Some 13 miles (20 kilometres) out to sea, AFP images showed the Solong cargo ship -- which on Monday hit the jet fuel-laden Stena Immaculate tanker, triggering a huge blaze -- was little more than a smoking wreck.

The still-anchored Stena Immaculate tanker was seen still anchored in the North Sea with a gaping gash to its side.

In Grimsby, once the home of the world's largest fishing fleet, the port area where rescued sailors from the two ships were taken remained cordoned off.

Twenty-four hours earlier the sound of helicopters and ambulances had filled the air as all but one of the crew members made it ashore.

Townspeople steeped in the area's fishing and seafaring history expressed astonishment that such an accident could happen in broad daylight despite modern navigation equipment.

The Stena Immaculate tanker carrying 220,000 barrels of jet fuel had been at anchor when the container ship Solong hurtled into it Monday morning.

"(I was) very surprised," Raymond Todd, 71, told AFP at a local cafe, because modern equipment meant such accidents "should not happen".

The retired fisherman, who went to sea at the age of 15 and spent his working life fishing waters around Iceland, Norway and Greenland, speculated that a "mechanical failure with the radar or something" might have been the cause.

Otherwise, he said, "I would think that (they) never had anybody manning the radar."

"Obviously it's thick fog out there so they should have had extra lookouts on the bridge and if it was doing 16 knots which I imagine is full speed why did they go so fast? In a busy shipping lane," he said.

Todd said he feared any oil spill or release of toxic products from the ships could "wreck" the livelihoods of those fishermen who still "actually go out there to earn a living".

Humberside police said Tuesday that a 59-year-old man had been arrested on suspicion of gross negligence manslaughter following the accident.

- Nature rich coastline -

In the mid-20th century, Grimsby was one of the world's leading fishing ports but the fleets of trawlers began to disappear in the 1970s.

Fishermen blamed the "cod war" over fishing grounds with Iceland, then EU quotas carved up the seas around Europe, reducing the catch of British boats.

Locals also expressed fears for the region's bird and nature-rich coastline.

Transport minister Mike Kane told parliament there was currently "no sign of pollution".

But Andrew Vear, 54, said his wife who works for a bird conservation group was "really concerned", as he cleaned windows at a local pub.

Vear said he too was worried about puffins and seals which have well-established colonies around the Humber estuary.

- Economic impact -

Helen Dawson, 84, was more optimistic about the impact on the coastline. "They'll get it cleared up somehow," she said.

But she cautioned that if the fish were affected it would have an impact not just on local fishermen, but also local restaurants and others involved in the town's economy.

"This is a fishing town, we're known for that," added massage therapist Amy Wilson, 34.

She said she was upset about the "human losses" -- one missing crew member is presumed dead -- as well as "the lasting impact on the environment".

For her, the accident was "definitely a another kick in the teeth" for the region which has seen a decline in its economic fortunes over recent decades.

Nearly a decade ago some 70 percent of people in the town voted for Brexit, hoping the UK's departure from the European Union would boost its flagging fortunes.

But Wilson said there was little sign of any economic boost.

"We keep getting promised improvements... It just isn't happening," she said.