Snowball effect of overfishing highlighted

7 January 2014

Source: Florida State University, via Science Daily


Florida State University researchers have spearheaded a major review of fisheries research that examines the domino effect that occurs when too many fish are harvested from one habitat.

The loss of a major species from an ecosystem can have unintended consequences because of the connections between that species and others in the system. Moreover, these changes often occur rapidly and unexpectedly, and are difficult to reverse.

"You don't realize how interdependent species are until it all unravels," said Felicia Coleman, director of the Florida State University Coastal and Marine Laboratory and a co-author on the study.

Coleman and her co-authors, led by FSU biology professor Joe Travis, examined case studies of several distressed ecosystems that had been thoroughly changed over the years because of overfishing.

For example, in the Northern Benguela ecosystem off Namibia, stocks of sardine and anchovy collapsed in the 1970s from overfishing and were replaced by bearded goby and jellyfish. But the bearded goby and jellyfish are far less energy-rich than a sardine or anchovy, which meant that their populations were not an adequate food source for other sea animals in the region such as penguins, gannets and hake, which had fed on the sardines and anchovies. African penguins and Cape gannets have declined by 77 percent and 94 percent respectively. Cape hake and deep-water hake production plummeted from 725,000 metric tons in 1972, to 110,000 metric tons in 1990. And the population of Cape fur seals has fluctuated dramatically.



For more, go to: www.sciencedaily.com/releases/2014/01/140107163737.htm