Intra- and interspecific densities shape life-history traits in a salmonid population

• Published in: Oecologia
• Main Authors: Montorio, Lucie, Evanno, Guillaume, Nevoux, Marie
• Other Authors: Écologie et santé des écosystèmes (ESE), Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, Pôle Gest'Aqua, Institut National de la Recherche Agronomique (INRA)-Office national de l'eau et des milieux aquatiques (ONEMA), Ministère de l'écologie, du développement durable et de l'énergie-Ministère de l'écologie, du développement durable et de l'énergie
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: Density dependence; Life-history tactics; Migration probability; Multi-event model; Juvenile survival; [SDV]Life Sciences [q-bio]; Atlantic salmon; Salmo salar
• Online Access: https://hal.inrae.fr/hal-02621085; https://doi.org/10.1007/s00442-018-4213-4

International audience Population dynamics can be regulated through intra- and interspecific density dependence. In species with close ecological requirements, interspecific competition for resources may add to intraspecific density, or even exceed its effect; it may impact single or multiple traits. However, the relative impact of intra- and interspecific densities on demographic parameters has been rarely empirically assessed. We analyzed 18 years of capture-mark-recapture data from brown trout (Salmo trutta) coexisting with Atlantic salmon (Salmo salar) during the juvenile freshwater phase in the Oir River (France) to estimate the relative effects of intra- and interspecific density on trout early life. In trout, a species with optional migration, we estimated the migration probability of young-of-the-year trout out of their natal site, survival probability during the first winter, as well as body size, in relation to both intra- and interspecific density. Trout density correlated negatively with body size and with winter survival in resident trout but not with trout migration. Salmon density correlated positively with trout migration, but no impact was detected on trout body size or survival. Our study highlighted contrasting effects of intra- and interspecific density on trout early life, and the need to account for both factors when studying population dynamics in coexisting species. In particular, by affecting trout migration decision, salmon density may drive trout life history.