Sea Otter Counts Near Subtidal Monitoring Sites Around San Nicolas Island, California 1980-2017

The data consist of counts of sea otters in each year from 1980 to 2017 that are within 2 kilometers of the location of the 6 original subtidal ecosystem monitoring sites around San Nicolas Island, California. Beginning with the reintroduction of sea otter to the waters of San Nicolas Island in 1987, three to four surveys have been conducted at the island each year. Shore-based observers, using binoculars and spotting scopes, counted sea otters in the island's surrounding waters and marked the otters' numbers and locations on maps of the area. These data were later entered into a GIS database and GIS software was used to calculate the number of sea otters within two kilometers of six permanent benthic ecosystem monitoring sites. Only the surveys yielding the highest total sea otter count in each year were used.