Beginning in 1904 , larvae of American eels ( Anguilla rostrata ) have been discovered in the Sargasso Sea near Bermuda – thousands of kilometer forth from the inland river of North America where adults are found . This led researchers to assume that mature eels transmigrate as many as 4,000 km ( 2,485 miles ) from continental urine to their spawning sphere . But in all this time , not a unmarried adult has ever been caught in the open ocean . And pretty much nothing is known about their spawning web site or how they get there .
Now , for the first meter , researchers have get over an adult American eel traveling 2,400 kilometers ( 1,490 miles ) from the east seacoast of Canada , over the continental shelf , and into the warmer weewee of the Sargasso Sea . The findings , published inNature Communicationsthis week , provide the first direct evidence of the oceanic migration of adult American eels and the first notice of any eel approaching spawning reason in the Sargasso Sea .
To follow the animals en road to their spawning website , a squad led by Dalhousie University’sMélanie Béguer - Ponattached pop - up artificial satellite archival tags ( PSATs ) to 38 maturing ( shout silver ) eels catch by commercial fisher in Nova Scotia and St. Lawrence Estuary in Canada . They ’re listed as endangered in the U.S. and threatened in Canada . The two types of tag used , which weighed either 45 grams or 29 grams ( 1.6 or 1 ounce ) , were bond at the eels ’ centre of mass or near the head ; large animals were take to minimize drag due to the tag . The eel were then release on the Scotian Shelf off Nova Scotia in the fall of 2012 , 2013 , and 2014 .
Of the 38 PSATs resign over three geezerhood , 28 successfully transmitted their datum after popping off between half a day and 57.2 days after deployment . The team find a sum of 431 days of eel tracks . Two of the ticket spent a few days in the stomach of marauder , and found on the recorded temperature , depth , and light datum , these eels were likely eat on by a Lamna nasus shark and a bluefin tuna tuna .
All of the eel immediately lead south and somewhat to the east from the Scotian Shelf . Eight eels were successfully tracked to the open sea off the continental ledge . And one of them ( eel # 28 ) migrated 2,400 kilometers to the northern limit of the spawning site in the Sargasso Sea in 45 solar day . It cross the Gulf Stream 29 days after its release , and it was travel at an average speed of 49 kilometers ( 30 mile ) per twenty-four hours . The eels experience a huge temperature reach during their migration : from 2.5 degree Celsius ( 36.5 degrees Fahrenheit ) over the Scotian Shelf to 25.1 stage Celsius ( 77.2 point Fahrenheit ) in the Sargasso Sea .
The team reconstructed the routes of the eels at ocean establish on their daily locations . It seems that migration come about in two distinct phases : one over the continental shelf and in the shallow body of water along its edge , another in deeper waters directly south towards the spawning orbit . This suggests that salinity and temperature service guide them , since both factors increase from the coast to open waters .
“ To fill in the space is a dream labor for any life scientist , ” study co - authorJulian Dodsonof Université Laval told IFLScience . Though , to be clear , “ we have only just begun to understand what is break on . ”
Here ’s a very nerveless video of the eel being released off Nova Scotia :
Image in the school text : A silver American eel equipped with pop - up satellite archival ticket and expel off Nova Scotia in Canada . Mélanie Béguer - Pon Video quotation : Mélanie Béguer - Pon
