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Energy Efficiency of Eating Dolphins

The recent articles on the Taiji dolphin hunt have generated a tremendous amount of discussion in the Japan Probe comments section. Many comments were well constructed and presented, while many were, well… not. One facet of the argument that I didn’t see come up (forgive me if you raised this point and I just missed it) is the energy efficiency (or rather lack there of) in eating top level predators, such as dolphins (or tuna for that matter).

Energy transfer between trophic levels is inefficient, about 10%. Thus, an herbivore only receives about 10% of the total energy captured by the plants it consumes. While determining a trophic level for any particular animal is not straightforward because of a varied diet, worldwide estimates for the bottlenose dolphin, Tursiops truncatus (the same species hunted in Taiji), place it at a level of between 4 and 5, probably closer to 4, which is equivalent to that of tuna, bonito, and other open-ocean large pelagic fish. This means if phytoplankton captured 100 units of net energy from the sun, by the time that energy is passed through two additional levels of animal and ultimately a dolphin on the way to your dinner plate, that you eat only 0.1 units.

However in theory, an herbivore, such a cow, provides 10 units of energy. In reality, the equation is not so simple, though. Just as physicists must invoke the hypothetical “frictionless surface” when explaining Newton’s First Law, I must invoke the hypothetical “free-range cow” because I am completely ignoring the energy and water costs of commercially raising cattle (not to mention the climate effects of bovine flatulence).

So, while in my honest, meat-eating opinion, many arguments against eating animal products made by some vegans are borderline silly, I have to agree with those that advocate, from the emotionally-detached perspective of efficiency and sustainable agriculture, eating primarily (though not entirely) corn, wheat, and rice. Having said that however, I sill plan to visit Fire House this weekend for what I consider the best bacon cheeseburger in Tokyo.

A side note on mercury in dolphins

A number of dolphin photo identification projects are ongoing in Florida, the oldest of which was started by Randy Wells in Sarasota Bay during the 1970s. By the late 1990s, it became clear that the mortality rate for first-born calves was unexpectedly high. The working hypothesis states that the transfer of bioaccumulated toxins and heavy metals from mother to calf is responsible for the high mortality rate. This seems to serve essentially as a “detox dump” for the mother, with deadly effects for the calf. Interestingly though, it is thought that this ultimately increases the longevity of female dolphins, allowing them to bear a larger number of offspring. Mortality rates for subsequently born calves is not unusually high.

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Contributor Bio: Steve has been splitting time between the US and Japan for the past 10 years or so and is now a post doctorate fellow at a large, lumbering University in Tokyo, where he gets paid to play with dirt.

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39 comments - What do you think? Posted by steve - September 15, 2009 at 6:19 am

Categories: General Japan Tags: dolphins, eco, food, taiji

Tre

Natural selection, baby – that’s all there is to it.
Kitty

My Grandma makes an awesome dolphin meatloaf!
LB

A problem with the “primarily grain” diet idea is that the human digestive system is not optimized for it. Cows and herbivores are able to convert a fairly strict grain, grass and bark diet into proteins, fats and amino acids. Omnivores like humans are not well equipped to do that. There are ways around that, such as nuts and beans, which will do the job for us quite well, but you have to plan and balance carefully. Soya can fairly effectively replace meat, but it also contains estrogen-like compounds in high enough concentrations that health problems can result if someone carelessly decides to just replace “meat” with “meat-like soy products”.

