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The Great Fish Debate

June 8, 2011

Thanks to my fellow bloggers at blogfish and Southern Fried Science, I recently learned of the very excellent ocean blog, The SeaMonster, and the EPIC discussion that the website recently facilitated.

Since that debate was so epic, I figured most people won’t have time to go through it all.  So, here I provide my very own Cliff Notes, which you can read in 10 mins or less.

Background

The ‘Great Fish Debate of 2011′ (as we’ll call it) was the result of a provocative NYT op-ed article by Dr. Ray Hilborn, a fisheries scientist at the University of Washington.  Titled “Let Us Eat Fish”, Hilborn argued that:

  1. Americans have been bombarded by false apocalyptic warnings with regards to the world’s fisheries,
  2. Fisheries management in the U.S. has been improving since the mid-1990s,
  3. Americans should eat more fish because fisheries are not approaching the fish apocalypse, and
  4. Eating fish is preferable to eating chicken, beef, and pork because they carry higher environmental costs.

The op-ed elicited a few response letters, and then ‘thangs got crazy’ with Dr. John Bruno’smost excellent response at The SeaMonster.  In response to this response…we got more responses.   And they came from some of the biggest names in fisheries science, including Enric SalaRashid SumailaTrevor Branch, and Callum Roberts.

The entire series can be found at The SeaMonster’s Forum on Fish, Food, and People.

Glaring Errors in Reasoning

Hilborn’s article got such a strong response because there were a few glaring errors of reasoning.  Here are the fishy fallacies.

The status of global fisheries is not as bad as we previously thought, therefore they are in good shape.  Absolutely wrong.  Sure, some scientists overstepped in 2006 and predicted that there would be no commercial fish stocks left by 2048…but Hilborn later helped write a follow up article because the prior article’s model was far too simplistic to ever have been published.  Of course, that follow up article still found a pretty bad situation:

63% of assessed fish stocks worldwide still require rebuilding, and even lower exploitation rates are needed to reverse the collapse of vulnerable species

U.S. fisheries are well-managed and are recovering from past overfishing, therefore all fish are fine to eat.  Again, very wrong.   Yes, U.S. fisheries are well managed these days, having made a very strong recovery since the mid-1990s.  But, what does this have to do with the rest of the world’s fisheries?  Again, as the article Hilborn himself helped write found, a majority of world fisheries are overfished.   And the U.S. gets 84% of its seafood through imports.

Livestock production carries high environmental costs, therefore we should eat more fish.  This here is just silly and a ridiculous stretch for a fisheries scientist.   There are no good studies saying the environmental costs of eating fish are less than livestock, and Hilborn made no attempt to produce such evidence.  Indeed, it seems he just pulled it out of his imagination and called it fact.  Consider that fishing can carry a high carbon footprint and lead to habitat destruction and ecosystem degradation.  And aquaculture, which makes up about half of the world’s seafood, is well known to have high environmental costs.

In sum, understanding these fallacies means that Americans cannot yet eat seafood ‘guilt-free’ and should be careful about what fish they choose to eat.

John Bruno explained these fallacies beautifully in his post (which is well worth reading!).  And many people in the forum agreed with him.

The Broader Discussion

The discussion participants added a great many other intelligent and needed points.  Summarizing them all would be too lengthy, so here I put what I thought were the most important.

Different methodologies will give us different estimates for the status of world fisheries. Where one study based on catch data has found that 63% of world fisheries are overfished, a new 2011 study based on biomass estimates (by Hilborn and Trevor Branch) found that only 28% of world fisheries are overfished or collapsed.

Fisheries data doesn’t support accurate global estimates.  As Bruno points out, Hilborn and Trevor Branch in their 2011 study were only able to assess 25% of world fisheries area and catch, with much of the developing world a mystery.   And as Branch responds, catch data – which are easier to come by – just so happen be biased towards “worsening trends”, meaning, without additional data, such as statistics on catches per unit of effort, we just don’t know if the trends are correct or not.  (Of course, the prolific Daniel Pauly argues that you can model for the spatial expansion of fisheries to find an accurate trend toward decline, but even still, there are wide margins of error.)

