Full Breakdown
Adriatic Bottlenose Dolphins Turn to Trawlers as Overfishing Depletes Prey
7/4/2026, 11:24:08 AM
Dolphins Follow Trawlers for Food
Bottlenose dolphins in the northern Adriatic are increasingly following commercial trawlers to scavenge discards. Researchers logged 859 trawler inspections over 148 days in Veneto and Marche, observing routine dolphin foraging near trawl gear.
Overfishing in the Adriatic
The Adriatic Sea is among the world’s most overfished; fishing pressure is twice the FAO’s sustainable level. Decades of bottom-trawl activity have damaged the seabed and removed most apex predators, leaving bottlenose dolphins as the only large marine predator.
Lead Researchers and Institutions
Lead author Giovanni Bearzi, president of Dolphin Biology and Conservation (Italy), collaborated with Silvia Bonizzoni, Nathan B. Furey, and Randall R. Reeves, chair of the U.S. Marine Mammal Commission’s scientific advisory committee. The study appeared in *Frontiers in Mammal Science*.
Extent of Dolphin-Trawler Interactions
- 76 % of otter trawlers in Marche and 26 % in Veneto were followed.
- Dolphins followed 41 % of otter, 35 % of mid-water, and 1.5 % of beam trawlers.
- Photo-identification shows 86–90 % of >1,000 dolphins trailing vessels; a separate analysis finds 24.7 % of all trawlers followed.
Ecological and Conservation Implications
Following trawlers exposes dolphins to gear entanglement, injury, and chronic noise-induced hearing loss, potentially altering diet, social structure, and communication. Calf learning of this behavior indicates a culturally transmitted dependence that may endure even if natural prey rebounds.
Official Statements & Responses
Bearzi said dolphins must find food on days without trawlers and urged less destructive fishing. Reeves warned that adequate prey may be unavailable in an overfished sea, making trawl reliance risky. Bonizzoni noted the population exceeds 1,000 dolphins, photographed near vessels.
Criticism of Trawl Practices
The authors describe trawling as causing profound damage to Adriatic ecosystems and call for conservation action to protect biodiversity. They deem continued trawl use inadvisable for dolphin welfare and the broader marine community.
Conflicting Reports & Data Gaps
Reported trawler-following rates vary: one analysis cites 24.7 % overall, while region-specific data show 76 % in Marche and 26 % in Veneto. The study does not quantify mortality from gear entanglement or long-term health effects.
Verbatim Quotes
- “These days the easiest way to find [bottlenose dolphins] is to look for trawlers,” — Giovanni Bearzi, President, Dolphin Biology and Conservation
- “The baby dolphins follow the trawlers with their mothers, watch the adults foraging and learn that kind of behaviour. It is transmitted culturally.” — Giovanni Bearzi
- “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,” — Randall R. Reeves, Chairman, U.S. Marine Mammal Commission
- “Dolphins may also suffer hearing damage that results from chronic exposure to the noise of trawlers.” — Randall R. Reeves
Future Outlook
The authors call for phasing out bottom-otter trawling and adopting less destructive fishing. They predict reduced pressure will let fish stocks recover, allowing dolphins to resume natural foraging and supporting broader biodiversity.
