Data from: Evaluating otter reintroduction outcomes using genetic spatial capture-recapture modified for dendritic networks

River otters (Lontra canadensis) were extirpated from New Mexico by the
1950s. A limited reintroduction occurred during 2008–2010 in which 33
otters sourced from Washington (WA) were translocated to the Upper Rio
Grande Basin (URG) of New Mexico. We conducted a noninvasive genetic
capture-recapture survey during the winter of 2018 by collecting fecal DNA
samples from river otter scats found at latrines in the URG dendritic
network of perennial waterways. Our objectives were to: 1) estimate
genetic diversity and effective population size; 2) genetic divergence
from the WA source population and potential connectivity with regionally
proximal populations; 3) spatially explicit population density and size;
and 4) population growth rate since the founder event. Between February
and April 2018, we collected 1,184 fecal DNA samples from 622 individual
scats at 20 latrines; genotyping was attempted at 10 otter-specific
microsatellite loci for a subsample of 543 samples. A bottlenecking
founder effect was strongly supported, which, combined with genetic drift,
reduced genetic diversity and effective population size by 20–26% and
106–170%, respectively, compared with the WA source population. Estimated
population density from spatial capture-recapture models was 0.23–0.28
otter/km of waterway, or 1 otter/3.57–4.35 km of waterway, corresponding
to a total population size of 83–100 otters across 359 km of the perennial
dendritic network from La Mesilla, New Mexico to Alamosa National Wildlife
Refuge, Colorado. Estimated average annual population growth rate since
the founder event was 1.12–1.15/year. Despite successful population
establishment, the URG river otter population remains small, is
genetically degraded, and does not yet meet the criteria for long-term
reintroduction success. Projections suggested that the population could
reach the recommended minimum viable population size of ≥400 otters by the
years 2030–2033, though sufficient habitat may not exist in the URG Basin
to support that many otters.

北美河獭（Lontra canadensis）于20世纪50年代从新墨西哥州区域性绝迹。2008至2010年间，当地实施了有限规模的再引入项目，将33只源自华盛顿州（WA）的河獭迁地放归至新墨西哥州里奥格兰德上游流域（Upper Rio Grande Basin, URG）。本研究于2018年冬季开展非侵入式遗传捕获-重捕（capture-recapture）调查，通过在URG常年性水系树状分布网络的河獭固定粪点处采集粪便样本，获取粪便DNA（fecal DNA）。本研究的目标为：1）估算种群遗传多样性与有效种群规模（effective population size）；2）分析该种群与华盛顿州源种群的遗传分化，以及与区域邻近种群的潜在连通性；3）开展空间显式（spatial explicit）的种群密度与总规模估算；4）估算自奠基事件以来的种群增长率。2018年2月至4月期间，研究团队在20个固定粪点中共采集到622份独立粪便样本，总计1184份粪便DNA；针对其中543份子样本，采用10个河獭特异性微卫星位点（microsatellite loci）开展基因分型尝试。研究结果强烈支持奠基者瓶颈效应（founder bottleneck effect），结合遗传漂变（genetic drift）作用，该种群的遗传多样性与有效种群规模分别较华盛顿州源种群降低了20%~26%与106%~170%。基于空间捕获-重捕模型估算的种群密度为0.23~0.28只河獭/公里水系，即每3.57~4.35公里水系对应1只河獭；对应覆盖从新墨西哥州拉梅西亚至科罗拉多州阿拉莫萨国家野生动物保护区的359公里常年性树状水系网络，总种群规模为83~100只河獭。自奠基事件以来，估算的年均种群增长率为1.12~1.15/年。尽管种群已成功建立，但URG流域的河獭种群依然规模偏小、遗传多样性受损，暂未达到长期再引入成功的判定标准。种群预测结果显示，该种群或可在2030至2033年间达到建议的最小存活种群规模（minimum viable population, MVP，≥400只河獭），但URG流域内或不足以提供承载该种群规模所需的栖息地。