| Summary: | Invasive fishes frequently change natural aquatic habitats due to predation and competition. The Alaska blackfish (Dallia pectoralis) is indigenous to some regions of Alaska but was illegally introduced to the Cook Inlet Basin in the 1950s. By the 1970s, fisheries managers expressed concern over possible ecosystem-altering effects of the blackfish introduction, especially in waterbodies containing popular sport fish. Descriptive food habit studies may assist fisheries managers in making decisions regarding management of non-native populations of Alaska blackfish. This project characterizes diet of three Cook Inlet Basin Alaska blackfish populations through stomach contents analysis. Shifts in diet across season, sex, and size of individuals from a lake, wetland pond, and stream are discussed using the Index of Relative Importance. Cook Inlet Basin Alaska blackfish consume similar invertebrate prey as native juvenile salmonids and stickleback, with major prey consisting of epiphytic/benthic dipteran larvae, gastropods, and ostracods. Piscivory, including cannibalism, is infrequent in these populations. Due to the high degree of dietary overlap with native fishes and stocked sport fish, and evidence that many Cook Inlet Basin waterbodies contain established populations of Alaska blackfish, fisheries managers should take actions to restrict the spread of blackfish through public awareness education, law enforcement, and funding for additional research. An Alaska blackfish husbandry manual outlines closed-system rearing and artificial fertilization protocols useful to researchers and educators for keeping live Alaska blackfish in the laboratory and classroom, in order to add to our body of knowledge about this species.
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