Evidence for size-based predation risk during Atlantic salmon (Salmo salar) smolt migration

Mensinger, Matthew A.; Mortelliti, Alessio; Zydlewski, Joseph D.

doi:10.1111/jfb.70011

i

Evidence for size-based predation risk during Atlantic salmon (Salmo salar) smolt migration

2025
By Mensinger, Matthew A. ; Mortelliti, Alessio ; Zydlewski, Joseph D.

Details

Journal Title:

Journal of Fish Biology
Personal Author:

Mensinger, Matthew A. ; Mortelliti, Alessio ; Zydlewski, Joseph D.
NOAA Program & Office:

NMFS (National Marine Fisheries Service) ; NEFSC (Northeast Fisheries Science Center) ; OAR (Oceanic and Atmospheric Research) ; CINAR (Cooperative Institute for the North Atlantic Region)
Description:

Hatchery supplementation is frequently employed during the conservation and recovery of imperilled salmon populations. At the smolt stage, hatchery rearing practices often produce individuals that are larger than wild conspecifics. Under this ‘bigger is better’ strategy, it is assumed that larger fish are less susceptible to predation during migration. We tested this hypothesis on hatchery-reared Atlantic salmon (Salmo salar) smolts with fork lengths representative of those of natural and hatchery origins, allowing us to isolate the influence of size from rearing history. From May to June 2023 we characterized predation risk for acoustic-tagged (n = 50) and tethered (n = 192) smolts of various sizes through a mostly free-flowing section of the Penobscot River, Maine, USA. Across both methods, more than 50% of smolts were predated, with the majority of predation events being attributed to smallmouth bass (Micropterus dolomieu). Tethered smolts of all sizes experienced similar predation risk. In the acoustic telemetry component of this study, smaller, wild-sized smolts incurred greater overall mortality relative to standard hatchery sizes (95% vs. 75%), the majority of which occurred within 3 km of the release site. Collectively, these results allude to a strong predation influence imposed by smallmouth bass on smolts in freshwater sections of the Penobscot River and small-bodied migrants may incur greater predation risk, particularly near stocking sites.
Keywords:

Atlantic Salmon Conservation Biology Endangered Species Predation (Biology) Smallmouth Bass Smolting Atlantic Salmon Conservation Biology Endangered Species Smallmouth Bass Salmo Salar
Source:

Journal of Fish Biology, 1–15
DOI:

https://doi.org/10.1111/jfb.70011
Format:

PDF
Document Type:

Journal Article
Funding:

Grant no. NA19OAR4320074
License:

https://creativecommons.org/publicdomain/zero/1.0/
Rights Information:

CC0 Public Domain
Compliance:

Submitted
Main Document Checksum:

urn:sha-512:c5c89d4cd91893d0a471931c17aab2efd4cb8e5521abfb0ce24357987127e131bd722ad229ad6d9840d7789136b1f8f25d628f93c9be8eccb66a4ad5121342f7
Download URL:

https://repository.library.noaa.gov/view/noaa/72317/noaa_72317_DS1.pdf
File Type:

[PDF - 2.76 MB ]

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