Bull Rays Invade Italian Gulf, Threatening Mussel Farms

The Gulf of Trieste has become a focal point for an unusual ecological event, with bull rays, a large species of protected eagle ray, congregating in large numbers. This phenomenon, unprecedented in the Mediterranean, has seen aggregations of up to 50 individuals, a significant increase in recent years.

Researchers attribute this surge to several factors, including changes in European fisheries policy that have reduced bycatch and improved reproductive success for bull rays. Furthermore, winter sea temperatures in the Gulf have become sufficiently mild, transforming it from a transit area into a suitable habitat for the species to settle.

While the increased presence of bull rays is a conservation success, it poses significant challenges for local mussel farms. The rays are damaging mussel lines, consuming a readily available food source. This interaction has necessitated the development of non-invasive technologies and solutions.

Conservation projects, including Life Eu Sharks and Life Prometheus, are actively engaged in Trieste. These initiatives employ drones for photo-identification and are testing electromagnetic deterrents on mussel lines. The goal is to find a balance that protects both the endangered bull rays and the livelihoods of mussel farmers.

The Gulf of Trieste is now viewed as a model for coexistence between marine species and human activities. Future steps include establishing dialogues with regional authorities to potentially designate specific areas for eco-tourism, such as snorkeling and underwater photography, to highlight the importance of these animals.