Factors influencing the population status of wild Chinese alligators (Alligator sinensis)
Factors influencing the population status of wild Chinese alligators (Alligator sinensis)
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2004
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通讯作者：
D. You
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作者：
D. You
1998年4 ~ 8月，在安徽省扬子鳄国家级自然保护区内的200个乡镇（村）发放调查问卷200份。根据问卷调查结果，分别于1999、2000、2001、2002和2003年7 ~ 10月在扬子鳄最可能栖息的地区进行了夜间聚光灯定量调查。调查区包括安徽省宣城、泾县、广德、郎溪、南陵5个县市的36个点，浙江省长兴县和安吉县的7个点，江苏省宜兴市附近的2个点（富溪涧和大汉街）。根据这些调查结果，我们估计目前安徽和浙江两省的野生扬子鳄数量为120只。该种群被分成23个孤立的小地方种群，每个种群有1 - 10个个体。江苏省没有发现鳄鱼。对我们数据的分析表明，自20世纪50年代以来，野生扬子鳄的数量及其分布急剧下降。目前野生扬子鳄的数量估计比20世纪80年代的水平下降了76.5%。然而，从1998年到2003年，种群似乎一直稳定，估计有120只。在过去的50年里，导致种群数量下降的主要因素各不相同，但总体而言是栖息地的破碎化和退化、狩猎、自然灾害（洪水和干旱）、生产力低下和污染。从20世纪50年代到90年代，栖息地的丧失和短吻鳄的捕杀是最重要的因素。目前，杀死短吻鳄已经不是一个问题，但栖息地的丧失几乎已经完成。因此，保护扬子鳄的首要任务必须是恢复扬子鳄的栖息地，这是通过释放人工繁殖的扬子鳄来重新引入扬子鳄的第一步。此外，还必须解决环境污染和野生扬子鳄种群遗传多样性降低的潜在后果。
During April - August 1998, 200 questionnaires were distributed and collected in each of 200 towns and villages in the National Chinese Alligator Nature Reserve in Anhui Province. Based on the re- sults of the questionnaires, quantitative nocturnal spotlight surveys were carried out from July to October of 1999, 2000, 2001, 2002 and 2003 in areas most likely to have wild alligator populations. The survey area included 36 sites in five counties or municipalities (Xuancheng, Jingxian, Guangde, Langxi, Nan- ling) in Anhui Province, seven sites in Changxing County and Anji County of Zhejiang Province, and two sites (Fuxijian and Dahanjie) near Yixing City in Jiangsu Province. Based on these surveys we estimate that the current size of the wild Chinese alligator population in Anhui and Zhejiang Provinces is 120 individuals. The population is fragmented into 23 isolated small lo- cal populations with 1 - 10 individuals each. No alligators were found in Jiangsu Province. Analysis of our data revealed that the wild Chinese alligator population and its distribution have declined sharply since the 1950s. The current population size of wild Chinese alligators has declined an estimated 76.5% from its levels in the 1980s. However, the population appears to have been stable from 1998 to 2003 with an estimated 120 individuals. The factors most responsible for the population decline have varied over the last fifty years but overall have been habitat fragmentation and degradation, hunting, natural disasters (floods and drought), low productivity and pollution. From the 1950s to 1990s, habitat loss and the killing of alligators were the most significant factors. Presently, killing of alligators is less of an issue but the loss of habitat has been virtually complete. Therefore, the highest priority for conservation of Chinese alligators must be habitat restoration as the first step towards reintroducing alligators by releasing captive-bred individuals. In addi- tion, the potential consequences of environmental pollution and reduced genetic diversity of wild Chinese alligator population must also be addressed.