Discarded Plastic Bottles Can Save Dolphins from Fishing Nets: New UK Research

Research published by Newcastle University on July 2, 2026, proves that discarded plastic and glass beverage bottles floating in the oceans can surprisingly play a crucial role in protecting marine mammals. Two recently published independent studies highlighted that by attaching upcycled bottles to fishing nets, dolphin bycatch can be reduced by up to 88 percent without significantly impacting the fishers’ catch. The method is simultaneously low-cost, globally applicable, and provides a useful, second life for polluting waste through recycling.

The Invisible Danger of Fishing Nets and How Acoustic Reflectors Work

The main threat to marine mammals worldwide is accidental capture in fishing gear, known as bycatch. Gillnets are made of nylon, making them almost completely invisible—both visually and acoustically—to echolocating animals in the water. The concept, developed by Per Berggren, Emeritus Professor of Marine Megafauna Conservation at Newcastle University’s School of Natural & Environmental Sciences, sought a simple, cost-effective solution to this global problem.

The core of the solution involves the use of reflectors on the nets. These are attached devices that make the otherwise invisible obstacle acoustically detectable to dolphins and porpoises. Discarded plastic bottles containing air attached to the nets act as excellent underwater sound reflectors. Additionally, glass bottles containing metal bolts were tested, which produce a continuous clinking sound in the ocean currents. Both methods help dolphins detect the exact location of the nets, allowing them to avoid the deadly trap while fishers can continue to harvest their target species undisturbed.

Results in Zanzibar, Peru, and Brazil: Differences Between Net Types

The first study—whose results were published in the scientific journal Fisheries Research—was conducted in surface-set driftnet fisheries in Zanzibar and Peru, and bottom-set gillnet fisheries in Brazil. Workshops were held with active involvement from local communities to introduce the project’s goals to the fishers and secure their participation. During the fieldwork, more than 1,600 fishing net deployments with attached bottles were monitored and compared with standard nets that had no bottles attached.

The experiment yielded instructive results. In Zanzibar and Peru, plastic bottles on surface nets actually increased the targeted fish catch; however, neither glass nor plastic bottles significantly reduced the bycatch of dolphins, porpoises, or sea turtles. In contrast, the trials in Brazil proved clearly promising for bottom-set net fishing: based on the data, the technique potentially reduced accidental dolphin captures while an increase in fish catch was also observed here.

The 88 Percent Breakthrough: Long-Term Observations in Brazil

Building on the encouraging results of the Brazilian bottom-set net experiment, the research team continued their investigations in a second, expanded study published in the journal Marine Mammal Science. During a five-year period between 2020 and 2025, a total of 318 fishing trips were monitored. Comparing the nets equipped with plastic bottles to standard gear brought a clear statistical breakthrough: nets fitted with the bottles proved to reduce dolphin bycatch by 88 percent. Meanwhile, the fishery yield of commercially important fish species remained completely unchanged.

Professor Per Berggren pointed out when evaluating the data that the drastic difference between the success of surface and bottom-set applications is likely explained by environmental noise levels. The surface water is a significantly noisier environment, which can heavily drown out sounds, thereby reducing the effectiveness of acoustic reflectors made from plastic bottles.

Recycling That Saves Lives in the Oceans

The lead researcher emphasized the dual benefit of the project. “This is a good news story and something that we strive for – a simple solution which benefits both dolphins and the fishers who use the gear,” Professor Berggren summarized. The researcher highlighted that the method is extremely cost-effective, so any fisher in the world can easily afford it.

Another major achievement noted was that the waste used during the experiments did not further pollute nature: the bottles were secured to the nets so stably and safely that not a single plastic bottle was lost in the ocean during the trials. The expert team is currently working with governments and agencies to spread this life-saving technique as widely as possible. The global testing of the methodology has not stopped: further research testing the effectiveness of plastic bottles is currently underway in Cambodian and Congolese fisheries.

References and Official Links:

• Original Source: Newcastle University Press Office (July 2, 2026): Discarded plastic bottles help save dolphins from fishing nets

• Government/State Reference: Official research summary by the US Marine Mammal Commission (.gov), which verifies the Brazilian experiments and the efficacy of plastic bottles in reducing bycatch: Highlighting Recent Research Grants – MMC.gov