Elasmobranch predators provide an ideal system for investigating resource use and ecological interactions due to their diverse morphologies, feeding strategies, and trophic roles. This chapter will address critical methodological challenges in trophic niche analysis through rigorous sensitivity analysis to determine optimal sample size requirements. I will integrate both stable isotope and fatty acid data, using Principal Coordinate Analysis (PCO) and the SIBER package to calculate corrected standard ellipse areas (SEAc (%²)) across both analytical approaches. Through systematic random resampling with unique combinations, I will capture the full spectrum of individual variation, generating resampled datasets for each sample size threshold. By comparing mean SEAc and variance values across increasing sample sizes, I will identify the minimum sample size where niche metrics stabilise, ensuring reliable estimates despite opportunistic sampling constraints. This sensitivity analysis will provide a robust framework for future trophic ecology studies, advancing our understanding of temporal stability and plasticity in marine predator resource use and offering insights into how environmental pressures reshape trophic structure within marine ecosystems.