Good point about toxins concentrating in animals the higher up the food chain you go. That is why DDT was so devastating to eagles. I have also read that among the Inuit it was traditionally forbidden to eat polar bear livers. There turned out to be a good medical reason: the levels of vitamin D in polar bear liver is toxic to humans. Polar bears eat seals which eat fish, and the vitamin D accumulates the higher up the food chain you go.
Aaron

In the case of sea creatures, energy efficiency isn’t as useful a measurement as it might otherwise seem, because in many case, the level 1 through 3 creatures are not eatable by many. As far as I know, we can’t get nutritive value from phytoplankton or krill, so it isn’t relevant that they are tier 4 or 5. This is different from land animals, since we could use the resources devoted to their production (land, water, people) to harvest crops that people could eat.
helical

Though certainly not decisive, the energy efficiency is certainly a compelling (and refreshingly rational) argument to me, at least for refraining from consuming too many animals at the top of the food chain.
That, and for developing a way for humans to photosynthesize, but I guess we won’t be seeing that one anytime soon.

Fire House is close by … I guess I’ll check it out soon. Even today, maybe.
The Overthinker

But while the engery required to make a certain amount of calories at the top end may be higher, what about the energy expended in acquiring it? Isn’t that why animals go carnivorous? A lion eats every few days – its prey basically does nothing but eat all day.

The energy argument also loses power in that since the energy originally comes from the sun, it’s not a supply we are about to run out of any time in the next couple of billion years. It’s not like fossil fuels where energy efficiency is important.

This is also a pretty good argument for eating baleen whales, though – just one level up. Blue Whale Burger, anyone?

LB

That lats sentence is a very good point – although it will probably really p*** off the anti-whaling types. But you are right – baleen whales would probably be, for humans, the most energy-efficient form of protein. However, they are actually two steps up – they eat krill, which feeds on plankton. They doubtless suck up a lot of plankton as well, but their main food source is the huge amount of krill eating all that plankton.

The Overthinker

Yeah, so it is. Two steps up, that is.

You know, I ma sure someone came up with krill burgers….
http://www.cmlre.gov.in/somlrp.html

OT

Krill Burger!

Yum!

hahaha

tomservo

That was a refreshingly rational argument. It would be interesting to have a truly independent study (which includes more than just the staple meats) examining things like energy efficiency and nutritional quality of a variety of meat.
kay Sato

ok so you state the facts. and then u ignore all of them and eat the meat anyway. Im not saying we all should be vegetarians. If people of the US were to eat one meatless dinner a week it would do the world a lot of good.

we dont need to eat red meat 3-4 times a week. bad for health, unsustainable for the environment.

steve

I believe in a balanced diet. I tend to like the Japanese approach of minimizing the meat. For example, you can make a tasty pasta sauce with the most miniscule amount of ground beef – just enough for the flavor to seep into the tomatoooos…. yum…

OT

Verrrrrrry interesting.

When I lived in England, we only ate Beef once a week – on Sundays. It’s a big deal in England, that Sunday Roast with the yorkshire pudding.

They also always made sure they ate fish on Fridays – albeit fried fish and in the form of fish & chips – now they eat Sushi like there’s no tomorrow (and there won’t be, at the rate that the world is eating sushi).

steve

Wanted to mention that this post was just my thoughts on efficient transfer of energy. I spend a lot of time thinking about these things, mainly from the point of view of supplying power to our societies.

In the open ocean or a typical forest, about 1% to 2% of incident solar radiation is captured during photosynthesis. subtract 90% for each increase in trophic level. Seems really inefficient. Obviously this is a much more complicated issue, though. Wholesale moving down the food chain by humans would be catastrophic to higher level marine animals, though evidence from 10 years ago suggests this is already happening.

http://www.sciencemag.org/cgi/content/abstract/279/5352/860
http://www.nytimes.com/1998/02/10/science/man-moves-down-the-marine-food-chain-creating-havoc.html

I hate to say it because I love eating fish, but ocean does need a break.

@LB

Sounds like you know a lot more about nutrition that I do. I agree that we are not optimized for an all grain diet, but it can be done… Just not by the likes of me.

@Aaron

Good point, we would typically not eat krill, in North America at least (though we could get nutrition from it) Though especially in Japan, we do eat primary producers (kelp – nori) and lower tier fish (think any small grilled/fried fish with beer). Also shells.

