Sunday, November 30, 2008

Farming the oceans

An NY Times article a couple weeks back included this snapshot of global fisheries decline, based on data compiled by the experts here at the UBC Sea Around Us Project. The image tells the story of the article, a story not repeated often enough. Without a drastic change in management, we are nearing the end of the wild harvest in fish.

The world is in the middle of phase transition from wild harvest to farming, similar to what happened with land animals. The depletion of the natural resource itself is driven in part by the rapid transition to an energy-intensive farming industry. Consider the proportion of wild fisheries required to support fish and animal feed:

Nearly one-third of the world’s wild-caught fish are reduced to fish meal and fed to farmed fish and cattle and pigs. Aquaculture alone consumes an estimated 53 percent of the world’s fish meal and 87 percent of its fish oil. (To make matters worse, as much as a quarter of the total wild catch is thrown back — dead — as “bycatch.”)

A substantial proportion of the wild harvest is used to maintain marine aquaculture of carnivorous species like salmon. It is wildly inefficient, the marine equivalent of farming wolves rather than herbivorous cattle. This is why many experts conclude that the future for pescetarians is probably the blander, lower-on-the-food-chain species like tilapia and catfish. Continued consumption of popular favourites like tuna and salmon could only happen with drastic improvements in fisheries management.

Marine aquaculture shares many of the shortcomings of industrial animal agriculture. A high input of energy (fish meal, animal feed) is required per unit of food production. Also, a large proportion of the natural resource base (wild-caught fish, agricultural land) must be used to produce the inputs. Finally, research concludes that shifting towards less energy-intensive options (lower on the food chain or "closer to the sun", effectively the same statement) would help sustain the natural resource.

The two forms of farming are now also highly intertwined. As the quote above notes, fish meal from wild-caught fish is including in animal feed. And one suggested solution to high energy demands of aquaculture is to produce fish feed from common feed crops like corn and soybeans.

Sure, fish did not evolve to eat grain. Then again, neither did cattle.

1 comment:

Navin Ramankutty said...

Thanks for this very interesting blog! Just as humans shifted from hunting to farming on land, the same transition is happening today in the ocean! It is an interesting parallel to think about. We often think of farming as an "invention", and imagine it to have happened fairly abruptly, and probably with a lot of forethought. However, such a shift is happening today in the oceans, and most people are probably unaware that a major transition is occurring. Now we can think back to 10,000 years ago, and imagine that a similar shift to farming happened with most people not thinking twice about it.