Abundance and conservation status of the Yangtze finless porpoise in the Yangtze River, China

Abstract

Endangered Finless porpoise (Neophocaena phocaenoides) Line transect A B S T R A C TThe Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) is endemic to the middle and lower reaches of the Yangtze River, China. It is the only freshwater population of porpoises in the world and is currently listed as Endangered by IUCN. In November and December 2006 we used two boats and line transect methods to survey the entire current range of the population, except for two lakes (Poyang and Dongting). Sighting results were similar for both boats, so we pooled all data and analyzed them using two line transect models and a strip transect model. All models produced similar estimates of abundance (1111, 1225 and 1000). We then added independent estimates of the number of porpoises from the two lakes for a total estimate of approximately 1800 porpoises. Our findings indicate that the population continues to decline and that its distribution is becoming more fragmented. Our current estimate in the main river is slightly less than half the estimate from surveys between 1984 and 1991 (which was probably an underestimate). We also found an apparent gap in the distribution of porpoises between Yueyang and Shishou ($150 km), where sightings had previously been common. Continued threats to Yangtze finless porpoises include bycatch in unregulated and unselective fishing, habitat degradation through dredging, pollution and noise, vessel strikes and water development. Immediate protective measures are urgently needed to ensure the persistence of finless porpoises in the Yangtze River. The survey design and analytical methods developed in this study might be appropriate for surveys of cetaceans in other river systems.

Population status, threats and conservation of the Yangtze finless porpoise

“…In November and December of 2006, a systematic survey was conducted over the entire current range of the population in the main stem of the Yangtze River (excluding the two lakes, Poyang and Dongting) using a modified standard line-transect survey method pre-designed based on the results of a pilot survey between Wuhan and Yueyang [14] (Figure 1). Experts and researchers from the USA, UK, Germany, Japan, Switzerland, Canada and China joined this international collaborative effort, which utilized both visual and acoustic methods [14,15] . The findings of this extensive survey indicated that the population of the Yangtze finless porpoise in the main stem was approximately 1000 1200; if the populations in the two lakes were included, the entire extant population was approximately 1800.…”

“…These survey results indicate that the current finless porpoise population in the main stem of the river is less than half that estimated from surveys conducted between 1984 and 1991, when the total size of the population in this same section was approximately 2550 [11] . It further implies an annual rate of decline of at least 5% for the entire population in the main stem of the river [14] . The results of the survey also prompted Zhao et al [14] to warn that the distribution of the Yangtze finless is becoming more fragmented, and some gaps in the range may already exist.…”

Establishment and characterization of fibroblast cell lines from the skin of the Yangtze finless porpoise

“…The Yangtze finless porpoise, the sole freshwater subspecies of N. phocaenoides, has been listed as an endangered species (EN C2b) in the IUCN Red Data Book since 1996 (Baillie and Groombridge 1996) and has now been listed in the First Order of the National Key Protected Wild Aquatic Animals List in China. Its population has been decreasing annually at a rate of 5% or more (Zhao et al 2008). An exhaustive survey conducted in 2006 by experts from seven countries found that the population of the Yangtze finless porpoise in the main river stem was approximately 1,000∼1,200 individuals, which was less than half of the population size estimated from the surveys from the year 1984 to 1991, and that the distribution is becoming more fragmented (Zhao et al 2008;Wang 2009).…”

“…Its population has been decreasing annually at a rate of 5% or more (Zhao et al 2008). An exhaustive survey conducted in 2006 by experts from seven countries found that the population of the Yangtze finless porpoise in the main river stem was approximately 1,000∼1,200 individuals, which was less than half of the population size estimated from the surveys from the year 1984 to 1991, and that the distribution is becoming more fragmented (Zhao et al 2008;Wang 2009). Immediate, proactive, and effective measures must be taken to prevent the Yangtze finless porpoise from following the fate of the Baiji (Wang et al 2006).…”

B-Mode ultrasonographic evaluation of the testis in relation to serum testosterone concentration in male Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) during the breeding season

“…The population of the YFP was estimated at $2700 in 1991 [3] but has dropped dramatically in recent years, due to the negative impacts of various human activities, such as illegal fishing, shipping, pollution, water projects, and so forth [4]. At present, the population contains approximately 1800 individuals [5]. Effective protective measures must be rapidly enacted to protect the YFP from extinction.…”