Second of two parts.

In the early-morning hours, workers at a Goldwell Trading Corp. warehouse in Boston load boxes of frozen escolar into vans for delivery to area sushi restaurants.

By the time the fish appears on diners’ plates, it has undergone a Cinderella-like transformation: the escolar, which can cause digestion problems, is presented as white tuna or albacore - more palatable and pricier fish.

Suppliers such as Goldwell use the names interchangeably, contributing to a little-known but pervasive problem in the international seafood industry: lower-quality and less expensive fish mislabeled as desirable species. Some distributors do this unknowingly, while others intend to deceive. Lax government oversight, industry indifference, and consumer ignorance allow mislabeling to flourish.

Fish misidentification is especially common at sushi restaurants, partly because they use various names for the same fish. The confusion can be compounded by packaging labels written in other languages that are incorrectly translated into English.

A Globe investigation detailed yesterday found that mislabeling of certain fish is endemic in the Boston area. DNA testing showed that 32 area restaurants that serve sushi - including Takara Sushi in Newton, Basho Japanese Brasserie in Boston, and Kowloon in Saugus - sold misnamed fish. For instance, tilapia stood in for red snapper, and farmed hybrid bass was identified as wild striped bass.

Overall, the testing revealed that nearly half of 183 fish samples collected at restaurants and supermarkets were not the species ordered.

Massachusetts has long played a major role in the nation’s seafood industry, with both fresh catches and frozen fish being sent here to get processed. Last year, about $673 million worth of seafood was processed in Massachusetts, according to the National Oceanic and Atmospheric Administration Fisheries Service, enough to rank the state fourth in the nation. (Alaska tops the list.)

The Globe investigation found that the majority of the restaurants selling mislabeled fish get their products from a handful of distributors, including True World Foods and Goldwell Trading, which operate Boston warehouses. Some suppliers implicitly or overtly encourage seafood misrepresentation, according to restaurateurs and their employees.

Restaurant invoices and product catalogs that were provided to the Globe show that suppliers often use two names for one species of fish. For example, Goldwell Trading, which delivers sushi to about 150 restaurants in Massachusetts, describes the same fish as white tuna and escolar on its invoices. The catalog of True World, a large supplier that says it delivers to high-profile clients such as the Red Sox clubhouse at Fenway Park, lists it the same way.