Historical analysis and anecdotes suggest that fisheries in the developed and developing world are overfished according to historical baselines.  John Bruno points to the “enormous literature” that has “documented the past collapse of fish populations around the world and their currenthighly depleted status.”  And Sumaila noted that he regularly hears of overfished and collapsed fisheries when he travels to developing countries.  So if we don’t have good enough data for statistical analysis…how much should we rely on less quantitative analysis?  I’d say a good deal.

We should expand the discussion to consider the ecosystem as a whole, not just the fishery. As Branch puts it, “most of us would agree that biomass well above Bmsy is better than biomass below Bmsy because of all the ecosystem benefits.”  And right he was.  Hilborn agreed (though with important caveats), as did Les Kaufman.  The SeaMonster’s forum editor, Emmett Duffy summed this all up really well:

The important point is that concluding that overfishing has ended is not at all the same as concluding that human impacts are negligible. This distinction is easily lost on the general public, and was absent from Ray’s NYT essay.

 And Hilborn?

It’s kind of hard to say what happened here.  For such a smart guy (who called out a bad 2048 prediction), Hilborn sure made some bad arguments.  And he wouldn’t own up to them, preferring instead to respond with more information on U.S. fisheries management and his suspicion that developing country fisheries are not that bad off (which in turn is in contradiction to anecdotal and historical analysis).

Hilborn also tried to defer blame to the NYT’s editors:

I didn’t want to give a personal opinion on this, but the NYT editors insisted I say what I thought we should do.

The original draft of the Op-Ed was built around the CITES listing of bluefin tuna back in November 2010, and I wanted to point out that US fisheries should not be tarred with the same brush. My original title was “the unheralded revival of Americas fish stocks.” The NYT editors chose the title and heavily edited the introductory paragraphs. However I am certainly willing to defend the assertion that Americans should eat fish without feeling guilty or I would not have allowed it to be printed.

And his push against the “apocalyptic warning” of 2048 was supposed to be done and buried after he published the follow-up piece with Boris Worm, one of the original co-authors.  As Worm puts it:

I am reluctantly chiming into the discussion precipitated by Ray’s ‘Let us eat fish’, because I was truly of the impression that we had moved beyond this.

Of course, to give Hilborn some credit, it is true that the 2048 prediction has continued to be passed along by the general public and even some professional conservationists.  For example, see this 1 min video on aquaculture. And heck, even the Human Planet oceans episode said that all fish may be depleted within the next 50 years.  And like Hilborn, I do think it’s really important to get our facts straight.

Want to read more?  The full debate can be found here.

(Photo Image: Fisheries scientists that participated in the debate. Credit:www.imachordata.com)

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7 Comments leave one →
  1. June 8, 2011 9:33 pm

    Thanks for the shout-out Mark. Nice to learn about Breaching the Blue too. Happy Oceans Day!

  2. June 8, 2011 9:35 pm

    Wow, thanks Mark for covering this, for the words of support and for the cliff notes! – John

  3. June 8, 2011 10:01 pm

    You’re quite welcome! I’m a big fan or your blog. Looking forward to more good stuff over there.

  4. September 8, 2012 3:05 am

    As a followup to the debate, you may be interested in the paper by Boris Worm and myself that just came out online in TREE (Worm & Branch 2012), which shows that average status of stocks assessed by FAO (which account for 80% of global catches) is better than the average status of stocks compiled for Worm et al. (2009), but the trend for the FAO stocks is declining. This implies that stocks without formal assessments might be in better shape now but with worse future prospects. This makes some kind of sense in that stock assessments come mainly from the North Atlantic which has the longest history of heavy exploitation, and are dominated by European fisheries.
    Ref: Worm, B. and T. A. Branch. 2012. The future of fish. Trends in Ecology and Evolution doi: 10.1016/j.tree.2012.07.005.

Trackbacks

  1. Cliff notes for the EPIC SM fisheries debate | SeaMonster
  2. EPIC Discussion on the Future of the Oceans « Breaching the Blue
  3. Blogging, One Year On « Breaching the Blue

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