A Straight Dope Classic from Cecil's Storehouse of Human Knowledge

Followup: Did Cecil exaggerate the decline of the world fish supply?

January 29, 2010

Dear Cecil:

I am writing to bring to your attention several errors contained in the recent edition of the Straight Dope titled "Farm-Raised vs. Wild Fish: The Facts" [December 25].

You begin your column by reminding readers of the collapse of Atlantic cod, claiming "the number of cod today is something like one percent of what it was in the 1960s." While that is a great rhetorical hook for readers, it is also a dated snapshot of those fisheries. The fact is that the cod stocks (there are two) in Georges Bank and Gulf of Maine are currently rebuilding spawning stock biomass to target levels. According to National Oceanic and Atmospheric Administration scientists, "In the Gulf of Maine, spawning stock biomass increased from 10,974 metric tons in 2005 to 33,877 metric tons in 2007. Although the stock remains low relative to the target level, the current spawning stock biomass is over half of the target level and is therefore no longer considered overfished."

What's more, you blame the status of the cod stocks completely on "rapacious factory fishing" while the very latest science on the issue published in the ICES Journal of Marine Science suggests "a relationship between climate change and the decline of bottom species like cod."

This is not to say that overfishing and mismanagement have not had an impact on certain stocks, but efforts to rebuild stocks and head off future collapses are a robust part of modern fisheries management. Ignoring those efforts means only telling half the story — the shocking, sensational half.

The reference to Boris Worm's 2006 paper, found in paragraph 8, is quite simply out of date — because Worm himself has disavowed the conclusions of his own paper. A minimal amount of research would have found that Worm published a new study in July in the journal Science that finds the marine ecologist saying he plans to be "hosting a seafood party" in 2048 instead of mourning the loss of all marine ecosystems.

In paragraph 9 you suggest that a rash of mislabeling is the result of "dwindling supplies." Here you show a lack of understanding about the species substitution issue. The cases of seafood being mislabeled cited by the FDA revolve around economic integrity, not sustainability. Misidentifying fish for sale is about fraud, plain and simple, not about suppliers' inability to obtain certain fish to offer on the open market. Again, a minimal amount of research like a phone call to someone at the FDA or the Better Seafood Board would have made that readily apparent.

In the very next paragraph you suggest "less desirable fish" are finding their way onto restaurant menus because "increasingly that's all there is left." What evidence do you have to support this comment? It would appear this is merely uninformed opinion stated as fact. The top 10 most popular seafood species in the U.S. make up more than 90 percent of all fish eaten in this country. Those fish are far from the exotic "less desirable fish" he suggests are so often now featured. A quick review of the list would reveal there are plenty of them "left." The top ten are shrimp, canned tuna, salmon, Alaska pollock, tilapia, catfish, crab, cod, flatfish, and clams.

Your foray into an explanation of issues associated with farmed salmon is another opinion-littered section. Your focus on higher levels of PCBs found in farmed salmon as opposed to wild exposes a complete ignorance and lack of perspective often associated with unqualified armchair nutritionists. The fact is, Harvard University researchers have calculated that 34 percent of PCBs found in the average American diet come from beef, chicken and pork, 30 percent come from dairy products, 20 percent come from vegetables, 9 percent come from seafood (all seafood not just farmed salmon) and 5 percent from eggs. The researchers concluded that heart disease benefits outweigh theoretical cancer risks by 100- to 370-fold for farmed salmon.

Furthermore I must ask that you please provide a source for your suggestion in paragraph 13 that aquaculture run off is responsible for increased mercury levels in wild fish. I am unaware of a single reputable study or even plausible scientific scenario that would support this statement.

Your poor research and insistence on hyperbole rather than perspective does a terrible disservice to your readers. In many cases, your "facts" are in grave error, not to mention commercially disparaging.

