Confusing Nemo (3): Enjoy your fish in 2049

Next in my little fact-checking exercise of The Black Fish's movie Losing Nemo:

If the fishing industry keeps fishing at its current rate, science predicts that all fish will be gone by 2048

This statement is based on a paper in Science (see a copy of the article here) by marine scientist Boris Worm, published in November 2006. Intriguingly, the objective of the article is not to predict anything like stock collapse: rather, it investigates the importance of biodiversity for the provision of a host of marine ecosystem services, such as fisheries, nursing juveniles of marine species, and filtering of waste from human sources. The article finds a crude but nevertheless convincing positive correlation between species richness and such traits as productivity and speed of recovery from overfishing: in other words, species-rich ecosystems produce more biomass than species-poor ecosystems, and also recover more easily from overexploitation. So is that where the 2048 prediction comes from, a projection of biodiversity decline that should lead to worldwide stock collapse around 2048?

Actually not. One of the driving forces considered in the article is fishing pressure, so it describes how more and more fish stocks have collapsed (defined as catches dropping below 10% of the highest catch ever recorded) since 1950, according to data from the Sea Around Us project. Based on these data the authors estimate a mathematical formula to describe this trend:

y = 0.0168*x^1.8992

where y denotes the percentage of fish species currently collapsed and x denotes the number of years after 1950. Later in the article the authors make the following remark:

This trend is of serious concern because it projects the global collapse of all taxa currently fished by the mid–21st century (based on the extrapolation of regression in Fig. 3A to 100% in the year 2048).

2048 is 98 years after 1950: indeed, 0.0168*98^1.8992 is about 101.

The perils of extrapolation
So that's where the 2048 comes from. A trend, based on data over about 50 years, extrapolated another 50 years until we reach 100 percent. This claim, and how the authors arrived at it, has attracted a lot of criticism, which I won't discuss in detail here, but in my view the most fundamental objection is that extrapolating any trend, especially an exponential trend describing a number with a natural maximum (like a percentage), by as far as twice the observed range is bound to give extreme and unrealistic outcomes. In this particular case, as more and more stocks 'collapse', you are bound to have stocks left that are actually quite well-managed. Most Atlantic pelagic stocks, such as herring and mackerel, are healthy and well-managed. Not only are the stocks large enough to ensure plenty of replenishment that compensates fishing mortality, the institutions to manage the fishery, like Exclusive Economic Zones, scientists doing stock assessments, and stringent government policies, are also in place. North Sea herring is MSC certified. Iceland has practically its own national cod stock which it would be crazy to deplete. A lot of overfishing is due to poor exclusivity of stocks and the ensuing Prisoner's Dilemma, but these institutional flaws are largely absent for most North Atlantic stocks. And this is just one example.

How a side remark came to define a paper

If the 2048 estimate is so shaky, why do the authors make this claim? Remember that the objective of the article has never been to predict fisheries collapse: the authors wanted to assess the importance of species richness for marine ecosystem services. The 2048 claim was a side remark that ended up as a red flag in the associated press release. Interestingly, in the same month the 2048 article was published, the American fisheries scientist Ray Hilborn complained in the American magazine Fisheries (see a copy of the article here) that more and more articles in marine science, especially in leading journals such as Nature and Science, were published not for their scientific merit but for the public impact of their press release:

These four examples [not including the 2048 article, RG] illustrate a failure of the peer review system and lack of the basic skepticism needed in science, and are unfortunately but a few of the many papers now appearing with similar sensational but unsubstantiated headlines. [...] Critical peer review has been replaced by faith-based support for ideas and too many scientists have become advocates.

