expert at the European Council on Foreign Relations.

“Destruction of access to food and water constitutes a war crime,” Mundy of the LSE noted in a paper published in September by the Global Network for the Right to Food and Nutrition.

“But who is to prosecute when the same international organisations and national states, which stood aside for months of bombardment and blockade, now play the role of humanitarian intervention to save Yemenis from famine and cholera?”