@Overthinker

It is my understanding that a lion eats every few days because that is about the best it can do. Actually I snapped a good photo of what lions pretty much do all day…

As an animal’s body gets bigger, there appears to be a threshold where it is no longer sustainable to be a predator. The largest animals in the sea are not carnivorous (baleen whales, whale sharks, etc.) The energy expended to propel such a large body in pursuit of food is greater than that received from the catch.

This of course depends on environment. Several million years ago, there were much larger predators in the ocean – think of fossil megladon teeth in southwest Florida. Due to higher sea level, that area was a major upwelling site (reason for the FL phosphate industry), meaning more prey and bigger predators.

Believe it or not, I once heard or read somewhere justification for Japanese whaling because baleen whales are eating krill, the harvesting of which was recently banned by NOAA in the US EEZ.

The Overthinker

“The energy expended to propel such a large body in pursuit of food is greater than that received from the catch”

Or the reduction in speed, I wonder, given the higher resistance of water? Also, we need to consider evolutionary pressures to grow: huge body size is not always beneficial, unless you are a prey animal needing the sheer mass to prevent being eaten.

I’d need to see some sources on the lion thing. It may be that they hunt that often, but feast off the kill for longer. However since the lions objected the last time I tried to interrupt their dinner, I won’t rush in any time soon….
However it applies to other animals as well – carnivores generally eat less often.

steve

I am definitely getting out of my comfort zone with it comes to land animals. I think you are correct that predators eat less often. I am not sure about the reasons, though. If they felt assured of a small meal everyday, would they prefer that over gorging every few days?

I spent about a month in Kenya some years back doing the safari thing. I have a photo of a pack of cheetahs that had just made a kill and finished eating. It was amazing how expanded their stomachs were. I also have a photo of a female lion on the hunt. The way to know she was hunting was her emaciated-looking stomach (according to the guide).

The Overthinker

I managed to lose my last effort, but in brief:
Predators definitely eat less often. They need a much larger mass for the same calories, and digestion is often not as efficient, grass etc being notoriously hard to extract nutrients from (why cows have four stomachs and chew their cud).

Don’t know if lions would prefer smaller regular meals. Probably, but my point was that they don’t *need* to eat as often.

And looking emaciated and actually starving are not of course the same thing. Aside from the expandable nature of the predator gut (a male lion can put away about 50kg at a gorging). hunting when starved is not a good idea as the animal lacks the energy to run and hunt properly.
steve

“Predators definitely eat less often. They need a much larger mass for the same calories..”

I got a little thrown off by this at first because I though you were saying that predators need more mass for same number of calories. But I see you meant herbivores. Your point is taken. Well.

yes of course I didn’t mean that they are actually starving. 50 kg – definitely need an expandable stomach for that.

You originally commented on the energy expended to acquire energy. This is incorporated in that 10% transfer rate, I believe.

For the heck of it I just did a back of the envelope, simple approximation. I didn’t consider the cost of plant respiration (i.e., net primary production vs. primary production) and am not considering the effort to digest difficult-to-digest nutrition.

Consider a 1 square meter of ocean surface completely filled with phytoplankton. If we assume 250 W hits the ocean, then 5 Watts (2%) is captured by plankton. 5 Watts = 5 Joules/second so:

5 J/s * 604800 s (1 week) = 3024 kJ = about 700 kcal or lunch at McDonalds. Run that energy through 3 additional levels and we are talking 0.7 kcal or about 19 years of primary production.
The Overthinker

Opps. Yes, I meant herbivores. That’s what comes from a quick rewriting on an eaten post….

kay Sato

just the idea of eating krill.. made me laugh a little. though u know i do love the baby sardines… shirasu, the more fresh version, or chirasu, semi dried tiny sardines. apparently a “heaping tablespoon” has as much calcium as a glass of milk, but half the calories.

also its interesting how picky americans are about food. like they don’t eat organ meat, many have no taste for seaweed. but i guess this is just me ranting.

steve

The Japanese are IMO some of the best when it comes to eating as much of an animal as possible. Americans are probably the worst. I like that Chinese saying – goes something like: if it has 4 legs, I’ll eat it unless it is a table or a chair.

