This data release is comprised of sea otter capture data from the capture of wild sea otters in Big Sur and Monterey, CA between the years of 2008-2011. These sea otters were captured for tagging and tracking during a comparison study designed to examine the biology, health, and survival of sea otters in a relatively pristine habitat (Big Sur) and a highly-impacted habitat (Monterey). At the time of capture a variety of data are collected on each individual sea otter. The otter may receive multiple identifiers including an otter number, color coded flipper tags, a PIT tag, VHF radio transmitter, and archival time-depth recorder. Capture information (date, time, GPS location and general area, capture team, capture method, if the otter was caught with other otters, if the otter was previously captured) is reported in this data set as well. A variety of physiological, morphometric, and health parameters are assessed and reported (reproductive status, sex, age class, age estimate, grizzle, nose wound status, weight, length, girth, tail length, right paw width, baculum length [if male], general tooth wear, comments on tooth condition or oral lesions, canine width, overall appearance). If the otter was caught with a dependent pup, the pup was given an otter number and was sexed, weighed, and measured whenever possible. Each otter is assigned a blood kit number corresponding to a blood sample. Release coordinates, methodology, and team are also noted.