Source: Wild, some farmed
Mercury Risk: Low
There are two types of eel that one might encounter at a U.S. sushi bar. The first, unagi, is the more common option and is discussed in the entry on freshwater eel. The other, anago, is less common, but recognition among American sushi patrons is growing.
What is Anago (Conger Eel)?
Anago is a general term for any marine eel that does not migrate from freshwater to the sea or vice versa. Usually anago is used to mean Conger miyaster, the white-spotted conger, which is found in the seas around Japan. The specific term for this animal is maanago, or “true sea eel.” In practice, however, anago refers to any type of marine eel, and the term is often translated as “conger eel” on sushi menus regardless of the actual species in question.
It should be mentioned that this same term may also be used erroneously in some sushi establishments to refer to Muraenesox cinereus, the daggertooth pike conger, which is of a different family. The proper Japanese term for M. cinereus is hamo.
Little is known about anago stocks and the environmental impact of anago fisheries. In the United States, sea eels are usually taken incidentally by fleets targeting other types of fish. Japan has a number of sea eel fisheries, some of which employ basket traps and target Conger miyaster in particular, but almost nothing is known about the strength of of these populations.
One of the largest problems with anago’s cousin, the freshwater eel, is the dubious management policies used by many Asian eel farms. Without adequate protection measures, these farms can disseminate disease and pollution as well as interfere with local eel populations.
There are also some anago farms in Japan, but this is a relatively new industry. Not enough is known about anago farming to determine whether or not farmed conger eel faces similar obstacles to those challenging the unagi industry.
At this point, anago is probably a better choice than unagi, but far too little is known about anago to make a solid recommendation one way or the other. Consequently, precaution is the watchword to avoid damaging stocks before we understand them better. Limit your eel consumption as much as possible, but if it’s a special occasion and you must have one or the other, have anago.