Impact of environmental conditions on fish early-life stages, an individual-based model approach

The duration and survival of dispersing fish Early-Life Stages (ELS) are influenced by biotic and abiotic factors. Moreover, current methods for estimating mortality rates based on laboratory experiments or field studies neglect key components, which can be investigated thanks to modeling. To address these gaps, a growth model is coupled with a Lagrangian model to simultaneously account for species-specific physiology, environmental variability and physical transport. Growth was modeled using Dynamic Energy Budget theory, coupled with a particle-tracking model that computes trajectories. Focusing on three species of Mediterranean coastal fishes, we first model their Pelagic Larval Durations (PLD) over realistic ranges of constant temperature and food density. Our modeling framework reproduces well the expected environmentally-driven variation of PLD. Then we estimated mortality as a function of spawning, using varying food density and temperature along dispersal trajectories. Mortality was estimated based on three criteria: time to metamorphosis, final position when metamorphosis occurs, and starvation. Variations of temperature and food density across the year induce seasonal variations of both PLDs and mortality rates, with slow growing species exhibiting higher mortality rates than those characterized by faster development. Our results showed that spawning phenology affects seasonal mortality rates, opening new opportunities to explicitly test the “match-mismatch” hypothesis.