The tiny, delicate and short-lived Delta smelt, already protected under both federal and state Endangered Species acts, now has other troubles: it is not a steady swimmer. And the fish's poor swimming ability has implications for how flows in California's Sacramento-San Joaquin Delta waterway -- its habitat -- should be managed. In laboratory testing, UC Davis researchers found that the finger-length fish varies significantly from other fish previously tested for their swimming capacities. The smelt, it turns out, isn't a particularly strong swimmer. Yet current flows and water management decisions are based on how other, larger fish such as salmon, shad and striped bass swim. When it comes to making realistic flow-management guidelines for the smelt, the fish requires a different experimental approach that incorporates behavioral preferences, says Joseph Cech, a UC Davis professor of wildlife, fish and conservation biology. The work of Cech and postgraduate researcher Christina Swanson analyzing the smelt's swimming performance was published recently in the Journal of Experimental Biology. Their work has serious implications for saving the smelt from extinction and for future water-management decisions in California. "It is absolutely crucial we figure out how these fish behave, so we can better manage our resources in this state," Cech said. He and other UC Davis biologists are collaborating with campus hydraulic engineering scholars to study Delta fishes' behavior and performance in a large "fish treadmill." The treadmill studies are funded by the California Department of Water Resources to help water and fish managers construct and operate large fish screens in the Sacramento-San Joaquin watershed.