Japan marked its annual eel-eating day on Saturday, but prices for the endangered fish remain high and supermarkets are giving growing attention to alternatives.

The domestic catch of juvenile eels for cultivation fell this season to 3.7 tons, the lowest level since 2003, when comparable numbers became available, government data showed. From November to May, Japan imported 11.5 tons of young eels, the second-highest amount on record.

On what is traditionally referred to as the Day of the Ox, many people in Japan eat eel, typically grilled with a teriyaki-like soy-based sauce, to honor an old saying that promotes consumption of the prized delicacy to help the body withstand the summer heat.