Sea Otter (Enhydra lutris) Foraging in Re-occupied Soft Bottom Habitats

Rare observation of sea otter in Haro Strait, perhaps first since 2014.

Tom Okey observed:

My son and I went tent camping at Island View Beach Regional Park so that I could try to confirm the sea otter (Enhydra lutris) sighting that my kids reported on 8 June. Our tent was 130 m from the beach and I got to the beach just before 7 am on June 21st with my Bushnell 8x42 binoculars. I spotted the sea otter within a minute or two beginning my scan of the part of the Haro Strait between Island View Beach and just south of James Island (Figure 1).

My arrival at the beach that morning was ~30 minutes before low tide (low tide: 7:26 am at 1.5 m). I stood on the exposed offshore sandbar adjacent (just east of) the northernmost parking lot of Island View Regional Park. I first sighted the sea otter about 1 km North-Northeast of my location (at an azimuth of 30 degrees from North). It was on its back travelling slowly to the South-Southeast (bearing ~155 degrees), continuing in that direction for 30 minutes. Toward the end of that time, when it was nearing its destination, I could see the otter turning its head frequently (from looking upward to looking downward into the water towards the substratum) while remaining on its back---apparently searching for a foraging location.

The channel just offshore of Island View Beach reaches well beyond 20 m depth, but it shoals to the East to between 15-20 m depth in the area that the otter stopped traveling (Figure 2 -- a section of Canadian Hydrographic Service Chart 3313). The otter arrived at this deep feeding location at low tide---7:26 am---when it stopped moving. I looked away to observe a Bald Eagle feeding on forage fish in open water, and when I looked back I saw what appeared to be a white large bivalve on the belly of this sea otter. This was a very large sea otter, and its belly was uncommonly large and sticking up, and so the large white bivalve with the morning sun reflecting off of it was visible from over a km away using my Bushnell 8x42 binoculars. This whole area south of James Island (the channel and the shoal) is marked as "sand" on Canadian Hydrographic Service Chart 3313.

Another interesting thing I observed about this sea otter is that it seemed to travel and keep positioned in a narrow surface slick. Surface slicks can be caused by higher surface pressure from two water masses colliding such as when onshore winds or tides are pushing a current that encounters a stationary water mass constrained by a coastline. Surface slicks can be caused by wind-driven Langmuir Cells, or Langmuir Circulation, but they can also reflect tidal currents moving past stationary water masses. Coastal slicks indicating currents often form a single slick a certain distance from a coastline, and these can often be seen from the clifftops along US Highway 1 along the California coastline when wind is blowing onshore.

In any case, areas of higher surface pressure are more resistant to the effects of wind, which is why they appear as "slicks." There are various potential explanations for why the observed otter observed in the present observation kept himself positioned in that coastal slick at around low tide. One is that he timed his morning commute to ride the current to his preferred foraging location, and then he positioned himself at the interface of the stationary water mass to maintain his location over his preferred spot on the substratum. I left the beach at 7:45 am because I had to wake my son and take him to school.

To my knowledge, the present observation with the observation by my kids on June 8th is the first confirmed sighting of a sea otter in the Haro Strait since a single otter was photographed and filmed in 2014 by Cheryl Alexander and her family in front of their home at Ten-Mile Point near Victoria--the southern entry of Haro Strait. They named that sea otter 'Salish', as possibly the first Sea Otter to enter the Salish Sea after over a century of extirpation. We have named the otter off Island View Beach 'Big Boy' because he appears to be an enormous (well fed) otter. It is possible that Salish and Big Boy are the same individual. The present observation of Big Boy is just 16 km North-Northwest of the 2014 observation of Salish (azimuth: 335 degrees). UPDATE on 28 June 2018): I learned this morning that Andrew & Debbie Dunning observed a pair of Sea otters off Island View Beach "about 3 weeks ago."

These sea otters that have recently arrived at the southern tip of Vancouver Island and now in the Southwestern Strait of Georgia (the Haro Strait), could have expanded from the West Coast of Vancouver Island. That population had expanded from Kyquot Sound to at least to Bamfield on the southern edge of Barkley Sound by 2007 (my own observation at Brady's Beach in Bamfield). It is a 175 km coastal route from Bamfield to Island View Beach. They could also have come from the sea otter population around Cape Flattery on the tip of the Olympic Peninsula, which is a 115 km route including a 20 km crossing of the Juan de Fuca Strait.

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