In this March 28, 2018, file photo, a North Atlantic right whale feeds on the surface of Cape Cod bay off the coast of Plymouth, Massachusetts. Credit: Michael Dwyer | AP

BOSTON — An aquarium in Boston has upgraded its directory of more than a million images of one of the world’s rarest whales.

The New England Aquarium keeps a database of photographs and physical details called the North Atlantic Right Whale Catalog. There are only about 400 of the whales left in the world. The catalog has images of more than 750 whales and goes back to 1935.

The aquarium said the upgrade improves an interface that was 15 years old. The improved database is also more accessible to the public, aquarium representatives said.

The catalog is made up of contributions from scientists, government officials, fishermen and boaters, the aquarium said.