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

Aug 13, 2014
The arapaima fish, which once dominated Amazon fisheries, is long and can weigh as much as 400 pounds. Credit: Sergio Ricardo de Oliveira

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 —with the lesser-known "fishing-down" theory, which predicts that large, high-value, easy-to-catch can be fished to extinction.

"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 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 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.

Explore further: Ecosystems can have their fish, and we can eat them too

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Lex Talonis
Aug 13, 2014
This comment has been removed by a moderator.
rockwolf1000
4.3 / 5 (3) Aug 13, 2014
Use METRIC - fuck you.

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


I learned to use metric and imperial when I was a small child. What exactly is your issue? Are you incapable of learning? Learning to use imperial for linear measures should take less than 15 minutes, though probably an unattainable goal for many posters here.

Haha. Sucks to be you.
antigoracle
1 / 5 (4) Aug 13, 2014
Congratulations rockturd.
Now, in what should I weigh your stupidity, the imperial or metric ton.
rockwolf1000
5 / 5 (2) Aug 13, 2014
Congratulations rockturd.
Now, in what should I weigh your stupidity, the imperial or metric ton.


Neither. You can use yg (yoctograms 10E-24) for me although it will have to be a non-integer as the value will be less than 1.

While we will continue to use solar masses to measure your stupidity, in reality it is infinite and cannot be measured.
antigoracle
1 / 5 (2) Aug 14, 2014
Oh rockturd, I guess mummy never warned her little turd -
It's better to keep your mouth shut and appear stupid than open it and remove all doubt.
rockwolf1000
5 / 5 (1) Aug 14, 2014
Oh rockturd, I guess mummy never warned her little turd -
It's better to keep your mouth shut and appear stupid than open it and remove all doubt.


Your desperation is palpable.
Porgie
not rated yet Aug 16, 2014
Gee the same thing killed the Dodo and the passenger pigeon. Try and stop them from catching them.
antigoracle
1 / 5 (1) Aug 19, 2014
Your desperation is palpable.
-- rockturd
I know, when I flushed you, I thought that was the end, but you keep floating up from that cesspool of ignorance to pollute this forum.