These raw data examine the synergistic effects of the sustainable, rapidly degraded antifouling biocide tralopyril combined with climate change stressors on Pacific oyster (Crassostrea gigas) mortality. Oysters were exposed to tralopyril under ambient temperature and a heatwave, then to a simulated tidal air exposure in a controlled laboratory setting to investigate how mortality changed with heat and toxin. This dataset includes all combinations of a fully factorial combination of heat and two toxin doses, recording the mortality of individuals in each of four replicates per treatment combination (n=4) at five different timesteps. Mortality was recorded before any treatment (T0), after toxin-only exposure (T1), after concurrent toxin-heat exposure (T2), after a tidal desiccation event (T3), and after a rest period (T4). Experimental oysters were collected from both a pristine habitat and a chronically polluted habitat to test population effects related to contaminant exposure history.