Paulsen Tora, Sandlund Odd Terje, Østborg Gunnel, Thorstad Eva B, Fiske Peder, Muladal Rune, Tronstad Stig
UiT The Arctic University of Norway, Tromsø, Norway.
Norwegian Institute for Nature Research, Trondheim, Norway.
J Fish Biol. 2022 Jan;100(1):218-228. doi: 10.1111/jfb.14937. Epub 2021 Nov 24.
Invasive pink salmon (Oncorhynchus gorbuscha) has been present in variable, but low, numbers in Norwegian waters since c. 1960, but beginning in 2017 their numbers have exploded in rivers in northern Norway, with considerable numbers also recorded in rivers in southern Norway and other countries bordering the North Atlantic. Analysis of pink salmon scales from two rivers draining to the western Barents Sea showed declining growth during the first weeks after entering the sea, and some individuals even showed a pronounced growth arrest, based on detailed scale circulus analyses. This was followed by a period of growth increase and stability during late summer and autumn, which may reflect a transition to better food sources, as the fish migrate from coastal waters to the open ocean, and as they grow larger and can eat larger and more energy efficient food items. Growth declined to a minimum during winter. Fish body size at spawning was positively correlated with the distance from scale focus to the last winter circulus, as well as with the number of circuli. When dividing scale growth into three periods, better growth during the first period at sea was related to increased fish body length at spawning, but this early growth explained only a minor part (6%) of the variation in final body length. The reason for this may be large individual variation in growth combined with large mortality during the first weeks at sea. If mortality is selective, removing fish with poor growth may reduce a correlation between early growth and body size at spawning. Scale growth during late summer and early autumn explained more of the variation in fish length at spawning (27%). Hence, late summer and early autumn was likely an important period for marine growth and survival in the invasive pink salmon.
自约1960年以来，挪威水域就存在数量不一但较少的入侵型细鳞大麻哈鱼（Oncorhynchus gorbuscha），但从2017年开始，其数量在挪威北部的河流中激增，挪威南部以及北大西洋沿岸其他国家的河流中也记录到了相当数量的细鳞大麻哈鱼。对流入巴伦支海西部的两条河流中的细鳞大麻哈鱼鳞片进行分析后发现，这些鱼入海后的头几周生长速度下降，基于详细的鳞片年轮分析，一些个体甚至出现了明显的生长停滞。随后在夏末和秋季出现了生长加速和稳定期，这可能反映出随着鱼从沿海水域迁移到开阔海洋，以及随着它们长大并能够食用更大且能量效率更高的食物，它们转向了更好的食物来源。冬季生长降至最低水平。产卵时鱼的体型与从鳞片中心点到最后一个冬季年轮的距离以及年轮数量呈正相关。将鳞片生长分为三个时期后发现，在海上的第一个时期生长较好与产卵时鱼体长度增加有关，但这种早期生长仅解释了最终体长变化的一小部分（6%）。其原因可能是生长的个体差异较大，再加上在海上的头几周死亡率较高。如果死亡率具有选择性，去除生长不良的鱼可能会降低早期生长与产卵时体型之间的相关性。夏末和初秋的鳞片生长解释了产卵时鱼长度变化的更多部分（27%）。因此，夏末和初秋可能是入侵型细鳞大麻哈鱼海洋生长和存活的重要时期。