Indeed, Worm's paper was accompanied by a press release running the secondary headline "Current trends project collapse of currently fished seafoods by 2050". Apparently, the headline was meant as a wake-up call:

In a note to colleagues that was mistakenly sent to The Seattle Times, Worm wrote that the projection could act as a "news hook to get people's attention." "One reason why nobody cares about marine biodiversity is that there seemed no clear end in sight," he continued. "... Well, it's time to wake up — IF the current trend continues we will see drastic consequences in our own lifetime." (Excerpt from The Seattle Times)

Trevor Branch recently published a very insightful analysis of how the article was received in the scientific community. He found that among the articles citing the Worm et al. paper, the ones referring to the 2048 claim "had characteristics that suggest unfamiliarity with the controversy surrounding this projection, namely papers with few authors, published in journals with low impact factors, in fields far removed from ecology and fisheries, and sharing no coauthors with the Worm et al. paper." In other words: it's the rebels without a clue who cite the article for its doomsyear 2048.

The usual disclaimer
I'm no environmental Pangloss. There is plenty to be worried about, like the criminally exploited bluefin tuna stocks, or the continuous decline of European eel. Institutional problems abound in many regions of the world, making it exceedingly difficult to implement a sustainable system of stock management. And then there are pressures like ocean acidification, proliferation of invasive species, accumulation of plastics, and so on.

But I also believe that activist science will eventually eat itself. If a scientist bases his claims on wild extrapolations such as these, he or she is making it the pseudo-skeptics just too easy.

Confusing Nemo (2): Fisheries subsidies, good and bad

Next in my little fact-checking exercise of The Black Fish's campaign movie:

"Every year, $25,000,000,000 of tax money continues to subsidize a very harmful industry"

And that's a literal quote from the movie. The implication is clear: our tax money - $25 billion of it - is being spent on promoting overfishing. Where does the figure come from?

Rashid Sumaila is a Canadian resource economist who has gained a big reputation with his work on game theoretic analyses of fisheries and big, global-scale analyses of fisheries subsidies. If anyone knows about the global scope of fisheries subsidies it is him; the $25 billion in The Black Fish's movie is based on his 2010 article in the Journal of Bioeconomics.

Interestingly, the article does not only give an estimate of the total amount of subsidies, but also distinguishes three types of subsidies: beneficial subsidies, capacity-enhancing subsidies, and ambiguous subsidies. The distinction is based on what the subsidy does to the resource stock: does it lead to bigger (beneficial) or smaller (capacity-enhancing) fish stocks? This criterion is fairly easy to apply and interpret, but it also leaves some issues out of the discussion, as we will see later.

Beneficial subsidies

Beneficial subsidies contribute to the resource stock, and include such expenses as monitoring programmes, research for stock assessments, and establishing MPAs. Their total amount is about $8 bln.

The article does not ask the question whether this should all be funded by tax money. The rule of thumb should be: subsidize public goods, but let the users of the public good pay whenever possible. As a fish consumer I'm willing to contribute (through a higher fish price, ideally) to a responsible management of our fish stocks, but I'm not sure I agree with sending the bill to those who have no stake in it, like vegetarians (or principled meat eaters, for that matter). The exception may be MPAs, which provide more public goods than just more fish (which is not as clear-cut as it seems, by the way).

Capacity-enhancing

This includes tax-payers' money spent on enhancing fishers' capacity to deplete fish stocks, like public money spent on port development, fleet renewal, and price support. With $16.2 bln this is the largest category. By far the largest type of capacity-enhancing subsidy (or any kind of fishery subsidy) are fuel subsidies: every year a whopping $6.4 bln is spent to lower the price fishers pay for their fuel. Sumaila et al.'s definition of fuel subsidies is interesting: they define fuel subsidies as the difference between what fishers pay for their fuel and what other sectors pay for the same fuel. This means that (partial) tax exemptions, like the red diesel that The Netherlands until recently had, are included; however, blanket fuel subsidies, like those in Indonesia, Nigeria, and Egypt, are not.

I don't know how the authors categorize subsidies for more selective, or low-impact fishing gear, such as the pulse trawl. It must have been difficult to identify exactly on what kind of innovation or renewal a subsidiy is spent, so I suspect the authors have filed this as capacity-enhancing.

You could also argue that port development is simply an investment in infrastructure, which is a public good. The government also builds roads, railways, and glass fiber networks, why single out port infrastructure as a subsidy to fisheries? Moreover, is port development bad if fish stocks are healthy and well-managed?

