By Emily DeRuyt and Sarah S. ScottA year ago, the world’s oceans were teeming with marine life.
It was no longer the case.
A new study found that the planet’s oceans have become less diverse, with fish stocks shrinking and fish species disappearing more frequently.
That’s not the only sign of a changing planet: the number of species that are still listed as endangered in the United Nations’ Red List of Threatened Species has doubled since 2012, according to the Global Fishery Index, which is compiled annually by the IUCN.
In the last 15 years, the global fishing industry has become more profitable, as fishing gear is increasingly expensive and the world is increasingly relying on commercial fleets for the majority of its fish, according the IFCS.
The global fishing fleet now employs nearly 1.6 billion people.
But this economic success doesn’t necessarily translate into a change in how people use the oceans.
In some cases, the economic changes that have occurred are not positive for fishing, according a new study published in the journal Conservation Biology.
“There are some areas of the world that are less sustainable and less productive,” said study co-author and oceanographer at the University of California, Santa Barbara, Dr. Paula Niehaus.
“For instance, it’s really difficult to sustain fisheries in the tropics and subtropics, which are areas of great variability and vulnerability,” she said.
Niehaus and her colleagues set out to assess the sustainability of fisheries across the globe.
They surveyed the fisheries of more than 100 countries over a 10-year period to better understand how well fish stocks are managed and what kind of impacts those changes have had on fisheries.
“It’s not just about what’s happened to fisheries in a particular country,” said Nieaus.
“There are other variables that we can look at as well, such as population density, and whether we have a lot of fishers or a lot less fishers, or the type of fish species, and we can also look at the amount of fish that are available and what the costs are,” she explained.
To do this, they used satellite imagery to track how fish stocks changed in a region over time, and compared that data to a global map of fishing quotas.
The researchers found that fisheries management is a major factor in the amount and diversity of fish stocks.
But the study also found that fish stocks have also declined more frequently over the past 15 years.
“Fish stocks have been declining more frequently in the past five years than they did in the 1990s,” said Dr. Mark Mather, a marine ecologist at the US Geological Survey.
“So we have this ongoing pattern of overfishing and overfishery management.”
To find out how fisheries management has impacted the amount, diversity and abundance of fish populations, Nieais and colleagues analyzed data from fisheries in 20 countries across four continents.
The study also showed that the most successful countries on the continent have experienced dramatic shifts in the composition of the fishing industry over the last decade.
For example, in 2010, only 13% of fish caught in the Caribbean Sea were harvested as wild caught fish.
That number has now risen to over 80%.
In addition, the fishing fleet is now largely powered by high-tech, high-yield fishing equipment, which has increased the amount fish can be caught from one day to several months, the researchers said.
But even with these improvements, the authors noted that there are still areas of uncertainty in the data.
“We’re not certain what we’re seeing in the results, and in some areas we’re not seeing the trends we expect,” said Mather.
“It’s hard to predict exactly what is going to happen, but we think it is possible that overfished areas may not necessarily recover to the same levels that they were at the beginning of the 20th century.”
And these are areas that have historically seen the largest declines in fish stocks, Niesaus added.
“The areas that are showing the most rapid changes are those that have the highest concentrations of fisheries equipment, the ones that are heavily fishing, or that have been experiencing a lot more fishing,” said Michael Haffner, a biologist at the California Academy of Sciences and an author of the study.
“They’re those places that are more exposed to climate change and are likely to have the greatest impact on the fish stocks,” he said.
In fact, for many countries, the study found, the amount per capita of seafood produced by the fishing sector has doubled in the last five years.
So if the fishing practices of your country are causing more fish to be lost to the ocean, you may want to think twice about taking part in that.