For stochastic growth processes, integrated mixed-effects (IME) models of capture-recapture data and size-at-age data from calcified structures such as otoliths can reduce bias in model parameters. Researchers have not fully explored the performance of IME models for simultaneously estimating the unknown ages, growth model parameters, and derived variables. We simulated capture-recapture observations for tagging experiments and skeletochronology (i.e. humerus growth) observations for stranded loggerhead sea turtles Caretta caretta based on previously published parameter estimates for 3 growth processes (logistic, Gompertz, and von Bertalanffy). We then fit IME models to the integrated and non-integrated data. For the integrated data (both tagging and skeletochronology), we found decreased bias and uncertainty in estimated growth parameters and ages, and decreased misspecification of the growth process based on AIC. Applying the IME model to Western Atlantic loggerheads, the von Bertalanffy growth process provided the best fit to the skeletochronology data for the humeri from 389 stranded turtles and capture-recapture data from 480 tagged turtles. The estimated mean growth coefficient (μk) and mean asymptotic straight carapace length (μ×) were equal to 0.076 yr-1 and 92.1 cm, respectively. The estimated mean ages of the stranded turtles and recaptured tagged turtles were 13.5 and 14.6 yr, respectively. Assuming the size-at-sexual maturity (SSM) is 95% of the asymptotic size, the mean and 95% predictive interval for the age-at-sexual maturity (ASM) was 38 (29, 49) yr. Our results demonstrate that IME models provide reduced bias of the growth parameters, unknown ages, and derived variables such as ASM.

Trophic interactions are proximate drivers of ecosystem function, including predator-prey dynamics, and their spatio-temporal variability may reflect ecosystem shifts and changes in trophic transfer. We investigated biogeographic structuring of trophic interactions by analyzing multi-decadal time series of diet for Pacific hake Merluccius productus and Chinook salmon Oncorhynchus tshawytscha from a large marine ecosystem. We compared our predictions for spatio-temporal variability of hake and salmon trophoscapes (i.e. spatially explicit predictions of trophic relationships) to inform ecosystem dynamics and fishery bycatch patterns. We have 3 inter-related findings pertaining to the spatial coherence of the trophoscapes and the potential consequences to juvenile and sub-adult (i.e. after the first year at sea but prior to maturation) salmon when sharing foraging areas with Pacific hake. First, the spatial scale of Pacific hake diet represents coastwide variability, and the spatial variability of Chinook salmon diets differs across regions and demonstrates a broad diet. Second, the expectation for increased diet and spatial overlap of Pacific hake and Chinook salmon during low productivity periods (e.g. periods with low krill biomass, suboptimal upwelling) can inform fishery management challenges. In this regard, we explore the role of shared foraging habitats on increased predation, and consequentially reduced recruitment, by Pacific hake on juvenile salmon during sub-optimal upwelling conditions. Third, we show that above-average bycatch of sub-adult Chinook salmon was associated with later spring transition, potentially as a result of both Pacific hake and salmon sharing foraging areas and prey species on the shelf and shelf break.

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