Cecil replies:

First let's get something straight. You represent the seafood industry. It's in your organization's interest to paint a rosy picture of the fisheries. To an extent your complaint is simply that I put a darker spin on things than you'd like. Accusing me of poor research and grave errors is another matter. I've reviewed some of the key scientific papers and consulted with Boris Worm, the fisheries expert at Canada's Dalhousie University whose views you think I've misrepresented. As we'll see, I disagree with your assertion that I was in error:

You begin your column by reminding readers of the collapse of Atlantic cod, claiming “the number of cod today is something like one percent of what it was in the 1960s.” While that is a great rhetorical hook for readers, it is also a dated snapshot of those fisheries. The fact is that the cod stocks (there are two) in Georges Bank and Gulf of Maine are currently rebuilding spawning stock biomass to target levels.

You take a sunnier view than the reality warrants. The two fishing grounds you mention, both in U.S. waters, constitute a relatively small portion of the North American Atlantic cod fishery. The larger part is off the coast of Newfoundland and Labrador; at its peak it was ten times the size of the Georges Bank and Gulf of Maine fisheries. The Newfoundland and Labrador fishery collapsed in the early 1990s and fell to less than 1 percent of the peak level. Professor Worm tells me in the last few years the stock may have risen to about 4 percent — which, OK, is more than the “something like one percent” I cited initially — but the offshore fishery remains closed. It would be foolish to call this modest improvement a recovery.

You blame the status of the cod stocks completely on “rapacious factory fishing” while the very latest science on the issue published in the ICES Journal of Marine Science suggests “a relationship between climate change and the decline of bottom species like cod.”

You cite a single paper in support of this contention, presumably "The Response of Atlantic Cod (Gadus morhua) to Future Climate Change" by Kenneth Drinkwater (2005). Drinkwater discusses the possibility that colder waters may have caused cod off Newfoundland to migrate south around the time the fishery there collapsed in the early 1990s. Here's what Professor Worm had to say about this:

"I don't think anybody doubts that fishing was the major factor in the collapse of the northern cod fishery. It is true that the collapse happened during a time of cool temperatures, but the fact is that those 'missing' fish never turned up again. Stocks south of Newfoundland declined at the same time. Hutchings and Myers published a string of papers in the 1990s clearly showing that fishing was the only viable hypothesis for the collapse. I don't see any contrary evidence in the Drinkwater paper."

Here's the response I got from Kenneth Drinkwater himself: "I am not saying the decline was due to migration to colder water. As I stated at the beginning of my paper, overfishing was a primary cause of the collapse ... the decline was due to the combination of fishing and climate ... Again, it was the intense fishing pressure during poor environmental conditions that contributed to the decline."

The reference to Boris Worm's 2006 paper . . . is quite simply out of date — because Worm himself has disavowed the conclusions of his own paper.

No, he hasn't. I quote Professor Worm: "The assertion that I have 'disavowed' my conclusions from 2006 is untrue. In fact, our new paper confirms independently the trend of increasing species collapse that we highlighted in 2009. What is true is that our new research has also shown that it is indeed possible to curb fishing pressure, and begin a process of rebuilding." I'll return to this in a moment.

Misidentifying fish for sale is about fraud, plain and simple, not about suppliers' inability to obtain certain fish to offer on the open market.

That's a narrow way of looking at it. While fraud is undoubtedly the immediate cause of much mislabeling, the underlying cause is dwindling supplies. As Jennifer L. Jacquet and Daniel Pauly ("Trade Secrets: Mislabeling and Renaming of Seafood," Marine Policy, 2008) put it: "Species are mislabeled because there is a shortage of the desired species or because the species itself was illegally caught (illegal, because there is a shortage). Species are renamed because an ever-growing demand for seafood creates new markets for fish that were once considered unmarketable (e.g., slimeheads, toothfish). Today's renaming and mislabeling is not only an indication of cheating, but is, fundamentally, an indication that global fisheries are in distress."

You suggest “less desirable fish” are finding their way onto restaurant menus because “increasingly that's all there is left.” What evidence do you have to support this comment? . . . The top 10 most popular seafood species in the U.S. [are the traditional favorites, including] shrimp, canned tuna, salmon, Alaska pollock, tilapia, catfish, crab, cod, flatfish, and clams.

