From Drought to Floods: Rocha
Artisanal fishermen working in the brackish coastal lagoons of Valizas famously supply premium shrimp, attracting tourism, gastronomy, and commerce. But when an unusual climatic effect interrupted the communication between the ocean and inlets of this ecosystem at an inopportune time, it caused a bumper harvest that turned catastrophic.
Alejandro Álvarez grew up and still lives in the department of Rocha, on the banks of the Valizas Stream, with his children and his wife. He is part of a small community of about ten families who have lived there for decades and whose main income comes from artisanal fishing.
They catch several species that thrive in the stream and in the Castillos Lagoon; one of them—shrimp—makes the difference in the income of the fishing families.
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Valizas is a shrimp fishery par excellence. The most renowned chefs of the region's leading tourist destinations—such as Punta del Este, José Ignacio, La Pedrera and Punta del Diablo—select the best specimens in Valizas, which they then serve in their restaurants to customers with fat wallets. Since 2015, a shrimp harvest festival called a camaronada has been held there each April, attracting locals and tourists from all over. In the summer season, and during the fishing season, hundreds of people migrate to the town to labor in the harvests. Valizas shrimp is highly prized and in demand.
Climate change is threatening the present and the future of this small community of Rocha fisherfolk—and that of all people and businesses involved in shrimp fishing in Uruguay, right up to the consumer.
A natural trap
Every year shrimp hatchlings arrive through the Atlantic from Brazil, passing through the Valizas Stream to then mature in the Castillos Lagoon, 10 km inland. They then migrate again as adults to reproduce in the waters off southern Brazil. Where the stream meets the sea is a sandbar formation called la barra, which opens and closes based on the accumulation of sand at specific times of the year. The dynamics of the sandbar at the mouth of the Valizas Stream allow the shrimp to enter the lagoon and later return to the sea. Human intervention accompanies this natural cycle, which in turn initiates a commercial food supply cycle through the fishing industry. The shrimp harvest in the Valizas area begins at the end of the summer, in March, and lasts until May.
Between 1991 and 1994, fishermen abandoned the use of beach nets in favor of shrimp traps, which increased the catch volume. The practice became more efficient and the physical effort of those working in the streams and lagoons was reduced. Uruguayan law authorizes each fisherman to use a maximum of 10 traps, although some fishermen tend to have up to 40.
Artisanal fishing is a trade that is passed down from father to son. Alejandro is the son and grandson of artisanal fishermen. He does not remember seeing or hearing of anything like what he experienced on February 28, 2023. There are no anecdotes of anything similar in the last three generations. None of the villagers interviewed for this report have memories of anything similar to that untimely and frenetic fishing day.
This atypical day was the result of an atypical dry season brought to the South American continent by a La Niña event. La Niña is a climatic phenomenon caused by the cooling of the waters of the tropical Pacific that began to manifest itself three years ago. But only in the last few months has the Uruguayan population become aware of its transformative power.
In January 2023, farmers and ranchers from the interior of the country were on television showing cracked land where there would normally be a watercourse. In Montevideo, the capital of Uruguay, the crisis arrived just 60 days later, when the reserves that supply drinking water to almost two million people, more than half of the country's population, reached critical levels. To alleviate the situation, officials went to the extremes of mixing fresh water with water from Río de la Plata, an estuary where the Uruguay River flows into the sea and merges with the saltwater ocean. For the first time in the country's history, the water supply network delivered non-potable water to Uruguayan homes.
In Valizas, the phenomenon manifested itself in decreasing the water level, closing off the connection between the Atlantic Ocean and the Valizas Stream, which then dwindled in size.
The channel that flows through the sandbar was closed off by February 5, as shown in satellite images. By February 28, it was still closed, and the water level of the Valizas Stream was at historic lows. Schools of shrimp were confined to a natural pond, also disconnected from the mainstream course. Any passersby who wanted to could catch them with just a bucket or even a towel.
From the dawn of February 28th, the news spread among locals, who went to the mouth of the stream in the morning and afternoon. Fearing that the small shrimp would die from a lack of water, fishermen and neighbors sought to catch as many as they could. The shrimp had yet to reach maturity or a decent weight.
The traps that fishermen regularly use for shrimp fishing were ridiculously large for the small amount of water that kept the stream alive. The use of small hand nets and seine nets proved to be more effective.
The artisanal fishermen filled huge, blue 200-liter plastic tubs with the shrimp hatchlings, without having a clear idea of what to do with them or how to keep them in good condition until they were ready for sale or consumption. The most professional refrigeration system they had were household freezers.
The alteration in the shrimp harvesting cycle is linked to an overabundance at atypical times that also has its origin in climate change. Biologist and researcher Santiago Silveira, a member of the Atlantic Fisheries Management Unit, explained that the "postlarvae"—the name scientists give to shrimp offspring—benefitted from the increased inflow of oceanic waters of tropical origin caused by the drought. After the opening of the season "there was a lot of fishing for five days," Silveira said.
The 2023 harvest had impressive figures: 1,000 traps were used and 160 tons of shrimp were caught. But as a direct effect of the early—and illegal—fishing, and due to a disregard for the policies that regulate the fishing seasons to ensure the sustainability of the species, the market initially had a large volume of smaller and lighter shrimp. This, in turn, had an impact on the value of the product and on the profit of artisanal fishermen.
That February 28, 2023, the sandbar was closed and remained closed through August 28th, the last date for which our team obtained imagery prior to the publication of this report. By May, when the harvest should have been in full swing, the abundance was over. The president of the Barra de Valizas fishermen's group, Luz Martínez, called it chaos. "It is a moment of total uncertainty; we don't know if the shrimp are finished."
Science is also unaware of a precedent for such a phenomenon in the area. "An event like this year's has never been seen before: Neither our memory nor that of the fishermen has any record of it," said veterinarian and zoologist Graciela Fabiano, a member of the Atlantic Fisheries Management Unit of the National Directorate of Aquatic Resources.
By the end of May, shrimp fishing continued in Castillos Lagoon and Valizas creek, although very few artisanal fishermen were engaged in catching them. There were 60 traps, the catch volume was low and although the remaining shrimp had reached the acceptable size—about 10 grams—to be caught, there was an unexpected incident: An invasive species of ctenophores (an organism similar in appearance to jellyfish) was saturating the nets, preventing harvesting.
According to Alejandro Álvarez, "this shrimp harvest was of no use to anyone. The fishing was a bust because the shrimp came up early and we didn't catch much. I got behind on [bills for] electricity, water, and up to my hands in debt. So imagine the toll this has taken on me."
Climate research by the Department of Atmospheric Sciences of the Faculty of Sciences of the University of the Republic indicates that for Uruguay "changes have already been detected" in some of these climate hazards and that "they will continue and worsen in a context of climate change".
Regarding the dynamics of rainfall and dry days, the research states that "the extremes of precipitation would increase, just as the number of days with light rains would decrease, implying a situation with a greater number of dry days separated by intense precipitation events." In other words, there will be more dry days interrupted by heavy rains.
If extreme weather events continue to intensify, shrimp fishermen will face a failed harvest for the second year in a row.
By: Miguel Ángel Dobrich and Gabriel Farías.
Geospatial data: Natalie Aubet and Nahuel Lamas.
Photos: Matilde Campodónico. Design: Antar Kuri.
Edits: Victoria Melián. Translation: Alexandra Waddell.
With special thanks to the Aerospace Remote Sensing Service of the Uruguayan Air Force (SSRA) and to the Technological University of Uruguay (UTEC).