James,

The estimates Wilson cites are from a 2000 Conservation International conference entitled "Defying Nature's End." Estimates of the cost of saving global fisheries are in Andrew Bamford et al. "The Worldwide Costs of Marine Protected Areas," Proceedings of the National Academyof Sciences, USA 101 (2004): 9694-97, and discussed by Henry Nicholls in "Marine Conservation: Sink or Swim," Nature 432 (2004): 12-14

From pages 97-99 of Wilson's "The Creation" (long quote)

"The costs of saving most of Earth's flora and fauna would be relatively trivial for the market economy and, of course, immensely profitable for the natural economy. In 2000 Conservation International sponsored a conference of biologists and economists, entitled "Defying Nature's End," to address this matter. They reviewed the many methods available at that time to secure wildland reserves while simultaneously improving local economies, then estimated the cost. They concluded that in order to put a protective umbrella over the twenty-five hottest spots on the land then recognized (nine more have since been added to total 34), plus core areas within the remaining tropical forest wilderness.... would require one payment of about $30 billion. The benefit, if the allotment is joined with wise investment strategy and foregn policy, would be susbstanntial for 70 percent of Earth's land-dwelling fauna and flora... This sinngle outlay (one payment only), or its equivalent spread over a few years, is approximately one part in a thousdand of the annual gross world product, that is, gross domestic product of all countries combined. By coincidence the latter amount, roughly $30 trillion, also happens to be the estimated rate of the ecosystem services given free by Earth's remaining natural environment.

A parallel study, made in 2004 by a second team, estimated the cost of protecting marine areas, the threatened Second Edens of our planet. .. To regulate a reserve network covering 20-30 percent of the ocean surface would cost between $5 billion and $19 billion annually. That outlay could be met by eliminating the current perverse subsidies given to the fishing industry, which fall between $15 and #30 billion annually - and are responsible in the first place for the over-harvesting and falling yield of preferred species."

Sorry for the long quote!