Schools of California Anchovy (Engraulis mordax)

Theo Okolowicz discovered a school of anchovies, and said:

"It was big. They were travelling in a donut form."

Tom Okey wrote:

My son Theo was exploring a cement outfall jetty along the shore of Ross Bay at Eberts Street at ~1 pm on 6 Oct 2019 during our Sunday walk when he discovered a school of California anchovy (Engraulis mordax). I was close behind, and also observed it.

The top of the cement jetty was about 5 cm above the ocean surface at that time; the water was clear; and we watched the anchovies swimming just under the surface, about 1-2 m away from us. We couldn't attempt to estimate the size of the school due to the glare and wind waves on the water's surface beyond 2 or 3 meters from us. The sea state was 0 (glassy) on the Beaufort Scale next to the jetty and 1 (ripples) beyond 2 or 3 meters away from the structure.

The fish were the size and shape of California anchovies; they appeared three toned in the sun (brownish above a darker lateral line color, and shiny beneath), with occasional individuals flipping over to show a bright silver shine. The school behaved like an anchovy school as well, based on my previous first hand observations in California, but the school did not appear to be feeding (with jaws wide and heads flashing reflections of the sun). There was one cormorant feeding nearby, but there was no feeding frenzy on this school when we were there at about 1:30 pm on 6 Oct 2019.

I returned on 8 Oct 2019 at 6:20-6:30 pm, just before sunset, and photographed juvenile California Gulls (Larus californicus) resting on the cement jetty (see photo). I also captured video footage of California anchovies from the cement jetty and a group of gulls feeding on the forage fish (see video). When Theo and I returned on 9 Oct 2019, a stand-up paddleboarder Tracey Cook landed next to the cement jetty, and reported that she had seen these small fish all over Ross Bay from the vantage point of her paddleboard, and that they were even more abundant in Gonzales Bay, which is just to the East of Ross Bay. She told us there were lots of birds feeding on these forage fish in Gonzales Bay.

The southern part of Vancouver Island is within the range of California anchovy, but their presence is highly variable in British Columbia because it is the northern edge of their range and also because their abundance is cyclical throughout its range (Baja California, Mexico to British Columbia, Canada). The abundance of California anchovy alternates with that of the Pacific sardine (Sardinops sagax): the California anchovy is more abundant during warm periods, and so their presence indicates warmer conditions. Anchovies are preyed on by a variety of predators including salmon, thus indirectly benefiting higher trophic level species including killer whales.

A news report from South Puget Sound during summer of 2019 described a 100-fold increase in this species in recent years, and that some experts had never seen Anchovy so abundant. Flights in the south Puget Sound during summer of 2019 revealed an abundance of schools visible from the air.