Specialist science journalists were in the minority among the spectators, but reporters from the broadsheets, magazines and TV networks were out in force – exactly the sort of people the team had hoped to attract.

Fenwick started by explaining the distinguishing features of an orca's anatomy. 'As you can see, its shape resembles that of a fish, but that's because nature adopted this body form for sea creatures that have evolved from land animals. It happens a lot. We call it convergent evolution: in order to cope with similar environmental pressures, two totally different species develop convergent structures – that is, structures designed to solve the same problem.'

He removed sections of the thick outer skin to expose the layer of fat. Fish, amphibians and reptiles are ectotherms, which means they're cold-blooded, so their body temperature corresponds to that of their surroundings. Mackerel, for example, are present in the Arctic Ocean and in the Mediterranean. In the Arctic their body temperature is four degrees Celsius, but in the Med it's twenty-four. The same doesn't apply to whales: they're warm-blooded, like us.'

Fenwick had uttered two little words that never failed to hit their mark. As soon as the spectators heard them, they sat up and paid attention.

Fenwick continued, 'They could be swimming in the Arctic or in the Baja California, it makes no difference. Wherever they are, whales have a constant body temperature of thirty-seven degrees, and to maintain it they accumulate the layer of fat we call blubber. See this white, fatty mass? Water normally draws heat away from the body, but this layer of fat prevents it happening.'

His gloves were red and slimy with the orca's blood and fat.

'But blubber can also be fatal to a whale. The reason they die when they get stranded is because of their weight, due in part to their magnificent fat layers. A blue whale measuring thirty-three metres and weighing a hundred and thirty tonnes is four times heavier then the biggest dinosaur that ever walked the Earth. Even an orca can weigh up to nine tonnes. Creatures of that size can only survive in water. It all comes down to Archimedes' principle, which states that the weight of a body immersed in fluid will decrease by an amount equal to the weight of the fluid it displaces. On land, whales are crushed to death by the pressure of their own weight- if they haven't already been killed by the insulating effect of their blubber, which absorbs the heat of the environment. Beached whales often die of overheating.'

'Is that what happened to this one?' asked a journalist.

'No. Over the past few years we've come across an increasing number of whales whose immune systems have collapsed. They all died of bacterial infections. J-19 was twenty-two, not exactly a youngster but most healthy orcas live to thirty. So, he died early and there are no external signs of a struggle. My guess is that an infection killed him.'

Anawak took a step forward. 'We can tell you why that happens, if you're interested,' he said, in as neutral a tone as he could muster. 'There's been extensive toxicological research into the problem, and the results show that the orcas off the coast of British Columbia are badly contaminated with PCBs and other environmental pollutants. This year we've found orcas with PCB levels of a hundred and fifty parts per million: A human immune system wouldn't stand a chance against that level of toxin.'

He saw a mixture of compassion and excitement in the listeners' upturned faces. The journalists had their story.

'The worst thing about toxins,' he continued, 'is that they're fat-soluble, which means they're passed to the calves in the mothers' milk. When human babies come into the world with AIDS, it's all over the media and everyone is appalled. Write about what you've seen here and make people angry about this. Hardly any other species on the planet is as packed with toxins as the orcas.'

'Dr Anawak.' The journalist cleared his throat. 'What happens when humans eat the flesh of these whales?'

'They absorb some of the toxin.'

'Does it kill them?'

'It might in the long-term.'

'In that case, aren't businesses that dump their chemicals in the water – like the timber industry – indirectly responsible for death and disease among humans?'

Anawak hesitated. The reporter was right, of course, but Vancouver Aquarium was keen to avoid direct confrontations with local businesses, preferring to try for a diplomatic solution. Painting British Columbia's economic and political elite as a bunch of near-murderers would increase the existing tensions. 'There's no doubt that eating contaminated meat would pose a risk to human health,' he said evasively.

'Meat that our businesses have knowingly contaminated.'

'That's something we're working on with those responsible.'

'I get it.' The reporter made a note of something. 'I was thinking in particular of the people where you come from, Dr…'

'I come from round here,' said Anawak curtly.

The journalist stared at him in surprise.

No wonder, thought Anawak. The poor guy had been snapped at for doing his homework.

'That's not what I meant,' the man responded. 'I meant where you came from originally-'

'Very little whale or seal flesh is consumed in British Columbia,' Anawak interrupted. 'By contrast, relatively high levels of toxins have been recorded among inhabitants of the Arctic Circle, in Greenland, Iceland, Alaska and further north in Nunavut, but also in Siberia, the Kamchatka peninsula and the Aleutian Islands. In other words, everywhere that marine mammals are part of the staple diet. It doesn't matter where the mammals pick up the toxins because they migrate.'

'Do you think the whales know they're being poisoned?' asked a student.

'No.'

'But in your books you say that they're intelligent. If only they realised there was a problem with their food…'

'Humans carry on smoking until they need an amputation or die of lung cancer. They're aware of the problem but it doesn't stop them. And humans are a good deal smarter than whales.'

'How can you be sure? It might be the other way round.'

Anawak made an effort to answer politely. 'You have to see whales as whales. They're highly specialised, but specialisation brings with it certain limitations. An orca is a streamlined living torpedo, but that comes at the expense of legs, hands, facial expressions and stereoscopic vision. They're not like humans. Orcas are probably cleverer than dogs. Belugas are intelligent enough to know who they are, and dolphins certainly have a unique brain. But take a moment to think about what they achieve with all that. Whales and dolphins share a habitat with fish and have a similar way of life, but fish get by with only a few neurons.'

Anawak was almost relieved to hear his mobile buzz. He signalled to Fenwick to carry on with the autopsy and took a few paces away from the group.

'Leon,' said Shoemaker, 'Can you prise yourself away?'

'Maybe. What's wrong?'

'He's back.'

THIS TIME ANAWAK was so angry he could barely contain himself A few days ago, when he'd been called back to Vancouver Island in a hurry, Jack Greywolf and his Seaguards had disappeared, leaving two boatfuls of disgruntled tourists in their wake. Shoemaker had been besieged by people complaining at being filmed and stared at like animals, and had only just succeeded in calming them down, in some cases by handing out free tickets. After that, things had seemed to return to normal. But Jack Greywolf had caused an upset, exactly as he'd hoped.

Back at the station they'd gone over all the options. Was it better to ignore the protesters or take action against them? If they made an official complaint they would give Greywolf a forum. People like him were as much of an irritation to serious environmental organisations as they were to the whale-watching business, but in the media uproar, an unsuspecting public would receive distorted information. Many would sympathise with Greywolf, without knowing the facts.