Zooarchaeological data recovered from shell midden sites are an important focus for coastal archaeology globally. These cultural deposits contain complex records of everyday life and can include millennia of Indigenous fish harvests. In our study area fish represent the most numerous vertebrate skeletal elements in shell middens, yet the composition and absolute quantity of fish contained in these coastal settlement sites is poorly resolved. Here we integrate zooarchaeological bone counts with geospatial data to derive estimates of the total amount of fish biomass represented in five shell midden sites. This approach links the volume of sediments with MNI counts and fish body mass estimates to derive harvested fish biomass. Across the five sites examined in our study area, our geospatial models calculate site volumes ranging from 846-21,833 m³ and our zooarchaeological data suggest that between 3,000-7,000 fish are present per m³ with larger-bodied fish contributing proportionally higher biomass than MNI counts might suggest. We estimate these five sites contain 48,100 m³ of shell midden and 126,000- 243,000.metric tons of harvested fish biomass spanning 4,500 years. These quantitative estimates add detail to the role which ancient Indigenous fisheries had in the marine historical ecology of the North Pacific.