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Wild Life: Fishy Numbers
Fishy Numbers
How many fish in the sea? More species than you might guess, but far fewer individuals in some fish populations.
Scientists have so far cataloged more than 15,000 fish species and are adding an average of three new species a week to a database as part of a $1-billion global research project, the Census of Marine Life. An estimated 5,000 types of oceanic fish are waiting to be discovered, project leaders said in a recent report.
But researchers have also uncovered a dramatic decline in the populations of big fish. Only about 10 percent of tuna, swordfish, cod, flounder and several other types of large fish are left. “Industrial fishing has scoured the global ocean,” says Ransom Myers, a Canadian fisheries biologist.
First Flight for Endangered Condor
A graceful flight it wasn’t, but it was historic nonetheless. When a young California condor jumped out of its nest in a remote canyon on the Colorado Plateau in November, it marked the first wild fledging in Arizona for this rare species in perhaps a century, and the first wild fledging anywhere since 1982.
Victims of shooting and lead poisoning, California condors nearly disappeared by the 1980s. For the past 12 years, government officials and conservationists have been releasing captive-bred condors in California and Arizona in hopes they would re-establish themselves in the wild. Since the release began, 13 eggs are known to have been laid in the wild in California and Arizona, and five previous chicks had hatched, but none had survived to take flight.
Conservationists watched eagerly as birds No. 123 and No. 127 mated and produced an egg in early 2003. The chick hatched in the spring, and on November 5 witnesses held their breath as the young condor left its nest cave, circled awkwardly in the air and landed on the ground about 500 feet below.
“Our biggest worry after the chick left the cave was how long it would take for the parents to find it,” says Chad Olson, raptor technician for the National Park Service. “To our great relief, [the female condor] flew to the nest about two hours after the chick fledged, realized that the chick was not in the nest cave, immediately found it, and dropped down to feed it.”
Adds Olson, “Since fledging is such a dangerous time for the chick, it is tremendous to be past this and on to another exciting phase.”
Winter of the Monarchs' Discontent?
Global climate change may soon wash out one of nature’s most colorful parades, the annual winter gathering of monarch butterflies in central Mexico, scientists say.
Hundreds of millions of monarchs migrate each fall from the eastern and central United States to a few small patches of forest high on volcanic peaks west of Mexico City. There, they ride out the winter clinging to the branches and trunks of fir trees. The wintering monarchs are truly regal when it comes to their weather preferences, requiring the cool, dry conditions found on these forested peaks.
In recent years, logging in the mountains has sparked concerns about the monarchs’ fate. Two American researchers wondered if global climate change might also pose a risk. So they ran computer simulations of how weather patterns in the monarchs’ winter habitat might change as global temperatures rise. Their results, published in the Proceedings of the National Academy of Sciences, show that, in as few as 50 years, winters would become wetter in these mountains. This is a potentially deadly change for the sensitive monarchs, which have perished in droves in past winter storms.
“We’re causing changes in the environment that are going to make it difficult or impossible for organisms like the monarch butterfly to survive in the niches to which they’re adapted,” says Karen Oberhauser, a biologist at the University of Minnesota-St. Paul who led the study. “Our behavior in this country can have big impacts on species here and elsewhere.”
