Environmental journalist Alanna Mitchell has won the $75,000 Grantham Prize for her book that chronicles the fragile state of the world's oceans — the first time the award has gone to a Canadian.

Alanna Mitchell's much-praised book is the first book to be honoured with the Grantham Prize for environmental journalism. (McClelland & Stewart)

Mitchell is being honoured for her book, Sea Sick: The Global Ocean in Crisis, which was published last year by McClelland & Stewart and the University of Chicago Press.

The book "clearly and eloquently explains the specific dangers facing global marine ecosystems," says Sunshine Menezes, executive director of the Rhode Island-based Metcalf Institute for Marine & Environmental Reporting — the administrator of the Grantham Prize.

"Mitchell faced her own demons to craft a story that showcases marine science — and scientists — in a balanced, accurate, and poetic fashion," Menezes said.

Mitchell, who used to report for the Globe and Mail, is now an associate at the Winnipeg-based International Institute for Sustainable Development and often speaks on environmental issues. She lives in Toronto.

To gather the material for her book, she joined scientific expeditions to nine oceanic zones facing extreme environmental pressures — everything from coral reef bleaching to rising acidification.

"Reading Alanna Mitchell convinces you that the ocean is at least as important as the atmosphere when we worry about climate change," said Philip Meyer, chairman of the Grantham Prize jury, in a release.

"You cannot put this book down without understanding that, for life on Earth to continue as it is, the ocean from which we evolved must remain healthy."

The Grantham Prize for excellence in environmental journalism is funded by the Grantham Foundation, which supports international environment research and conservation efforts.

The annual prize was first awarded five years ago. Previous winners have all been American newspaper reporters.