The Swarm

'What happened?'

'It smashed them to pieces with its tail. A man died. He had a heart-attack after plunging into the water.'

'What kind of whales were they?'

'No one knows. They disappeared too quickly.' Anawak looked across at the Barrier Queen's hulclass="underline" there was no sign of any damage. 'I can't imagine a whale attacking her.'

Roberts followed his gaze. 'It was the tugs they were attacking,' he said, 'not the Barrier Queen. They came at them from the side. It was obvious they were trying to capsize them, but they didn't succeed. So they tried to prevent them attaching the tow line, which was when-'

'They launched their attack.'

'Yes.'

'Impossible,' Anawak asserted. 'Whales can overturn objects as big as or smaller than themselves. Certainly nothing any bigger. And they wouldn't attack a larger object unless they had no choice.'

'The crew swears blind that that was what happened. The whales attacked and-'

'What kind of whales?'

'God knows.'

Anawak frowned thoughtfully. 'Let's imagine the scenario. Suppose the tugs were attacked by blue whales, the largest species. Balaenoptera musculus can grow up to thirty-three metres long and weigh over 120 tonnes. They're the largest animals to have lived on this planet. Now, supposing" a creature like that tried to sink a boat of the same or similar length. It would have to be as fast as the boat, if not faster. Still, over short distances a blue whale can manage fifty or sixty kilometres per hour without too much hassle: its body is streamlined and there's almost no resistance. But how much momentum would it have? And what would be the counter-momentum of the boat? To put it simply, in the event of a collision, who would be knocked off course?'

'A hundred and twenty tonnes is pretty heavy.'

Anawak nodded at the truck. 'Do you think you can pick that up?'

'Of course no.'You see? The ground's supporting you and you still can't lift it. In the water you don't have that luxury. When you're swimming, you can't lift more than your weight. It doesn't matter if you're a whale or a human. It's all a question of relative mass. Besides, you've still got the problem of the displaced water. How much does it weigh in relation to the whale? It doesn't leave you with much, just the propulsion from the flukes. With a bit of luck the whale might nudge the ship off course. On the other hand it might deflect at an angle from the hull. It's a bit like billiards, if you see what I mean.'

Roberts scratched his chin. 'Some say they were humpbacks. Others talk about fin whales. And the crew on board the Barrier Queen think they saw sperm whales.'

'Three species that couldn't be more different.'

'Dr Anawak, I'm a reasonable man,' Roberts said. 'It seems to me that the tugs could have found themselves in the middle of a herd by accident. Maybe the boats weren't rammed by whales but the other way round. Maybe the crews did something stupid. But one thing is certain, the smaller craft was sunk by whales.'

Anawak could hardly believe what he was hearing.

'The crew had just connected the cable,' continued Roberts. 'It was a taut steel one reaching from the Barrier Queen's bow to the stern of the tug. The whales rose out of the water and crashed down on top of it- so, you see, in this instance there was no displaced water to slow the momentum. And they were pretty big specimens, according to the crew.' He paused. 'The tug whipped round and sank. It lifted up and over in the air.'

'And the men?'

'Two missing. The others were rescued. Tell me, Dr Anawak, is there any explanation for their behaviour?'

Good question, thought Anawak. Dolphins and belugas recognised themselves in the mirror. So, could they think? Could they plan? Could they plan in a way that we could understand? What motivated them? Did whales have a future and a past? What possible reason could they have for ramming or sinking a tug?

Unless the tug had threatened them or their young.

'It just doesn't fit with whales,' he said.

'That's what I thought,' Roberts said helplessly. 'But the crews see it differently. In any case, the bigger tug was also rammed. In the end they managed to attach the cable. This time it didn't come under attack.'

Anawak stared at his feet, searching for an answer. 'Coincidence,' he said. 'A horrible coincidence.'

'Do you really think so?'

'We'd have more chance of working it out if we knew what had happened to the rudder.'

'That's why we've called in the divers,' Roberts told him. 'In a few moments they'll be ready to go down.'

'Did they bring a spare set of equipment?'

'I expect so.'

Anawak nodded. 'I'm going too.'

THE WATER WAS REVOLTING, but it always was in docks. The thick dark liquid contained at least as much dirt as it did water. The bottom was covered with a metre-thick coating of mud, over which swirled a permanent cloud of organic matter and silt. As the waves closed over Anawak's head he asked himself how he was supposed to see anything. He could just about make out the hazy outlines of the two divers in front of him and beyond them a dark, misty patch – the Barrier Queen's hull.

The divers gave him the OK sign. Anawak made a circle with his forefinger and thumb in return. He released the latent air in his dive vest and dropped slowly down the side of the boat. They had only gone a few metres when they switched on their head-torches. Exhaled air bubbled and thundered in Anawak's ears. Little by little the rudder emerged in the half-light. Notched and stained, its plate was bent at an angle. Anawak felt for his depth gauge. Eight metres. Ahead of him, the divers disappeared behind the rudder, leaving two stray beams of light flitting through the darkness.

Anawak approached the rudder from the other side.

At first he could see only raised edges and irregular hollows. Then it hit him. The rudder was encrusted with black-and-white mussels. He swam closer for a better look. At the bottom of the rudder, where the plate swept the shaft, the mussels had been ground to pieces. A thick gritty paste filled the cracks and grooves. No wonder it wouldn't respond. It was clogged.

He swam further down the hull. The mussels continued. He reached out gingerly to touch the shells. They were glued to each other in layers, small molluscs no more than three centimetres long. Very carefully, to avoid cutting himself on the edges, he pulled at the mussels until some came loose. They were half open. The fibres that had anchored them in position now poked out of the shells, like tendrils. Anawak stowed them in one of his collection bags, and racked his brains.

His knowledge of molluscs was sketchy. A number of species had a similar-looking byssus, composed of adhesive fibres secreted by the foot. The best known and most feared were the zebra mussels that had been brought over from Asia. In recent years they had colonised the ecosystems of Europe and America, destroying native fauna. If the mussels that had infested the Barrier Queen were zebras, it would explain why there were so many of them. They could establish themselves in no time, spreading at an alarming rate.

Anawak prodded the creatures with his finger. So, the rudder had been invaded by zebra mussels. It seemed the only explanation. But how? They usually preferred a fresh-water habitat. They could survive and reproduce in salt water, but that didn't explain how they could overrun a moving vessel miles from the seabed in the middle of nowhere. Had they latched on to it before it set sail?

The freighter had been en route from Japan. Did Japan have a problem with zebra mussels?

Further down the stern, two curved blades loomed up like ghostly apparitions from the murk below. Anawak swam towards them, kicking his fins until he could grip the edge of one. The propeller measured four and a half metres in diameter. Eight tonnes of solid steel. For a moment he imagined what it would be like when it was turning at full speed. It seemed impossible that anything could so much as scratch it without being shredded.