Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Giant Amazon fish becoming extinct in many fishing communities, saved in others

13.08.2014

An international team of scientists has discovered that a large, commercially important fish from the Amazon Basin has become extinct in some local fishing communities.

The team compared mainstream bioeconomic theory — which policymakers have depended on in order to protect fish populations — with the lesser-known "fishing-down" theory, which predicts that large, high-value, easy-to-catch fish can be fished to extinction.


The arapaima fish, which once dominated Amazon fisheries, is long and can weigh as much as 400 pounds.

Credit: Sergio Ricardo de Oliveira

"Bioeconomic thinking has predicted that scarcity would drive up fishing costs, which would increase price and help save depleted species," said study leader Leandro Castello, an assistant professor of fisheries in Virginia Tech's College of Natural Resources and Environment. "If that prediction were true, extinctions induced by fishing would not exist, but that is not what has happened."

The research was conducted with arapaima, a 10-foot long fish that can weigh more than 400 pounds.

"Arapaima spawn on the edges of floodplain forests and come to the surface to breathe every 5 to 15 minutes, when they are easily located and harpooned by fishers using homemade canoes," said Caroline C. Arantes, a doctoral student in wildlife and fisheries science at Texas A&M University and an expert on fish biology and fishery management.

The giant fish dominated fisheries in the Amazon a century ago, but three of the five known species of arapaima have not been seen for decades, said Donald J. Stewart, professor in the College of Environmental Science and Forestry at the State University of New York at Syracuse, who recently discovered a new species of arapaima.

The research was based on interviews with 182 fishers in 81 communities who were selected by their peers as being experts and on fish counts in 41 of the fishing communities, accounting for 650 square miles of floodplain area.

The results indicate that arapaima populations are extinct in 19 percent of communities, depleted (approaching extinction) in 57 percent, and over-exploited in 17 percent.

The results are reported this week in the journal Aquatic Conservation: Freshwater and Marine Ecosystems.

"Fishers continue to harvest arapaima regardless of low population densities," said Castello, an expert on tropical fish, fisheries, and conservation.

When the mature, large fish are gone, fishers use gill nets to harvest other, smaller species, unintentionally capturing juvenile arapaima and further threatening remaining populations.

The good news is that in communities that have implemented fishing rules, imposing minimum capture size and restricting gill-net use, for instance, density of arapaima is 100 times higher than where there are no rules or the rules are not followed, said David G. McGrath of the Earth Innovation Institute in San Francisco.

"These communities are preventing further arapaima extinctions," said McGrath.

Only 27 percent of communities surveyed have management rules for fishing arapaima. The community of Ilha de São Miguel banned the use of gill nets two decades ago and now has the highest arapaima densities in the region.

"Fisheries productivity in Ilha de São Miguel is also the highest in the study area," said Castello. "Cast nets are allowed because they are much more selective yet they yield abundant fishes for local consumption, so food security for the community is not compromised."

"Because tropical regions suffer from widespread illegal fishing and a lack of data, these findings suggest that many similar fishing-induced extinctions likely are going unnoticed," he continued. "There is also a lack of economic alternatives for the fishers."

But the experience in Amazonas State, Brazil, shows that things can be different.

"Many previously overexploited arapaima populations are now booming due to good management. The time has come to apply fishers' ecological knowledge to assess populations, document practices and trends, and solve fisheries problems through user participation in management and conservation," Castello said.

Fabio De Souza of the nonprofit Society for Research and Protection of the Environment in Santarém, Pará, Brazil, is developing and implementing community management for arapaima in the region.

"There is willingness among fishers to implement management, but our efforts require more support from governmental agencies," De Souza said.

Lynn Davis | Eurek Alert!
Further information:
http://www.vt.edu

Further reports about: Amazon Environment fishing floodplain populations species

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>