Daniel Uria/Staff Writer
The ocean is home to a complex ecosystem that contains many diverse creatures. But this ecosystem is also fragile, and according to members of the Marine Science Program it faces serious threats from humans in the form of overfishing. Overfishing refers to the practice of catching marine species faster than they are able to reproduce.
Over time the removal of these species through overfishing causes a disruption in the marine ecosystem. According to Kevin Boswell, a fisheries ecologist and assistant professor with Marine Science Program, the most common form of disturbance comes from the removal of the top predator.
“The classic case is the trophic cascade, whereby removing the upper trophic level, those below are actually impacted and can impart substantial shifts in lower trophic level,” Boswell said.
Michael Heithaus, an associate professor of the Department of Biological Sciences has experienced this type of disturbance in his studies with sharks. The shark population has been declining rapidly in recent years due to rampant overfishing.
“As top predators, sharks can keep populations of their prey in check,” he said. “If sharks disappear, the numbers of their prey can go way up and then they over-consume their foods and the whole ecosystem could be disrupted.” He cites his studies with tiger sharks in Australia’s Shark Bay as an example. “If we lose tiger sharks, sea cows and sea turtles might eat too much sea grass and the system could collapse. Without enough sea grass there won’t be places for small fish, shrimps and crabs to grow up – that would mean less there for people.”
Aside from sharks that Boswell says are, “certainly among the top of the list of concern for species experiencing overfishing,” he also said that regional species such as blue fin tuna and gulf red snapper and certain groupers are also victims of overfishing. Overfishing occurs all over the world for a variety of different reasons.
In the case of sharks, Heithaus said, in Asia they are fished for a delicacy known as shark fin soup that is in high demand. “The increasing demand for fins to be used in shark fin soup, as well as for meat, has led to increasing pressure on shark populations,” Heithaus said.
Boswell says that the largest contributor to overfishing is the lack of systems to temper the habits of overzealous fisherman. “The main causes of overfishing are often mismanagement and greed. And unfortunately the systems, often the underdeveloped countries that are most fraught with overfishing are a result of poor management (or lack thereof) as they don’t have the resources for enforcing sustainable practices. The biggest problem is not controlling the exploitation, and can be a lack of useful information or willingness to enforce the sustainable practices.”
But despite all of this, there are several campaigns in place to help stop overfishing and reverse its effects. According to Heithaus, Asian countries are seeking to curb the intake of shark fin soup and the dish is no longer served at official Chinese functions. And with a move towards more responsible fishing it is conceivable that the effects of overfishing can be erased or at the very least minimized.
“There is quite a bit of compelling evidence that appropriate management strategies can act to provide sustainable resources with a reasonable level of harvest,” Boswell said. “It takes the willful buy in of the managers and stakeholders. Can you reverse its effects? Maybe. Can overfishing create noticeable changes in the marine ecosystem? Yes, indeed.”
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