Beamer, E., Haug, J., Rice, C. and Wolf, K., 2009. Final Report Nearshore Fish Assemblages in Reference and Spartina Removal Sites Located in South Skagit Bay. Skagit River System Cooperative, La Conner, WA. pp. 33.

Spartina is an invasive, non-native, salt-tolerant vascular plant in Puget Sound. It was intentionally introduced in Puget Sound near Stanwood in 1961 and because of its invasive nature, the Washington Department of Fish and Wildlife began a Spartina eradication program in southern Skagit Bay in the late 1990s. The objective of this study is to evaluate the effect of Spartina removal treatment on the fish assemblage, including juvenile salmon, in the southern Skagit Bay near the town of Stanwood, Washington.
In 2007 we made 185 beach seine or fyke trap sets catching 9,852 fish of 12 different species within a study area comprised of reference and treatment habitats types relative to Spartina removal. In 2008 we made 94 beach seine or fyke trap sets catching 4,471 fish of 15 different species. Juvenile salmon utilize habitat within treated Spartina marshes. Juvenile chum, Chinook, and pink salmon were captured in both reference (flooded mudflat, blind tidal channels within native marshes) and treated Spartina marsh (flooded and blind channel) habitats. We also demonstrate that other fish species utilize habitat within treated Spartina marshes including these dominant nearshore species: surf smelt, shiner perch, Pacific staghorn sculpin.
Fish assemblages in reference mudflat flooded intertidal habitat were similar to fish assemblages in flooded mudflat w clone intertidal habitat (e.g., treated Spartina marshes) over the two years sampled. Mudflat w clone areas used to be Spartina marsh, but were successfully treated and have now reverted to a physical habitat similar to mudflat, which is a natural reference habitat. These results suggest that Spartina marshes that are treated and revert toward a mudflat condition are likely to have fish assemblages similar to mudflats never colonized by Spartina.
Fish assemblages in native marsh blind channels were similar to the fish assemblages in blind channels found in clone areas (i.e., treated Spartina marshes) in one of the two years sampled. This result suggests that blind channel habitat within successfully treated Spartina marshes can result in fish assemblages similar to those in blind channel habitat in native marsh.
Since all fish habitat within the study area is intertidal, differences in elevation by habitat types will directly relate to the frequency, depth, and duration of tidal inundation. Lower elevation habitats will be wetted more frequently, to a deeper depth, and for a longer period of time than higher elevation habitats. Relative difference in fish access opportunity to the surface elevation of each habitat type is ordered greatest to least: reference mudflat, mudflat w clones (treated Spartina marsh), Spartina marsh, and native marsh. We also found Spartina marshes have less blind channel area than native marshes when standardized by marsh area. These results suggest that mudflats colonized by Spartina are less accessible to fish than both the original mudflat (as a result of increased elevation), but also when compared to native marshes which have approximately triple the blind channel habitat area.