The renowned Izumoya eel restaurant in Tokyo's Nihonbashi district, which opened for business in 1946, stopped serving eels caught in the wild about five years ago because the costs became prohibitive and their quality unreliable.

Meanwhile, around 50 eel restaurants across Japan have closed so far this year as high eel prices curb customer demand and many others are in the red amid declining sales, according to an association of grilled eel dealers.

The Metropolitan Central Wholesale Market says wholesale eel prices averaged ¥4,718 per kilogram in June, just ahead of the peak midsummer season for eel consumption — roughly 40 percent higher than the previous year.