Utne Kjell Rong, Brieuc Marine Servane Ono, Fjeldheim Per Tommy, Urdal Kurt, Østborg Gunnel Marie, Glover Kevin A, Harvey Alison, Skaala Øystein
Department of population genetics, Institute of Marine Research, Bergen, Norway.
Rådgivende Biologer AS, Bergen, Norway.
PLoS One. 2025 May 8;20(5):e0316075. doi: 10.1371/journal.pone.0316075. eCollection 2025.
Understanding changes in abundance and survival in Atlantic salmon populations requires knowledge of growth rates and age. Salmon are typically aged through scale reading, but such estimates are rarely validated against age-verified fish from the wild. Here, we present a unique dataset of scales from 254 PIT-tagged Atlantic salmon with known sea-age. In addition, the freshwater age is known for 81 of these fish, through genetic parent-offspring identification. This dataset was used to estimate precision and bias in age readings and back-calculated length, as estimated by three independent experienced salmon scale readers. Overall, readers had an accuracy of 97.1% for sea-age and 71.7% for freshwater-age. For sea-age, scale reading was less accurate for salmon that had spent 2 or more years at sea than for salmon that had spent 1 year at sea. Freshwater age did however not affect scale reading accuracy. None of the scale readers erroneously misclassified freshwater- or sea-age with more than one year, and there was no significant pattern of misclassified ages to be under- or overestimate by the scale readers. Back-calculated smolt length was significantly different to length when measured as a smolt prior to seaward migration: it was shorter than the measured body-length for small smolts and longer for large smolts. This unique dataset, including the age-validated images of all scales, is now made openly available providing an important resource for training and testing salmon scale readers globally.
了解大西洋鲑鱼种群数量和存活率的变化需要掌握生长率和年龄信息。鲑鱼通常通过鳞片读数来确定年龄，但此类估计很少与野外经年龄验证的鱼进行比对验证。在此，我们展示了一个独特的数据集，该数据集来自254条带有已知海龄的PIT标记大西洋鲑鱼的鳞片。此外，通过遗传亲子鉴定，其中81条鱼的淡水年龄也已知。这个数据集被用于估计由三位经验丰富的独立鲑鱼鳞片读数员估计的年龄读数和反推长度的精度和偏差。总体而言，读数员对海龄的准确率为97.1%，对淡水年龄的准确率为71.7%。对于海龄，在海上度过2年或更长时间的鲑鱼的鳞片读数比在海上度过1年的鲑鱼的鳞片读数准确性更低。然而，淡水年龄并不影响鳞片读数的准确性。没有一个鳞片读数员将淡水年龄或海龄错误分类超过一年，并且鳞片读数员也没有明显的将年龄错误分类为低估或高估的模式。反推的当年幼鲑长度与在向海洄游前作为当年幼鲑测量的长度有显著差异：对于小当年幼鲑，它比测量的体长短，而对于大当年幼鲑则更长。这个独特的数据集，包括所有鳞片的年龄验证图像，现已公开提供，为全球培训和测试鲑鱼鳞片读数员提供了重要资源。