The Overthinker

Hell, the Chinese don’t stop at four legs. Or even legs.

LB

“they don’t eat organ meat”

I beg your pardon – liver, tripe, kidney pie, blood sausage (aka blood pudding), gizzards, hearts, tongue – all readily available in any well-stocked supermarket I ever saw in the US.

Still, general point taken. My only complaint is the Japanese tendency to comment on how delicious the fish in the aquarium look. Or worse, the rock lobster display in the aquarium on Miyajima actually went so far as to describe the types of lobster and the best way to cook and eat them…

The Overthinker

I would add “skin” (which is an organ, the biggest) to that list – all that KFC….

kay Sato

i know many caucasians who wouldn’t touch a bit of organ meat. middle class america has largely moved away from organ meat. u don’t see it in chain food stores. only high class restaurants which say they make it delicious.

Ai

Hi.
Well here goes my point of view.
Human beings in order to be able to live need to take the live form another living being. You may think that killing a plant is less important than killing an animal, I don´t. I believe life has the same value in a simple vegetable and in an animal, of course I understand this point of view is not shared by most people. Well talking about dolphins, it is not a sport where you waste a life and nobody takes profit from it. I agree with Japanese hunting dolphins, they have the right to do so. It is no different from killing a pig, or a cow, or any other animal.
I criticize this society because we don’t accept the fact that we kill in order to live. We don´t want to see the reality and leave other people kill our food, this way we don’t look guilty. If we had to kill our own food we would be shocked, to say the least.

have a nice day.
Sanman

Dolphins are not food! Get that to your thick heads!!

helical

As opposed to pigs, cows, chicken, turkey, or sheep?

steve

Get that to your thick heads!!

through
steve

Many commenters quickly realized the purpose of this post was to look at eating dolphins from a thermodynamical perspective.

This is obviously a very simplified view, as I originally acknowledged, and must also be applied to big fish as well. So there are many, many interesting and intelligent points to discuss here, what we feel is ethical to kill or not kill is probably not one of them and has been pretty well covered already.

hint: Ever notice that in the typical supermarket, the only top-level predators (barring the occasional carnivorous cetacean) are fish? Why don’t we eat birds of prey? Wolves? Is the practical consideration of having a wolf farm?

The Overthinker

Wolves eat the wolfherds….
You have an interesting point, and my initial response would be to say that most of the carnivores on land that are edible sizes are too dangerous to keep easily – after all, the herbivores we eat from the land are domesticated, whereas the carnivorous fish we eat are not. Hunter-gather tribes will eat both, actually.

Also, assuming we could domesticate them, given that the greenies are always telling us how many hectares of land are needed for one cow, then how many more would be needed for the cows to feed our lion farm? There is no jump up in caloric density between cows and lions, after all.

So, in sum:
Carnivores are great if you don’t need to keep them, but otherwise herbies are less hassle.

Marc Clement

What about the taste of dolphin’s meat ?

Any good recipes available ?
RMilner

This energy argument is something of a red herring. The Sun constantly pours inexhaustible energy onto the Earth, most of which is not transformed into biomass, yet a sustainable ecosystem still resulted.

It doesn’t make any difference whether a human eats a cow, or a lion eats a cow, or the cow dies of natural causes and bacteria and maggots eat it. The same amount of energy was needed to grow the cow and gets returned to the environment when it is digested or decayed.

What matters is whether the balance of numbers of cows, lions, humans, and so on is sustainable.

Clearly, human activity is unsustainable in areas, for instance the overfishing of many species including anchovy, tuna and cod, but that’s not specifically to do with energy transfer up the food chain. There are many factors involved.

steve

This energy argument is something of a red herring. The Sun constantly pours inexhaustible energy onto the Earth, most of which is not transformed into biomass, yet a sustainable ecosystem still resulted.

