Like every autumn morning, the mussel boats approach the port of Vilanova de Arousa between the fog banks, loaded with molluscs recently collected from the pan, another element of the Galician landscape of the coast. Only in the Arousa estuary are found nearly 2,000 floating structures where mussels growwhose culture is essential to the region’s economy. However, both boatmen and organizations and institutions agree that for years the production of this bivalve has been in decline, with fewer specimens and growth problems.
This was demonstrated by several markets in towns near estuaries, where specimens were difficult to find in summer due to the lack of fattening in previous months. A worrying situation given the economic importance of this activity in the Rías Baixas, where ideal conditions exist for maritime currents that transport nutrients for the cultivation and development of mussels, making it the main European nursery of this mollusk.
THE the factors are multiple, from acidity, salinity, pollution or increased water temperature, but ignorance of the main problem to be solved prevents taking specific measures to solve a scourge that causes headaches to workers linked to this activity. First there were the shellfish fishermen, where these factors made themselves felt first, with serious consequences on their activity. The phenomenon now also affects mussels, cultivated in the open sea, where neither currents nor the lower temperature compared to the intertidal zone exempt them from this damage.
“Over the last two or three years, we have seen [la caída en la productividad]“, says Marcos while unloading a mussel boat in Vilanova. The ‘bateeiro’ adds that during the previous campaign “there was no natural selection, or very little” and that, although this year was better, “the growth was very bad”. “It is a real and tangible problem”, which particularly affects the production of “quality molds”, where it has “dropped a lot”. “There are a lot of mussels, but small,” he concludes.
The “bateeiros” who gradually arrive at the port share this concern. One of them emphasizes that the mussel did not grow because of the “filth” and the “mud” which affected its diet, “a year to forget”, he emphasizes, while helping to equip the crane with the pallets to lift the mold to the port, where it is packaged for transport. Francisco comments after leaving another mussel boat that the production problem particularly affects the rafts located inside the estuary, those closest to the river mouths. “A catastrophic year”he describes, specifying that they have only harvested “25% of what is normal” and that the problem has been going on for a long time, since they started having problems collecting the seeds from the rocks: “It Three years ago they completely disappeared.”
Paddles in Vigo
From the Organization of Mussels Producers of Galicia (Opmega), the most representative of the sector, they agree that the production problem has increased in the last three years, “a complex and difficult issue to explain”, because there are several factors at playindicates its president, Ricardo Herbón. He emphasizes that studies are underway to determine “what is the most determining factor in all of this” in order to carry out actions that “minimize” the problem.
Increased acidity
One way to analyze the possible causes of the phenomenon is to use data obtained by the measuring stations of organizations such as the Technological Institute for the Control of the Marine Environment of Galicia (Intecmar). In this case, they monitor the state of the production areas and are responsible for analyzing their condition, as well as their opening or closing, taking into account factors such as the amount of phytoplankton and microbiological and chemical contaminants.
In fact, according to the microbiological load (the indicator of which is the E. coli bacteria), the zones are classified A, B or C depending on whether they are larger or smaller. While in areas classified A, the product can reach the consumer directly without its consumption presenting any risk, classification B basins – the majority in the case of Galicia – require prior purification and those of type C have prerequisites. more demanding.
The director of Intecmar, Covadonga Salgado, explains that the microbiological situation is increasingly better in Galicia “in general”, although he is also aware of the complaints of the “bateeiros”. Even if the pollution does not seem to get worse over time, indicates that “the pH generally drops”. An acidification of water which increases “in thousandths” each year but which represents “hundredths” when analyzed in decades, adds Salgado. A change that affects the development of the mollusc’s shell and could explain the reduced ability to adhere to raft ropes, becoming detached and lost at sea.
But this is just one factor, such as increased water temperature, which affects rafts in front of shell beds less due to the depth at which they are found, on surfaces colder with greater nutrient outcrops, although “It cannot be ruled out that this affects the seeds”, which are collected in the rocks, Salgado points out.
High temperatures
Another consequence of increasing maritime temperatures is its impact on the mussel ecosystem. The researcher from the Marine Research Center (CIM) of the University of Vigo, Paloma Morán, highlights this factor as being decisive in explaining the proliferation of algae and natural predators of this mollusclike a starfish. Another factor to add to explain the phenomenon. “Because the sea temperature is so high, more algae is breeding and displacing other species. SO, [los mejillones] “They face problems like starfish, which go to the ropes of the raft and eat them,” Morán explains.
The teacher and researcher is participating in several studies currently underway to analyze aspects such as the breeding of this bivalve and its development in facilities such as the island of Toralla. Together with other initiatives developed by institutions such as Intecmar or the Regulatory Council of the Designation of Origin of Mussels of Galicia, this is the main asset to determine the extent of this problem and to be able to design lines of clear actions to resolve the problem.
The head of the R&D&i department of this Regulatory Council, Ángeles Longa, adds the cyclical factor to the equation, a possibility given that there has already been bad campaigns in the past. In any case, he emphasizes the importance of studies so that bateeiros can make decisions with “much more truthful information.” It also highlights the importance of “correct identification” of this product which is part of Galician “tradition” and the fight against fraud.
Possible solutions
Although some offer solutions such as move the trays so that the molds are deeper, andFor colder waters, or to finance the cleaning of these floating structures, which would have a high cost, the president of Opmega emphasizes that beyond individual cases, “the solution must come from elsewhere”.
” Let’s go adapt to circumstances and try to accelerate the processes to the extent that we can intervene, because there is a part which is nature itself”, declares Ricardo Herbón, who advocates “the continuation of the fights” while waiting to identify “the main enemy” after the fall of the mold. production and growth difficulties.
However, there are other factors whose impact is unknown and difficult to measurewith the impact of reservoirs or pollution dumped into rivers that flow into the sea. A waiting melon that could illuminate the shadow that permeates this mollusk.
