Tuesday, June 29, 2010

Behold the Power of Tuna: RECOGNIZE

Wow, I am terrible at updating lately.  Things are probably going to continue to be not-so-great for a while because I'm in the preliminary stages of relocating from Michigan to Texas; after Texas I'll possibly be relocating internationally for work, but let's not worry about that right now.  Instead, let's worry about other stuff like:

Carnival of the Blue 37, hosted at blogfish.  Lots of neat contributions, I hope someday to be able to contribute myself.

Also relevant is that June 11th was World Ocean Day and the 100th anniversary of the birthday of Jacques Cousteau.  Like so many other folks who blog about the sea, Cousteau definitely impacted my love/interest in the ocean.

My mother was and has always been excellent about bringing my brother and I to the local library.  When I was 4-5 or so I discovered a series of books by Cousteau on the shelf and proceeded to check them out obsessively, a habit I totally never repeated later in life (bless you, Madeleine L'Engle).  It was a cycle, we'd check some of them out and then I'd recheck them out as long as they'd let me.  I couldn't even read at the time, but it didn't matter, I'd make my mother or father read them to me.

A nudibranch!  I used to pronounce the "-branch" as in the things that 
grow out of trees, not with a final -k. I am reasonably sure that this will be held 
against me at some point.

In this way, my childhood was filled with nudibranchs, eels, basking sharks, barracudas, tuna, squid, giant clams, etc...and this is completely ignoring marine mammals in the equation, which I think may be as universally appealing to children as dinosaurs.  I wish I could pinpoint which books they were, they were definitely not aimed at children.  They must've been older as this was around 1989-1990 and they weren't terribly new back then. 

But yes: Jacques Cousteau, we salute and will continue salute you for having such an impact on so many people who love the ocean now, due in part to your efforts to spur our imaginations oceanward.  Maybe astronomers have similar feelings about the venerable Carl Sagan?


Actually, I've decided that this post will be devoted to something near and dear to the hearts of Japan and the United States, though in completely different formats: TUNA.

I'd wager that most folks in the U.S. take tuna, the nationally most-consumed fish, for granted because this is what tuna looks like in the national consciousness:

I honestly wonder how many U.S. folk who don't have reason to spend much time around fish know what a tuna looks like.  For the record, the fish that the meat in the can came from looked something like this:

I don't know if you can tell from this distance, but the first thing that caught my eye about the fish (a skipjack tuna) were the rows of little knobs running near the tail.  These knobs are called "finlets" (and "tails" in fish are actually called "caudal fins", but we can have fish anatomy lessons another day) and mark the tuna as a member of the Scombridae family, which is where mackerels and wahoo are also categorized.  Note that finlets are not exclusive to this family, but they're still distinctive.

My oceanographer professor (when he wasn't talking about catching sea bass in Baja) occasionally referred to tuna as "horses of the sea" because they are built for speed and gratuitous face-rocking.

Yellowfin tuna are faster than you. 
Unless you happen to be a cheetah.

AWESOME TUNA FACT: They're...not exactly cold-blooded.  They're not exactly warm-blooded either, but they're certainly more warm-blooded than most fish.  The term "cold-blooded" means that an animal is unable to regulate its body temperature; its body temperature is the same as the temperature of its surroundings.  The LSU AgCenter says it more succinctly than I can:   

Tunas (and a few sharks) have developed the ability to control their body temperature through a network of veins and arteries called a "rete mirabile" that traps (and dumps) body heat. Even smaller tunas can maintain temperatures 50ºF higher than surrounding water temperatures...for most cold-blooded fish, the colder the water and therefore their body is, the slower and more sluggish they are. Tunas' warmer body temperatures speed up the chemical reactions in their body that produce energy and allows their muscles to contract more quickly. This provides faster swimming speeds and increases their endurance...

Compared to other less active fish, tunas have hearts that are ten times larger for their body weight, pump three times more blood, and have blood pressure three times higher. They also have a much higher proportion of red muscle in their bodies than the average fish, which allows them to cruise at higher speeds more efficiently.

http://www.seagrantfish.lsu.edu/biological/mackerels/yellowfintuna.htm; text bolded by me 

If you are thoroughly entranced by the particulars of scombroid physiology, the University of California has a treat for you!  Very thorough examination of several scombroids, both inside and out.  Don't worry, they're polite and don't rudely shove fish viscera (fishera?) under your nose, you have to click links if you want to see guts.

But yeah, have you ever wondered why tuna steaks look like this (top) and say, catfish fillets (bottom)  look like this?

DING DING DING: Tuna have more red muscle than other fish in order to fuel their eternal swim, not unlike some shark species that must utilize ram ventilation to respirate.  To burn the oxygen required by these hefty piscine muscles, tuna have myoglobin, a type of protein, in their muscles. Myoglobin actually forms the pigments that gives raw "red" meat its color, and is also responsible for making red meat that has been frozen turn brown.   

Because consumers enjoy their red meat really red ("bright red"="fresh" in the human brain), this has led some dealers of both tuna and red meat to treat their products with processes that prolong this red color; one way to do this is to expose the meat to carbon monoxide before it's frozen.  As the venerable Alton Brown says, this isn't a bad thing in theory, but it can be unscrupulously used by the powers of darkness.

Of course, not all tuna are bright red, across both individuals, species and parts of the body.  The sushi/sashimi eaters in the crowd will know that otoro, meat from the fattiest part of the bluefin tuna, is actually quite pale because well, it's fat:

  Not the pieces that look like watermelon.

