Invasive species hitching a ride into Puget Sound

We hear about the “balance of nature,” but it’s not something that we can truly understand until the balance is thrown out of whack by something like climate change or invasive species.

Until I began a recent reporting project for Puget Sound Institute, I never realized that San Francisco Bay was such a hotbed of invasive species. Beginning with the California Gold Rush, ships began moving in and out of the bay in unbelievable numbers, arriving from ports all around the world. Now, more than 200 non-native species are making their permanent home in the bay — including some species that have thoroughly altered the local ecosystem.

So far, we have been lucky in Puget Sound. Experts say we have about 75 firmly established non-native species, yet none of them have created the widespread damage caused in San Francisco Bay by European green crabs and Asian clams or in the Great Lakes by zebra mussels. The video on this page does a good job of telling the Great Lakes story, which has been repeated all over the world.

Once people in Washington state realized how disruptive invasive species can be, the struggle was on to protect Puget Sound from alien invaders — particularly those found in San Francisco Bay, which is just a short hop away on the world scale. My series of stories talks about concerns for Puget Sound and the efforts to control a possible invasion.

Three weeks ago in Water Ways, I described legislation that would reduce state and federal controls over invasive species. See “Bill could increase risks of alien species invasions in Puget Sound waters.”

On the East Coast, where they are native, striped bass are one of the most popular sport fish. Here, Angela Anning of Connecticut shows off her impressive striper. On the West Coast, striped bass could be considered an invasive species. Photo: NOAA
On the East Coast, where they are native, striped bass are one of the most popular sport fish. Here, Angela Anning of Connecticut shows off her impressive striper. On the West Coast, striped bass could be considered an invasive species.
Photo: NOAA

Invasive species range in size from microscopic viruses to four-foot-long striped bass. In California, the striped bass became a prized sport fish after it was intentionally introduced in 1879. But over the past decade concerns have grown for their effects on the salmon population. The jury is still out on whether high numbers of stripers should be sustained for anglers or the population should be fished down rapidly to save salmon and other species. Check out these stories:

Meanwhile, striped bass have been moving up the West Coast, possibly because of warmer waters due to climate change. A few years ago, a 55-pounder was caught in the Columbia River, and I’ve heard rumors that they have been seen in the Strait of Juan de Fuca.

On the small side, I report on a tiny crustacean, an invasive copepod that has almost entirely displaced native copepods in Samish Bay in northern Puget Sound. Copepods are important prey for small fish, including herring, which feed the larger salmon. The invasive copepods are smaller and more difficult for fish to see, which could have a cascading effect on the entire food web.

Invasive copepod Oithona davisae under magnification Photo: Jeff Cordell, University of Washington
Invasive copepod Oithona davisae
Photo: Jeff Cordell, UW

A major concern for Puget Sound biologists is the European green crab, which could move into Puget Sound from San Francisco Bay in ballast water or with warm ocean currents during an El Niño year, like the one just past. As I describe in the new series, a major program involving citizen science volunteers is ongoing in a search to find the first green crabs before they gain a foothold.

Pacific oysters, another non-native species, were intentionally brought to the Northwest from Japan in the early 1900s to replace the native Olympia oyster, which had been decimated by poor water quality. Pacific oysters soon became a mainstay of the shellfish industry in the Puget Sound region and are now growing thick in numerous areas.

European green crab Photo: Washington Sea Grant
European green crab
Photo: Gregory C. Jensen, UW

Similar introductions of Pacific oysters occurred in California beginning more than 100 years ago, but for some reason the oyster populations never took hold, according to a report in the publication California Fish and Game (PDF 1.7 mb). Finally, in the early 2000s, the invasion began to take off.

“It remains unclear why there should be a successful invasion now, given the failure of previous attempts to deliberately introduce the species both locally and throughout California…,” the report says.

“If populations in Southern California waters do continue to expand and grow, as they have in other areas where they have invaded, it will undoubtedly bring changes to the way our estuarine intertidal habitats function as well as in the way we must manage them.

Pacific oyster Photo: Washington Sea Grant
Pacific oyster
Photo: Washington Sea Grant

“Because Pacific oysters rapidly reach large sizes, they could pose problems related to fouling of maritime equipment, infrastructure, and vessels,” the report continues. “Pacific oysters stand out as one of the most transformative invaders of marine ecosystems.”

As Washington state takes steps to keep alien species from invading Puget Sound from California, California officials may adopt similar measures to block invaders from coming into that state.

Please take a look at this package of stories I wrote for Puget Sound Institute, with editing by Jeff Rice and design by Kris Symer: