The researcher Bernardo Quintella justified this Saturday the scarcity of lampreys in the Tagus River, which affects fishermen and tourism, with the destruction of habitats, the lack of water and the construction of dams and dikes.
“We think that one of the main factors that contributed to fewer lampreys, in general in Portugal, but also in the Tagus River, has to do with the systematic reduction of habitat, with the lack of water and with the construction of dams. and reservoirs, which have systematically reduced the habitat available for this type of species,” said the scientist linked to the Center for Marine and Environmental Sciences (MARE), noting that “the migration peak would be in March/April” and that very few lampreys are seen in the rivers.
In statements to the Lusa agency, this official, also a professor at the Faculty of Sciences of the University of Lisbon, also left some data on the Tagus and added that in the last 100 years the river has lost between 80% and 90% of ‘habitats’, mainly due to prey or prey.
“In the Tagus, we are talking about a habitat reduction of between 80% and 90% (…) that was available for the lamprey 100 years ago, and that is no longer available. It is a brutal reduction, because instead of having the animals scattered throughout the river and its tributaries, we end up having the animals concentrated in a much shorter stretch and we end up being more susceptible to being captured by the fishermen”, he pointed out.
Bernardo Quintella said that the Tagus river still has an “aggravating factor, which is the lack of water, both due to the transfers that occur in Spain, and due to climate change”, in a “combination of factors” that turns out to be “extremely harmful ” for these species.
“What I say for sea lamprey is also true for tarpon and will also be true for trout and salmon in rivers further north. This is to mention only the anadromous species, which are the ones that go up the rivers to reproduce. Like lampreys and salmon, they breed in freshwater, then have a feeding phase in a marine environment,” he observed.
The scarcity of lampreys in the Tagus has left fishermen empty-handed and tourist activity has also suffered, with the riverside municipalities of Mação and Vila Nova da Barquinha canceling the traditional gastronomic festivals dedicated to the cyclostome.
Luís Grilo, a 67-year-old fisherman from Tramagal (Abrantes), and many others linked to the river, assures that he has never seen such a bad year for lampreys, having not been able to catch any for the sample.
“I have no recollection of such a thing. For many years now it has not happened that nothing is caught and that there are practically no lampreys in the Tagus. There were always many lampreys, sometimes fewer, but there always were, and not now. Nothing appears, ”he said, after suggesting a ‘closed season’ with a fishing ban“ to see if the lamprey recovers ”.
Upstream, in Ortiga (Mação), Francisco Pinto, a professional fisherman for 35 years, says that this year he only caught two lampreys and that they went below the Abrantes dam.
“Here in Ortiga nothing arrives. This year I really hit bottom and I already gave up. There is no memory. I spent 17 nights fishing for lampreys and I didn’t catch anything, I only managed two and it went under the dam. This is the worst year in 35 years of professional fishing,” she lamented, expressing little expectation that the lamprey will recover for the year.
“These are seven-year cycles, let’s see,” he shot, in a mixture of doubt and uncertainty.
For the Pelo Tejo Movement – proTEJO, the lack of lamprey “derives, to a large extent, from the irregularity of the flows”, after reiterating the need for “implementation of regular, continuous and instantaneous ecological flows in the Tagus, measured in cubic meters per square meter”. second, respecting the seasonality of the seasons”.
Concerned about the impacts on the fauna, flora and riverside biodiversity, Paulo Constantino stressed the importance of “the preservation and safeguarding of ecosystems to create, regenerate, purify, create and retain water”, after defending “prevention and the participation of the Governments in this matter in order to move towards a greener, more balanced and environmentally sustainable future”.
For Bernardo Quintella, the “fluctuation of the water level, which occurs because it is not an ecological flow, can also be very problematic, especially since lampreys have a phase of their life cycle, a larval phase, in which they live buried in the sandy sediment of the rivers, during a period that can go from four to six years”.
“Therefore, if by chance they bury themselves in areas that periodically run out of water, this can cause very significant mortality and this is a problem that can especially affect the Tagus, because there are quite significant fluctuations in the Tagus,” he pointed out. .
After mentioning that the lamprey problem “is not exclusive to the Tagus”, the researcher said that “the same is happening this year in the Mondego river and in the Miño river”.
“It is being a reduction that is affecting all the Portuguese rivers transversally,” he said, ruling out, however, an extinction scenario.
“Lamprey on the brink of extinction I wouldn’t say, but lampreys can very quickly find themselves in a situation where commercial exploitation is no longer profitable, especially in the Tagus,” he concluded.
Source: Observadora
