Massachusetts Institute of Technology professor Yet-Ming Chiang likes to fish. And it was through fishing, back in the early 1990s, that he started to notice that the New England waters were warming. “We used to catch lobster in Cape Cod,” said Chiang, in a call from his office with a Japanese-style fish print of a striped bass he’d caught behind him. “Now we catch mahi-mahi. It’s really nuts.”