Science  06 Apr 2012:
Vol. 336, Issue 6077, pp. 18
  1. Panel: Conserve Forage Fish To Protect Ecosystems


    Seabirds have not recovered from overfishing of anchovetas.


    Fishing of small species near the base of the food web—forage fish such as herring—should be more conservative, because these species are prone to collapse and are an important source of food for seabirds and other predators, according to a blue-ribbon panel of scientists.

    In 2009, the Pew Charitable Trust's Lenfest Ocean Program commissioned 13 scientists to study how fishing impacts forage fish and their predators. Under conventional management, forage fisheries have a 42% chance of collapsing, they found. If fishing rates are cut in half, the likelihood of collapse falls to 6%, and predators are less likely to go extinct.

    Fishing less could also have an economic payoff: Forage fish are worth more when left in the ocean, because the predatory fish that eat them can be sold for more money. Based on computer models of 72 ecosystems, the researchers found that the global value of forage fish caught is $5.6 billion a year, but those left in the ocean contribute twice that amount to other fisheries. “They have an important value in the ecosystem, and that value can translate into big dollars,” says Ellen Pikitch of Stony Brook University in New York, who led the study.

  2. Case Closed: CO2 Helped End Last Ice Age

    Any doubts about carbon dioxide's power to warm the world can be put to rest. A new record of global temperatures as Earth came out of the last ice age demolishes the contrarian contention that carbon dioxide merely followed global warming.

    The problem had been that ice core records from Antarctica showed carbon dioxide rising only after warming was in full swing. But climate scientists knew that no one place is representative of trends in global climate. So Jeremy Shakun of Harvard University and his colleagues carefully combined 80 paleo-temperature records from around the globe—from pollen in Alaskan lake muds to microfossils in Indian Ocean sediments.

    In this week's issue of Nature, Shakun and his colleagues report that about 18,000 years ago, global warming did in fact lag the rise of carbon dioxide by a few centuries, as it should if the greenhouse gas were helping drive the world out of the ice age. “All in all, a solid study,” says climate scientist Michael Mann of Pennsylvania State University, University Park; carbon dioxide is indeed a potent climate changer.

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