Genomic analysis reveals population dynamics of Japanese eels

Grilled eels are a seasonal treat in summer, especially on the Day of the Ox during the Doyo period, when they are eaten to build stamina in the humid climate. In recent years, however, the cost of domestic eel dishes has risen significantly due to a decline in the number of wild and farmed eels. In fact, while about 3,000 tons of eel were caught in Japan in the 1970s, only 11.1 tons were caught in 2021. This indicates that the Japanese eel population has declined significantly. In fact, the Japanese eel is listed as an endangered species by the International Union for Conservation of Nature (IUCN). Researchers at the Institute of Freshwater Biology are using genomic analysis to study current and past populations of Japanese eel. By studying past changes in the Japanese eel population, we can gain a better understanding of its current population dynamics. According to the study, published in bioRxiv, Japanese eels experienced population declines during the Pliocene Epoch (1-4 million years ago) and the Last Glacial Maximum (20,000-30,000 years ago). These events were likely caused by changes in sea level and ocean currents that restricted the Japanese eel’s natural reproductive processes (juvenile drift and adult migration). These population declines and bottlenecks may make Japanese eel more vulnerable to current and future population declines. Research on the current Japanese eel population is ongoing.