Asymptotically we'll all be dead
Superbly done:http://www.sciencemag.org/cgi/content/abstract/315/5820/1846March 30, 2007Cascading Effects of the Loss of Apex Predatory Sharks from a Coastal OceanBy Ransom A. Myers, Julia K. Baum, Travis D. Shepherd, Sean P. Powers, Charles H. PetersonImpacts of chronic overfishing are evident in population depletions worldwide, yet indirect ecosystem effects induced by predator removal from oceanic food webs remain unpredictable. As abundances of all 11 great sharks that consume other elasmobranchs (rays, skates, and small sharks) fell over the past 35 years, 12 of 14 of these prey species increased in coastal northwest Atlantic ecosystems. Effects of this community restructuring have cascaded downward from the cownose ray, whose enhanced predation on its bay scallop prey was sufficient to terminate a century-long scallop fishery. Analogous top-down effects may be a predictable consequence of eliminating entire functional groups of predators.
http://www.nytimes.com/2007/03/30/science/30sharks.html?ex=1332907200&en=5a2fa826c0df7587&ei=5090&partner=rssuserland&emc=rssMarch 30, 2007Study Finds Shark Overfishing May Lower Scallop Population By HENRY FOUNTAINFor years, conservationists have warned about overfishing of large sharks in the northwestern Atlantic, as the demand for meat and fins, coupled with slow growth and reproduction rates of many species, has caused sharp declines in populations of hammerheads, duskies and other sharks.Researchers are now reporting repercussions beyond the declining shark populations. Depletion of large sharks, they write today in the journal Science, has led to the destruction of the bay scallop fishery along parts of the Eastern seaboard. The study, by Ransom A. Myers of Dalhousie University in Halifax, Nova Scotia, and colleagues, is among the few to document the cascading effects that the loss of a top predator can have on a marine ecosystem. In the absence of large sharks, the researchers say, the smaller sharks, skates and rays that they feed upon have thrived. In turn, the study shows that as one of these middle links in the food chain, the cownose ray, has become more abundant, it has wiped out scallop beds in North Carolina."People are always asking me why we should care about sharks," said Ellen Pikitch, a marine biologist at the University of Miami and executive director of the Pew Institute for Ocean Science, a major funder of the study. "This is a great example of why sharks matter to the broader ecosystem." ...anne
Wow; now there is an ecological study.
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