Why European eels are endangered

populations of these endangered young eels have been mysteriously declining. Photo Credit: PAULO OLIVEIRA/ALAMY STOCK PHOTO
In addition to its deliciousness, European eels have plagued biologists for more than a century. They spend their adult lives in estuaries and streams and travel to the sea of horsetail algae near Bermuda to breed. The tiny transparent young fish then returned to Europe on a "wind train" of the Gulf Stream. However, the eel population has been mysteriously declining, prompting extreme measures to restore its population.
today, researchers have learned about one of the dangers young eels face on their journey: hungry fish. It was once thought that these young fish were difficult for most predators to detect and catch. However, a new study looking for TRACEs of DNA in the intestines of fish near eel breeding waters suggests that at least six marine species can quickly eat young eels.
european eels were once common, but their numbers have fallen sharply over the past 45 years. What's more, the number of young fish that end up in Europe as "glass eels" has fallen by 90 per cent, leaving some wondering what they might have experienced. Did some creatures eat them up?
seems unlikely. Young eels - about the size of a small willow leaf - were detected only once in the intestines of other fish at the end of the 19th century. Or it could be that once swallowed, they disappear so quickly that they leave no trace. In fact, the eel is hard to spot, "even in a basin of water," said Mads Reinholdt Jensen, co-author of the paper and now a graduate student at Aoghus University in Denmark. Researchers looking for a decline in eel populations analyzed all possibilities except who was eating young eels.
Jensen and colleagues at the University of Copenhagen did not analyze the young eels themselves, but looked at the DNA of 62 eels collected by a Danish team in 2014 and quickly frozen. The team had been looking for adult eels to hatch in the sea of horsetail algae, but to no avail. Jensen's team developed specific molecular labels for eels. These labels "grab" any eel DNA in the fish's intestines. Eventually, the researchers verified the DNA of European eels in six different species of fish. They reported the
in a recently published journal.
the latest findings come as a surprise to Tracey Sutton, a marine ecologist at Southeastern University in Florida who was not involved in the study. "This is contrary to the idea that these fish prey mainly on crustaceans." "The latest research shows a new approach to the food chain that we didn't know about before," he explains. (Source: Zong Hua, China Science Daily)