The Ebro is filling with brown prawns, an invasive species that we are going to find more and more on our plates.

When a fisherman from Vinaròs arrives at the fish market with his catch of the day, he finds more and more specimens of a crustacean that should not be there: the brown shrimp. Four years ago there were barely one or two per boat. Today there are days when up to 40 kilos are caught. This invasive species has arrived in the Mediterranean, has reproduced, and has no intention of leaving.

The presentations. Its scientific name is Penaeus aztecus and comes from the Gulf of Mexico and the east coast of the United States. Although for the non-expert eye, the one who finds a plate of prawns on the table on Christmas Day, at first glance there is not much aesthetic difference with the normal one, there is.

Thus, it has a uniform brown color that tends to be yellowish, it lacks those bands characteristic of the native, its body is more stylized and its head is pointed, and its antennae have a characteristic reddish tone.

BioInvasions Records. Authors from the Institute of Marine Sciences (CSIC, Barcelona)

Chronology of an invasion. The first time They detected the brown shrimp in the Mediterranean It was in Turkish waters in 2009. It possibly arrived as a stowaway in the ballast water of large ships that load water in the Caribbean to stabilize and then release it in Mediterranean ports along with larvae of this invasive species.

From there, it has expanded rapidly westward. In 2023 the CSIC confirmed with morphological and genetic analyzes its presence on the Catalan coast and in the area of ​​the Ebro delta. Later, it has been seen in other ports of the Valencian Community and in the Mar Menor (Murcia) in record time.

A perfect invasion. But the clearest proof of its expansion is not geographical but biological: the discovery of mature females in the Ebro delta confirms that the species is capable of completing its reproductive cycle in Spanish waters. It is already an established population. The testimony of the fishermen’s brotherhood of the Vinaroz fish market It constitutes a good alarm thermometer, detailing that in just four years they have gone from encountering a unit to capturing 40 kilos and the curve does not stabilize: each campaign surpasses the previous one.

The brown shrimp is a thermophilic species. If it has found an ideal new home in the Mediterranean, it is partly because the sea is warming and its waters are already more and more similar to its original habitat.

What’s wrong with the shrimp here? At the moment there is no data that shows the collapse of the native shrimp, but there is a reality: it is competing with the brown shrimp for space and food. And there is a mirror in which to look: in the Gulf of Taranto in Italy, the presence of the native shrimp has already reversed. And a reminder: the one with the blue crab.

Is it eaten? The “good news” is that brown shrimp is edible and, in fact, gastronomically speaking, it is tasty. However, its market price is noticeably lower: 12-13 euros per kilo compared to more than 40 euros per kilo for native shrimp.

But there is an underlying problem: they can give you a hard time and pay for brown shrimp at the price of native shrimp, since it is sold mixed and unlabeled. This is a traceability problem for the consumer.

What can be done. Converting the consumption of brown shrimp as a way to control its population is a possibility, either directly or with preparations, although it is imperative to establish regulation in the fish market to differentiate it.

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Cover | BioInvasions Records and Natural History Sciences