Jackson_et_al_2001 - Historical Overfishing and the Recent...

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Unformatted text preview: Historical Overfishing and the Recent Collapse of Coastal Ecosystems Jeremy B. C. Jackson, 1,2 * Michael X. Kirby, 3 Wolfgang H. Berger, 1 Karen A. Bjorndal, 4 Louis W. Botsford, 5 Bruce J. Bourque, 6 Roger H. Bradbury, 7 Richard Cooke, 2 Jon Erlandson, 8 James A. Estes, 9 Terence P. Hughes, 10 Susan Kidwell, 11 Carina B. Lange, 1 Hunter S. Lenihan, 12 John M. Pandolfi, 13 Charles H. Peterson, 12 Robert S. Steneck, 14 Mia J. Tegner, 1 ² Robert R. Warner 15 Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degrada- tion of water quality, and anthropogenic climate change. Historical abun- dances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone. Few modern ecological studies take into ac- count the former natural abundances of large marine vertebrates. There are dozens of places in the Caribbean named after large sea turtles whose adult populations now number in the tens of thousands rather than the tens of mil- lions of a few centuries ago ( 1 , 2 ). Whales, manatees, dugongs, sea cows, monk seals, croc- odiles, codfish, jewfish, swordfish, sharks, and rays are other large marine vertebrates that are now functionally or entirely extinct in most coastal ecosystems ( 3 – 10 ). Place names for oysters, pearls, and conches conjure up other ecological ghosts of marine invertebrates that were once so abundant as to pose hazards to navigation ( 11 ), but are witnessed now only by massive garbage heaps of empty shells. Such ghosts represent a far more profound problem for ecological understanding and management than currently realized. Evi- dence from retrospective records strongly suggests that major structural and functional changes due to overfishing ( 12 ) occurred worldwide in coastal marine ecosystems over many centuries. Severe overfishing drives species to ecological extinction because over- fished populations no longer interact signifi- cantly with other species in the community ( 5 ). Overfishing and ecological extinction predate and precondition modern ecological investigations and the collapse of marine eco- systems in recent times, raising the possibil- ity that many more marine ecosystems may be vulnerable to collapse in the near future....
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This note was uploaded on 08/06/2008 for the course ESM 260 taught by Professor Lenihan during the Spring '08 term at UCSB.

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Jackson_et_al_2001 - Historical Overfishing and the Recent...

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