Yes, unless were talking about 5 billion years in the future, the sun is an inexhaustible source of energy for the earth, but that does not mean the sun provides an infinite amount of energy. It actually provides about 1300 W/m2 of power to the earth. About 30% of that is reflected back to space leaving around 1000 W/m2 that when averaged over the spherical surface of the earth yields an average of 250 W/m2, which a finite amount. (all of this are approximations to yield nice round numbers)

A sustainable ecosystem has resulted because the carrying capacity of the earth has not been reached.

It doesn’t make any difference whether a human eats a cow, or a lion eats a cow, or the cow dies of natural causes and bacteria and maggots eat it. The same amount of energy was needed to grow the cow and gets returned to the environment when it is digested or decayed.
What matters is whether the balance of numbers of cows, lions, humans, and so on is sustainable.
Clearly, human activity is unsustainable in areas, for instance the overfishing of many species including anchovy, tuna and cod, but that’s not specifically to do with energy transfer up the food chain. There are many factors involved.

I agree with you on this. And this got me thinking: what is the carrying capacity of the earth for humans? A quick search will reveal a huge range of numbers from 1 to 15 billion.

I made a quick estimate based solely on primary production (not NPP) assuming all humans eat exactly 2000 kcal per day and it is all plants. Very simple (and of course unrealistic). I assumed that 50% of the earth’s 510,000,000 km2 surface area produces this food and 2% of the solar radiation gets captured by photosynthesis. I also assumed that all this energy captured by plants is available for human consumption.

The answer I got from this very simplified, first-principle and completely unrealistic approach was 13 billion. We are at about 6.7 billion now, and population has been growing exponentially.

The Overthinker

To be honest, I think this figure is just too vague to be of any use – it reminds me of the Drake Equation in that it just gets more and more into assumptions and guesswork. This sort of thing is fine for thought experiments and speculation among people who know the limitations, but if this was a press release you can bet there would be news articles saying “Energy scientist says world population limit is 13 billion!” or even “World population can expand to 13 billion!” without any of the subtlety. Call me cynical, but this link speaks the truth:
http://www.phdcomics.com/comics/archive.php?comicid=1174

steve

hahaha, I haven’t even clicked the link, but I bet the comic end’s with the grad student getting a tinfoil hat from his grandma. [clicks link, chuckles.] A great example is cold fusion. These guys went to the press immediately before peer review. Oops.

You have a very good point, but this is exactly a thought experiment, a back of the envelope calculation that should by no means be taken seriously.

I commonly see two types of models used, one being similar to a hugely complex general circulation model that attempts to reproduce the world because, since there is only one earth, it is impossible to conduct proper experiments.

The other that I see often is a simple model with few terms, the sole purpose of which is to try and test the sensitivity of a particular parameter to changes in boundary conditions without the confounding effects of many variables.

To properly attempt to model the carrying capacity would require the former type of model, but as these models fail to converge on a single solution (unlike many GCMs used in the IPCC report), it is clear that the system is not well-enough understood or constrained. When this is the case, it can be interesting to go back to basics and play with sensitivity of a few parameters.

futureal

Cows are not “optimized” grain feeders. They are grass eaters. They only eat grain now because ranchers feed it to them to make them gain weight in the months before slaughter. Good luck finding an animal that subsists on corn, oats and soybeans in the wild.

Humans can subsist on only plant matter. There may have been a time when certain populations had to supplement the plants that were available to them with animal protein, but nobody living in Japan in this century close enough to civilization to have internet access is in that situation.
Che

Just the thought of eating dolphin makes me want to throw up. I think all humans should just eat vegetables and fruit.
Chuck Eikholtz

Wrong species of Dolphins discussed in article.

Energy Efficiency of Eating Dolphins

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