River tales

Oysters in the raw

The San Dieguito River in its renaissance continues to serve up surprises, not the least of which are clumps of Pacific oysters (Crassostrea gigas) clinging to old pilings of the Grand Avenue Bridge on the south side of the lagoon.

One of the most globalized marine invertebrates, these four- to six-inch, non-native bivalves with their rounded, fluted shells can also be spotted at low tide on pilings in the river channel just east of the Interstate 5 bridge as well as on the concrete abutments of the bridge itself.

The Pacific oyster begins its life as a male but after a year or so functions as a female, living up to 30 years unless consumed by crabs, fish, or wading birds. They breed in the warm water of the lagoon with fertilization occurring when free-swimming larvae group together to find habitats to settle.

Pilings from the old Grand Avenue Bridge just off San Dieguito Drive in Del Mar

It’s not as if oysters are newcomers to the region though. Some 8,500 years ago the Kumeyaay, the original native inhabitants of what is now San Diego County and Northern Baja, Mexico, foraged for oysters among other food sources, primarily in the San Elijo Lagoon region, as evidenced by shell middens in the estuary. Today, in Baja, delicious Pacific oysters known as Kumiai are commercially farmed both in Ensenada and further south in Guerrero Negro Lagoon.

But are these oysters for eating? Probably wisest to enjoy them from a distance. As filter feeders, feeding on phytoplankton and detritus in water, even if some fool survived a waist-deep (and illegal) foray through the mud to pluck an oyster from the pilings near the Grand Avenue viewing platform, only the same fool would attempt to eat one without knowing the quality and toxicity of the water, even this long after the lagoon’s restoration.

Del Mar’s train station with the mouth of the San Dieguito in the distance – in 1926 and today.

South of the mouth, then and now

It starts as a trickle on Volcan Mountain, flows downward as Santa Ysabel Creek, westward as the San Pasqual, then finally comes into its own below Lake Hodges as the San Dieguito River – the largest watershed in San Diego County – before spilling into the Pacific Ocean at Del Mar, some 50 miles later.

Much has changed along the banks of the San Dieguito over time – from semi-permanent Native American villages, Spanish ranchos, tomato and bean fields, roads, golf courses, and housing estates – but the course of the river through droughts, floods, and its recent restoration near the coast has remained much the same.

Del Mar has evolved from a sleepy seaside resort established in the late 19th century into the thriving beach community it is today; the two pictures above show the altered landscape where the San Dieguito meets the sea.

The San Dieguito River flowing through Del Dios Gorge in 1912 before construction of the Lake Hodges Dam.

Surprise landing, August 24, 2021

It’s a bird, it’s a plane…

Birders, photographers, and others frequenting the San Dieguito River trail are regularly treated to great blue herons, egrets, or osprey circling above the river, but rarely do they spy a low-flying Piper Saratoga like the one that swooped over the trail recently and landed in the fast lane of Interstate 5.

Nine minutes after the single-engine plane took off from Montgomery Field around noon on August 24th, the pilot reported engine trouble over Del Mar and made an emergency landing on the freeway. The plane clipped a couple of cars as it touched down, lost half of its starboard wing in the back of an Audi SUV, and came to rest against the center divider. Thankfully there were no injuries and the plane’s two passengers, a flight instructor and private pilot, walked to safety from the aircraft.

A wily coyote hunting along the riverbank

Out in the midday sun

On a recent summer afternoon, a discreet coyote was daintily wading in greenish-brown water along the south bank the of San Dieguito River, hunting for a meal. The stealthy, unexpected movement, caught out the corner of one eye, produced a double take and quick U-turn on the San Dieguito River Trail to observe this common yet remarkable creature.

A member of the Canidae family that includes dogs, wolves, and foxes, coyotes have no fear of water and will often follow prey such as small birds into the water, or hunt like this one for unsuspecting fish, crawfish, turtles, or frogs. Coyotes are also known to bathe in rivers to cool down or to wash mud from their coats. Their thick and buoyant fur serves them well when crossing rivers and lakes as needed – mostly to escape from predators – but when swimming, they paddle slowly, with powerful paws keeping their heads above water while their large, bushy tails serve as rudders.