Yes, I am a Monty Python fan and I like to play the “Find the Fish” video on YouTube when I need some midday amusement. However, this video brings up the topic of eating less red meat and enjoying more fish on my dish. My husband and I are trying to curb our beef-eating activities by diversifying the protein sources in our diet. We have recently adopted some dining rituals that include Friday Fish Fry (leaning more toward broiling, even though it’s hard to resist a traditional Wisconsin fish fry) and Meatless Mondays for vegetarian fare. One reason for doing this is to hopefully find more sustainable approaches to supporting a healthy diet.
So I was intrigued to learn more about fish farming (aquaculture) at sea when I read Sarah Simpson’s article in the February 2011 issue of Scientific American titled “The Blue Food Revolution”. Sustainability has become more important in many of the buying choices I have made lately, especially after learning that our global population will reach 7 billion in 2011 and is expected to grow to 9.3 billion by 2050. Yikes! How do we provide high-quality protein and nutrition to so many people?
Well, we could encourage folks to eat more vegetarian meals. Over 50% of the protein for world consumption comes from vegetable sources right now. However, promoting a vegetarian diet has been an ongoing campaign since I can recall when Linda McCartney came out with her own line of vegetarian frozen entrees in the early ‘90s. Not everyone is ready for tofu burgers and seitan hot dogs (yes, it sounds like “satan”). The truth is that as developing countries around the world build wealth, the demand for meat inevitably rises. The World Health Organization predicts a 25% increase in per capita meat consumption by 2050. According to the article, if the demand for meat stayed constant, land for crops to feed animals as well as for grazing would need to increase 50–70% to feed the population in 2050. The result would be mean more fertilizers introduced into the environment, more greenhouse gases from farm equipment emissions, and more fuel consumption for planting and harvesting.
So why not simply catch more wild fish? Fish accounts for only 7% of the world’s current protein supply and demand is on the rise. Many governments promote the health benefits of including fish in the diet as a source of omega-3 fatty acids for preventing cardiovascular disease and other chronic conditions. As you may have already guessed or seen on the evening news, we have overfished certain species to near extinction. The best example of overfishing has been seen in the collapse of Atlantic Cod populations off the coast of Newfoundland, Canada, where a mere 20 years of overfishing depleted the stocks to where the government placed an indefinite moratorium on cod fishing in 1992. The article points out that wild tuna caught for sushi requires 9–10 years to reach a harvestable size, whereas an aquaculture-raised tuna of the same size is harvested at about three years of age. Harvesting aquaculture-raised fish sooner is possible because of the “couch-potato” lifestyle they lead. No need to expend energy on warding off predators, hunting for food or finding a mate to reproduce.
Modern aquaculture raises marine fish in a variety of methods; on-shore tanks, coastal pens or further off shore in cages, usually less than 3 miles off shore. When fish farming started over 30 years ago, operations were not sustainable, spreading disease and parasites throughout the fish population, and draining stocks of small fish (e.g. sardines) to feed more profitable, larger fish. As aquaculture evolved, improvements have been made in these key areas, giving hope to a more sustainable source of high-quality protein.
To address sustainability, aquaculture feeding practices had to improve. If you think dog food smells bad, imagine kibble made from anchovies and sardines. To prevent overfishing of these small feeder fish, kibble fed to an aquaculture has reduced the anchovy/sardine content from 70% down to 30%. The remainder of the formulation is soybean meal mixed with chicken oil. Unfortunately, going below this 30% feeder fish content would change the taste of the larger fish. Nothing is worse than expecting to taste fish and you get chicken or vise versa in the case of Nordic egg farmers who fed their chickens fish meal.
The “golden ratio” of the modern fish farmer is to have one pound of small fish give one pound of large fish. This ratio seems to work well for fresh water fish like catfish, but not for marine fish like tuna where the industry standard is three pounds. This is still better than wild-caught tuna that can consume up to 100 pounds of food in its lifetime before harvesting. Attempts at increasing the coveted omega-3 fatty acids found in fish have lead to advances in algae-based nutritional formulations. These sea-based plant crops could potentially replace the land-based constituents (soy meal and chicken oil) to improve sustainability of the feed and improve production efficiencies (faster growth). The article did not mention any details of whether there are other additives in the feed such as antibiotics or hormones to help increase fish growth. It would be interesting to investigate what effect releasing these substances into the oceans would have on marine life.
The article goes on to describe how scientists are starting to compare the environmental impact of land-based farming to sea-based farming. As you can imagine, the sea overcomes many of the drawbacks of raising a heard of cattle on land. First the run-off from fertilizers for crop production to feed animals produces dead zones that are a mere fraction of the size of those created underneath coastal fish farms. Newer approaches to aquaculture take advantage of positioning cages at sea in the path of light ocean currents to help sweep away debris and excrement (fish sewage), avoiding dead zone build-up underneath. It has been estimated that raising Angus beef requires 4,400 times more pasture land than sea floor to raise the equivalent weight in salmon. Another approach to controlling the fish sewage is to design the aquaculture in food chain layers. The debris from large fish above becomes food for bottom feeding fish, mussels or shrimp below.
Shifting protein production from land to the sea could have an enormous impact on another natural resource, fresh water. Although animal meat represents about 3.5% of the food produced in the world, it consumes 45% of the fresh water used in agriculture. The article did not indicate how much water this represents in liters or gallons but when you consider that agricultural activities consume about 30–47% of all the fresh water in the US, it’s substantial. If anyone can calculate this for me, let me know.
Aquaculture already accounts for 47% of all the seafood (fish, mussels, shrimp, etc.) that consumers eat worldwide and this has grown compared to 38% back in 1980. Where does most of this seafood come from? Aquacultures in Asia supply almost 90% of all farmed seafood. The US aquaculture industry only provides 4%, which makes you wonder why isn’t this number higher. Government subsidies and powerful industry lobbies to the fish trawling, beef, pork and poultry industries keep these methods of food production profitable despite their impact on the environment. No doubt any food production activity will have some impact on the environment, aquaculture included, and the government’s job is to provide regulations and guidelines to help minimize any negative effects.
The challenge will be to find that ideal balance between reducing the environmental burden imposed by these industries while maintaining a viabile commercial enterprise (ideally without government subsidies). Currently, a license is required in order to establish an aquaculture off-shore within US coastal waters. This comes under the jurisdiction of the US National Oceanic and Atmospheric Administration (NOAA), who is developing federal aquaculture policy. Once this is established, there should be guidelines available to address commercial activities that not only safeguard the quality of the food but the environment as well. And with a federal policy in place, incentives can then be structured to encourage good environmental and safety practices. As NOAA director, Jane Lubchenco, commented “We don’t want the blue revolution to repeat the mistakes of the green revolution. It’s too important to get it wrong, and there are so many ways to get it wrong”. So like any good article, Ms. Simpson, you left me with more questions I want to explore. I hope you continue to report on how this blue revolution can succeed because I really like eating salmon…and shrimp…and mussels, oh, my!
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