We used sibship analysis to further our understanding of Alligator Gar Atractosteus spatula reproductive biology. Quantifying the relative contributions of spawners and spatial patterns of reproduction is important in making management decisions, especially with regard to long‐lived, large‐bodied fish like Alligator Gar, for which exploitation of large females may negatively impact recruitment. Using genetic data from age‐0 fish, we estimated the effective number of breeders (N_b) and the number of spawning adults (N_S) at multiple spatial and temporal scales in two Texas systems over a 2‐year period. Analysis of 265 fish collected in 2015 from six sites within an approximately 3,000‐ha floodplain wetland system on the Trinity River identified no full siblings or half siblings with a probability greater than 0.90. Estimates of N_b (24–30) and N_S (21–33) were comparable among sites, with low levels of relatedness among individuals within sites. Analysis of an additional 136 age‐0 Alligator Gar collected during 2015 from six other sites distributed over 275 river kilometers downstream of the wetland system revealed similar patterns. Age‐0 fish collected in Choke Canyon Reservoir (N = 131) in 2015 also demonstrated close correspondence between estimates of N_b and N_S (54 and 56, respectively). Age‐0 Alligator Gar (N = 88) were again collected at three sites in the Trinity River system during 2016; results were comparable to those of the previous year, with no evidence of repeat spawning at each site. The similarities we observed between the estimated N_b and N_S indicated little variance in the number of offspring produced among individual spawners. Because individual spawners appear to contribute somewhat equally to the year‐classes and spawning appears to occur over a broad geographic extent, there is likely little risk of year‐class failure from harvesting a sustainable number of spawning adults.

中文翻译：

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同胞分析，以表征两个德克萨斯州系统中扬子鳄的生殖贡献

我们用亲缘关系分析，我们进一步鳄雀鳝的理解Atractosteus锅铲生殖生物学。量化产卵者的相对贡献和繁殖的空间模式对于制定管理决策非常重要，尤其是对于长寿命大体鱼类，例如短吻鳄，对大雌鱼的剥削可能会对招聘产生不利影响。利用0岁以下鱼类的遗传数据，我们估算了育种者的有效数量（N _b）和产卵成虫的数量（N _S）在两年内在两个德克萨斯系统中处于多个时空尺度。2015年对三位一体河上约3,000公顷的洪泛区湿地系统中六个地点采集的265条鱼进行了分析，发现没有完整的兄弟姐妹或一半的兄弟姐妹概率大于0.90。地点之间的N _b（24-30）和N _S（21-33）的估计值具有可比性，地点内个人之间的相关性水平较低。对2015年期间从分布在湿地系统下游275河公里处的六个其他地点收集的另外136个0岁的扬子鳄的分析发现了类似的模式。在oke谷峡谷水库中收集的0岁以下鱼类（N  = 131）在2015年也证明了N _b和N _S（分别为54和56）估算值之间的密切对应关系。2016年，在三位一体河系统的三个地点再次采集了0岁鳄鱼皮Gar（N  =  88）。结果与上一年相当，没有证据表明每个站点重复产卵。我们在估算的N _b和N _S之间观察到相似之处表示各个个体中产生的后代数量几乎没有差异。由于各个产卵场似乎对年级的贡献均等，并且产卵似乎发生在广泛的地理范围内，因此，收获可持续数量的产卵成年后，年级失灵的风险很小。