Issue link: http://read.dmtmag.com/i/29869
to the recovery of the pallid sturgeon. Researchers have gained insights into long-term migration patterns and movement history by mapping the locations of individually identifiable fish. Beginning in summer 2005, researchers with USGS and NGPC initiated development of a telemetry project to track movements and habitat use of pallid sturgeon in the Lower Missouri River. The study involves simulta- neous data collection from multiple field crews across 810 miles of river from the Gavins Point Dam near Yankton, S.D., to the confluence of the Missouri and Mississippi Rivers near St. Louis. Such a large-scale study requires a robust and standard- ized data collection platform as well as near-real-time data delivery methods. To this end, the Sturgeon Information Management System (SIMS) mobile-mapping application was developed to streamline data collection and eliminate the need for cumbersome hardcopy field data sheets. Pallids Under Pressure Habitat modifications are thought to be responsible for the decline of the pallid sturgeon. Until channel modifications began in the 1800s, the Missouri River was a dynamic and ever-changing river composed of multiple channels, chutes, sloughs, backwater areas, side channels, migrating islands and sandbars. Today, approximately one-third of the Missouri River has been impounded behind a series of dams constructed for flood control, hydropower, navigation and water supply that greatly modify the river’s natural flow variation. In addition, these dams have created physical barri- ers that prevent long-distance migratory movements of the pallid sturgeon. The river’s downstream third has been channelized, which was completed by straighten- ing the river’s channel, stabilizing the banks and divert- ing flow out of secondary channels. These activities have substantially altered riverine habitats available to the pallid sturgeon. Telemetry: Finding the Target Since the telemetry study began, approximately 150 adult pallid sturgeons were captured, surgically implanted with small telemetry transmitters and released back into the Missouri River. Each telemetry transmitter is uniquely coded and emits a signal every 10 seconds for one to two years, depending on the battery life. Tracking pallid sturgeon by two-member field crews in high-tech tracking boats begins almost immediately after the fish are released back into the river. The tracking boats are equipped with a ruggedized laptop computer, a sub-meter-accuracy GPS unit, and telemetry equipment such as hydrophones and receivers (see Figure 2). The laptop computer runs the SIMS mobile-mapping application and the software necessary to decode the Mobility/GPS Special Issue lFigure 1. Named for its pale coloration, a mature pallid sturgeon averages between 30 and 60 inches in length and up to 85 pounds in weight. transmitter’s signal. The GPS unit, which is connected to the laptop, precisely identifies the boat’s location. Hydrophones are specialized underwater microphones used to “listen” for a signal from the transmitters implanted in each fish. The telemetry receiver is con- nected to the underwater hydrophones and the laptop computer to recognize and decode the signal from each uniquely coded transmitter associated with the fish. The most-common tracking method entails idling the boat downstream at a slow rate of speed with three hydrophones lowered into the water directed to three different directions (port, starboard and directly lFigure 2. Researchers use boats outfitted with telemetry equipment to track the pallid sturgeon. A P R I L 2 O 1 1 / W W W . G E O P L A C E . C O M 15