“Herring is one species, but it consists of several populations with distinct behaviors and adaptations. If we don’t identify which populations are being caught, we could unintentionally overfish specific groups,” said researcher Florian Berg.
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A new study by the Norwegian Institute of Marine Research reveals that current herring management practices fail to align with the actual migration patterns of various herring populations, potentially leading to serious consequences for the species.
Lead researcher Florian Berg said that herring caught north of 62 degrees latitude - traditionally managed as Norwegian spring-spawning herring (NVG herring) - are, in reality, a mix of different herring populations.
“Herring is one species, but it consists of several populations with distinct behaviours and adaptations,” Berg explained in a Norwegian-language news release. “If we don’t identify which populations are being caught, we could unintentionally overfish specific groups,” he warned.
These populations differ in spawning seasons (spring, autumn, or winter) and environmental preferences such as salinity and temperature.
The researchers tracked genetic markers to identify 12 genetically distinct herring populations.
Surprisingly, these populations appear in areas outside traditional fishery management zones, leading to mismatches in fishing practices. For instance, some fisheries may unknowingly target populations outside their intended stock, raising the risk of overfishing.
One specific population at risk is the western Baltic spring-spawning herring, whose numbers are so depleted that zero fishing is recommended. However, during their grazing migration, these herring enter the North Sea, where they are still being caught.
The study suggests replacing fixed management zones with dynamic, flexible fishing areas that adapt to herring movements. Real-time stock monitoring - similar to practices used for skrei and coastal cod - could also better protect the diverse herring populations, the researchers propose.
“These measures would help ensure sustainable fishing while maintaining the balance among different herring populations,” Berg stated.
The findings are detailed in the study: Seljestad, GW, Quintela, M., Bekkevold, D., Pampoulie, C., Farrell, ED, Kvamme, C., Slotte, A., Dahle, G., Sørvik, AG, Pettersson, ME, Andersson, L. , Folkvord, A., Glover, KA, & Berg, F. Genetic Stock Identification Reveals Mismatches Between Management Areas and Population Genetic Structure in a Migratory Pelagic Fish. (2024)
