Essay Title: 

‘With the aid of a detailed case study assess the impact of human activities on a marine biome.’

April 1, 2016 | Author: | Posted in american history, history

The Impact of Human Activities on Sharks in the Northwest Atlantic

The earth is a finite space . Everyone and everything on it must share its vast yet limited resources , and the actions of one species effects many , if not all , others . Over time , we have come to realize that human activities are having disproportionately negative effects on the global environment . An excellent example of this within the marine biome can be seen in analyzing shark populations of the Northwest Atlantic

In their study , Collapse and Conservation of Shark Populations in the Northwest [banner_entry_middle]

Atlantic (2003 , Julia K . Baum , et al . traced the changes in the populations of eight shark species from 1986 to 2000 (two species were only recorded from 1992 onward . They looked at the areas comprised of the Caribbean , Gulf of Mexico , Florida East Coast , South Atlantic Bight , Mid Atlantic Bight , Northeast Coastal , Northeast Distant , Sargasso /North Central Atlantic , Tuna North /Tuna South ‘ In this region , they noted an 89 decline in the hammerhead shark population over a period of 14 years . Similarly , white sharks declined 79 , tiger sharks 65 , and thresher shark populations declined by 80 between 1986 and 2000 . In fact , each of the eight species saw a population decline over the course of the study . The study concludes that The magnitude of the declines estimated .suggests that several sharks may also now be at risk of large-scale extirpation

The study goes on analyse the causes of such drastic decline over such a short period of time . Citing overfishing as a significant culprit it claims , In the past half century , as fishing fleets expanded rapidly in the open ocean , have large marine predators been subject to this intense exploitation ‘ Overfishing however is not a new phenomenon and has indeed been a factor in depleting populations of marine species historically as well . In his 2001 colloquium , What was natural in the coastal oceans ‘ Jeremy B . Jackson cites 19th century overfishing in cause live coral abundance declined to 1-2 cover from values of 50 or more ‘ in the 1908s . He claims that while this was noted in the 1980s it is the result of historical trends by determining Coral communities did not change noticeably until the epidemic mortality of Diadema antillarum in the 1980s because ecological redundancy of herbivores obscured the potential effects of the loss of large herbivorous fishes for well over a century . Macroalgae were not able to overgrow corals until the last major herbivore was lost from the system ‘ The ramifications for sharks and other carnivorous species as is significant because declining herbivore populations means there is a food scarcity and thus will result in a decline in predator populations as well

The Baum study notes that their finding of large and rapid declines .are in addition to substantial historical reductions Overexploitation of elasmobranchs (sharks , skates , and rays ) is known to have already nearly eliminated two skate species from much of their ranges ‘ They then engage in a discussion of appropriate measures that could be… [banner_entry_footer]


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