Center for Shark Research, Mote Marine Laboratory, Sarasota, Florida, United States of America.
PLoS One. 2011 Feb 11;6(2):e16918. doi: 10.1371/journal.pone.0016918.
To aid recovery efforts of smalltooth sawfish (Pristis pectinata) populations in U.S. waters a research project was developed to assess how changes in environmental conditions within estuarine areas affected the presence, movements, and activity space of this endangered species. Forty juvenile P. pectinata were fitted with acoustic tags and monitored within the lower 27 km of the Caloosahatchee River estuary, Florida, between 2005 and 2007. Sawfish were monitored within the study site from 1 to 473 days, and the number of consecutive days present ranged from 1 to 125. Residency index values for individuals varied considerably, with annual means highest in 2005 (0.95) and lowest in 2007 (0.73) when several P. pectinata moved upriver beyond detection range during drier conditions. Mean daily activity space was 1.42 km of river distance. The distance between 30-minute centers of activity was typically <0.1 km, suggesting limited movement over short time scales. Salinity electivity analysis demonstrated an affinity for salinities between 18 and at least 24 psu, suggesting movements are likely made in part, to remain within this range. Thus, freshwater flow from Lake Okeechobee (and its effect on salinity) affects the location of individuals within the estuary, although it remains unclear whether or not these movements are threatening recovery.
为了协助美国水域中小齿锯鳐（Pristis pectinata）种群的恢复工作，开展了一项研究项目，以评估河口地区环境条件的变化如何影响这一濒危物种的存在、移动和活动空间。2005 年至 2007 年间，在佛罗里达州卡卢萨哈奇河口下游 27 公里范围内，对 40 条幼年小齿锯鳐进行了声学标记监测。在研究地点，锯鳐的监测时间从 1 天到 473 天不等，连续出现的天数从 1 天到 125 天不等。个体的居留指数值差异很大，2005 年的年平均值最高（0.95），2007 年的最低（0.73），当时由于干旱条件下几条小齿锯鳐向上游移动超出了探测范围。平均每日活动空间为 1.42 公里的河道距离。活动中心 30 分钟之间的距离通常小于 0.1 公里，这表明短时间内的移动范围有限。盐度选择性分析表明，其对 18 至至少 24 个盐度单位的盐度有亲和力，这表明部分移动是为了保持在该范围内。因此，奥基乔比湖（Lake Okeechobee）的淡水流量（及其对盐度的影响）影响了个体在河口的位置，尽管尚不清楚这些移动是否对恢复构成威胁。
