Goodbody-Gringley Gretchen, Strand Emma, Pitt Joanna M
Bermuda Institute of Ocean Sciences, St. George, Bermuda.
University of Rhode Island, Kingston, RI, United States of America.
PeerJ. 2019 Jul 4;7:e7244. doi: 10.7717/peerj.7244. eCollection 2019.
Small-bodied marine fishes play an important role in the food web, feeding both larger fishes and seabirds. Often referred to as baitfishes, they concentrate seasonally in coastal areas in large, often heterospecific assemblages that are targeted by both commercial and recreational fishers. Given apparent declines in at least some of Bermuda's baitfish species over the past 40 years, it is useful to determine the species composition of baitfish assemblages, and how it varies among sites, in order to inform management. Using genetic barcoding of the Cytochrome c oxidase 1 gene (COI), we confirm species identity, assess intraspecific genetic diversity locally, and determine rates of broader genetic connectivity for baitfish assemblages in Bermuda. Species analyzed included , , , , and . Species identification based on molecular barcoding revealed some misidentification of individuals based solely on gross morphological characteristics, with an error rate of 11%, validating the usefulness of this approach. Interestingly, sequence results for the endemic Bermuda anchovy, , were within 1% similarity to the more broadly distributed big-eye anchovy, , and thus additional analyses are warranted to evaluate the genetic basis for endemism. Estimates of genetic diversity within and among baitfish assemblages in Bermuda were high, indicating high rates of local connectivity among sites for all species. As such, management should consider Bermuda's baitfish species as single, highly mixed populations. However, with the exception of and the endemic , significant genetic differentiation and population structure were found when comparing Bermuda's baitfish populations with those from other regions, suggesting limited gene flow between other regions and Bermuda for these species. Limited regional connectivity has implications for management, as strong genetic divergence suggests that populations in Bermuda are predominantly self-seeding and thus not likely to be replenished from distant populations. These results therefore support precautionary management of baitfish species in Bermuda.
小型海洋鱼类在食物网中发挥着重要作用，它们既是大型鱼类的食物，也是海鸟的食物。它们常被称为饵料鱼，季节性地集中在沿海地区，形成大型的、通常是异种混合的鱼群，商业和休闲渔民都会捕捞这些鱼群。鉴于在过去40年里，百慕大至少一些饵料鱼物种明显减少，确定饵料鱼群的物种组成及其在不同地点的变化情况，以便为管理提供依据是很有必要的。通过对细胞色素c氧化酶1基因（COI）进行基因条形码分析，我们确认了物种身份，评估了当地的种内遗传多样性，并确定了百慕大饵料鱼群更广泛的遗传连通率。分析的物种包括 、 、 、 、 和 。基于分子条形码的物种鉴定显示，仅根据总体形态特征对个体进行鉴定存在一些错误，错误率为11%，这验证了这种方法的有效性。有趣的是，百慕大特有种百慕大鳀鱼 的序列结果与分布更广的大眼鳀鱼 的相似度在1%以内，因此有必要进行进一步分析，以评估其特有性的遗传基础。百慕大饵料鱼群内部和之间的遗传多样性估计值很高，表明所有物种在不同地点之间的本地连通率很高。因此，管理部门应将百慕大的饵料鱼物种视为单一的、高度混合的种群。然而，除了 和特有种 外，将百慕大的饵料鱼种群与其他地区的种群进行比较时，发现了显著的遗传分化和种群结构，这表明这些物种在其他地区和百慕大之间的基因流动有限。有限的区域连通性对管理有影响，因为强烈的遗传差异表明百慕大的种群主要是自我繁殖的，因此不太可能从遥远的种群中得到补充。因此，这些结果支持对百慕大的饵料鱼物种进行预防性管理。
