A dolphin leaps from the water. [Photo/WeChat account: qianjiangwanbao]

A large group of dolphins was spotted swimming alongside vessels just off Dongji Island, Zhoushan, East China's Zhejiang province, on Aug 25. The playful scene lasted nearly 20 minutes as dolphins leapt from the sea and delighted the crew of Zhong Guo Huan Jian Zhe 001 during an open expedition.

This was the second large-scale dolphin sighting recorded this year by the Marine Ecological and Environmental Monitoring Center of Zhejiang Province, following a similar encounter in July. Dolphins have also been spotted by local coast guard patrols, fishermen, and tourists, highlighting the area's rich biodiversity.

Tang Jingliang, chief expert at the center, explained that dolphins often follow boats when propellers stir up small fish, making it easier for them to feed. The frequent sightings suggest an improving marine environment.

Zhejiang's coastal waters have long faced challenges such as nutrient overload and red tides caused by industrial discharge and river runoff. However, tighter controls on nitrogen and phosphorus have led to steady improvements. Monitoring data shows that from 2021 to 2024, 52.5 percent of coastal waters reached good quality standards, up 9.1 percentage points from 2020. The improvement ranks among the highest nationwide, supporting a sustained recovery of marine ecology in the region.