Many years ago, Daniel Pauly of the University of British Columbia and the Sea Around Us project set out to determine the true of extent of human exploitation of marine fish populations. Last week Pauly and his colleague Dirk Zeller published their startling results in a Nature Communications study called Catch reconstructions reveal that global marine fisheries catches are higher than reported and declining (January 19, 2016, open access).
Graph from the Nature News report Independent study tallies 'true catch' of global fishing
We reached "peak" wild-caught fish in the mid-1990s. This text if from the Nature News report linked-in above:
According to Pauly and Zeller, global fisheries catches hit a peak of 130 million tonnes a year in 1996, and they have been declining strongly since then. This is substantially higher than the data collected by the Food and Agriculture Organization of the United Nations (FAO), which report that catches reached 86 million tonnes in 1996 and have fallen only slightly.
The FAO numbers have long been the only estimate of how many tonnes of fish are caught at a global level. But “the FAO doesn’t have a mandate to correct the data they get”, Pauly told journalists during a conference call.
This leaves the organization reliant mainly on the numbers submitted by member countries, he says, and “the countries have the bad habit to report only the data they see”. This means that many official statistics do not account for a huge amount of the world’s fisheries catch, such as that by small-scale and subsistence fisheries or fish thrown back as ‘discards’ — species other than those being hunted.
To fill in the holes in official statistics, Pauly’s team embarked on an epic project to supplement the official baseline data from member nations...
The "holes" in the official statistics are actually zeros (Nature News, March 17, 2015).
Pauly says that the problem boils down to the fact that “people, when they don't know, they put zero”.
Fishery officials report that they do not catch any of a particular species, or they do not have any small-scale subsistence fishing — people in small boats providing for their families. “But these zeroes that are soft zeroes — reflecting uncertainty — become hard zeroes.”
This led him to his next realization — that someone had to undertake the mammoth task of fixing this problem, and “recreating the statistics of the world from the bottom up”.
The study itself indicates large uncertainties with Pauly and Zeller's estimates—see Figure 1 and Figure 2 and the associated discussion. However, Pauly was forced to present the results with large associated uncertainties.
Pauly also feels that his team has had to jump through hoops to publish the paper. He notes that the paper has very large uncertainty levels on the graph detailing the key findings of the paper (see Figure 1).
In fact, he says, the team had come up with relatively narrow confidence intervals by using a popular statistical method known as Monte Carlo. But one reviewer objected and, Pauly says, forced the use of a different method that gives “absurdly large confidence intervals”.
“In reality, given that our country estimates are independent (we made sure of that), some will be too high, some too low and things will cancel out, and thus generate narrow confidence intervals,” Pauly wrote in an e-mail toNature.
Overall, however, he is happy to point to the simple message of the research: “The catch of the world is higher than reported.”
Human overfishing breaks down like this:
Figure 4 — Reconstructed global catch by fisheries sectors. "Artisanal" indicates small-scale commercial fishing.
Quartz reported on the study in We may be running out of fish far faster than we realized. This quote is relevant to ongoing disputes about Pauly and Zeller's data (pertaining to methodology, discards and quota countries).
Asked about the significance of the new study, Trevor Branch, a marine conservation and statistics professor at the University of Washington, described it to Quartz as “a huge effort to get more accurate data.” Branch is also unaffiliated with the study.
Pauly and Zeller do emphasize in their paper that they include fairly large uncertainty of these estimates, given the many assumptions on which they rely.
In fact, the confidence intervals are so broad that they include the original FAO estimates, notes Branch.
This is shoddy journalism. See my brief discussion above. Here's the bottom line, from Trevor Branch.
“I would not be too surprised if the results were correct, though,” he says.
Exactly.
Gizmodo came up with an attention-grabbing "angle" on this overfishing story. These quotes are from We're Emptying the Oceans of Fish and Filling Them With Plastic.
Two reports out this week paint an alarming future for Earth’s oceans. The first one, published by the Wold Economic Forum, finds that by 2050, the oceans will contain more plastic than fish by weight.
The second [the Pauly/Zeller Nature Communications study] reveals that our nets have raked in far more fish over the past 60 years than we realized.
“This is a huge problem and a distributed problem,” Jackie Savitz, vice president of US Oceans at Oceana, told Gizmodo. Savitz added that while nobody knows exactly how much plastic is entering the ocean, or how many fish are leaving it, she “wasn’t at all surprised by the numbers” that surfaced this week.
The plastics report, which can be downloaded in its entirety here, was produced by the Ellen MacArthur Foundation, based on interviews with over 180 experts in the plastics industry.
It found that a staggering 32 percent of all plastics we produce escape any collection system—finding their way into rivers, lakes, and the ocean—while only 14 percent of plastic is collected for recycling even once. More plastic is entering the ocean every day, mostly, due to the growth of plastics production in “high leakage markets”—developing countries with inadequate waste management.
Here's the key finding from the plastic study, as quoted by Gizmodo.
Each year, at least 8 million tonnes of plastics leak into the ocean – which is equivalent to dumping the contents of one garbage truck into the ocean every minute. If no action is taken, this is expected to increase to two per minute by 2030 and four per minute by 2050...
The best research currently available estimates that there are over 150 million tonnes of plastics in the ocean today. In a business-as-usual scenario, the ocean is expected to contain 1 tonne of plastic for every 3 tonnes of fish by 2025, and by 2050, more plastics than fish (by weight).
This sounds pretty dire, but the prediction that ocean plastic will outweigh ocean fish 35 years from now may be conservative.
That’s because the report assumes the amount of fish in the ocean will stay constant.
Look at the ratio of "plastics to fish" (by weight) as estimated in 2050. That estimate assumes that fish in the ocean (by weight) will be constant. Graphic from the World Economic Forum.
Read the Gizmodo article to get the obligatory hope in the latter part of the article. I won't bother with the hopium here, except to quote this final paragraph. The quote is from Oceana's Jackie Savitz.
There’s no denying the oceans are in dire straits, and it’s going to take a lot of action, from consumers to national policy makers, to clean them up.
But the fight is only over if we say it is.
Hmm.... The Flatland model says that humans don't get to say the fight is over when they say it is. There is no "fight" here, though Savitz harbors the useful delusion that there is one. The inevitable outcome was determined a long, long time ago.
Under "business as usual" — for humans, is there any other kind? — you can kiss those marine ecosystems goodbye. More plastics by weight than fish. As go the oceans, so goes the biosphere.
The biosphere will recover in a few million years. Good news!
I hear Timo Hannay says we can create new fish species and restore the oceans.
Posted by: Ken Barrows | 01/25/2016 at 10:21 AM