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Thursday, August 11, 2011

Threats to the ocean come from surprising places

If I were forced to name the Four Horsemen that are most likely to ride at the front of an Ocean Apocalypse - the four that have the most potential to cause disruption or destruction across a range of species and ecosystems - I would probably identify them as: Ocean Acidification, Overfishing, Climate Change, and Dead Zones. 

This is an actual photo of one of the Four Horsemen. Who knew?

One of the obvious yet striking things about that short list is that three of the four are primarily caused by our activities on land. It's for this reason that we must expand what we think about when we seek to live an ocean-friendly life.

For proof, look no further than your dinner plate. As we first discussed on this blog many months ago, a convincing case may be made that eating some kinds of meat and dairy products may, in many ways, be worse for the oceans than eating seafood. This is because the chemical inputs and emissions associated with terrestrial livestock production are substantial drivers of climate change and ocean dead zones, and likely are not-insignificant contributors to ocean acidification as well.

Looking back on that post, I realize that it didn't go far enough. It didn't mention the role that livestock production has in sucking vast amounts of small, schooling fish from the ocean. These are things like herring, anchoveta, menhaden - the ecologically critical 'forage fish' that serve as the food source for so many other ocean species. Their vast, dense schools are a vital source of food for a variety of marine life, but there are other animals that are eating them - animals that will never see the ocean.

Take pigs, for example. While we may like to think of our morning bacon as having come from some sunny farm where a barnyard of jolly, rotund little porkers dined on the dinner scraps from old Uncle Bill's slop bucket (or, if he slipped and bonked his head, old Uncle Bill himself), in reality it most likely came from a factory farm where the swine were fattened up on industrial feed - feed that uses a lot of fish meal and fish oil, wrung from countless forage fish. According to a 2008 study led by Jacqueline Alder of the University of British Columbia (download it here), pig feed used 24% of the world's fish meal and fish oil in 2002. And it's not just swine: chicken feed consumed another 22%, meaning that feed for swine and chickens accounted for nearly half of the world's use of fish meal and fish oil that year. (If you're wondering, the report states that aquaculture accounted for the same amount - 46%).

I'm sure there's more than one good person out there who eschews seafood out of concern for the future of our oceans, but if they're replacing it with pork or chicken, it's likely that they're replacing it with something that had its snout or beak buried deep in a marine ecosystem.

Of course, other products derived from livestock don't fare much better when it comes to ocean impacts. As we mentioned in that previous blog post, it's well known that beef production is a very greenhouse gas-intensive process, and according to a recent study by the Environmental Working Group, lamb, cheese (!) and pork are pretty emissions-heavy as well. Greenhouse gas emissions, of course, drive climate change and ocean acidification, which are two of the Four Horsemen. Furthermore, the chemicals used to grow the crops for livestock are major sources of the pollution that leads to ocean dead zones - which is the last of the Horsemen.

So, there you have it. As they gallop across the globe, Climate Change, Ocean Acidification, Overfishing, and Dead Zones threaten ocean ecosystems with the changes that they wreak. To 'save' our oceans, we need to confront these Horsemen head-on. One of the primary battles takes place on your kitchen table, every day, and if you choose to gird your loins for it, bear in mind: in this struggle, it is often difficult to tell ocean friend from ocean foe.
OK, if you've read this far, you're probably my mother (Hi Mom), or you're truly concerned about this issue and are wanting to know what is actually OK to eat when judged from these bazillion different angles. At the risk of sounding too simplistic, I would say: start eating small fish now and then. Ideally you'd be able to find mackerel on the east coast of Canada, or B.C.-caught sardines on the west - both of which are on SeaChoice's green list. If you're lucky enough to be able to find these, just start working them into your diet. Even if you can't find these specific types, eating small fish is generally a good way to go from a sustainability perspective: Monterey Bay Aquarium's Seafood Watch program rates herring, sardine, and mackerel fisheries as either green 'best choice' or yellow 'good alternatives', with only one exception (sardines from the Mediterranean, which are 'avoid'). Furthermore, fisheries for small, schooling fish can be very efficient in terms of the food that they produce relative to the fuel that they burn and emissions that they create (and don't worry too much about 'food miles' if you are concerned about emissions. Cheap things like little fish are likely to be transported in relatively efficient bulk methods). So, when you just have to eat something derived from an animal, a good rule of thumb is that small fish are just about as good as you can get from both a fisheries and an emissions standpoint.


  1. I failed to mention the most important reason for why 'food miles' aren't likely to be very important when it comes to the overall emissions footprint of small fish. Basically: in fisheries, the vast majority of greenhouse gas emissions occur during the fishery. What happens after the fishing boat touches the dock usually doesn't have nearly as much impact in terms of greenhouse gas emissions.

    This has been shown in several life cycle assessment studies: the transportation, storage, and packaging of the catch generally doesn't add much to the seafood's footprint - UNLESS, of course, it goes for a ride in a plane. Air transportation adds a lot to the footprint. Road, rail, or container ship transportation don't have the same impact as air.

    Since small fish don't command the kind of market that would justify air transportation, I would guess that a good rule of thumb is that small fish likely weren't transported by air, and therefore that its food miles probably haven't added a lot to its overall carbon footprint.

    This is what I should have written the first time.

  2. Well I DID read that far, and I AM your mother. But I can still be totally objective, and that blog is the best blog ever written by anyone in the world.