species, occurs in small, isolated patches, but is uncommon relative to the other seagrasses 
(Bayer, 1996). 
Recent surveys identified over 168 species of macroinvertebrates in Yaquina Estuary, 
with diversity and biomass highest in the lower estuary and lowest in the upper estuary (WED 
unpublished data). Polychaetes are the most numerous macroinvertebrate taxa, but ghost and 
mud shrimp (Neotrypaea cahforniensis and Upogebia pugettensis ) dominate the infaunal 
biomass (WED unpublished data). Bioturbation, bioirrigation, and feeding activities of these 
shrimps accelerate carbon and nutrient cycling within the estuary, and enhance the flux of 
dissolved nitrogen from sediments to the water column (DeWitt et al., 2004). Deposit and filter 
feeders are the most abundant benthic consumers, with filter feeders, primarily mud shrimp, 
dominating in the lower estuary. As mud shrimp abundance declines up-estuary, deposit feeders 
become more abundant. 
Five species of bivalves (cockle [ Clinocardium nuttali ], soft-shell clam [ Mya arenaria], 
littleneck clam [ Venerupis staminea ], gaper clam [Tresus capax ], and butter clam [, Scixidomus 
giganteus ]) are harvested recreationally, primarily in the lower portions of Yaquina Estuary. 
Although commercial harvest of these species is currently allowed, there have been no 
significant landings since the mid-1990's. Prior to that time, commercial landings, varied 
between 1,000 and 8,000 lbs. per year (P.M. Vance, Oregon Department of Fish and Wildlife 
(ODFW), personal communication). Non-native Pacific oysters (Crassostrea gigas) are grown 
commercially on 519 acres of leased tidelands in the middle reach of Yaquina Estuary, near 
McCaffrey and Poole Sloughs, with an annual production of 15,028 bushels valued at $594,000 
(Oregon Department of Agriculture 2000-2005). This equates to 45% of the Oregon commercial 
oyster production on state-owned tidelands. 
At least 62 species of finfish and epibenthic crustaceans occur in Yaquina Estuary, with 
the highest diversity and abundance found in the lower estuary, and reduced diversity and 
abundance upriver (DeBen et ah, 1990). Fish and crustacean abundance and diversity is highest 
during summer and lowest in winter. Estuary-wide, English sole [ Parophrys vetu/us\, Pacific 
snake blenny [Lumpeniis sagitta ], and shiner sea perch [Cymatogaster aggregate ?] are the three 
most abundant fishes, and sand shrimp [Crangon spp.], dungeness crabs [ Cancer magister ], and 
mysids [Neomysis mercedis ]) are the three most abundant epibenthic crustaceans (DeBen et ah, 
1990). Of these, dungeness crabs have the greatest economic value, supplying recruits to the 
10 
