In-river behaviour and freshwater return rates of sea trout, Salmo trutta L., from two coastal river populations
Date
2022-07-22
Journal Title
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Publisher
Wiley
Abstract
The effective management of anadromous Salmo trutta resources is challenging
because long-term data on life history, phenology and survival are sparse and most
stocks across the range are highly diverse and data-limited. The current study
employed acoustic telemetry to tag 448 sea trout across three life stages, to describe
the phenology, spawning behaviour and return rates of smolts, finnock (0+ sea age)
and adult (≥1+ sea age) sea trout in two Irish river systems during 2018–2021.
Tagged smolts (n = 206) exhibited river to sea transition rates of 78%–92% and a
number of surviving smolts returned to their natal river as 0+ sea age finnock, exhibiting overall smolt to finnock return rates of between 6% and 17%. Short-term
vagrancy occurred among smolts, and 14 individuals were detected in adjacent nonnatal rivers. Finnock tagged during the late summer (n = 205) exhibited a range of
behaviours with a minority (<30%) ascending upstream to spawning areas. Tagged
adult sea trout (n = 37) ascended upstream to the spawning grounds and between
50% and 80% successfully returned to sea as kelts after spawning. Subsequent return
rates of kelts back to the river in the following year ranged from 9% to 40%. The
current study indicated that body size was an influential predictor of behaviour and
survival across all three life stages. Increased body size was positively associated with
marine transition success in smolts, long-term marine survival in kelts and spawning
behaviour in finnock. This work further demonstrates the complexity of sea trout
life-history dynamics and provides a comparative perspective across different age
classes. An understanding of life-history variation, behaviour and survival is f
Description
Publication history: Accepted - 9 July 2022; Published online - 14 July 2022.
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Article
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Keywords
anadromy, life-history, salmonids, telemetry
Citation
Kennedy, R.J., Barry, J., Roche, W., Rosell, R. and Allen, M. (2022) ‘In‐river behaviour and freshwater return rates of sea trout, Salmo trutta <scp>L</scp> ., from two coastal river populations’, Journal of Fish Biology. Wiley. doi:10.1111/jfb.15162.