Q: Should I eat farmed or wild salmon? I know that farmed salmon may not be as healthy, and fish farms tend to be environmentally damaging. However, many wild runs of salmon are on the brink and I do not want to contribute to their demise.
Asked by Amy Fowler, MS '83, San Jose, Calif.
You are what you eat. It turns out fish are what they eat, too, so let's take a closer look at the diets of farmed and wild salmon, to see what your choice in fish means for your health. Then we'll look at what your choice in salmon means beyond your health and what message it sends to the fish markets.
Salmon are carnivorous fish. In the wild, they dine on 10 to 20 pounds of zooplankton, krill and small fish to gain one pound of weight. Farmed salmon are often given a similar diet in ground-up, pellet form. However, since these fish don't expend nearly as much energy swimming as their wild counterparts do, only three pounds of ground-up fish is needed to produce one pound of farmed salmon. The feed includes anchovies, herring and sardines and those are often fished in unsustainable ways. But this only accounts for 70 percent of the salmon feed contents. Most of the rest is vegetable meal and oil, along with antibiotics and other additives. Farmed salmon often have higher levels of certain contaminants, such as PCBs, dioxins and pesticides, and fish that have been fed a primarily vegetarian diet often have nutrition issues that can make them sick.
Around 20 percent of the food given to farmed salmon goes uneaten and joins fish feces in polluting the surrounding environment. Some of this is nutrient pollution, including nitrogen, phosphorus and organic carbon, which can lead to potentially dangerous algal blooms. The additives in the fish feed, such as pesticides and antibiotics, are also cause for concern. These chemicals are used to maintain the health of the fish in their cramped quarters, but when the chemicals are released into the environment, they can promote antibiotic resistance in bacteria.
There are some fish farms that work to be more sustainable, including AquaSeed. This company focuses on raising salmon in freshwater tanks on land, to avoid water pollution and potential escape. While their land-based technique prevents many of the negative impacts of salmon farming, it is far from becoming the norm for salmon farms. Most farms still use a process that is damaging to the environment, and potentially to the consumer's health. Unfortunately, as mentioned in the Essential Answer, the quantity of wild salmon available is not sufficient to provide for the demand for salmon.
Perhaps you're wondering what happened to the wild salmon populations in the first place. Urbanization brought about changes in the streams where salmon spawned. Forests once provided shaded areas with forest debris in the water, creating perfect spots for laying eggs. As trees were cleared from the area, direct sunlight made streams warmer, and lack of wood debris left the salmon without a place to lay eggs. The construction of water management projects, like dams and canals, blocked the migration of the fish, both upstream and downstream. While these changes in habitat contributed to the decrease of reproduction of the salmon, overfishing in the ocean put even more pressure on the existing populations, leading to their decline.
In Alaska, where the salmon runs are still healthy, the government has restricted salmon fishing in several different ways. First, the government limited the areas in the ocean where fishing is allowed. For example, fishing too close to any river or stream is restricted since salmon are more vulnerable at these crowded locations. The government opens and closes these areas on a daily basis, depending on the number of salmon that have made it up the stream. The fishing licenses available are limited in number, and in order to obtain one, you have to buy it off of someone who already has one. Even the fishing equipment is regulated, from the material used and the size of the net, to the length of time it can be used. There are dozens of organizations that aim to protect and preserve the habitat around salmon streams, ensuring the preservation of the habitat for future generations of salmon. The Alaskan government has even prohibited salmon farming to protect their native Pacific populations from the release of invasive Atlantic farmed fish.
The type of fish you buy sends a message to fish markets. Wild Alaskan salmon sends the message that you care about the environment and you support the well-maintained fisheries of Alaska. Other wild fisheries are not as healthy as the Alaskan fisheries, but money spent towards these wild fisheries shows that they are in demand, and more efforts to restore and maintain the fisheries will be put in place. Purchasing farmed salmon, but ensuring it is from a company like AquaSeed, shows that you care about the environment, but perhaps do not consider wild salmon the best option due to price or quantity available. Traditionally farmed salmon, however, sends a message of low standards for human and environmental health as long as the fish is cheap.
If you just can't get enough salmon, consider moving to Alaska, where residents have subsistence fishing rights, allowing residents to catch a significant number of salmon—enough to eat throughout the year. I hear the winters are pretty brutal, but having spent a summer there, I can say the fresh-caught salmon is delicious—even more so when you catch it yourself!
SAM FOX plans to receive her master's in civil and environmental engineering in 2011.
