A slippery tale of human greed, climate change and the mysteries of the deep
O n a warm morning in mid-March, a group of researchers from Ferrara University examine their catch after delicately emptying out a net from the mouth of the Valli di Comacchio, a vast system of wetlands in the province of Ferrara, on the eastern Adriatic coast of Italy. It takes a trained eye to spot a glass eel amongst the thousands of other tiny fish. Just over a year old, the eels are a few centimetres long, thin and spindly, and virtually transparent. The investigators count twenty-nine. One pauses and turns to his colleagues with something close to jubilation. “A success,” he declares, “usually, there are far fewer”.
Until a couple of decades ago, the same net placed around the same period of the year would have harvested at least a thousand glass eels, all destined to populate the surrounding wetlands, or ‘valleys’ in the local parlance. Much has changed since then. The number of eels arriving in Comacchio today is only two to three per cent of the figure for the 1970s and 1980s. LIFEEL, the research project in which the University of Ferrara is participating, aims to understand the reasons behind the eel population’s steep decline, not just in Comacchio, but around the world.
LIFEEL is the first conservation project for the species conceived at the entire Po River basin scale, with the goal to increase and maintain the wild population of Anguilla anguilla (European eels).
It is a consequential project, because the ramifications of this drop are not just environmental. They are also economic and social, especially in areas such as Emilia and Romagna, where eels have long been the lifeline for many communities. It is ambitious, too: eels remain one of science’s great unsolved enigmas.
They are such a mystery that it is difficult to know even what the risk of extinction is. No one can say how many of them there are in the world to begin with. And a reliable population estimate is the first criterion used by the International Union for the Conservation of Nature (IUCN) to determine whether a species is endangered or not. The second criterion is even trickier: in addition to an idea of the total population, you need to have an estimate of the number of “breeding individuals” – that is, the number of eels that are sexually mature, ready to reproduce. That’s where things get really complicated.
