The Cornell scientists are still pondering all of the interacting factors in whale reproduction. Right whale physiology requires at least three years between births (a full year of lactation after the previous birth, another year to eat heartily -- if they can -- and amass fat stores for the next pregnancy, then a yearlong gestation), Pershing observes. "We think we're seeing a one- to two-year time lag until poor feeding conditions take effect, as well as a slightly longer time lag from when changes in the NAO occur to when they have their effect on copepod abundance," Green says, "and that gives us some confidence in predicting whale births a year or more in advance."
Longer-term predictions of the right whales' fate would be easier in an era of unchanging climate -- which is rarely the case, especially in recent years. "Rather, we could be heading into a period of increased climate variability as a result of continually rising greenhouse gas concentrations," Greene says. And 1996, when the NAO flipped even as right whales were enjoying a banner birth year, "could have been an unusual event -- or a sign of the larger swings in climate that we might expect in the future."
Development of the computer model by the Cornell ecologists was funded by the Northeast Consortium's Right Whale Program. Right whales were so named by 18th and 19th century whalers becaus
Contact: Roger Segelken
Cornell University News Service