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（9号库区与11号库区）采集鱼类卵粒。基于已发表的形态学特征，将所获卵粒明确鉴定为隶属于入侵性亚洲鲤属（Asian carp genus）的物种。随后，对其中一子样本采用分子生物学方法进行分析，以确定其具体物种。研究人员尝试借助细胞色素c氧化酶亚基1（cytochrome c oxidase 1, COI）基因，对总计41枚卵粒开展遗传鉴定。由于采用福尔马林（formalin）固定保存技术导致DNA降解，仅成功获得17枚个体的有效基因序列。所有成功测序样本的遗传鉴定结果均显示，其最可能的物种为非鲤类鲤科鱼类（non-carp cyprinids），多数隶属于钝吻鱼属（Notropis spp.）。既往发表的研究表明，区分入侵性鲤鱼与非鲤类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类鲤科鱼类的卵粒中，有不少在发育早期的直径可达4.0毫米，其尺寸下限与亚洲鲤卵粒的尺寸范围存在重叠。建议其他从事鱼类卵粒及早期生活史研究的科研人员，留存部分采集到的卵粒样本用于遗传分析，以验证形态学鉴定结果。