## World Ocean Census: A Global Survey of Marine Life

• Darlene Trew Crist,
• Gail Scowcroft &
• James M. Harding Jr
Firefly Books: 2009. 256 pp. $40/£30 1554074347 | ISBN: 1-554-07434-7 Begun in 2000, the first global marine census is due to be completed next year. In anticipation of the official release of these results, a beautifully illustrated book highlights the findings to date of this massive project. World Ocean Census also hints at the studies that might stem from the millions of samples collected. Recent discovery: Kiwa hirsuta, named after the goddess of shellfish, is better known as the yeti crab. Credit: A. FIFIS/IFREMER The Census of Marine Life aims to catalogue the oceans' inhabitants now, place them in a historic context and project what might be found in the oceans of the future. As of 2008, it involved some 2,000 scientists from 82 nations, and had US$500 million of funding. A bold undertaking, it marks a “Herculean decade of exploration”, explains oceanographer Sylvia Earle in her foreword to the book.

Science writer Darlene Trew Crist and educators James Harding and Gail Scowcroft emphasize that marine science is in an age of discovery. When the census started, only 250,000 species were known out of the millions estimated to live in the ocean. Researchers expect to find many thousands more, but will undoubtedly fall short of a complete accounting, given the size of the task. Just three recent expeditions to the Southern Ocean yielded some 700 likely new species, and one litre of seawater alone can host 20,000 different microbes.

Like the census, the book is organized by oceans past, present and future. Information dating back 500 years or more is gleaned from old whaling logs, scientific expedition records and even old restaurant menus that provide snapshots of species exploitation. Although not always rigorously quantitative, such records can offer a baseline for conservation targets. Past levels of some exploited fish, such as cod, were surprisingly high. “It is virtually impossible to imagine how much the oceans of the past teemed with life,” census researchers have remarked.

Life nevertheless flourishes in today's oceans. The book is at its best when it offers glimpses of the astonishing array of sea creatures revealed by the survey, such as the deepest comb jelly-fish ever recorded — found at 7,000 metres — which uses long filaments to anchor itself to the seafloor like a kite. Special sections tell of the widespread loss of bluefin-tuna stocks, the surprisingly long distances travelled by great white sharks and efforts to protect coral reefs.

The book is full of high-quality photographs. These reveal strange, recently discovered species such as the yeti crab, so named for its hairy legs and claws. The text, however, gets bogged down in lengthy and repetitive descriptions of the technologies used to conduct the studies, including tagging techniques and underwater exploration vehicles. Readers may be tempted to skip ahead, wanting to learn what has been found before reading how it was discovered.

Predicting what will live in future oceans is a challenge. Census studies suggest that the loss of exploited fish is coupled to wider shifts in the ecosystem balance, causing problems that will be exacerbated if current fisheries trends persist. Depleted shark populations in the northwest Atlantic, for instance, have led to an overabundance of the cownose ray, a key shark prey that, in turn, wiped out a scallop fishery. On a more positive note, a study based on a review of practices in Norway suggests that Maine lobster fishermen could reduce both the number of traps they use and the length of their fishing season without reducing catch size. This would substantially decrease the number of critically endangered right whales in the North Atlantic killed by entanglement in lobster-fishing gear.

Fittingly, World Ocean Census begins and ends with spectacular photos of jellyfish, which are supremely suited to exploiting the niches created by overfishing. How humans respond to the trends revealed by the census will largely determine whether this 'jellification' of the ocean will continue, or if crippled marine populations may have a chance to recover.