Does size matter? A test of size‐specific mortality in Atlantic salmon Salmo salar smolts tagged with acoustic transmitters

• Published in: Journal of Fish Biology
• Main Authors: Newton, M., Barry, J., Dodd, J. A., Lucas, M. C., Boylan, P., Adams, C. E.
• Other Authors: European Union's INTERREG IVA Programme
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2016
• Subjects: Thumb; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1111/jfb.13066; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjfb.13066; https://onlinelibrary.wiley.com/doi/pdf/10.1111/jfb.13066

Mortality rates of wild Atlantic salmon Salmo salar smolts implanted with acoustic transmitters were assessed to determine if mortality was size dependent. The routinely accepted, but widely debated, ‘2% transmitter mass: body mass’ rule in biotelemetry was tested by extending the transmitter burden up to 12·7% of body mass in small [mean fork length ( L F ) 138·3 mm, range 115–168 mm] downstream migrating S. salar smolts. Over the short timescale of emigration (range 11·9–44·5 days) through the lower river and estuary, mortality was not related to S. salar size, nor was a relationship found between mortality probability and transmitter mass: body mass or transmitter length: L F ratios. This study provides further evidence that smolt migration studies can deviate from the ‘2% rule’ of thumb, to more appropriate study‐specific measures, which enables the use of fishes representative of the body size in natural populations without undue effects.