ISTANBUL, Dec. 18 (Xinhua) -- On a chilly winter morning along the European shores of the Bosphorus Strait, anglers cast their lines as giant container ships and oil tankers glide past a few hundred meters away. The low hum of engines blends with gulls' cries, a constant reminder of the strait's heavy maritime traffic.
As one of the world's busiest waterways, the Bosphorus links the Black Sea to the Marmara Sea, and beneath its busy surface lies a pressing question: can its waters endure rising shipping pressure and mounting environmental stress?
According to Transport and Infrastructure Minister Abdulkadir Uraloglu, 29,710 vessels transited the Bosphorus in the first nine months of 2025, with the total number expected to exceed 40,000 by the end of the year. He added that 1.2 billion gross tons of vessels passed through both the Bosphorus and the Dardanelles straits during this period.
The Istanbul branch of the Chamber of Agricultural Engineers estimates that the Bosphorus Strait, which cuts through Türkiye's largest city of Istanbul with a population of around 16 million, can accommodate up to 50,000 vessel transits per year. While the strait has not yet reached its full capacity, its narrow channels and sharp bends make it highly congested and at times risky.
On September 19, a passenger ferry collided with a cargo vessel in the Bosphorus Strait, injuring 12 people.
Local experts also warn that rising vessel traffic could pose growing environmental risks.
"Marine pollution remains one of the most serious threats, as rising vessel traffic increases the risk of oil spills, chemical discharges, and litter," said Murat Kapikiran, head of the Istanbul branch of the Chamber of Agricultural Engineers. He added that all ship discharges must be strictly monitored.
To address these challenges, Türkiye has introduced round-the-clock vessel monitoring and tighter controls on ship waste and ballast water. Under the 2025 tariff, pollution fines were raised by about 44 percent from 2024 levels. An oil spill from a tanker of up to 1,000 gross tons now incurs a fine of about 4,584 Turkish liras (107 U.S. dollars) per gross ton, with higher rates applied to larger vessels.
Another environmental pressure in the strait comes from underwater noise generated by ship engines. Kapikiran warned that excessive noise, especially during seasonal migrations, can disrupt fish behavior and increase their vulnerability as they adapt to changes in salinity and water density.
"Such noise can interfere with communication, feeding, predator detection and navigation, sometimes forcing fish to alter or abandon critical habitats," he said. While Türkiye has implemented measures to curb noise from small surface vessels,such as decibel monitoring by coast guard teams and fines for violations, experts say more protections are needed against underwater noise, which disrupts the habitats of marine life.
Pollution-driven ecological stress is reflected in recurring jellyfish blooms. Professor Firdes Saadet Karakulak of Istanbul University's Faculty of Aquatic Sciences emphasized that jellyfish, once largely seasonal, are now observed year-round in the Bosphorus Strait and the Sea of Marmara due to rising nitrogen and phosphorus levels.
"These blooms are fueled by pollution and overfishing, which reduce predators and increase plankton -- jellyfish's main food -- while warmer waters extend their reproductive period," she said, highlighting the mounting ecological pressures on the strait.
The environmental strain on the Bosphorus Strait extends beyond shipping. The Istanbul Environmental Status Report 2025, prepared by the Istanbul branch of the Chamber of Environmental Engineers, shows that about 55 percent of Istanbul's wastewater treatment capacity relies on preliminary treatment. Experts warn that this contributes to oxygen depletion, jellyfish blooms, and broader ecological stress in the strait. ■
