West Coast Region. The location of the 32 selected 

 ELMR West Coast estuaries are shown in Figure 16, 

 and the common and scientific names of the 47 

 selected ELMR West Coast species are listed in 

 Table 16 (p. 42). The initial pilot study for NOAA's 

 ELMR program was completed for several West 

 Coast estuaries in 1986 (Monaco 1986). Results for 

 the entire West Coast region are summarized in 

 Distribution and Abundance of Fishes and Invertebrates 

 in West Const Estuaries, Volume 1: Data Summaries, 

 ELMR Report No. 10 (Monaco et al. 1990). Life 

 history summaries and tables for the species in this 

 region were published in Volume II: Species Life 

 History Summaries (Emmett et al. 1991). 



Along the West Coast of the continental U.S., the 

 Coast Range mountains have restricted the extent 

 of low-elevation coastal plain. The San Francisco 

 Bay and Puget Sound estuarine systems were formed 

 when continental valleys sank during orogenic 

 (mountain-building) tectonic activity (NOAA 

 1990b). Puget Sound was further affected by glacial 

 action during the Pliestocene ice ages. Circulation 

 in the large systems (e.g., Puget Sound, San Fran- 

 cisco Bay, Santa Monica Bay) is dominated by tides, 

 while circulation in riverine systems (e.g., Colum- 

 bia River, Eel River) is dominated by freshwater 

 inflow. 



The 47 species selected for the West Coast are rep- 

 resentative of both the cold-temperate fauna of the 

 Oregonian marine biogeographic province, and the 

 warm-temperate Californian province. Although 

 two separate species lists could have been pre- 

 pared, it was deemed most feasible to consider the 

 entire U.S. West Coast as a single region. It should 

 be noted that the list includes several introduced 

 species. The Pacific oyster and Manila clam were 

 introduced to the U.S. from Japan in the early 1900s. 

 Softshell clam, American shad, and striped bass 

 were introduced from the U.S. East Coast. 



Table 17 (p. 43) readily conveys the occurrence of 

 the selected 47 ELMR species in each of the 32 West 

 Coast estuaries. This table depicts the highest rela- 

 tive abundance of the adult or juvenile life stage of 

 each species, in any month, in any salinity zone 

 within each estuary. The spawning, egg, and larval 

 life stage categories are not considered. This table 

 also suggests the zoogeographic distribution of spe- 

 cies among West Coast estuaries, and the contrast 

 between the Oregonian and Californian provinces 

 are evident. For example, deepbody anchovy, 

 slough anchovy, kelp bass, and barred sand bass are 

 not scored as present north of Pt. Concepcion. The 

 anadromous sturgeon and salmonid species gener- 

 ally' occur from San Francisco Bay northward. Sev- 



eral of the introduced species, such as American 

 shad and striped bass, are now well established and 

 considered abundant in some West Coast estuaries. 

 In contrast, several native stocks of anadromous 

 salmonids have been listed, or are under consider- 

 ation for listing, under the federal Endangered Spe- 

 cies Act (NMFS 1995). Estuarine habitats are essen- 

 tial to these stocks as a rearing area for juveniles 

 migrating seaward, and as a migration corridor for 

 adults returning to spawn in fresh water (Emmett 

 and Schiewe 1997). Therefore, these estuarine habi- 

 tats must be conserved in order to achieve recovery 

 of the threatened and endangered runs of salmon 

 and steelhead. 



To examine seasonal patterns of species presence/ 

 absence in West Coast estuaries, the numbers of 

 species present, ranked as "rare" or greater, were 

 counted by month and by salinity zone for the 

 adult, juvenile, larval, spawning, and egg life stages. 

 The original ELMR West Coast data set was used 

 with no revisions (Monaco et al. 1990). In Figure 17 

 (p. 45), the numbers of species were averaged across 

 estuaries and plotted by month for these life stages. 



• The number of species appears to be lowest in 

 the tidal fresh zone. However, this may have 

 been partially due to the fact that the selected 

 West Coast ELMR species are primarily estua- 

 rine and marine, not freshwater. Many of the 

 West Coast ELMR species found in fresh water 

 are anadromous salmonids that use the tidal 

 fresh zone as a migration corridor to and from 

 freshwater spawning and rearing areas. 



• Juveniles and adults are the predominant life 

 stages present in estuaries, followed by larvae, 

 eggs and spawning. 



• The number of species present as juveniles and 

 adults peaks in June, and is lowest from Decem- 

 ber through March. 



• The number of species present as larvae in the 

 mixing and seawater zones is highest in May 

 and June. 



Text continues on p. 45. 



40 