So how do they use all these thick muscles that I keep going on about?  In conjunction with their highly streamlined bodies.  As I research, the word that keeps coming up to describe the body of the tuna is "missile".  They have:
  • grooves along the sides of their bodies to tuck their pectoral fins into place
  • eyes that are flush with their bodies, tunas don't have time for protruding eyes slowing them down
  • a stiff body and skull to increase speed
  • forked crescent-shaped (lunate) tails optimized for rapid oscillation i.e. going really fast
Speaking of sushi, since Japan's consumption of tuna is highly relevant to this conversation, we should probably talk about it a bit.  First, the Sushi FAQ will give us a brief education about the particular cuts of tuna used in sushi.  We also have this beautiful image if you prefer a graphical approach.  Available in both Traditional Chinese characters and Romanized Japanese!

While there nine species of true tuna (fish who belong to the genus Thunnus), there are 9-10 others that belong to the greater tuna family and happen to have the word "tuna" in their names.  The skipjack tuna, the fish in your can (unless you buy "white meat" tuna, which is albacore) is actually a member of this latter category; don't worry though, it's still a scombroid.  The most well-known members of the tuna family include the albacore, yellowfin (ahi), blackfin, bigeye and several species of bluefin tuna.

While they're all of interest, we're going to focus on the bluefin here because that is what you're eating when you order maguro at your local sushi establishment.  Bluefin are by far the biggest tuna around: the most ridiculous on record was an Atlantic bluefin caught off of Nova Scotia in 1979 that weighed 1,496 lb/678.57 kg.  The same site provides a photo gallery of more absurdly large bluefin tuna.  

However, the AVERAGE weight of the Atlantic bluefin tuna (no, I'm not giving you averages for every subspecies of bluefin tuna, live with it) is around 550 lb/250 kg, with a length of 6.5 ft/2 m.  Regardless, even a small mature bluefin is still a Large Fish.

Rows of frozen tuna torpedoes at the Tsukiji fish market in Tokyo.  
More hydrodynamic than when actually alive!

Bluefin tuna are also Not in a Good Way.  In addition to them being good eats pretty much everywhere, Japan has a special fondness for the bluefin.  In addition to eating them with enthusiasm, there is a great deal of money to be had in supplying them.  As of January 2010, the record price for a single bluefin tuna at Tokyo's premier Tsukiji fish market (which I really need to post about too) sat at a cool 16.28 million yen, slightly over $175,000 US (depending on the day), for a 511 lb/232 kg individual.  They are very serious about their tuna.  So serious that the estimates I've seen suggest that Japan consumes 70-80% of the world's Atlantic and Pacific bluefin tuna catch.

As is so often the case, demand is exceeding supply: this level of consumption is simply not sustainable.  We are seeing the bluefin tuna go the way of Atlantic cod and salmon; it's more disturbing yet because while there is no commercial fishing of wild Atlantic salmon and cod (check the point of origin of your salmon; if it's Atlantic salmon, I can almost guarantee that it was farmed off the coast of western South America), bluefin is still being commercially overfished.


There have been some attempts at farming bluefin tuna (or "ranching", both terms sound silly), but farming a large voracious fish that literally has to keep moving or it will die?  Um, good luck with that.  For the interested, Wired also posted an article about 11 months ago about the myriad joys of tuna ranching.

I don't know what the fate of the bluefin tuna will be.  Like pretty much everything that lives in the water, it was sacrificed to the almighty dollar at CITES in Doha this year.  While the possibility of a ban was presented and voted down, Japan pretty much said that bluefin tuna aren't that endangered, despite a wealth of evidence from a wealth of sources that says that Japan is apparently pulling its numbers directly from its anus, probably still a little poopy. 

Just in time for me to post this entry, there's a 9-page article on the New York Times that covers much of what I'm talking about: Tuna's End.  I suggest reading if you have the time/interest.  If you REALLY want to read more, marine conservationist and artist Richard Ellis has just the book for you (and me!): Tuna: A Love Story.   

You're going to have to earn that albacore, son.
So uh, what to do?  I strongly suggest not eating bluefin, yellowfin or bigeye tuna, for one. The Environmental Defense Fund provides both a recommended seafood list and a Sushi Selector for those of you having trouble with this blast to the sushiverse that others are dealing with by burying their heads in the sand as quickly as they can. The Monterey Bay Aquarium also has seafood watch resources.

Ocean and environmental conservation organizations will often provide action alerts to you to contact legislators and politicians regarding tuna regulations; Oceana comes to mind, but there are many others out there.  I know that Greenpeace has been doing some work regarding tuna seining (referenced the NY Times article) and putting pressure on retailers who market unsustainable species of fish; if you agree with their tactics, it may be another venue for you.

EDIT 07/01/10: A commenter at BoingBoing drew my attention to the inaccurate comment I made implying that all sharks must continually swim to respirate. This error has been corrected. I appreciate having my attention drawn to this so that I don't make an off-handed factual error and provide inaccurate information, which is the opposite of my intent.


  1. I love tuna! Both in canned and steak format, but they are charming little ones while alive. The finlets are wonderful.

    This post reminds me that I should watch my seafood's sources and species a little more closely. I don't want to eat my favorite dudes into extinction.

  2. I guys,

    Check the Tuna page at
    a comprehensive catalogue of marine species to sea lovers.