BIODIVERSITY & THE SALISH SEA
The San Juan Islands are located in the middle of the Salish Sea, so called today in recognition of the indigenous Coast Salish peoples that have inhabited its shores and sailed its waters for millennia. Coast Salish peoples and their closely related languages are coextensive with the Salish Sea watershed, which includes Puget Sound, Hood Canal, the Strait of Juan de Fuca, Haro Strait, and the Gulf and Strait of Georgia.
The Salish Sea is a very complex drainage basin fed by many rivers, including the Snohomish River and Skagit River in the south on Puget Sound, and the Homathko River at the north entrance of Georgia Strait. The Fraser River is by far the largest freshwater influence on the Salish Sea, however: so large that the marine waters surrounding the San Juan Islands function like an estuary of the Fraser, with reduced salinities and significant loads of silt and nutrients transported from interior British Columbia.
Much of the Salish Sea is relatively shallow, particularly within the San Juan-Gulf Archipelago. Its shorelines are geologically young and complex, ranging from broad fine sandy beaches to steep rocky precipices with thousands of tiny bays and islets. Rains and rivers transport vast quantities of silt and terrestrial nutrients into the Salish Sea each year where they stimulate dense plankton growth and feed migrating salmon, herring, seabirds and marine mammals along thousands of kilometers of seashore.
The San Juan and Gulf Islands emerged gradually from glacial melt-waters barely 9,000 years ago, stripped bare of their pre-glacial vegetation and soils. Humans, plants and animals began to re-colonize the islands at the same time, so there was no “natural” post-glacial landscape or ecosystem in the archipelago. All ecosystems included people from the beginning, and must be regarded as cultural artifacts. The indigenous people of the islands subsisted chiefly by hunting for thousands of years. They began to rely more on fish and shellfish after salmon and cedar re-appeared in the Salish Sea, facilitated by changes in sea levels and climate about 4,000 years ago. Large cedar-plank villages and extensive sea-trade developed, supported by two key technologies: reef-net (fixed-gear) fishing for the enormous sockeye salmon runs that returned annually to the Fraser River, and the cultivation of camas, a nutritious bulb-forming relative of the lilies. By the time of the Roman Empire in Europe, the first islanders were farming; spinning yarn from the hair of specially bred dog flocks; as well as harvesting hundreds of tons of salmon every year. It was a sustainable livelihood until the arrival of European diseases and firearms.
Humans undoubtedly brought many animal and plant species to the islands over the past nine millennia. At the same time, many animals and plants have gradually made their own way to the archipelago, swimming, flying, or hitching rides on floating debris. The present-day distribution of animals and plants in the islands differs greatly from the mainland areas of the Salish Sea, and is still changing. We have few native mammals—and many of them are restricted to a single island where they chanced to colonize. Many animals in the islands form distinct populations and possibly cryptic species, genetically isolated for millennia from their mainland cousins. And because we are in the Olympic rain shadow, we have many native plants that are more typical of Eastern Washington and the Okanogan!
Island ecosystems, whether in the Pacific Ocean like Hawaii or the Galapagos, or here within the Salish Sea, tend to be fragile. This is especially true of the San Juan and Gulf Islands because they are very young ecosystems with unusual “missing parts” when compared to the mainland, such as the historical absence of larger carnivores (other than wolves, which were extirpated in the 1860s). Humans continue to import exotic animals and plants to the islands unrestricted, threatening the islands’ isolated native species and genetic heritage. From Eastern gray and Appalachian fox squirrels to Asian carp, brook trout, and large-mouth bass, a growing number of invasive species are being introduced, even by Washington State agencies, while native species have not yet been inventoried fully.
And while the San Juan Islands appear lush, green and untouched to visitors, they are actually surrounded and influenced by large cities: Vancouver, Victoria, Seattle, and Tacoma. Winds, tides and currents transport contaminants from these urban areas to the islands’ seemingly pristine shores and mountains. With only moderate circulation, the Salish Sea tends to trap contaminants, resulting in very high concentrations in sediments, water and animals in comparison with the ocean. Urban chemical influences, as well as careless use of household, automotive and garden products by islanders, pose increasing threats to the islands’ unique biological diversity.