A new report from the International Institute for Sustainable Development (IISD) has found that the rapid spread of new fisheries and intensive farming techniques have pushed global waters back by more than half a million square kilometers in just the past three decades.
The study found that fisheries have shrunk by more that 60 percent globally over that period.
“We see a clear shift from the early 1900s, when fisheries were a major driver of global water supply, to today’s climate,” said Dr. Robert A. Smith, an IISD senior fellow and the study’s co-author.
Smith’s study looked at the impact of new species and fishing methods on marine ecosystems across a wide range of countries.
It found that, in the 1970s, fishing and intensive fishing accounted for roughly 30 percent of all freshwater and ocean ecosystems worldwide.
By 2020, that share had fallen to just over 15 percent.
And by 2050, the figure had fallen by half, to around 5 percent.
By 2030, fisheries accounted for less than 2 percent of the world’s freshwater and oceans, but that figure is projected to reach more than 10 percent by 2050.
A report from The Associated Press (AP) found that by 2050 the number of fish species in the world will have increased by a staggering 50 percent.
In the past, scientists have estimated that more than 50 percent of freshwater resources in the oceans and seas were managed by humans.
But the latest IISd study suggests that humans are contributing to the situation by changing the water quality and altering how much fish can eat.
The study analyzed the impact on marine and freshwater ecosystems around the world.
In the United States, the study found a rapid increase in the number and size of shrimp-driven fisheries.
The number of shrimp and other marine species in U.S. waters doubled between 1996 and 2016.
The amount of shrimp harvested by shrimp-fueled fisheries has also increased dramatically in recent decades, and scientists say this is driving the rapid expansion of new, intensively farmed species.
One of the main threats to fisheries is climate change, said Smith, who co-authored the report.
IISd researchers used satellite and other data to calculate how much freshwater resources are lost to ocean acidification, which is when water becomes less salt-stable and is therefore less able to absorb nutrients.
They found that during this time, freshwater fisheries have declined by more then 30 percent.
They also found that fish-eating species in coastal waters around the globe have declined, from the size of the Atlantic cod fishery to the size and species of cod in the North Atlantic and Pacific.
At the same time, shrimp-farming fisheries have grown, with a 40 percent increase over the same period.
The report notes that some fisheries have also become more dependent on human-assisted farming techniques.
The IISDs research found that for some species, such as sharks and rays, fisheries have increased their reliance on human farming, while others have experienced declines in their reliance.
For example, the sharks in the Gulf of Mexico have been increasing their reliance by 50 percent since 1996, the researchers said.
As more people move to the coasts, these species are being displaced from the water and are now more susceptible to pollution.
Scientists have long suspected that these fisheries are the primary drivers of the rapid increase of species in many regions, but the IIS davide of the study said the results suggest that “fishing is not the only driver.”
The Iisd report, which appears in the Journal of Biological Chemistry, also found large decreases in the numbers of species and the number that have adapted to the changing climate.
That includes the numbers and types of fish in some of the oceans that have changed dramatically over time.
The researchers also found an increase in species of marine animals that are able to survive in the sea, including a sharp decline in shark populations.
There are many other changes happening in the ocean, too, with the number, species and types changing at a rapid pace.
Smith noted that this is one of the reasons the Iisds study focuses on fisheries and not ocean ecosystems.
He said that we need to understand the mechanisms of change in order to understand how these changes will impact species and ecosystems.
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