Harvey Alison C, Tang Yongkai, Wennevik Vidar, Skaala Øystein, Glover Kevin A
Institute of Marine Research Bergen Norway.
Freshwater Fisheries Research Center Chinese Academy of Fishery Sciences Wuxi China.
Ecol Evol. 2017 Aug 11;7(18):7490-7502. doi: 10.1002/ece3.3304. eCollection 2017 Sep.
Fisheries-induced evolution can change the trajectory of wild fish populations by selectively targeting certain phenotypes. For important fish species like Atlantic salmon, this could have large implications for their conservation and management. Most salmon rivers are managed by specifying an angling season of predetermined length based on population demography, which is typically established from catch statistics. Given the circularity of using catch statistics to estimate demographic parameters, it may be difficult to quantify the selective nature of angling and its evolutionary impact. In the River Etne in Norway, a recently installed trap permits daily sampling of fish entering the river, some of which are subsequently captured by anglers upstream. Here, we used 31 microsatellites to establish an individual DNA profile for salmon entering the trap, and for many of those subsequently captured by anglers. These data permitted us to investigate time of rod capture relative to river entry, potential body size-selective harvest, and environmental variables associated with river entry. Larger, older fish entered the river earlier than smaller, younger fish of both sexes, and larger, older females were more abundant than males and vice versa. There was good agreement between the sizes of fish harvested by angling, and the size distribution of the population sampled on the trap. These results demonstrate that at least in this river, and with the current timing of the season, the angling catch reflects the population's demographics and there is no evidence of size-selective harvest. We also demonstrated that the probability of being caught by angling declines quickly after river entry. Collectively, these data indicate that that the timing of the fishing season, in relation to the upstream migration patterns of the different demographics of the population, likely represents the most significant directional evolutionary force imposed by angling.
渔业诱导的进化可以通过选择性地针对某些表型来改变野生鱼类种群的轨迹。对于像大西洋鲑这样的重要鱼类物种，这可能对它们的保护和管理产生重大影响。大多数鲑鱼河流是通过根据种群统计学指定预定长度的垂钓季节来管理的，而种群统计学通常是根据捕捞统计数据建立的。鉴于使用捕捞统计数据来估计人口统计学参数存在循环性，可能难以量化垂钓的选择性本质及其进化影响。在挪威的埃特内河，一个最近安装的陷阱允许每天对进入河流的鱼类进行采样，其中一些随后被上游的垂钓者捕获。在这里，我们使用31个微卫星为进入陷阱的鲑鱼以及许多随后被垂钓者捕获的鲑鱼建立个体DNA图谱。这些数据使我们能够研究相对于河流进入时间的钓获时间、潜在的体型选择性捕捞以及与河流进入相关的环境变量。体型较大、年龄较大的鱼比体型较小、年龄较小的雌雄鱼更早进入河流，体型较大、年龄较大的雌性比雄性更丰富，反之亦然。垂钓捕捞的鱼的大小与陷阱中采样的种群大小分布之间有很好的一致性。这些结果表明，至少在这条河流中，并且在当前季节的时间安排下，垂钓渔获量反映了种群的人口统计学特征，并且没有体型选择性捕捞的证据。我们还证明，河流进入后被垂钓捕获的概率迅速下降。总体而言，这些数据表明，垂钓季节的时间安排，相对于种群不同人口统计学特征的上游洄游模式，可能代表了垂钓施加的最显著的定向进化力量。
