Endangered pallid sturgeon (Scaphirhynchus albus) (right) and shovelnose sturgeon (Scaphirhynchus platorynchus) (left) from the Lower Missouri River, captured as part of the USGS Comprehensive Sturgeon Research Program. Early spring sampling for reproductive adult pallid sturgeon on Lower Missouri River. High-resolution multibeam bathymetric map to characterize habitat around tagged sturgeon locations. Microscopic image of sturgeon larval stage. Field researchers capture Scaphirhynchus sturgeon for telemetry studies using baited trotlines.

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Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:°F =(1.8×°C)+32 Multiply By To obtain Length millimeter (mm) 0.03937 inch (in.

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We assessed changes in proximate body composition, wet mass, and the occurrence of mortality among sedentary and actively swimming (15 cm/s) juvenile rainbow trout (Oncorhynchus mykiss) (120–142 mm total length) that were held at 4.0, 7.5, or 15.0 °C and fasted for 140 days. Warmer water temperatures and swimming activity accentuated declines in lipid mass, but they did not similarly affect lean mass and wet mass. Swimming fish conserved lean mass independent of water temperature. Because lean mass exceeded lipid mass, wet mass was not affected substantially by decreases in lipid mass. Consequently, wet mass did not accurately reflect the effects that water temperature and swimming activity had on mortality of fasted rainbow trout. Rather, lipid mass was more accurate in predicting death from starvation. Juvenile rainbow trout survived long periods without food, and fish that died of starvation appeared to have similar body composition. It appears that the ability of fish to endure periods without food depends on the degree to which lipid mass and lean mass can be utilized as energy sources.

Intensive management of the Missouri and Mississippi Rivers has resulted in dramatic changes to the river systems and their biota. These changes have been implicated in the decline of the pallid sturgeon (Scaphirhynchus albus), which has been listed as a United States federal endangered species. The sympatric shovelnose sturgeon (S. platorynchus) is more common and widespread but has also been in decline. The decline of pallid sturgeon is considered symptomatic of poor reproductive success and low or no recruitment. In order to organize information about these species and provide a basis for future development of a predictive model to help guide recovery efforts, we present an expert-vetted, conceptual life-history framework that incorporates the factors that affect reproduction, growth, and survival of shovelnose and pallid sturgeons.

Radiotelemetry is a useful tool to describe habitat use by fish, but studies may inaccurately describe microhabitat use due to failure to account for errors when identifying fish locations. We developed a technique that identifies the extent of location errors of a hand-held radiotelemetry system. The ranges of location errors were determined among different observers, between land and water, and at an array of distances (5 -125 m) between transmitters and receivers. No significant differences occurred among three observers at distances of 100 m or less or between transmitters on land or in water. Location error increased significantly with distance between transmitter and receiver; mean error was 0.5 m a t 5 m and 4.5 m a t 100 m. The 95th percentile of location errors was 1.5 m a t 5 m and 10.5 m at 100 m. The number of trials needed to define location errors within 20% of the true mean ( P I 0.05) was 109 a t 5 m and 46 a t 100 m. Determination of location error with radiotelemetry equipment can be conducted by two people on land with a relatively small amount of effort when the results are to be applied to relatively shallow waters.