Shipwreck provides window into Tudor-era cod fishing

An army marches on its stomach, the saying goes, but so too sails a navy. And when Tudor England was starting to ramp up its fleet, on its way to becoming a global naval power, its navy drew its food supply from far and wide, a new study shows. By the mid-16th century, globalization had begun.

Commercial fishing and the growth of sea power reinforced globalization in Renaissance Europe, William Hutchinson of the University of Hull in England and colleagues write September 9 in Royal Society Open Science.

The evidence comes from the Mary Rose, an English warship that sank in the Solent, the straight between mainland England and the Isle of Wight. The ship went down on July 19, 1545, about 18 months before Henry VIII died. It met its demise during an attack by the French, possibly when an untimely gust of wind hit the sails of the unstable ship while her gunports were open. The wreck was discovered in 1971 and salvaged in 1982, yielding thousands of artifacts that have provided insight into not only naval warfare but also navigation, health care and musical instruments of the time.

Among the remains are 4,384 fish bones, nearly all cod and none with heads. During the Tudor era, cod was a dietary staple. And the fish were typically decapitated near where they were caught. Then they were dried or salted, which preserved them for long periods of time and long-distance transport. But was the English navy eating cod caught near where its ships were stationed, or was it drawing from waters farther away?

Organisms contain several kinds of records of where they lived. For the cod, Hutchinson and his team looked at two types of indicators. The first was isotopes (or forms) of carbon and nitrogen in bone protein, which reflect the diet and local environment in which the fish lived. The second was the fish’s genes; local populations of fish have similar genetic markers.

But first Hutchinson and colleagues had to make a map of the carbon, nitrogen and genetic characteristics of cod from sites where the English navy may have been sourcing its fish in the 16th century. Modern cod’s map wouldn’t be accurate since these markers change over time. So the researchers used cod cranial bones (the fish heads that were removed before the fish were dried or salted) from archaeological sites near the places where the fish could have been caught. These sites included locations around the British Isles, Iceland and Scandinavia.

Then the team analyzed the bone protein and genetic markers in 11 cod bones from the Mary Rose. None of the fish came from southern England, near where the ship sank, the researchers found. Instead, they probably came from waters near Iceland, Arctic Norway and possibly as far away as Newfoundland.

“Given that the dried fish were served as the main naval ration for three of every seven days at this time, it is reasonable to infer that military needs contributed to the demand for cod from distant waters,” the researchers write.

Getting enough food at a good price was probably a bigger concern than buying local back then.

At the time of the Mary Rose’s sinking, England was still a tiny naval power with only 58 ships, but that was soon to change. To protect the island nation, Elizabeth I developed a navy capable of rivaling the powerhouse Spain. A great navy then allowed England to explore and conquer large parts of the world. That may have been helped in those early times by fisherman catching cod in distant waters.

And as England has rose and then dimmed as a global superpower, so too has cod seen ups and downs. The Iceland population of the fish is doing OK, and the fish in the North Sea appear to be recovering after overfishing in the late 20th century. But closer to home, the northwest Atlantic cod population, which also collapsed due to overfishing, has yet to recover despite severe limits on fishing.

Editor’s note: The image captions in this post were updated on September 14,2015.