Conservation scientists rarely have the information required to understand changes in abundance over more than a few decades, even for important species like Pacific salmon. Such lack of historical information can underestimate the magnitude of decline for depressed populations. We applied genetic tools to a unique collection of 100‐year‐old salmon scales to reveal declines of 56%–99% in wild sockeye populations across Canada's second largest salmon watershed, the Skeena River. These analyses reveal century‐long declines that are much greater than those based on modern era abundance data, which suggested that only 7 of 13 populations declined over the last five decades. Populations of larger‐bodied fish have declined the most in abundance, likely because of size‐selective commercial fisheries. Our findings illustrate how a deep historical perspective can expand our understanding of past abundances to a time before species incurred significant losses from fishing, and help inform conservation for diminished populations.

中文翻译：

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具有百年历史的鱼鳞的遗传学揭示了种群下降的模式

保护科学家很少能了解几十年来的丰度变化，即使对于像太平洋鲑鱼这样的重要物种也是如此。缺乏历史信息可能低估了沮丧人口的下降幅度。我们将遗传工具应用于100年前的鲑鱼鳞片的独特收集中，发现加拿大第二大鲑鱼流域Skeena河的野生红鲑种群下降了56％–99％。这些分析揭示了一个世纪以来的下降幅度，其下降幅度远大于根据现代时代的丰裕度数据得出的下降幅度，该数据表明，在过去的五十年中，只有13个人口中的7个下降了。体型较大的鱼类种群数量下降最多，这可能是由于规模选择性的商业性渔业造成的。