The recent drop in the ayu sweetfish catch in the renowned Lake Biwako has raised significant concerns among fishermen and officials in the Shiga prefecture. Known as a representative fish species in the area, the ayu sweetfish plays a vital role in the local fishery industry, accounting for about half of the entire fish catch from Japan's largest lake. This decline in the January haul, being the smallest on record, has been attributed to poor spawning conditions resulting from the scorching heat experienced during the previous summer.
Fishermen, many of whom have dedicated decades to their trade, expressed their dismay over the unprecedented situation, highlighting the challenges faced during this fishing season. The traditional method of catching ayu fry, known as "hiuo," involves the use of netting structures called "eri," with the Shigacho fisheries cooperative association operating multiple of these nets in Lake Biwako. Despite efforts to maintain these traditional fishing methods, the average catch per net in January was alarmingly low compared to historical data, indicating a significant decline in the ayu population.
The adverse impact of the extreme heat leading to high water temperatures in the rivers flowing into Lake Biwako has disrupted the natural spawning patterns of the ayu sweetfish, ultimately affecting their population size in the lake. Additionally, low rainfall and decreased river water volume have compounded the difficulties faced by fishermen, as evidenced by the disruption in water currents around the nets, hindering the fish from reaching the traditional catching grounds. The unusual findings of significantly fewer ayu shoals compared to previous years have prompted further investigations by the prefectural government to unravel the underlying causes of the diminished catch.
As the drought persists and the water level in Lake Biwako remains low, concerns grow over the sustainability of the ayu sweetfish population and the economic stability of the fishermen reliant on this precious resource. With the inability to meet orders from breeders and fulfill demands from retailers and restaurants, the local fishery industry faces a challenging period, leading to suspensions in operations and financial strains on the fishermen. Governor Taizo Mikazuki's acknowledgment of these challenges at a recent news conference underscores the urgency of the situation as authorities and fishermen work together to understand and address the significant decrease in the ayu sweetfish catch in Lake Biwako.