Overfishing has caused problems for cod for some decades now, possibly longer. The pressure of constant harvesting by humans makes it difficult to be certain of the causes of range shift in fished species. Some species that lived in northern waters before European settlement are now considered "warm-water" species, but it was fishing that drove them south, not temperature. Cod have hung around, but recent work tracking fish populations in the northwest Atlantic, including the New England coast, has show that cod are not only moving north, but are also seeking deeper water, where temperatures tend to be lower.
As a species, cod have been of great importance to the development of New England. The most obvious illustration of this is the name of the region's most visible coastal feature - Cape Cod. They are still an important food stock, though less common than they were, and cod liver oil is still a common supplement found in most pharmacies and grocery stores. Cod fishing is no longer a staple industry in New England, but it is an integral part of our history.