The distribution patterns of Atka mackerel Pleurogrammus monopterygius were examined, both seasonally and spatially, to identify essential feeding habitat and to add to existing knowledge of diet composition. The study focused on two local aggregations in the Aleutian Islands, Alaska: one at Seguam Pass and one near Amchitka Island. At each locale, we examined the mean stomach fullness (i.e., feeding intensity) and diet composition of randomly selected fish within and outside of trawl exclusion zones (TEZs). The trawl exclusion zones extend out 10–20 nm from Steiler sea lion Eumetopias jubatus rookeries and haulouts; no trawling is allowed inside these zones. During four of the six periods examined, mean stomach fullness was higher inside the TEZ than outside it. At Seguam Pass, fish were distributed into northern and southern aggregations and diet composition varied by age, season, and location relative to the TEZs. Feeding intensity appeared to be greatest inside the TEZ in the northern portion of Seguam Pass near a productive frontal region characterized by a transition zone of well-mixed (upwelling) and stratified water. At Seguam Pass, piscivory occurred almost entirely inside the TEZ in June. Near Amchitka Island, feeding intensity was significantly higher inside the TEZ, which coincided with an increase in egg cannibalism in October. Based on these observations, we suggest that the areas of increased feeding activity in conjunction with diet composition at Seguam Pass and Amchitka Island represent essential feeding habitat for Atka mackerel.