North Pacific Anadromous Fish Commission

Technical Report 17

Table of Contents

Physiological Tools for Evaluating Growth Status of Migrating Salmon

Authors: 
Munetaka Shimizu

Abstract Excerpt:
Growth-dependent mortality of juvenile salmon during the early phase of their marine life has been an active area of research. Although the exact timing and the extent of growth-dependent mortality are not clear (Beacham et al. 2017), the general belief is that large and/or fast-growing juveniles have a better chance to survive and will be recruited to the stock (Beamish and Mahnken 2001). Monitoring growth status of out-migrating juveniles is therefore of particular importance. However, a direct measure of growth of individual fish requires marking and recapture of the same individuals, which is extremely difficult to conduct on free-swimming salmon. Instead, indirect methods are often used to evaluate/estimate growth. Among them, scales and otoliths are useful to reconstruct past growth patterns and habitats. However, they may not provide information on the recent/current growth rate. Biochemical growth indices such as muscle RNA/DNA ratio have been used to monitor recent/current growth, although their validity is somewhat incomplete (Johnson et al. 2002). Ideally, growth indices should be directly involved in the growth process and not a result of growth (Couture et al. 1998).

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DOI:
https://doi.org/10.23849/npafctr17/113.115.

Citation

Shimizu, M.  2021.  Physiological tools for evaluating growth status of migrating salmon.  N. Pac. Anadr. Fish Comm. Tech. Rep. 17: 113–115.  https://doi.org/10.23849/npafctr17/113.115.