NIFS announced that it clarified the precise timing of Pacific herring (Clupea pallasii), which is a representative cold-water fish, entry into Jinhae Bay and the migration patterns for spawning in winter. Pacific herring is a representative cold-water fish species. 

NIFS said that the entry into the spawning ground began in late-December, peaked in mid-to-late January, and declined toward late-February. It also said C. pallasii first appeared when bottom temperatures fell below 10 ℃, and the highest catch occurred when bottom temperatures averaged 6.72℃.

These findings suggest that water temperature serves as a strong environmental cue triggering herring migration into Jinhae Bay. 

All captured C. pallasii were adults, mostly in the ripe or spent stages of reproductive maturiy, indicating the mass migration into these waters for spawning. The C. pallasii school signals were detected more at night than during the daytime, and strong echo signals were observed in the middle-to-bottom layers at night. A spike in eDNA concentrations were also observed between surface-and bottom-layer in mid-January, which coincides with the peak time for spawning (mid-to-late January) confirmed through acoustic monitoring and catch survey. 

Going beyond the exisiting single survey, this study integrated △long-term acoustic monitoring, △gillnet surveys, and △eDNA analysis* by utilizing scientific ecosounder, resulting in improved credibility. On February 2nd, PLOS One, a prominent international scientific journal, published the article in February 2026, recognizing the scientific excellence of the research. 

*Environmental DNA (eDNA) analysis reveals the presence and diversity of species through genetic traces in water samples. 

NIFS president Kwon Soon-wook said, “This study clarified the ecological characteristics of Pacific herring by applying integrated surveys, at the same time being recognized internationally as a best practice in terms of the survey. For the sustainability of our fisheries resources, NIFS will use all its tools and expertise for systematic research by closely monitoring the variability of fisheries resources in Korean waters.”