Negative growth in body mass of trout and salmon in a small stream network

Canadian Journal of Fisheries and Aquatic Sciences
By: , and 

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Abstract

In species inhabiting stressful environments, some individuals experience negative growth in body mass during their lives, potentially influencing survival, reproduction, populations, and ecosystems. Using data from a long-term (1997–2015) study of brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), and juvenile Atlantic salmon (Salmo salar) in Massachusetts, USA, we analyzed the frequency, causes, and consequences of seasonal mass loss. Negative growth occurred in 14.8% of observations (3573 instances), with the highest prevalence during summer (June–September). Species differed markedly: 42.5% of juvenile Atlantic salmon, 24.9% of brook trout, but only 7.7% of brown trout exhibited negative growth. The likelihood of mass loss increased with size, age, and low stream flows, particularly in summer. Brook trout in the small or isolated tributaries exhibited less summer mass loss than those in the larger streams. Other factors, including temperature and population density, had minimal or inconsistent effects. Individuals experiencing negative growth, especially brook trout in summer and autumn, were less likely to be re-encountered. As we observed no association of mass loss with movement, this suggests a potential survival cost of negative body mass growth.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Negative growth in body mass of trout and salmon in a small stream network
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/cjfas-2024-0376
Volume 82
Year Published 2025
Language English
Publisher Canadian Science Publishing
Contributing office(s) Eastern Ecological Science Center
Description 14 p.
First page 1
Last page 14
Country United States
State Massachusetts
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