A fish eye view of global warming

Global warming will extinguish dozens of marine fish species that cannot migrate to colder waters, according to a study by University of British Columbia researchers Pauly and Cheung.  Science synopsis of research   Replacing the lost biodiversity with new species will take millions of years.   A change in ocean temperature of even a degree or two forces species to migrate to new ecosystems with different foods and different predators.  Indeed, already almost two-thirds of fish in the North Sea now live in different locations or depths because of rising sea temperatures (Science, 13 May 2005, p. 937).

Pauly, Cheung and their colleagues have done ocean-wide modeling of the effects of climate change on marine fishes.  They modeled a range of habitat conditions that species can tolerate such as water temperature, depth, and distance from sea ice, predicted habitat changes that will occur in response to global warming, and predicted how fish and invertebrate populations will respond to those changes.

Changes in the polar region will likely include extinction of about 50 species of commercial fishes living at or near the poles that require cold polar water, such as the Antarctic toothfish (Dissostichus mawsoni).  Other species, living farther from the poles, will probably migrate toward the Arctic or Southern oceans, disturbing existing ecosystems.  Yet other populations such as the giant croaker (Totoaba macdonaldi), of the Sea of Cortez  and local hake (Merluccius merluccius) from the Meditteranean  Sea will be unable to migrate to colder waters and therefore face extinction.