The ayu sweetfish, known locally as "hiuo" or ice fish for its translucency, is a key species in Shiga Prefecture's fishing industry, with approximately half of the fish catch from Lake Biwako being ayu. However, the recent haul in January was a mere fraction of the average and the smallest recorded since data collection began in 2009.
The poor spawning of the ayu sweetfish has been attributed to the unusually high temperatures experienced over the summer, leading to adverse effects on the fish population. Fishermen, some with over 40 years of experience, have expressed concern over this unprecedented situation, highlighting the impact on their livelihoods and the local economy. The decline in ayu catch has also affected the supply chain, with fisheries cooperative associations struggling to fulfill orders from breeders and falling behind in shipments to retailers and restaurants.