Weighing in at over 400 pounds and 10 feet long, one Amazonian fish species proves that size isn't the only thing that matters. Fighting for survival in the unregulated regions of Brazil, the once thriving species is quickly dwindling in numbers and is in danger of impending extinction.
The largest fish species in the Amazon River basin, the Arapaima gigas (commonly called the 'pirarucu' by Amazonian natives) is a monolithic giant that is the result of eras of evolution. Unlike other fish, this prehistoric wonder is capable of breathing air courtesy of a primitive lung, and in conjunction with its gill system, the giant can roam the open river and even some of the most anoxic waterways that lead into the jungle. An evolutionary advantage that allows the species to transition into more niche habitats, this ability to breathe air is also a disadvantage when it comes to humans-making them easier prey to be caught researchers say.
"Arapaima spawn on the edges of floodplain forests and come to the surface to breathe every five to fifteen minutes, when they are easily located and harpooned by fishermen using homemade canoes" participating doctoral researcher of wildlife and fisheries science at Texas A&M, Caroline Arantes said.
Published in the Journal of Applied Ichthyology, a recent survey conducted in fishing communities of the state Amazonas in Brazil indicated that the giant species is already on the verge of extinction. According to the study's co-author Donald Stewart from the State University of New York at Syracuse, in recent decades only two of the five known species of arapaima have survived in the wild.
Commercially important for the survival of many river-situated Amazonian communities, the species serves as a traditional delicacy and a natural resource whose abundance and harvesting are not largely regulated by the Brazilian government.
"Fishermen continue to harvest arapaima regardless of low population densities" lead researcher from Virginia Tech, Leandro Castello said. In 19 percent of the 81 communities the arapaima was found to already be extinct, and in 57 percent of the communities studied, the species numbers were depleted to verge of extinction indicating a severe problem in the regulation of local fishing.
The researchers don't solely blame fishermen for the overkill of the species, but also look to local policymakers who believe that a bioeconomic frame of thought would save the species as a form of checks and balances.
"Bioeconomic thinking has predicted that scarcity would drive up fishing costs, which would increase prices and help save depleted species" Castello says. "But that is not what has happened; if that prediction were true, extinctions induced by fishing would not exist."
However, the research team did find that in some regions regulation was a successful indicator towards the conservation of the species. Although only practiced in roughly 27 percent of the 81 communities surveyed, limitations on capture size and restrictions on netting have allowed for the species to once again flourish, with arapaima density nearly 100 times greater than communities without such restrictions.
"Many previously overexploited arapaima populations are now booming due to good management" Castello says. "The time has come to apply fishermen's ecological knowledge to assess populations, document practices and trends, and solve fisheries' problems through user participation in management and conservation."
Hoping to encourage local fishermen and alter the thoughts of local policymakers, the team believes that incremental change could save the prehistoric species, letting them come up for air now and again.
