MEPS 734:79-90 (2024)  -  DOI: https://doi.org/10.3354/meps14564

ABSTRACT: The Norwegian-Barents Sea (NBS) system is very productive; however, the extent to which this productivity varies remains uncertain for many species. Cod Gadus morhua, haddock Melanogrammus aeglefinus, and capelin Mallotus villosus are 3 key species that overlap in a large portion of the NBS ecosystem. In this hypothesis-driven study, we investigated the interaction of these 3 species during their pelagic larval stage and assessed the impact of their spatio-temporal overlap on survival. We hypothesised that the spatio-temporal overlap between the larvae of the 3 species, as they likely drift together, influences their survival at later stages. We calculated the spatio-temporal overlap of each pair of the 3 studied species and tested it against their recruitment. We utilised a multiple linear regression model with temperature, spawning stock biomass, and spatio-temporal overlap among larvae, their food, and competitors as explanatory variables; this model explained ∼43, ∼24, and ∼73% of the variability in cod, haddock, and capelin recruitment, respectively. The overlaps between larval cod and competing species and/or food have a negative influence on cod recruitment, whereas the sign of the relationships pertaining to haddock and capelin varies. These results improve our understanding of how these fish species use their critical habitats to face emerging environmental stressors.

KEY WORDS: Recruitment dynamics · Fish survival · Larval competition · Spatio-temporal modelling