Asian carp eggs cannot be distinguished from other cyprinid species on the basis of morphology alone: Supporting Data

Eggs were collected in the Upper Mississippi main stem (Pool 9 and Pool 11) during the summer of 2013. Using previously published morphological characteristics, eggs were positively identified as belonging to an invasive Asian carp genus. A subsample of these eggs was subsequently analyzed using molecular methods to determine species identity. Genetic identification of a total of 41 eggs was attempted using the cytochrome c oxidase 1 (COI) gene. Due to the preservation technique used (formalin) and resulting DNA degradation, sequences from only 17 individuals could be recovered. In all cases, non-carp cyprinids were identified as the most likely species identity (usually a Notropis spp.). In previously published reports, the primary morphological characteristic that distinguishes invasive carp from non-carp cyprinids is size. However, many of the eggs that were identified as non-carp cyprinids genetically were as large as 4.0 mm in diameter (at early developmental stages), large enough to overlap in size with Asian carp eggs on the low end of their size range. Other researchers studying fish eggs and early life history stages should plan on preserving a subset of collected eggs for genetic analysis to confirm morphological identifications.

2013年夏季，研究人员于密西西比河上游干流（第9池与第11池）采集了鱼卵。依托已发表的形态学特征，这批鱼卵被确证为入侵性亚洲鲤属物种所产。随后，研究团队选取该批次鱼卵的子样本，采用分子生物学方法开展分析以明确其物种归属。针对总计41枚鱼卵，研究人员以细胞色素c氧化酶亚基1（cytochrome c oxidase 1, COI）基因尝试开展遗传鉴定。但由于采用福尔马林（formalin）保存方案导致DNA降解，最终仅从17个样本中成功获取了有效基因序列。所有成功鉴定的样本中，其最可能的物种归类均为非鲤属的鲤科鱼类（通常为钝吻鱼属（Notropis spp.）物种）。既往发表的研究表明，区分入侵鲤与非鲤属鲤科鱼类的核心形态学特征为体型大小。然而，经遗传鉴定确认为非鲤属鲤科鱼类的这批鱼卵中，有不少在发育早期的直径可达4.0毫米，其尺寸下限已与亚洲鲤鱼卵的尺寸范围发生重叠。建议其他从事鱼类鱼卵及早期生活史阶段研究的科研人员，留存部分采集到的鱼卵样本用于遗传分析，以验证形态学鉴定结果。