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After our initial scouting effort we could see that all six regions we surveyed were very different in their topographic, environmental, and habitat structures. The information we collected enabled us to map the location of clams and features of their surrounding environment. The maps presented on this webpage display where we found clams of each species and at what densities. Overall, we found that both region and tidal stratum affect the distribution and abundance of the four clam species we investigated, and that each species of clam can be associated with aspects of the environment.
As you look over the maps below, keep in mind:
region drives species distribution
AND
tIdal height drives species distribution
This map shows the layout of tidal strata across Coos Bay. There is a range of tidal heights in all regions and unique depressions, bays, channels and high spots at each tide flat. Tidal height plays a role in structuring environmental patterns. For example, eelgrass is more abundant and more widely distributed across low tidal heights in all regions.
Butter clams are found in high densities in Coos Bay, and have increased since the surveys done in the 1970s. They are often found on high sandy bars, called butter bars, and occur in areas with little algae. They are most common at Pigeon Point.
There are considerably fewer cockles than butters or gapers in Coos Bay. There are fewer cockles throughout the bay compared to the surveys done in the 1970s. Cockles live near the surface and they are found in areas with oxygenated sediment and plentiful algae. Cockles are most abundant at the South Slough, Pigeon Point, and Airport tide flats.
Gapers are also found in high abundance in Coos Bay. In most areas they have increased since the 1970s. They are found in low tidal areas with plenty of eelgrass (Zostera marina). Today they are most abundant at Clam Island.
Native littlenecks were rarely found during our survey. Historical comparisons indicate that there has been a dramatic decrease in the littleneck population in Coos Bay. They are found in low tidal areas with eelgrass and oxygenated sediment. They are present at Pigeon Point and South Slough.
Historic decline in the native littleneck population in Coos Bay
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