That salmon, cod, and the like remain popular with American consumers doesn't change the fact that these varieties have been badly overfished, as they famously have. The resulting scarcity of such longtime staples clearly helped open the door for once-scorned but now rebranded species like Chilean sea bass and monkfish, as well as easily farmable newcomers like tilapia. If you dispute this, you might want to take it up with the people at the trade magazine Seafood Business, where they're running articles like this one suggesting that an up-and-comer fish called cobia is proving "a popular substitute for species that are overfished."

My colleagues at Mother Jones looked at fish rebranding recently and saw it the same way:

"Once a rare catch, escolar came on the scene in the past few decades after fishing vessels began using deeper-water longlines to catch tuna and swordfish. Along with escolar, the new equipment pulled up other deepwater fish rarely seen on the market before — Patagonian toothfish, orange roughy, monkfish, and rattail. As target species began declining due to overfishing in the '60s and '70s, the industry turned to the bycatch as potential new product."

Your [discussion of] farmed salmon is another opinion-littered section. . . . Harvard University researchers have calculated that 34 percent of PCBs found in the average American diet come from beef, chicken and pork, 30 percent come from dairy products, 20 percent come from vegetables, 9 percent come from seafood (all seafood not just farmed salmon) and 5 percent from eggs.

The PCB statistics you cite don't address the question of farmed fish versus wild. However, since you raise the subject, let's take a closer look at the numbers. You say 34 percent of PCBs in the American diet come from beef, chicken and pork and 9 percent come from seafood. Bear in mind that the average American ate about 16 pounds of seafood in 2007 versus 221 pounds of red meat and poultry. Fish thus accounts for 7 percent of U.S. meat consumption (meat here broadly construed to mean animal flesh) but 21 percent of PCB intake from this source. That appears to support my caution about PCBs.

I'm hardly alone in my opinion of farmed fish. For example, "a study by Goldburg and Naylor calculated that developing a $5 billion offshore aquaculture industry . . . would dump into the ocean the nitrogen equivalent of untreated sewage from more than 17 million people every year, or about the amount of nitrogen in annual waste from North Carolina's hog industry" (Engelhaupt, Erika, "Farming the Deep Blue Sea," Environmental Science & Technology, 2007). Likewise, many studies attest to the nutritional deficiencies of farmed fish.

I don't mean to condemn farmed fish. It's certainly better than no fish, and given the decline of wild fish populations we don't have a lot of choice. The fact remains that wild-caught fish is better in important ways.

Please provide a source for your suggestion . . . that aquaculture run off is responsible for increased mercury levels in wild fish. I am unaware of a single reputable study or even plausible scientific scenario that would support this statement.

Here you go: Debruyn, Adrian et al, "Ecosystemic Effects of Salmon Farming Increase Mercury Contamination in Wild Fish," Environmental Science & Technology, 2006.

I don't claim the situation is hopeless. Professor Worm's recent work indicates the situation can be turned around through determined effort. But major reforms are essential, the most obvious in my opinion being a comprehensive, global system of fisheries management. If instead we pretend all is well and continue down our present path, we're sunk.

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References

Debruyn, Adrian et al, "Ecosystemic Effects of Salmon Farming Increase Mercury Contamination in Wild Fish," Environmental Science & Technology (2006).

Drinkwater, Kenneth, personal communication.

Drinkwater, Kenneth, "The Response of Atlantic Cod (Gadus morhua) to Future Climate Change," ICES Journal of Marine Science (2005).

Engelhaupt, Erika, "Farming the Deep Blue Sea," Environmental Science & Technology (2007).

Fisheries and Oceans Canada, "Stock Assessment of Northern (2J3KL) Cod in 2009," DFO Canadian Science Advisory Secretariat Science Advisory Report 2009/009

Forristall, April, "Cobia: Sustainable characteristics make the farmed species a fish with a future," SeaFood Business, January 11, 2008: http://www.seafoodbusiness.com/archives.asp?ItemID=3651&pcid=192&cid=193&archive=yes

Jaquet, Jennifer L. and Daniel Pauly, "Trade Secrets: Mislabeling and Renaming of Seafood," Marine Policy (2008).

Tsui, Bonnie, "The Ex-Lax Fish," Mother Jones, November/December 2009: http://motherjones.com/environment/2009/11/green-around-gills

Worm, Boris, personal communication.

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