One gets the feeling that the decision to frame the title The Death of the Oceans? as a question may have been taken at the last minute in order to discourage immediate despair on the part of the viewer.

If the programme itself communicated anything, however, it's that dead oceans are a much stronger possibility than that question mark implies.

The threat, in fact, appears to be immediate and all but irreversible. One scientist said: We risk losing species before we've even been introduced to them. The living ocean is very fragile, said another. Don't for a minute believe that we can't screw it up much worse than it is today.

With the sound turned down, this looked like another lush and lavish documentary about sea creatures fronted by David Attenborough, complete with weird-looking squid and humpback whales glinting in the sun.

But the soundtrack was, for the most part, a litany of stark warnings and dire statistics: our seas fished clean by 2050; all coral poised to die from ocean acidification unless the amount of CO2 in the atmosphere is drastically reduced; all whale conversations eventually drowned out by our increasingly noisy shipping.

Before we can take the most basic steps to save our oceans, we need something we've never come close to having: a baseline survey of what's in the sea already. That's where the diligent folks of the Census of Marine Life come in.

They're painstakingly measuring every aspect of ocean life, although it's hard to watch them do it in the present circumstances without wishing they'd do it a bit faster. Dr Julian Caley and his team spend months examining the creatures in one cubic foot of Australian coral reef.

The worm specialist alone has found 22 new species. The fish parasite guy logs, on average, one new species a day; 6,000 previously unknown species have been discovered across the whole census so far.