Multidecadal daily resolved growth increments reveal climate effect on the growth of a highly migratory shark in the North Atlantic

Abstract

Substantial progress has been made in identifying large-scale climate effect on somatic growth through the use of ageing-based methods in aquatic environments, yet their annual/seasonal temporal resolution seems too coarse for such a fast process. Temporal resolution is a missing dimension in our understanding of climate effects on growth. Here, an alternative source of high temporal resolution growth increments embedded within a multidecadal traditional tag-recapture database was analysed to identify climate signals in the somatic growth of blue sharks Prionace glauca in the North Atlantic. Results indicate the growth response of P. glauca to the NAO occurred at a daily scale with a time-lag. Non-parametric modelling reveals an optimal response curve around the historical average of the NAO, and a significant negative response for large positive NAO anomalies. Growth predictions show that the last four decades are mostly associated with negative responses compared to the historical average. The temporal resolution of this study is unprecedented among current ageing-based studies with a comparable temporal coverage. Integrating high temporal resolution into long-term climate effect studies can open new avenues for research on identifying climate effect on growth and provide detailed clues to its mechanisms of action.