I always ask students to tell me about Unagi day. Many people don’t know much about the origins of this tradition and eat unagi, simply because it is promoted. One of my high school students explained the history of Unagi day as coming from a simple promotion strategy for eel catchers back in the edo period.
Unfortunately it seems that Japanese eels have been over consumed to the point where they are becoming extinct. A news report that i saw today says that the volume of imported eel has dropped by 35% this year due to decline stocks even from outside Japan.
Undoubtedly prices have gone up but the problem is really that people don’t seem to care that species extinction has a real impact on our environment. People buy eels because its “tradition” (ie. doing something for the sake of doing it) or because people are told to do so, and now people will buy it as a luxury item as it becomes rare and expensive.