BEIJING–A chemical applied to ship hulls is robbing Chinese sturgeon of their eyes and causing other deformities, according to a new study. The toxin may deal a death blow to the already-endangered fish, a living fossil that the Chinese government considers a “national treasure.”
The Chinese sturgeon (Acipenser sinensis) has lived in the Yangtze River for 140 million years, making it one of the world’s oldest fish. Although the 450-kilogram sturgeon once thrived in these waters, overfishing and the loss of spawning areas to dams has cut its numbers by roughly 85% over the past 30 years. As of 2007, there were only about 500 spawning sturgeon left in the Yangtze.
Now Chinese scientists have identified a new threat: triphenyltin (TPT), a biocide applied to ship hulls and fishing nets that prevents the buildup of algae and other aquatic hitchhikers. The compound has slowly washed from ships and accumulated in Yangtze sediments. In this week’s issue of the Proceedings of the National Academy of Sciences, Hu Jianying, a professor at the College of Urban and Environmental Sciences at Peking University in Beijing, and colleagues report a direct correlation between TPT levels in water and sturgeon deformities. The team captured more than 1000 Chinese sturgeon larvae from the Yangtze and recorded the incidence of mutations: 6.3% exhibited morphological deformities such as gnarled spinal cords, and 1.2% had only one eye or no eyes at all. Sturgeon raised in a TPT-free environment in land-based breeding facilities, by comparison, had a 0.66% rate of morphological deformities and no ocular deformities.