A wolf pack discovered on Pleasant Island in Southeast Alaska, USA defies the assumed obligate relationship between wolves and ungulates by persisting on sea otters and other marine prey after causing the local extirpation of deer. This pack is also subjected to additive anthropogenic sources of mortality in apparent isolation from other wolves. We used molecular methods to determine the origin of Pleasant Island wolves and ask how they persist under these circumstances. We applied DNA metabarcoding and genotyping by amplicon sequencing with a novel SNP panel to quantify variation in marine foraging behavior within packs, among sexes, and individuals using 957 scats collected from the island and the adjacent mainland from 2016-2022. We additionally used tissue samples to quantify relatedness and gene flow with reduced representation sequencing. Male, female, and individual island wolves all consistently consumed sea otter (63.2% wPOO). In contrast, mainland wolves fed on ungulates (51.8%), voles (19.5%), and sea otters to a lesser extent (14.3%) with more variation annually, among sexes and individuals, indicating both individual variation in the diet of a cooperatively hunting predator and varying hunting strategies among individuals within the same pack. We also found limited dispersal to and from the island with only one unrelated wolf coming from the mainland during the six-year study period. Our findings suggest wolves are more flexible in their foraging strategies than is commonly appreciated and that the recolonization of sea otters can allow wolves to persist on predominantly non-ungulate, marine resources. Nevertheless, anthropogenic and natural mortality, and a lack of movement to and from the island may threaten the continued persistence of the Pleasant Island wolves.