Yangtze River Porpoise in Danger
The Yangtze River porpoise, the only freshwater finless porpoise in existence, is in danger of becoming extinct .A study published in Environmental Toxicology and Chemistry has found concentrations of man-made chemicals in tissue samples from the endangered mammal which may be the cause of an encroaching extinction.
The Yangtze finless porpoise occurs only in the middle and lower reaches of the Yangtze River and in the Poyang and Dongting lakes in southeast China. The population of this porpoise has been decreasing by approximately 7.3 percent each year over the last several decades. In the early 1990s, the population was surveyed at nearly 2,700 .A 2006 survey estimated a maximum total population of 1,500. The porpoise is projected to become extinct in 24 to 94 years, unless conservation measures are taken.
The present study is the first to investigate the impacts of contaminants on the river porpoise population. The researchers collected five stranded Yangtze finless porpoises between 1998 and 2004 and sampled organs to study accumulated levels and preliminary effects of several contaminants including polychlorinated biphenyls, polybrominated diphenyl ethers, and polychlorinated dibenzo-p-dioxins and dibenzofurans.
The findings indicate that chemical contamination may be a contributing factor in the decline of the porpoise. Dongting Lake receives approximately 800 million tons of wastewater per year. A portion of this is chemical waste from local agriculture and industry .Other contributing factors to porpoise decline include fishing, transportation and dam construction.
Study results also indicated that there may be a greater hazard to finless porpoise calves than to adults from these contaminants because calves may experience greater exposure at a developmentally critical age. The results suggested that reducing environmental contamination may contribute greatly to protecting this highly endangered species.