Diggings logo

WSU/Pend Oreille Extension introduced the Sense of Place series in 1999, with a focus on place-based stewardship education. Since 2001, a partnership with the Kalispel Tribe of Indians Natural Resources Department (KNRD) has supported this newsletter and allowed us to expand class offerings through EPA funding. Further staff support comes through Renewable Resources Extension Act (RREA). Our newest partner, sponsor of the Rain Garden Challenge, is the Pend Oreille Conservation District. Many thanks to our partners and to you, our readers, for your continued enthusiasm for "digging" into the natural history and culture ofthis part of the world.

River Mainstays

by Jack Nisbet, author and historian

For the past few months, an exhibit at the Northwest Museum of Arts and Culture (the MAC) in Spokane has displayed early photographs of the free-running Columbia River. Shots of a wide delta at the mouth of the Spokane, a thunderous Kettle Falls, and the legendary sudden drop as the Pend Oreille enters the mother river all provide spectacular reminders of what the north Columbia used to be. They also provoke questions about what elements of our native rivers might still exist. The mollusks that kids often find when they wade around the mouths of fast-running larger creeks--bivalves that look like they belong on an ocean beach, living here as animals comfortably adapted to the inland world--provide one hopeful sign.

Although introduced species more adapted to slow, warm water have joined the mix here, several native freshwater mussels or clams do still live in the Pend Oreille drainage. They still provide an important food source for muskrats, river otters, raccoons, and ducks such as goldeneyes. And although not many people think of eating them now, mussel shells discarded by humans appear in many archaeological digs on the Columbia Plateau. The life of these mollusks has been intimately connected to communities here for as long as salmon, deer, or camas.

Freshwater mussels have a worldwide distribution, with over two hundred different species occurring in North America, and a couple of dozen in the vast reaches of the Columbia River drainage. Only three kinds were routinely gathered by prehistoric groups, and of these the most widespread one goes by the mellifluous Latin name of Margaritifera falcata. Pried opened, Margaritiferas are beautiful to look at--the nacre, or iridescent interior layer of the shell, shows hues that range from salmon pink to royal purple, and the colors serve as an identifying trait.

The life history of Margaritifera plays out in several stages, each of which sounds like science fiction. The living mussel has four gills that filter nourishing particulates from passing water. Adult females use spaces within these gills as marsupia, or brood pouches, to harbor their embryos. Like many mollusks, Margaritifera are remarkably fecund, and one female can brood over a million embryos at a time. When the water temperature reaches a certain level, usually in late summer, a female poofs out her entire cloud of embryos in a minute or two, dispatching them on to the next stage of their journey.

The baby mussels drift through the water as tiny parasites, searching for a host. Less than one percent of them happen upon a suitable fish--usually a salmon, steelhead, or trout--and attach themselves to the interior of that fish’s gills with their half-dozen little teeth. Once secure, they immediately encase themselves in a protective cyst and begin to absorb nutrients from their host. Over the next few weeks, the hitchhikers may increase in size up to five hundred times before dropping away to drift once again, this time to the bottom. Only those that land on a stable bed of gravel stand a chance of surviving.

Each of those lucky mussels produces a byssus thread and attaches itself to a stone, then burrows into the substrate. They remain semi-buried, rear end up, filtering water through their gills for food, over the next decade or so. When they approach the length of a finger segment, they detach their anchoring thread and become mobile again. In this adult stage they continue to grow, and finally begin to breed. Given the right conditions, a single Margaritifera might reach a length of five inches, live for 130 years, and produce over 200 million embryos.

Few detailed studies have been made on mussel habits in the wild, but one performed in the Kettle River in the 1960s found individual Margaritiferas sensitive to muddy water and tolerant to very cold temperatures. The mussels preferred fast-moving current, with concentrated “beds” found in sand and gravels just downstream from protective boulders in water depth ranging from 20-60 inches. In an area of 150 square yards, one population was estimated to contain several thousand individuals.

This kind of abundance practically ensures that there would be some interaction between people and freshwater mussels, and indeed, human-deposited shell heaps or “middens” have long been recognized and debated by archaeologists. On the Columbia Plateau, several different categories of shell middens, ranging from a single family meal to long-term deposition by a village, appear in the archaeological record. Mussels appear at campsites as early as 9,000 years ago, but show a marked increase beginning around 5,000 years before the present. Freshwater mussels and their shells have been recorded as being used for food, bait, spoons, ear ornaments, house floors or fill, shell walls, and fire pits; the most common occurrence is of a pile of discarded matched shell halves mixed with fire-cracked rock, lesser amounts of animal and fish bones, and large striking tools nearby--exactly the kind of footprint left on a beach after a modern clambake.

Several oral accounts gathered by anthropologists in the early part of the twentieth century described mussels as “starvation food,” a resource to be used only during hard times or difficult seasons of the year. There are few mentions of collection techniques, leading to the assumption that most of the gathering was done by women and children wading during low water. Mussels were boiled in baskets of water heated with hot rocks, or roasted in underground ovens; the meat of the mussels was dried and strung on circular strings or on sticks for the long term.

Becky Stevens, currently with Archaeological and Historical Services at Eastern Washington University, wrote her master’s thesis at EWU on the remains of Margaritifera shells found at several Plateau archaeological sites. Her research explored the question of whether the mussels might be more than starvation food. Stevens’ lab analysis showed that Margaritiferas were comparatively low in calories and protein, contained no detectable vitamin C, only a trace of potassium, and small amounts of niacin and sodium. The mussels provided more carbohydrates than salmon or deer, but less than familiar roots like camas or bitterroot. During periods of nutritional stress, it would have taken a couple of hundred mussels a day to provide enough protein to keep a family alive, and a couple of thousand of them to provide a basic amount of calories. It is no wonder that early anthropologists termed them starvation food.

But Stevens also found that Margaritiferas are extremely rich in calcium and iron. For a family of five, it would take less than a dozen mussels to satisfy the USDA minimum daily requirement for iron, and less than five dozen for calcium. With the mussels living in such abundance here, this means that even the kids in a family could have brought home enough to meet these needs. Iron and calcium are two minerals of special importance to pregnant and lactating women. Today, most mothers get these minerals from dairy products or supplemental pills, but in past time the mussels may well have been a key dietary constituent for growing Plateau families.

It seems possible that those early anthropologists did not take into account the subtleties of season, individual needs, supply, and availability in a large natural system. The people of the Plateau, especially women and children, had a need, and they somehow knew that Margaritifera could supply it. All it took to satisfy that need was a pleasant wade in the creek.

<----previous article...Diggings Spring 2008...next article---->