Abstract Escaped farmed salmon are a major concern for wild Atlantic salmon (Salmo salar) stocks in Norway. Fish scale analysis is a well-established method for distinguishing farmed from wild fish, but the process is labor and time intensive. Deep learning has recently been shown to automate this task with high accuracy, though typically on relatively small and geographically limited datasets. Here we train and validate a new convolutional neural network on nearly 90 000 scale images from two national archives, encompassing heterogeneous imaging protocols, hundreds of rivers, and time series extending back to the 1930s. The model achieved an F1 score of 0.95 on a large, independent test set, with predictions closely matching both genetic reference samples and known farmed-origin scales. By developing and testing this new model on a large and diverse dataset, we demonstrate that deep learning generalizes robustly across ecological and methodological contexts, supporting its use as a validated, large-scale tool for monitoring escaped farmed salmon.
Identifying escaped farmed salmon from fish scales using deep learning
M. Willmes,Anders Varmann Aamodt,Børge Solli Andreassen,Lina Victoria Tuddenham Haug,Enghild Steinkjer,G. Østborg,Gitte Løkeberg,Peder Fiske,Geir R Brandt,Terje Mikalsen,Arne Siversten,Magnus Moustache,June Larsen Ydsti,B. Florø-Larsen
Published 2025 in Biology Methods and Protocols
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- Publication year
2025
- Venue
Biology Methods and Protocols
- Publication date
2025-11-26
- Fields of study
Biology, Medicine, Computer Science, Environmental Science
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Semantic Scholar, PubMed
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