Tracking Eels Across the Oceans
History
Eels have puzzled humans for a very long time. Worldwide, there are stories and legends about the origins of eels; one in particular gives the eel its scientific family name Anguillidae. This came from Greek mythology where the white armed-goddess Anguilla and the king of Greek gods, Jupiter, together produced eels. Māori call both the shortfin and the longfin eel Tuna. South Island Māori legend states the origin of the Tuna, is from the heavens known as Orukateraki. Due to the heat of the sun and the lack of water, Tuna's skin had been burnt and turned black which made him sad. After meeting Tawhaki, a man who had travelled from the earth to the heavens, Tuna descended to Papatuanuku, the earth, where he found a cool pool in which to live called Muriwaiowhata. Sometime later, Tuna was discovered by a woman named Hineturepo, who saw Tuna as a taniwha, or monster. The people of the area caught Tuna in a large hinaki (eel pot), killed him and cut him into pieces. The pieces of Tuna were scattered and became the various types of 'eel' we have today; the conger eel, the lamprey, the hagfish and the freshwater shortfin and longfin fin eels.
The mystery of eel migration spans the history of western science. Because fishermen never caught anything they recognised as a young eel, the animal's life cycle was an enigma. The Greek philosopher Aristotle (384-322 BC), who did the first known research on eels, believed they emerged spontaneously from mud – no fertilisation needed. Roman naturalist Pliny The Elder (c77AD) suggested they grew from horsehair. It wasn't until 1777, when an Italian, Carlo Mondini, identified the creature's gonads, that eels were proved to be fish. The migration and reproduction of freshwater eels remained a mystery until 1922 when a Danish scientist, discovered the spawning grounds of the Atlantic eel in the Sargasso Sea between Bermuda and Puerto Rico. While all 15 species of freshwater eel spawn at sea, the spawning grounds of only four species are known with certainty. Not included in the four are the two common New Zealand species.
Until very recently, the only way of figuring out where freshwater eels spawned was to tow fine-mesh nets at depths ranging from 50m to 300 m, and try to catch progressively smaller larvae - a time-consuming and costly business. The development of radio-tracking devices and satellite coverage has made the process easier and more accurate.
