Changes in the way some small fish are managed could have major implications for the ocean ecosystem and marine industries on the East Coast, according to conservationists, fishing groups and scientists. Interstate regulators are considering altering the way they manage menhaden to better account for its role as one of the most important fish in the sea. The schooling fish makes up a key piece of the Atlantic Ocean’s food web, as important prey for whales, seabirds and large fish.