EXTENSION OF 2 NONINDIGENOUS FISHES, ACANTHOGOBIUS-FLAVIMANUS AND POECILIA-LATIPINNA, INTO SAN-DIEGO BAY MARSH HABITATS

Two nonindigenous fishes, the yellowfin goby, Acanthogobius flavimanus , and sailfin molly, Poecilia latipinna, were found in a variety of in tertidal wetland habitats in Sweetwater Marsh National Wildlife Refuge in San Diego Bay, California. This is the first published documentati on of these species in San Diego County tidal wetlands and an extensio n of their known ran!aes. The yellowfin goby, one of the larger specie s in the marsh fish assemblage and a generalist predator, was common i n samples throughout the refuge (44% frequency of occurrence [FO] in l arge channels), Although mean densities were low (0.04 individuals/m(2 )), all size classes were present, suggesting a self-sustaining popula tion, Adult sailfin mollies, which are largely herbivorous, were less common in channels (11% FO in locations sampled), but were concentrate d in areas with modified tidal action and pooling surface water, Juven ile sailfin mollies (<15 mm total length) were collected on the marsh surface from shallow, hypersaline (>40 parts per thousand) puddles fro m August to October 1995, despite extreme temperatures (>30 degrees C) , We recommend manage!ment actions that reduce off-season freshwater i nflows and return tidal action to impounded saltmarsh areas in order t o favor native species and prevent further spread of exotics.