A recent study conducted by researchers at Uppsala University has identified a unique genetically distinct type of Baltic herring that has adapted to a fish-based diet, setting it apart from its Atlantic counterpart, which primarily feeds on plankton. This adaptation is likely due to the Baltic Sea’s specific environmental conditions and the absence of larger predatory fish, allowing these herring to exploit a previously underutilized food source. Published in Nature Communications, the study highlights the ecological importance of Atlantic and Baltic herring, which serve as a crucial link in the food web between plankton and higher-level predators.
The researchers discovered a population of larger, fast-growing fish-eating herring, nicknamed "Slåttersill" in Sweden. They utilized genetic analysis and examined various traits, such as morphology and fat content, observing that these herring had evolved over hundreds to thousands of years. Notably, the fish exhibited damaged gill rakers indicative of their dietary shift. Moreover, the herring had higher fat levels and lower dioxin contamination, making them potentially more suitable for human consumption. The study also identified at least two distinct subpopulations of these fish-eating herring within the Baltic Sea, further emphasizing their evolutionary significance in this relatively young marine environment.
