Annual California sea otter census - 2019 spring census summary

The spring 2019 mainland sea otter count began on May 1 and was completed by July 9. Overall viewing conditions this year were very good, better than those encountered during the 2018 spring census (View Score = 3.0 this year compared to 2.4 last year, where 0=poor, 1=fair, 2=good, 3=very good, and 4=excellent). The surface canopies of kelp (predominantly Macrocystis pyrifera) were qualitatively noted by observers to be much less than the seasonal normal in the central portions of the range (from Monterey to Cayucos) and about normal near both ends of the range. Sea otters along the mainland coast were surveyed from Pigeon Point in San Mateo County in the north, to Santa Barbara Harbor in Santa Barbara County in the south. A separate, ground-based survey of the sea otter population at San Nicolas Island was completed earlier in the spring (April 19 - 23) under good-very good survey viewing conditions (View Score = 2.5). Macrocystis canopies at San Nicolas Island were estimated to be below normal for the time of year.

These data support the following U.S. Geological Survey Data Series:
Hatfield, B.B., Yee, J.L., Kenner, M.C., and Tomoleoni, J.A., 2019, California sea otter (Enhydra lutris nereis) census results, spring 2019: U.S. Geological Survey Data Series 1118, 12 p., https://doi.org/10.3133/ds1118.