There are few landscapes more symbolic and associated with Galicia than the raft polygons spanning the estuaries. They are so popular that in the summer of 2013, the Tour of Spain, a tribute to the community, started one of its stages from one of these wooden platforms in Vilanova. Now, with more than 3,300 mussel farming structures spread across much of the Galician estuaries between Vigo and Ares, the region’s government wants to know more: How are they affecting the coastal ecosystem? Does it have a purifying or polluting effect? And most importantly, how many rafts should be in the different estuaries?

It has already recruited a group of experts to clarify this.

How do bets affect it? The stakes are a symbol of Galicia. And twice as much. They form one of the most recognizable sights in society, and every year thousands and thousands of tons of them emerge from one of the most popular delicacies: mussels. Both questions are beyond doubt, so the regional government has now set out to answer a fundamental question: How do these large aquaculture structures affect the marine ecosystem that surrounds them? So what is the capacity of estuaries?

alliance with science. To answer both questions, Marine Portfolio Minister Alfonso Villares signed an agreement a few weeks ago with the University of Santiago de Compostela (USC), an institution tasked with comprehensively studying the community’s estuaries. Specifically, the job will fall to the Institute for Water Environment for Global Health (IARCUS) and the CRETUS research center, both affiliated with USC.

The multi-year agreement to finance their research amounts to 413,700 euros. And with the participation of several Galician fishing guilds and another that will focus on mussels, Xunta’s total investment will be close to 600,000. The regional government emphasizes that the aim is to “increase the productivity” of Galicia’s estuaries by 2026.

What is the purpose? Learn more precisely how rafts affect their environment. Both positive and negative. In the words of Consellería do Mar, the research aims to “know the impact of polygons devoted to mussel cultivation on the quality and production of ecosystems in estuaries, and to evaluate both the purifying and concentrating effects of chemical and organic pollutants.” and microbial”. Another of the unknowns to try to solve is what impact the rafts have on the quality of sediments and water, as well as food availability for other species.

focus on shooting. We do not currently know the results of the CRETUS and IARCUS analyses, but we do know how their experts plan to obtain these analyses. To evaluate the impact of the rafts, they will start with two estuaries with very different situations in Arousa and Muros-Noia on the coastal map of Galicia. Why? In terms of density of polygons, they are almost at opposite poles: the first is where aquaculture is most concentrated. Second, at least. The scientists also plan to take samples from various sectors in the domestic, central and external regions to further develop their analysis.

How many bets are there? The Mexillón de Galicia regulatory council cites approximately 3,400 rafts spread across 44 polygons located in the Ares-Betanzos, Muros-Noia, Arousa, Baiona, Pontevedra and Vigo estuaries. Among them, Vigo and especially Arousa have the largest number of structures. Arousa alone exceeds 2,300; i.e. 68.5% of the total.

A report from USC in 2006 cited 3,300 rafts distributed throughout the Galician estuaries, generating an initial sales volume equivalent to approximately 114 million euros per year; Another report from the Department of Agriculture puts the number of rafts in the community at very similar numbers, at just over 330 by 1992. Their numbers may not have changed much in the last decade, but their production today is much higher than the recorded half. century.

One of the aims of the study that USC will conduct on behalf of Xunta will be to determine exactly how many polygons are suitable for estuaries. Or, in Consellería do Mar’s own words, “analyze the suitability of the carrying capacity of mollusc farming, especially mussels.”

Is there no previous study? Yes there is. The analysis, commissioned by Xunta, will focus on analyzing how mussel rafts affect the “quality and production” of ecosystems; But he won’t be the first to address the issue. Years ago, the University of Vigo analyzed pollution caused by rafts, focusing on one specific issue: sediment deposits that accumulate at the bottom of estuaries due to aquaculture. As collected in 2000 Voice of GaliciaThe investigation warned of the accumulation of polluting residues on the seabed.

Environmental organization WWF has also spoken out about the rafts, warning that rafts dedicated to mussel production in 2021 “threaten the ecosystems of several Galician estuaries”, both due to their volume and the “very serious deficiencies” perceived at the time. his management. Based on its data, the group warned that the “cumulative impact” of more than 3,000 rafts in the estuary could “exceed the carrying capacity of the ecosystem.” He argues that this impact harms the ecosystem in some estuaries, as well as the entire fishing and shellfish industry and wildlife.

Pictures | Nacho Pintos (Flickr) and Amaianos (Flickr)

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