Ambiguous subsidies

For researchers this is the most interesting category because its effect is unclear. Buyback subsidies, for example, may reduce fishing capacity on the short term, but on the long term the effect is less clear-cut. The vessels bought may go to other countries at dumping prices; fishers may also anticipate future buybacks when deciding whether or not to invest in new fishing capacity. Ambiguous subsidies amount to about $3 bln.

Do tax-payers spend $25 bln on overfishing?

Now I'm confused. $8 bln + $16.2 bln + $3 bln = $27.2 bln, not $25 bln as the movie states. The article's abstract, however, estimates the global amount of subsidies at between $25 bln and $29 bln. Does The Black Fish prefer to give a conservative estimate, rather than the best estimate according to the article? But then why lump together scientific research and establishing MPAs (which I cannot believe The Black Fish would oppose) with fuel subsidies (which are undoubtedly wrong)?

Confusing Nemo (1): How much is too much?

The Black Fish, an environmental NGO, has made an animation movie on fisheries. Laudibly, the organisation provides the sources for its (albeit not all) claims. I agree with some statements they make, but not all. Let me go through some of them one by one in a series of posts. Number one:

"The global fishing fleet hauls in 80 million tonnes of sea food"

The latest FAO report on the State of the World's Fisheries and Aquaculture (SOFIA) on this states that the amount of fish captured in marine areas is indeed around 80 million tonnes each year. I suspect, however, that this only includes the recorded landings: figures on discards and illegal landings are probably too shaky to be included in these figures. So catches might actually be higher.

So the 80 million tonnes seems accurate, but is it much? For comparison: FAOSTAT states that the world produced almost 300 million tonnes of meat in 2011. But that says little about whether 80 million tonnes (or perhaps more, due to discards and illegal landings) is too much. The most widely used benchmark for this is maximum sustainable yield (MSY). The SOFIA does that, and concludes that around half of evaluated stocks is fully exploited (around MSY); overexploited stocks (stocks that, in the report's definition, "produce lower yields than their biological and ecological potential", due to low stock abundance) make up about 30% of the stocks evaluated. Of the remaining 20% harvests can be increased sustainably. What the report also says is that

The declining global catch over the last few years together with the increased percentage of overexploited fish stocks and the decreased proportion of non-fully exploited species around the world convey a strong message – the state of world marine fisheries is worsening and has had a negative impact on fishery production.

In other words, the fact that slowly the number of overexploited stocks is increasing while catches stabilize or decline should, according to the FAO, be taken as a bad sign.

If you want a second opinion, this article by Boris Worm and others should be a good place to start. The authors examined the exploitation rate and biomass of 166 stocks worldwide and found, among others, that

For about two-thirds of the examined stocks (63%), biomass (B) has dropped below the traditional single-species management target of MSY, that is, B < B_MSY. About half of those stocks (28% of total) have exploitation rates that would allow for rebuilding to B_MSY, that is, u < u_MSY, whereas overfishing continues in the remainder (u > u_MSY in 35% of all stocks).

That's the bad news. Interestingly, the article also states that

Since the 1990s, Iceland, Newfoundland-Labrador, the Northeast U.S. Shelf, the Southeast Australian Shelf, and California Current ecosystems have shown substantial declines in fishing pressure such that they are now at or below the modeled u_MMSY. However, only in the California Current and in New Zealand are current exploitation rates predicted to achieve a conservation target of less than 10% of stocks collapsed.

So is the 80 million cited in Losing Nemo accurate? It seems so. Is 80 million too much? For the short run it also seems so, but on the long term it is more difficult to say. As Worm et al. state, it is still possible to rebuild stocks, and we can only do so by catching less. So far I haven't found any figures on how productive world fisheries stocks could be if we managed them well: 70 million tons? 90 million tons? In any case, things are moving in the right direction as the exploitation rate is slowly declining in most, albeit not all fishing grounds.