If you’re looking for small carbon footprint and big nutrition look below the surface
When you sit down to write an eye-catching essay about the best meal in the world your first instinct is to go with one of the sleek creatures that have historically captured the human imagination. Salmon battling 20 knot currents to reach their spawning grounds at the headwaters of the world’s mightiest rivers. Bluefin tuna charging faster than thoroughbred racehorses, crossing the Atlantic and the Pacific and circling the bottom of the world. But when you sit down to write about sustainability and seafood and try to consider which creatures might supply us with the most nutrition for the least amount of environmental damage you have redefine your definition of “best”. You must choose a much more meditative set of organisms that are equally amazing as salmon and tuna yet much less visibly so.
Consider, then, the mussel.
Mussels, like nearly all the creatures grouped under the term “bivalve” tend to stay put. After a brief window as free swimming “veligers” they choose a place to settle, extend a “foot” and attach themselves to a rock, a line, a piece of wood, what have you, for the most of the rest of their lives. Though they can, in a pinch shorten their byssus threads and tumble themselves to a new location, they prefer not to. They do not move to hunt their prey. They do not move to flee from predators. Rather, they grow a shell to armor their tender insides. Their only exposure to the outside world are two “valves” (hence bivalve) through which they filter their waters around them and patiently put on weight.
What all this means is a creature that while very modest in appearance is in fact remarkably potent and efficient in both cleaning the ocean and providing humans with protein, fat and essential nutrients.
It is this passive, complacent act of filtration that is the quiet miracle of mussels. They are, in a sense the Buddhas of their domain. Just as in meditation we’re told to note our inbreaths and our outbreaths and to allow ourselves to merge with the universe, mussels take in worlds of microscopic phytoplankton with every pulse of their gills. From this constant micro-buffet mussels glean energy, minerals and an array of fats including omega-3 fatty acids. They do this all while growing remarkably quickly. In just two years, a mussel can go from the size of an infant’s pinky-nail to the width of an adult human palm. During that time that same mussel will have filtered in excess of 10,000 gallons of water.
What all this means is a creature that while very modest in appearance is in fact remarkably potent and efficient in both cleaning the ocean and providing humans with protein, fat and essential nutrients. One need only compare it to the much more frequently consumed forms of seafood for its positive qualities to shine even brighter.
Consider the most consumed finfish in America, the salmon, most of which come to us in farmed form. Farmed salmon might be silvery bright on the outside, lustrous orange on the inside but to bring all of that appetizing beauty to market involves considerable environmental inputs. In the early days of farming salmon it could take as much a six pounds of wild fish to grow a single pound of farmed salmon. To its credit, the salmon industry has greatly reduced that ratio over the last 30 years, but they have done so by putting a lot more farmed soy and other land agricultural products into salmon feed. All this adds up to a product that costs the planet much a fair bit.
The purists among us might throw up their hands at this point and say, “well forget it. From now on I’ll only eat wild seafood.” This “solution” is also remarkably short-sighted. Take for example the second most consumed seafood in America, the 23 odd species of fish grouped roughly under the market name “tuna” which come to us mostly in their wild form. Tuna are caught in the far corners of the world. Having overharvested our domestic tuna stocks we now rely on tuna spirited away from the portions of the ocean that fall under no nation’s jurisdiction. It’s for this reason that fish catches from poorly regulated “high seas” regions of the oceans have increased by 800% over the course of the last decade. There is simply no more room for the tuna industry to grow any larger. Most tuna stocks are either exploited as far as they can be exploited or overexploited at this point. And what is true of tuna is true of all wild fish. The global catch of wild seafood flat-lined at around 85 million metric tons 20 years ago. It is unlikely to ever grow any larger. Lest readers think we could farm our way out of a tuna shortage think again. The very thing that makes tuna so sexy — their speedy sleekness, their high energy thick steaks — is the very thing that makes them poor choices for farming. Early experiments in farming tuna have shown that it can take as much as twenty pounds of wild fish to grow a single pound of farmed tuna.
If you’re not yet won over to the mussel yet, consider this . Mussels, farmed well, and sited correctly actually can contribute to more fish in the sea. One of the things juvenile fish like most is something ecologists call “edge” — protected declivities that slow the speed of current and give places for young fish to hide. A full scale mussel rig increases the surface area of hiding places and thus can turn a once sterile piece of ocean into usable habitat.
And remember when you farm them, you don’t have to feed a mussel anything at all. It feeds itself. And in the process of living a life in this very efficient manner the mussel costs the planet very little in carbon emissions. A kilo of beef costs the planet 27 kilos of CO2. A kilo of farmed salmon somewhere in the 5–10 kilo range. The mussel? In some cases as low .6
So next time you sit down to contemplate your next meal meditate a bit on the quietest, gentlest choice. All things being equal, those superficial distractions that have led you to date in bad dietary directions should be seen as the distractions they truly are. A much better nature lies on the interior of the mussels hard shell.
More thoughts on food and sustainability in The Climate Diet, out this spring from Penguin Press.