A study reveals bottlenose dolphins in the Adriatic are increasingly following trawlers for food, with alarming implications for marine biodiversity.
New Delhi, India Jul 3, 2026 ALN: Bottlenose dolphins in the Adriatic Sea are increasingly relying on fishing trawlers for food, a behavior that raises concerns about the health of marine ecosystems. According to a recent study, baby dolphins are learning to scavenge from their parents, following trawlers to forage in their wake. This shift in feeding behavior is indicative of the broader issues affecting marine life in the Adriatic, where overfishing has drastically altered the food web.
Giovanni Bearzi, co-author of the study and president of Dolphin Biology and Conservation in Italy, noted, “These days the easiest way to find bottlenose dolphins is to look for trawlers. Many of them are followed by the dolphins that go to forage and scavenge in their wake.” This reliance on human fishing practices underscores the challenges dolphins face in finding natural prey due to the significant decline in fish populations resulting from overfishing.
The Mediterranean Sea is one of the most heavily fished areas in the world, with fishing pressure reported to be twice the sustainable level as defined by the Food and Agriculture Organization (FAO). This unsustainable fishing practice has led to a significant decline in fish populations, forcing dolphins to adapt their foraging strategies. Overfishing not only affects the targeted fish species but also disrupts the entire marine ecosystem, where each species plays a crucial role in maintaining ecological balance.
Bearzi explains that dolphins are now scavenging on discards and unwanted organisms left behind by trawlers. “When I say scavenge, I mean that they also feed on discards and unwanted organisms. Dolphins are following the trawlers because natural prey is very hard to find. Why is it hard to find? It’s overfished,” he stated. This behavior is not just a sign of desperation; it also indicates a fundamental shift in the dolphins' hunting and foraging strategies, which have evolved over thousands of years.
Overfishing in the Mediterranean has led to a significant reduction in key fish species, disrupting the food chain and affecting various marine organisms. The loss of fish not only impacts predators like dolphins but also has cascading effects on other species that rely on similar prey. The decline of fish populations can lead to increased competition among marine mammals and other predators, further complicating their survival strategies.
The study monitored trawlers in the Adriatic over 148 days, conducting 859 inspections across various regions and types of trawlers. The results were alarming: while a study from the 1990s found that only 10% of trawlers were followed by dolphins, the recent study showed that in one area, 76% of trawlers were being followed. This dramatic increase highlights the extent to which dolphins have adapted to a changing where their natural hunting grounds have become increasingly barren.
This increase in scavenging behavior is not unique to dolphins. Many species with diminished prey availability, such as polar bears, have been observed scavenging near human settlements. Trawlers may represent a more accessible food source in an increasingly impoverished ecosystem. However, this behavior raises questions about the long-term viability of such adaptations. Relying on human activities for sustenance can lead to a host of problems, including increased interactions with fishing gear and boats, which can be dangerous for marine mammals.
Despite the apparent benefits of scavenging, this behavior poses risks to dolphins. Dr. Randall Reeves, another author of the study and chair of the Committee of Scientific Advisors at the US Marine Mammal Commission, warned, “It is known that bottlenose dolphins are occasionally injured or killed by trawl gear, and that foraging behind trawlers can affect dolphins’ diet, social organization, and communication.” The dangers associated with scavenging near trawlers are significant and can lead to physical harm or even death.
Additionally, chronic exposure to the noise generated by trawlers may lead to hearing damage in dolphins. The sounds produced by trawlers can interfere with the dolphins' communication and echolocation abilities, which are essential for their hunting and social interactions. However, the dire circumstances of finding sufficient prey away from trawlers may compel these animals to take such risks, illustrating the desperate measures they are willing to undertake for survival.
Bearzi emphasized the cultural aspect of this behavior, stating, “The baby dolphins follow the trawlers with their mothers, watch the adults foraging, and learn that kind of behavior. It is transmitted culturally.” This learning process underscores the importance of parental guidance in the survival strategies of young dolphins. The transmission of foraging techniques from one generation to another is critical for the long-term survival of dolphin populations, especially as they adapt to rapidly changing s.
The decline of other dolphin species, such as common dolphins in the Adriatic, serves as a stark reminder of the fragile state of marine biodiversity. Bearzi noted, “The common dolphins are not common anymore. Except for a very few hotspots in the Adriatic, they have virtually vanished. One species has gone, and that is not a good sign. It’s a warning sign.” The loss of biodiversity can have far-reaching consequences for marine ecosystems, leading to imbalances that can affect not only dolphins but also other marine life and the health of the oceans as a whole.
The researchers are advocating for immediate action to protect marine biodiversity and the diverse species that inhabit these waters. They advise against the continued use of trawlers, which threaten the delicate balance of the Adriatic ecosystem. The implications of continuing current fishing practices are dire, not just for dolphins but for the entire marine .
Bearzi concluded with a strong message: “When I was younger, I just wanted to study the behavior of dolphins. I wouldn’t even think about human encroachment back then. But what we saw in past research is entire communities of dolphins disappearing. If you stop destructive fishing, the marine resources would bloom very quickly. Dolphins would be able to feed again on their natural prey, as they did for centuries in this same area. Fish less. Fish in less destructive ways. This is really the message.” This call to action reflects a growing recognition of the need for sustainable fishing practices that can support both human needs and the health of marine ecosystems.
The study, titled Bottlenose Dolphin Reliance on Trawlers in Prey-depleted Adriatic Sea Regions, was published in the journal Frontiers and involved a team of researchers who have dedicated decades to studying dolphin behavior in the Mediterranean. The findings serve as a critical reminder of the interconnectedness of human activity and marine life, emphasizing the urgent need for conservation efforts that protect vulnerable species and restore the health of our oceans.
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