Long-term observational study reveals early weaning and dietary shifts in coastal bottlenose dolphins, indicating artisanal gillnet fisheries subsidize juvenile foraging transitions.
Key Points
To assess whether recurring interactions with artisanal gillnet fisheries provide food subsidies that accelerate weaning and drive ontogenetic dietary shifts in coastal bottlenose dolphins.
Analyzed long-term photo-identification records (2002–2023) across 14 mother-calf pairs (N = 14 females, N = 23 calves) in Veracruz, Mexico, to calculate maternal dependency durations.
Measured stable carbon and nitrogen isotopes (δ13C and δ15N) in dentin growth layer groups from stranded dolphins (N = 8) and muscle tissue from local prey fish (N = 123 across 25 species).
Modeled proportional dietary shifts across developmental stages using a Bayesian SIARMix mixing model.
Calves exhibited a short mean dependency period of 2.6 years, indicating rapid weaning and an early shift to independent foraging.
Dentin chronologies demonstrated lower δ13C and δ15N values in calves (0–2 years) compared to juveniles (3–5 years).
Bayesian mixing models suggested a directional dietary shift from estuarine prey commonly caught in gillnets during infancy toward a broader mix of reef, pelagic, and demersal fish in maturing juveniles.