Johansen Torild, Besnier François, Quintela María, Jorde Per Erik, Glover Kevin A, Westgaard Jon-Ivar, Dahle Geir, Lien Sigbjørn, Kent Matthew P
Institute of Marine Research (IMR) Tromsø Norway.
Institute of Marine Research (IMR) Bergen Norway.
Evol Appl. 2020 Sep 5;13(10):2673-2688. doi: 10.1111/eva.13070. eCollection 2020 Dec.
Challenging long-held perceptions of fish management units can help to protect vulnerable stocks. When a fishery consisting of multiple genetic stocks is managed as a single unit, overexploitation and depletion of minor genetic units can occur. Atlantic cod () is an economically and ecologically important marine species across the North Atlantic. The application of new genomic resources, including SNP arrays, allows us to detect and explore novel structure within specific cod management units. In Norwegian waters, coastal cod (i.e. those not undertaking extensive migrations) are divided into two arbitrary management units defined by ICES: one between 62° and 70°N (Norwegian coastal cod; NCC) and one between 58° and 62°N (Norwegian coastal south; NCS). Together, these capture a fishery area of >25,000 km containing many spawning grounds. To assess whether these geographic units correctly represent genetic stocks, we analysed spawning cod of NCC and NCS for more than 8,000 SNPs along with samples of Russian White Sea cod, north-east Arctic cod (NEAC: the largest Atlantic stock), and outgroup samples representing the Irish and Faroe Sea's. Our analyses revealed large differences in spatial patterns of genetic differentiation across the genome and revealed a complex biological structure within NCC and NCS. Haplotype maps from four chromosome sets show regional specific SNP indicating a complex genetic structure. The current management plan dividing the coastal cod into only two management units does not accurately reflect the genetic units and needs to be revised. Coastal cod in Norway, while highly heterogenous, is also genetically distinct from neighbouring stocks in the north (NEAC), west (Faroe Island) and the south. The White Sea cod are highly divergent from other cod, possibly yielding support to the earlier notion of subspecies rank.
挑战长期以来对鱼类管理单元的认知有助于保护脆弱种群。当一个由多个遗传种群组成的渔业被作为一个单一单元进行管理时，较小的遗传单元可能会出现过度开发和枯竭的情况。大西洋鳕鱼（）是北大西洋一种具有经济和生态重要性的海洋物种。包括单核苷酸多态性（SNP）阵列在内的新基因组资源的应用，使我们能够检测和探索特定鳕鱼管理单元内的新结构。在挪威水域，沿海鳕鱼（即那些不进行大规模洄游的鳕鱼）被国际海洋考察理事会（ICES）划分为两个任意的管理单元：一个在北纬62°至70°之间（挪威沿海鳕鱼；NCC），另一个在北纬58°至62°之间（挪威南部沿海；NCS）。这两个单元共同覆盖了一个面积超过25000平方千米、包含许多产卵场的渔业区域。为了评估这些地理单元是否正确代表了遗传种群，我们分析了NCC和NCS的产卵鳕鱼，检测了超过8000个单核苷酸多态性位点，同时分析了俄罗斯白海鳕鱼、东北极鳕鱼（NEAC：大西洋最大的种群）的样本，以及代表爱尔兰海和法罗海的外群样本。我们的分析揭示了整个基因组遗传分化空间模式的巨大差异，并揭示了NCC和NCS内部复杂的生物学结构。来自四个染色体组的单倍型图谱显示了区域特异性的单核苷酸多态性，表明存在复杂的遗传结构。目前将沿海鳕鱼仅划分为两个管理单元的管理计划并未准确反映遗传单元，需要进行修订。挪威的沿海鳕鱼虽然高度异质，但在遗传上也与北部（NEAC）、西部（法罗群岛）和南部的相邻种群不同。白海鳕鱼与其他鳕鱼差异很大，这可能支持了早期关于亚种等级的观点。
