Wacker Sebastian, Skaug Hans J, Forseth Torbjørn, Solem Øyvind, Ulvan Eva M, Fiske Peder, Karlsson Sten
Norwegian Institute for Nature Research Trondheim Norway.
Department of Mathematics University of Bergen Bergen Norway.
Ecol Evol. 2021 Apr 6;11(9):3917-3932. doi: 10.1002/ece3.7279. eCollection 2021 May.
Genetic methods for the estimation of population size can be powerful alternatives to conventional methods. Close-kin mark-recapture (CKMR) is based on the principles of conventional mark-recapture, but instead of being physically marked, individuals are marked through their close kin. The aim of this study was to evaluate the potential of CKMR for the estimation of spawner abundance in Atlantic salmon and how age, sex, spatial, and temporal sampling bias may affect CKMR estimates. Spawner abundance in a wild population was estimated from genetic samples of adults returning in 2018 and of their potential offspring collected in 2019. Adult samples were obtained in two ways. First, adults were sampled and released alive in the breeding habitat during spawning surveys. Second, genetic samples were collected from out-migrating smolts PIT-tagged in 2017 and registered when returning as adults in 2018. CKMR estimates based on adult samples collected during spawning surveys were somewhat higher than conventional counts. Uncertainty was small (CV < 0.15), due to the detection of a high number of parent-offspring pairs. Sampling of adults was age- and size-biased and correction for those biases resulted in moderate changes in the CKMR estimate. Juvenile dispersal was limited, but spatially balanced sampling of adults rendered CKMR estimates robust to spatially biased sampling of juveniles. CKMR estimates based on returning PIT-tagged adults were approximately twice as high as estimates based on samples collected during spawning surveys. We suggest that estimates based on PIT-tagged fish reflect the total abundance of adults entering the river, while estimates based on samples collected during spawning surveys reflect the abundance of adults present in the breeding habitat at the time of spawning. Our study showed that CKMR can be used to estimate spawner abundance in Atlantic salmon, with a moderate sampling effort, but a carefully designed sampling regime is required.
用于估计种群规模的遗传方法可以成为传统方法的有力替代方案。近亲标记重捕法（CKMR）基于传统标记重捕法的原理，但个体不是通过物理标记，而是通过其近亲进行标记。本研究的目的是评估CKMR在估计大西洋鲑鱼产卵群体数量方面的潜力，以及年龄、性别、空间和时间采样偏差如何影响CKMR估计值。根据2018年返回的成年个体及其2019年收集的潜在后代的基因样本，估计了一个野生种群中的产卵群体数量。成年个体样本通过两种方式获得。第一，在产卵调查期间，在繁殖栖息地对成年个体进行采样并放生。第二，从2017年植入PIT标签的洄游幼鱼中收集基因样本，并在它们于2018年作为成年个体返回时进行记录。基于产卵调查期间收集的成年个体样本的CKMR估计值略高于传统计数。由于检测到大量亲子对，不确定性较小（CV < 0.15）。成年个体的采样存在年龄和大小偏差，对这些偏差进行校正后，CKMR估计值有适度变化。幼鱼的扩散有限，但成年个体的空间平衡采样使CKMR估计值对幼鱼的空间偏差采样具有稳健性。基于返回的植入PIT标签的成年个体的CKMR估计值大约是基于产卵调查期间收集的样本的估计值的两倍。我们认为，基于植入PIT标签的鱼类的估计值反映了进入河流的成年个体的总数量，而基于产卵调查期间收集的样本的估计值反映了产卵时繁殖栖息地中成年个体的数量。我们的研究表明，CKMR可用于估计大西洋鲑鱼的产卵群体数量，但需要适度的采样工作，并且需要精心设计采样方案。
