It seems pretty clear at this point that as the world population keeps on growing eating the food we do becomes less and less sustainable.
Meat in general, and beef in particular, have a massive sustainability footprint compared to other foods, and people are starting to take notice of it, some of the world's biggest food websites have stopped publishing new beef based recipes and high end restaurants are turning more to plant based foods.
The answer for some people is to reduce the amount of meat in their diets while they increase the amount of fish and other seafood that they eat. Which raises the question of just how sustainable eating fish is. The answer is not so simple but one thing is clear, farmed salmon is the beef of the sea when it comes to sustainability.
A study published last week by David F. Willer at the University of Cambridge casts a spotlight on how we could reduce the footprint of eating fish by choosing to eat smaller fish instead of using them to feed farmed salmon.
Over the last decade the increase in demand for seafood had driven a huge expansion in the amount of aquaculture going on worldwide, and of course when you farm anything you need to feed it.
Ninety percent of commercial fish food that is used worldwide is made up of wild caught food-grade smaller fish, species like sardines and anchovies, which could also be used to feed humans.
o analyze the efficiency of aquaculture in terms of net nutrient production, researchers first quantified the volume of micronutrients and wild fish retained by fish-fed farmed salmon using 2014 data on Scotland's farmed salmon production. They calculated the volume of micronutrients used as aquaculture inputs and compared it to salmon aquaculture nutrient outputs. Using these data, the researchers modeled several seafood production scenarios to assess potential sustainability benefits of alternative seafood systems.
The researchers found that in 2014, 460,000 tonnes of wild-caught fish were used to produce 179,000 tonnes of Scottish salmon. 76 percent of the wild-caught fish were edible for human consumption. The data also suggest that multiple alternative seafood production models would be more efficient in terms of net nutrient production, so could significantly reduce wild fish capture while increasing global seafood supply. However, these data were limited to only one year (2014). Future studies are needed to better understand how to operationalize a global shift away from farmed fish toward sustainable fisheries.
According to the researchers, "Feed production now accounts for 90% of the environmental footprint of salmonid production. Allowing salmonid production to expand further via its current approach will place exceptional stress on global fish stocks already at their limit. Our results suggest that limiting the volume of wild-caught fish used to produce farmed salmon feed may relieve pressure on wild fish stocks while increasing supply of nutritious wild fish for human consumption."
The authors add: "Nutritious fish stocks are being squandered by salmon farming. Scientists reveal that eating the wild-caught fish destined for salmon farms would allow nearly 4 million tons of fish to be left in the sea while providing an extra 6 million tons of seafood."
Maybe we need to rethink the fish that we eat, but that's not such an easy task. While salmon is seen as something somehow glamourous and a delicacy, to many people the humble anchovy is just something that you pick off of a pizza before you eat it.