Something is happening in the estuaries of Galicia. Earlier this month, Noia (La Coruña) closed the worst season in its history with seafood mortality exceeding 60%. Shortly after that, the brotherhood of Rianxo, in the Arousa estuary, confirmed that a large number of dead mollusks had also arrived on their shores. Finally, last week the closure of the season in Pontevedra was announced in an effort to “save the Christmas campaign” in the face of a mortality of at least 50%, and which was also extended to the Vigo estuary. An economic and environmental disaster, in which climate warming and more rains have a lot to do with it, but the part of the sector does not say that it is the only one. In the case of the Muros-Noia and Arousa estuaries They demanded a protocol that would prevent the emptying of reservoirs at low tidean action that, they say, is the final blow to an already vulnerable population.
On November 2, the Noia Brotherhood closed the shortest period in its history. In the ten days they fished, they collected dozens of tons of dead mollusks, which the current saw fit to carry closer to shore. In August, data from the Xunta confirmed what the sector reported in January: Where in other seasons there are 200 specimens per square meter, this summer there are only 15. The brotherhood itself asked to start the campaign to ensure high mortality, and also asked to open the ban for at least six months to ensure the recovery of bivalve populations, although they do not expect to return to fishing until next October explained Santiago Cruz, his senior boss.
The Arousa estuary follows the same path. The beaches of Rianxo and Carril also received a lot of dead mollusks at the beginning of November, “especially those that enter commercial size,” explained the senior patron, Miguel Iglesias. Last week that was announced The estuary of Pontevedra will also close shellfish harvesting until the following day on the 27th., with the hope that the product will recover after encountering a 50% loss, as explained on Thursday by the mayor of Lourizán, Mari Carmen Vázquez, to Ep. A little further south, in Arcade and Vilaboa, in the estuary of Vigo, they also asked for a halt to the activity to try to save “what little seafood there is”, after the death also reached their beaches, although they consider the campaign lost. Christmas.
Ecosystems like that of estuaries, with the perfect mix of salt and fresh water that mollusks need to survive, are extremely dangerous. According to Xaquín Rubido, president of PDRA (Platform in Defense of the Ría de Arousa), there are many factors that influence its balance, and changing one affects the others like a kind of domino effect. “Now,” he said, «there are studies that confirm a progressive decrease during the last fifteen years in the intensity of norses —north wind—and increase in water temperature«, which has a direct effect on the »movement of the sea in the estuaries«.
The estuaries, explained Rubido, are governed by the Coriolis effect. To the south, northerly winds bring cold water from the ocean floor, “carrying nutrients derived from decaying organic matter.” It moves the food chain, which promotes the development process and, therefore, “promotes fattening and strength” of mollusks. Instead, a current is created that displaces the existing water along the north side. This circulation allows the transformation of food and purification of possible contaminants, but As the north decreases, the effect of rotation decreases, the temperature rises and “there is less food and, as a result, weaker individuals.”
This has a direct impact on the development of seafood. Like other living creatures, it is selective in the destination of its energy, especially if it is weak like the Galician estuaries. They prioritize “moving in search of food, building their shell to defend themselves, hiding sand and giving birth” and, “if there is any energy left,” they dedicate it to growth. In the face of rains as abundant as we have experienced, which overflowed the rivers, the mortality increased dramatically. If there is a decrease in salinity, a healthy bivalve can escape, but to do this it needs energy, “and the less it is, the less energy it has.” Rubido showed that all the brothers of the estuary agree that there is no bivalve in commercial size and that, on the other hand, there are many breeding “very small and weak individuals”, which means a population more sensitive to ecosystem changes.
freshwater avalanches
But shellfish harvesters don’t blame the climate alone. In January, they reported an “avalanche of fresh water” coming from the Ulla, Umia, and Tambre rivers, which last winter reduced the salinity of the estuaries to “practically zero.” However, they warn that it will have consequences for production in the future. The reason, they say, is not only the rain but also the lack of protocol prohibiting the emptying of reservoirs at low tide—as they reported happened in December in Barrié de La Maza, in Tambre—flooding the estuaries with a lot of fresh water and suddenly changing the ecosystem. Due to the effects of climate change, such as the disappearance of Nordés, the death rate will be “30 or 40%”, With these actions, “it goes up to 60 or 70%,explained Cruz, who in his 47 years of working at sea has never “seen anything like this” at the mouth of Noia.
In February, the associations for the defense of the estuaries of Arousa and Muros-Noia, PDRA and Plademar, presented a letter to Augas de Galicia—responsible for the Department of Infrastructure and Mobility and responsible for the management of the reservoirs— requested an informative file in which the causes and responsibilities of this reduction of salinity will be explained. The document indicates that “this is not the first time this has happened,” and that it occurred at the same time as a “significant increase in the turbidity of the waters downstream, as a result of the contribution of the suspended particles from the bottom drains of the mud from the reservoirs, which are emptied, causing their deposition in the shellfish beds and the mussel beds.
That’s not all the sector is asking for protocol that prohibits emptying it when the water is low, as they assured happened today, but even if the weather forecast predicted heavy rain, a small percentage was released preventively to avoid emergency evacuation. Now, after five trials and “eight months of administrative silence,” Rubido denounced the “absolute contempt” of the sector, and that “the interests of the electricity companies come first here.”
“We also ask that, in a country where how the reservoirs are emptied is very important,” he explained, “because it affects many sectors and many families,” the information “be public.” In this regard, Cruz said that many times they did not know when the dam would open, and that “one day in December at five or six in the morning,” however. We had to rescue some shellfish harvesters with a boat because the current from the emptying of the Tambre reservoir was taking them out to sea.. To prevent these situations, the sector “promotes the Popular Legislative Initiative to declare fishing, shellfish harvesting and coastal aquaculture to be of general interest”; and “the development of these activities in the estuaries is guaranteed compared to others that may not be compatible,” explained Rubido.
They free the reservoirs
However, the Department of Infrastructure and Mobility assured the ABC that “episodes of low salinity in estuaries cannot be attributed” to the reservoirs. In this regard, they explain that “in a hydrological regime characterized by its irregularity”, in addition to the main use they have built, these infrastructures “They often have the added benefit of laminating floodplains, that is, reducing the risk of flooding. when it rains very hard.” When this happens, »they don’t empty themselves, they just let the water that comes to them pass”, they clarified.
They also show that the exploitation of the reservoirs is carried out by their owners, “under the protection of an adequate and sufficient legal title”, and that the concession of the waters of the state provides for “necessary guarantees to minimize the effects that the use of these waters may cause.” To this they added that “the regulatory framework It does not provide for the existence of evacuation protocols, but for operating rules and emergency plans that guarantee that its exploitation is carried out in accordance with current regulations.. For all these reasons, they concluded that “in the case of high rainfall, the reservoirs do not increase the flow” of the rivers and, “therefore, it does not directly affect the reduction of salinity in the estuaries, but on the contrary .”
Regardless of the reasons, the consequences of this influx of fresh water can be seen these weeks, at least now, four estuaries on the Atlantic coast. Noia’s mortality rate was “very high,” Cruz explained. “On the first day we collected about 45 tons of dead mollusks, and the second another 25,” where it is estimated that they managed to save 15%. In addition, what can be seen on the beach are only the most recent storms that have risen from the bottom of the estuary: “Where there is depth, we can see a meter thick dead mollusk.” “We have been asking for measures for a long time,” added Rubido, who assured that “the production of the Arousa estuary has been declining since 2008-2013.” “There are many factors,” he said, which is why he called for a “multidisciplinary study” to provide a comprehensive solution, something that “hasn’t been done so far.”
