Claims about the sustainability of fish farms have been greatly exaggerated
VIKEN KANTARCI/AFP via Getty Images
It has been claimed that it is a fish farming it’s a sustainable food source that will help feed our growing human population while protecting wild fish populations, but that’s just not true.
“Fish farming is no substitute for catching wild fish from the ocean,” he says by Matthew Hay at New York University. “In fact, it relies on catching wild fish from the ocean.”
Hay and his colleagues have shown that the number of wild the fish the death to feed farmed fish is between 27 and 307% higher than previous estimates.
Carnivorous farmed fish eat several times their weight in the wild fish they catch from it the ocean More than what is achieved in agriculture, says Hayek. For example, it may take 4 to 5 kilos of wild fish to produce one kilo of salmon.
But the catch of wild fish is not increasing in line with the growing demand for farmed fish. “For multiple fisheries, we’re heading toward a shortage of fish in the ocean,” Haye says.
As a result, as the aquaculture industry expands, an increasing proportion of the world’s wild fish catch is fed to farmed fish.
This means people in places like Southeast Asia and West Africa can no longer buy the fish because it is more valuable as a source of fishmeal and fish oil for farmed fish, the team says. Patricia Majluf At the Oceana conservation organization.
Increasing the proportion of plant products in the diet of carnivorous fish, or raising omnivorous or herbivorous fish – such as tilapia, carp and catfish – creates another set of problems. If plant-based foods that people can eat are fed to fish, more land and water are needed to produce fish food, resulting in problems such as deforestation.
“Because those sectors are growing so fast, we’re now feeding more crops off the ground than ever before,” Hayek says.
“You can’t escape the impacts while you’re eating animals somewhere,” he says. “Farmed animals need more resources to grow and develop their bodies than you can get from eating them. That is a fundamental fact of biology.”
But farmed shellfish, such as mussels, which are fed by filtering seawater, are much more sustainable, he says.
There are a number of reasons why Hayek’s team’s estimate of the number of wild fish needed to produce a given number of farmed fish is much higher than past estimates. One is that the team used a wider range of sources than previous studies, Hayek says, meaning there is less likely to be statistical bias.
The team also counted all fish used to produce fishmeal or fish oil, not just those caught to feed farmed fish.
Finally, the team also calculated the number of fish that died but were not brought to the market. Unwanted the species they are often thrown from fishing boats, but usually do not survive. Seine nets are also sometimes left slightly open to allow unwanted fish to escape, but are often injured and killed.
The number of wild fish killed to feed the farmed fish is still inferred to be higher than previous estimates, even after excluding these additional deaths, Hayek says. But counting adds between 20 and 50 percent to the total, he says.
“They show that the use of fishmeal and fish oil in aquaculture is more complex than many industry analysts think,” he says. Stefano Longo at the University of Gothenburg, Sweden. “Inputs of fishmeal and fish oil in aquaculture systems are likely, and perhaps greatly, underestimated.”
Topics:
