FRIENDSHIP, Maine — Imagine Cape Cod without cod. Maine without lobster. The region’s famous rocky beaches invisible, obscured by constant high waters.

It’s already starting to happen. The culprit is the warming seas — and in particular the Gulf of Maine, whose waters are heating up faster than 99 percent of the world’s oceans, scientists say.

Long-established species of commercial fish, like cod, herring and northern shrimp, are departing for colder waters. Black sea bass, blue crabs and new species of squid — all highly unusual for the Gulf — are turning up in fishermen’s nets.

The Gulf of Maine’s warming reflects broader trends around the North Atlantic. But the statistic — accepted by scientists at the National Oceanic and Atmospheric Administration — underscores particular fears about the Gulf’s unique ecosystem and the lucrative fishing industries it supports.

“These changes are very real, and we’re seeing them happen quickly,” said Malin Pinsky, a biology professor at New Jersey’s Rutgers University.