## Ayu Fry Catch in Lake Biwako Hits Record Low
The January haul of ayu sweetfish from Lake Biwako was a mere 3% of the average, marking the lowest catch since record-keeping began in 2009. This alarming decline is attributed to poor spawning conditions caused by last summer's scorching heat.
"This is something I have never experienced during my career of more than 40 years," said a fisherman with the Shigacho fisheries cooperative association.
Ayu, a representative fish species of Shiga Prefecture, accounts for about half of the total fish catch from Lake Biwako, Japan's largest lake. The fishing season for ayu fry, called "hiuo" (ice fish), opens in December.
Traditionally, hiuo are caught using a maze of netting called "eri" fixed in the water during winter and early spring. The Shigacho fisheries cooperative association operates the most eri in the prefecture, with a total of 12.
A study of 14 eri, or about half of all nets operated by fisheries cooperative associations, revealed an average catch of 4.3 kilograms per eri in January. This is a staggering 97.1% decrease compared to the average catch of 149 kg per net over the past ten years (2014-2023).
The latest figure is even lower than the record-poor catch of 6.5 kg in January 2017, which was caused by poor ayu growth due to excessive spawning.
Officials believe the extreme heat that lasted through September 2023 is the culprit behind the low catch. The high temperatures resulted in a 2-degree increase in the water temperature of rivers flowing into Biwako during the ayu spawning season of September and October.
The searing temperatures and low rainfalls also decreased the river water volume, leading to a significant reduction in the number of ayu eggs found between August and October 2023.
Despite the low catch, an odd observation was made in January by a fishery experiment station. They found about 20% as many ayu shoals as there are in an average year. The prefectural government is currently investigating this discrepancy.
The low water level in Biwako since autumn has prompted the prefectural government to establish a drought management headquarters for the first time in 18 years. While no confirmed causal relation exists between the drought and the poor catches, fishermen report that the low water level has altered water currents around the eri nets, affecting ayu migration patterns.
The poor catches have caused difficulties for fisheries cooperative associations, who are unable to fulfill orders placed by ayu breeders. Shipments to retailers and restaurants have also been delayed.
"It pains me when we cannot meet demand," said the Shigacho fisheries cooperative fisherman. "Some fishermen have suspended their operations because they don't pay. We would be very badly off if things were to remain like this.