Behavioral Ecology and Conservation of the Sex-Role Reversed Tidewater Goby

The tidewater goby, Eucyclogobius newberryi, is an annual species endemic to California's coastal lagoons, creeks, and marshes. This benthic fish prefers stillwater habitats and feeds opportunistically on benthic invertebrates. Fish are larger in the marsh than in lagoon or creek, suggesting that marsh habitats may have greater food resources or impose fewer energetic demands. Reproduction occurs over an extended period, with two peaks in spawning activity (spring and late summer). The male digs a spawning burrow, preferably in sand. The female lays her entire clutch with a single male, and the male accepts only one clutch per brooding cycle. Both sexes spawn repeatedly, but females are ready to spawn sooner than males can complete egg brooding.  This difference in potential reproductive rate skews the operational sex ratio toward females. As a result, the tidewater goby is sex-role reversed, meaning females compete more intensely than males for access to mates. Both sexes initiate courtship, but females display more striking breeding coloration and greater intrasexual aggression. Sex-role reversal is uncommon among animals, especially fishes. The tidewater goby is also a species at risk, in part due to narrow habitat preferences, isolation of populations, short lifespan, lack of marine dispersal, and vulnerability to introduced predatory fishes. Attributes that favor its recovery include euryhaline tolerances, rapid reproductive rate, its potential for opportunistic feeding, and the possibility of natural recolonization under certain circumstances. Potential conservation measures include protecting coastal marshes that adjoin creeks and lagoons, maintaining natural hydrologic regimes, preventing artificial breaching of the sandbar at the estuary's mouth, and preventing introductions of predatory fishes.