Wooller Matthew J, Bradley Parker, Spaleta Karen J, Massengill Robert L, Dunker Kristine, Westley Peter A H
Alaska Stable Isotope Facility, University of Alaska Fairbanks, Fairbanks, Alaska, United States of America.
College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska, United States of America.
PLoS One. 2024 Dec 27;19(12):e0315320. doi: 10.1371/journal.pone.0315320. eCollection 2024.
The capacity for a non-native species to become invasive largely hinges on existing dispersal capacity or adaptation of dispersal in new environments. Here we provide early evidence that invasive Northern Pike (Esox lucius), a Holarctic freshwater top predator, illegally introduced in the late 1950s into Southcentral Alaska, are now dispersing through estuarine corridors. This finding represents the first known documentation of estuary use and dispersal by Northern Pike in North America, exacerbating conservation concerns for already depressed populations of culturally and economically important species such as salmonids. To reconstruct the migratory pathway of individual Northern Pike captured at locations known to be recently invaded, we analyzed the strontium isotope composition (87Sr/86Sr) in otoliths. In Vogel Lake, where Northern Pike were first observed in 2019, the smallest (youngest) Northern Pike collected had relatively constant 87Sr/86Sr values consistent with 87Sr/86Sr values of freshwater samples from the region and indicating a wholly freshwater existence. However, the largest Northern Pike (95.5 cm) in Vogel Lake had isotopic signatures indicating its early life had been in an estuarine habitat before moving into Vogel Lake through a short 4.8 km creek connecting it to the ocean. We subsequently analyzed otoliths from two other Northern Pike, from two additional separate locations in Southcentral Alaska, revealing signatures consistent with colonization through an estuarine corridor. It is unclear whether estuarine dispersal ability has evolved de novo in these Northern Pike populations or was retained by plasticity. Regardless, this early evidence is of considerable concern in Alaska and other regions of North America confronting Northern Pike introductions and underscores the urgency to monitor connected freshwater systems most vulnerable to invasion via adjoining estuarine habitats.
外来物种成为入侵物种的能力很大程度上取决于其现有的扩散能力或在新环境中对扩散的适应性。在此，我们提供了早期证据，表明入侵性白斑狗鱼（Esox lucius），一种全北区淡水顶级捕食者，于20世纪50年代末非法引入阿拉斯加中南部，现在正通过河口走廊扩散。这一发现代表了北美首次有记录的白斑狗鱼利用河口并通过河口扩散的情况，加剧了对鲑科鱼类等在文化和经济上具有重要意义且数量已减少的物种的保护担忧。为了重建在已知最近被入侵地点捕获的个体白斑狗鱼的洄游路径，我们分析了耳石中的锶同位素组成（87Sr/86Sr）。在2019年首次观察到白斑狗鱼的沃格尔湖，收集到的最小（最年幼）白斑狗鱼的87Sr/86Sr值相对恒定，与该地区淡水样本的87Sr/86Sr值一致，表明其完全生活在淡水中。然而，沃格尔湖最大的白斑狗鱼（95.5厘米）的同位素特征表明，它的早期生活是在河口栖息地，然后通过一条连接它与海洋的4.8公里短溪进入沃格尔湖。我们随后分析了来自阿拉斯加中南部另外两个不同地点的另外两条白斑狗鱼的耳石，发现其特征与通过河口走廊定殖一致。目前尚不清楚这些白斑狗鱼种群的河口扩散能力是全新进化而来还是通过可塑性保留下来的。无论如何，这一早期证据在阿拉斯加和北美其他面临白斑狗鱼引入的地区引起了相当大的关注，并强调了监测通过相邻河口栖息地最易受到入侵的相连淡水系统的紧迫性。
