Spatially Heterogeneous Responses of Body Growth to El Niño‐Southern Oscillation Signal During Different Life Stages in Jumbo Squid ( Dosidicus gigas )

ABSTRACT

Climate variability can affect growth differently across life stages, but whether these effects vary among spatially distinct groups remains poorly understood. We investigated how climate variability experienced at different life stages interacts with spatial context to shape the growth trajectories of jumbo squid ( Dosidicus gigas ) in the eastern Pacific Ocean. We analyzed a dataset comprising statolith‐based age estimates for 1415 female jumbo squid collected over multiple years. Spatial growth patterns were modeled using nonlinear mixed‐effects growth models, and life stage‐specific effects of the El Niño–Southern Oscillation (ENSO) were assessed using generalized additive models based on Niño 1 + 2 sea surface temperature anomalies experienced from birth to 8 months of age. The Schnute growth model with spatial random effects on growth rate provided the best fit. Equatorial squid grew faster, matured earlier, and exhibited lower interindividual variability than southern squid. Early in life, ENSO effects on growth were broadly consistent across individuals, with cold phases associated with enhanced growth and warm phases associated with reduced growth. During mid‐to‐late ontogeny, however, this pattern reversed, with cold phases negatively and warm phases positively affecting growth. This reversal occurred earlier in equatorial individuals than in southern individuals. These findings demonstrate that climate exposure at different developmental stages has ontogenetically variable effects on growth in D .  gigas , shifting from a cold‐phase growth advantage early in life to a warm‐phase advantage later in development. The timing of this shift differs between equatorial and southern groups, reflecting spatial contrasts in thermal regimes and life‐history schedules. These asynchronous reversals in ENSO responses demonstrate that climate–growth relationships cannot be generalized across either space or development and highlight the need for spatially explicit management of migratory marine species.