Herring are among the most important fish group on the planet. They are the dominant converter of the enormous production of zooplankton, utilizing the biomass of copepods, mysids and krill in the pelagic zone. Small herring feed on phytoplankton, and large herrings feed on small fish and fish larvae. On the other side of the food chain, they are a central prey item for higher trophic levels, including seabirds, dolphins, porpoises, seals, sea lions, whales, sharks, swordfish, dog fish, tuna, cod, salmon, halibut, and numerous other large fish.
For humans, they also are very important, being harvested for their meat and eggs. They have been a known staple food source since 3000 B.C.E. They are very high in healthy long-chain Omega-3 fatty acids and a source of vitamin D.
These values reflect the concept of bi-level functionality, whereby organisms not only advance a function for the individual, but also a function for the whole (ecosystem, human beings).