It isn’t clear what has led to the increase, but River Herring numbers up in NH, although still far short of past years

“They were a huge part of the ecosystem here, especially in near-shore environments where everything eats them – fish, seals, gulls, ospreys,” said Matt Carpenter, fisheries biologist for New Hampshire Fish and Game. “Historically, they were one of the species that ran up all the rivers all along the coast, but were wiped out by dams, some overfishing issues, ocean predation and other ocean issues, predation (in fresh water) by striped bass.” continued