Why are Rome's dolphins fighting each other? A scientific study's surprising discovery
The "Capitoline dolphins," as Italian researchers have renamed them, have inhabited the coast off Rome for thousands of years, as evidenced by several Roman-era mosaics. What is happening within this colony today?
Rome is known worldwide as the famous Eternal City, revered for its history, art, culture, and food. However, few know that less than an hour away, where the Tiber River flows into the Tyrrhenian Sea, there is something that makes the area even more unique: a population of some 500 bottlenose dolphins.
The "Capitoline dolphins," as Italian researchers have dubbed them, have inhabited the coast outside Rome for thousands of years, as evidenced by mosaics at the archaeological site of Ostia Antica, which depict them stealing fish from fishermen's nets 2,000 years ago. However, only recently, since 2016, have they been studied in depth.
What's happening to Rome's dolphins?
A recent study, published in April 2025 in the journal Aquatic Conservation: Marine and Freshwater Ecosystems, analysed more than 400 photographs taken between 2016 and 2023, involving 39 dolphins from the resident population. Led by Daniela Silvia Pace, a researcher at La Sapienza University of Rome, and her doctoral student Alice Turchi, the study examined physical signs on the dolphins' bodies, a common technique for assessing the health and living conditions of cetaceans.
Even more alarming is the high number of bite marks, which indicate an increase in dolphin conflicts, likely linked to competition for increasingly scarce food resources in the central Tyrrhenian Sea.
An internal conflict motivated by the scarcity of food resources
Although the Tiber estuary has traditionally been a food-rich area, the study suggests that prey abundance is declining, likely due to overfishing.
"It's strange because we're in a food-rich area," commented Alice Turchi. "The majority of the population is malnourished, and this is a strong warning sign," added Daniela Silvia Pace.
These conflicts are not only a sign of stress, but also an indicator of an ecosystem under pressure, where dolphins, known for their sociable nature, are forced to fight for survival.
The impact of pollution and human activities
Pollution is another critical factor threatening Capitoline dolphins. The Tiber carries a significant amount of pollutants into coastal waters, including waste and debris from vessels, which compromise water quality.
This contributes to the high incidence of skin diseases observed in dolphins. Furthermore, fishing activities, with their nets and lines, pose a direct physical danger, causing injuries and, in some cases, mutilations. The combination of these factors is testing the resilience of this population, despite the fact that bottlenose dolphins are known for their adaptability.
The importance of conservation
Despite the challenges, researchers emphasise that there is still hope for Rome's dolphins. However, the coastal area is currently unmanaged, meaning there are no meaningful conservation measures to protect this stretch of sea.
Alice Turchi and her team propose the establishment of a Site of Community Importance (SCI), which could ensure greater protection not only for the dolphins but for the entire marine ecosystem in the area. However, Daniela Silvia Pace cautions that the process for obtaining such a designation is very complex and requires strong political commitment. The researchers hope that increased public awareness of the dolphins' plight will prompt policymakers to take concrete steps to protect them.