The ancient Romans might have traded live fish across the Mediterranean Sea by endowing their ships with an ingenious hydraulic system, a new investigation into a second century A.D. wreck suggests.
Consisting of a pumping system designed to suck the sea water into a fish tank, the apparatus has been reconstructed by a team of Italian researchers who analyzed a unique feature of the wreck: a lead pipe inserted in the hull near the keel.
Recovered in pieces from the Adriatic sea in 1999, the ship was carrying a cargo of processed fish when it sank six miles off the coast of Grado in northeastern Italy.
The small trade vessel, which was 55 feet long and 19 feet wide, was packed with some 600 vases called amphoras.They were filled with sardines, salted mackerel, and garum, a fish sauce much loved by the Romans.
Now the archaeologists suspect that some 200 kilograms (440 pounds) of live fish, placed in a tank on the deck in the aft area, might have also been carried by the ship during its sailing life.
"The apparatus shows how a simple small cargo vessel could have been turned into one able to carry live fish. This potentiality, if confirmed by future studies, shows that trading live fish was actually possible in the Roman world," Carlo Beltrame, a marine archaeologist at the Ca' Foscari University of Venice in Italy, told Discovery News.
Indeed, a number of historical accounts have suggested that the Romans might have transported live fish by sea. For example, the scientist and historian Pliny the Elder (23 – 79 A.D.), wrote that live parrotfish were shipped from the Black Sea to the Neapolitan coast in order to introduce the species into the Tyrrhenian Sea.
Measuring 51 inches in length and featuring a diameter of at least 2.7 inches, the unique lead pipe was located in a sort of "small bilge-well" and would have been connected to a hand operated piston pump (which had not been found within the wreck).
Ending with a hole right in the hull, the pipe intrigued the researchers.
"No seaman would have drilled a hole in the keel, creating a potential way for water to enter the hull, unless there was a very powerful reason to do so," Beltrame and colleagues reported in the International Journal of Nautical Archaeology.
According to the researchers, the reason wasn't the need for removing bilge water from the bottom of the boat through the pipe.
Indeed, bucket chain pumps were able to discharge bilge water from the side in a much safer way, possibly recovering between 110 and 225 liters (30 to 60 gallons) of water per minute.
"It seems unlikely that sailors aboard the small Grado ship abandoned the usual chain-pumping apparatus in favor of the more complex bilge pump," Beltrame said.
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