Prepared in cooperation with the U.S. Army Corps of Engineers Recovery —Integrated Science Program The Pallid : Scientific Investigations Help Understand Recovery Needs

By Aaron J. DeLonay

Understanding of the pallid sturgeon ( reproductive physiology of pallid sturgeon and relations to albus; fig. 1) has increased significantly since the species was environmental conditions; (2) determining movement, habitat listed as endangered over two decades ago. Since 2005, scien- use, and reproductive behavior of pallid sturgeon; and (3) quan- tists at the U.S. Geological Survey (USGS) Columbia Envi- tifying availability and dynamics of aquatic habitats needed by ronmental Research Center (CERC) have been engaged in an pallid sturgeon for all life stages. interdisciplinary research program in cooperation with the U.S. Army Corps of Engineers Missouri River Recovery Program, Reproduction and Environmental Cues: How do U.S. and Wildlife Service, Nebraska Game and Parks environmental factors influence reproductive Commission, and numerous other State and Federal coopera- success? tors to provide managers and policy makers with the knowledge Pallid sturgeon may live a long time and take many years needed to evaluate recovery options. During that time, the to reach reproductive maturity. Female pallid sturgeon in the USGS has worked collaboratively with river scientists and man- Missouri River may not until they are 10 years old or agers to develop methods, baseline information, and research older, and then they do not spawn every year. Environmental approaches that are critical contributions to recovery success. factors that control the frequency and timing of reproduction The pallid sturgeon is endangered throughout the Missouri have a strong influence on the potential of a sturgeon popula- River because of insufficient reproduction and survival of early tion to recover (Wildhaber and others, 2007). Scientists at the life stages. Primary management actions on the Missouri River CERC are evaluating the readiness of pallid sturgeon to spawn designed to increase reproductive success and survival have in hatcheries and the river by using a suite of blood chemistry focused on flow regime, channel morphology, and propagation. measurements and histological examinations. These measure- The CERC research strategies have, therefore, been designed to ments provide an accurate assessment of each fish’s reproduc- examine the linkages among flow regime, re-engineered chan- tive status and nearness to spawning. Results indicate that nel morphology, and reproductive success and survival. Specific reproductive readiness and spawning in pallid sturgeon is the research objectives include the following: (1) understanding result of a complex interaction between internal physiological conditions and environmental factors or “cues” (fig. 2). Day length and temperature appear to be the most important of the cues that trigger reproductive readiness (DeLonay and others, 2009); however, conditions at the spawning site, the presence of other reproductive adults, and the reproductive health of the fish may ultimately play an important role in determin- ing precisely how successful spawning will be and whether will hatch and survive. Sturgeon species in the Missouri River with intersex, teratogenic tumors, testicular deformities, and parasites have been documented by CERC scientists (DeLonay and others, 2009). To date, it is not known what is causing these reproductive abnormalities Figure 1. Reproductive adult male pallid sturgeon (Scaphirhynchus albus).

U.S. Department of the Interior Fact Sheet 2010–3024 U.S. Geological Survey April 2010 or whether they are influencing sturgeon reproductive success. that wild and hatchery–origin pallid sturgeon are spawning at There is concern that contaminants in water and the food chain multiple locations in the Lower Missouri River, however, it is as may be causing these pathologies. Through laboratory studies yet unknown how many adults are spawning and whether any in progress at the CERC, researchers are beginning to evalu- young are surviving to contribute to the population. Compari- ate whether chemicals measured in the Missouri River at levels sons between adult sturgeon that do spawn and those that do of concern for other species may be affecting reproduction in not provide insight into the possible factors that may promote shovelnose (S. platorynchus) and pallid . spawning success. Data from these studies provide informa- tion that managers may use to facilitate migration or create Migration and Spawning: Are pallid sturgeon conditions at spawning sites that are optimal for aggregation of spawning successfully in the Missouri River? adults, egg deposition, and survival of young.

Scientists at the CERC use physiological assessments in Habitat Use and Availability: What types of habitats conjunction with telemetry tags and advanced microsensors to do sturgeon use, and how much is available? monitor pallid sturgeon migrations and track pallid sturgeon to their spawning locations. Adult pallid sturgeon are implanted Hydrologists use advanced sonar and hydroacoustic with transmitters and small data storage devices that record depth, velocity, and substrate mapping tools to assess habitats temperature and depth. Researchers follow the fish as they where sturgeon are found (fig. 4). Research at the CERC has move upstream to spawn, thus recording habitats used during shown that sturgeon may integrate information at multiple migration and at the eventual spawning destination. Results spatial scales when choosing which habitats to occupy or with limited numbers of pallid sturgeon show that females in the move through. Transitional zones between habitat types and Lower Missouri River exhibit spawning behavior characterized the arrangement of habitat patches and features may be among by rapid upstream movement, stopping then spawning within the more significant factors in determining where sturgeon are hours, followed by a variable intermittent downstream move- found and how they migrate (Reuter and others, 2009). All ment (DeLonay and others, 2009) (figs. 2 and 3). Spawning is female pallid sturgeon tracked during reproduction appeared verified by the recapture of females that have released their eggs to have spawned in areas of swift, converging flow on outside after spawning and by observation of spawning aggregations bends, over or adjacent to gravel and cobble (DeLonay and with high-resolution sonar imagery. The CERC studies show others, 2009). Hydraulic models developed from these data can

Spawning location (Apex) Sturgeon movement Temperature

Discharge

Pre-spawn Post-spawn phase phase DISTANCE DISCHARGE TEMPERATURE

Peak spawning period

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Figure 2. Conceptual model of migration and spawning behavior of female pallid sturgeon (Scaphirhynchus albus). 780 25 0 100,000 PLS07-004 Reproductive female 760 2 20 80,000

4 740

15 60,000 6 720

8 700 10 40,000 DEPTH, IN METERS IN DEPTH,

RIVER MILE, MISSOURI RIVER MILE, RIVER 10 680 5 CELSIUS DEGREES IN TEMPERATURE, 20,000 DISCHARGE, IN CUBIC FEET PER SECOND PER FEET CUBIC IN DISCHARGE, 12 660 0 14 0 March 26 April 2 April 9 April 16 April 23 April 30 May 7 May 14 May 21 2007 EXPLANATION Fish depth from data storage tag Telemetry location Water temperature from data storage tag Initial release Discharge from , South Dakota, Recapture river mile 811 Figure 3. Pallid sturgeon (Scaphirhynchus albus) females in the Missouri River move rapidly upstream to spawn in spring. be used to quantify how flow and channel morphology altera- DeLonay, A.J., Papoulias, D.M., Wildhaber, M.L., Mestl, G.E., tions combine to change habitats used by sturgeons. These same Everitt, D.W., and Chojnacki, K.A., 2007, Movement, habitat models also provide insight into larval transport, barriers or use, and reproductive behavior of and pathways for migration, and processes of sediment transport—a pallid sturgeon in the Lower Missouri River, in Korschgen, critical component of the environmental conditions that create C.E., ed., Factors affecting the reproduction, recruitment, and maintain quality habitat. Managers can use this information habitat, and population dynamics of Pallid Sturgeon and to determine if critical habitats are limiting, to assess relative Shovelnose Sturgeon in the Missouri River: U.S. Geological habitat quality, and to evaluate the trade-offs between flow Survey Open-File Report 2007–1262, p. 23–102. change and channel re-engineering to achieve habitat goals for Reuter, J.M., Jacobson, R.B., Elliott, C.M., and DeLonay, A.J., the pallid sturgeon. 2009, Assessment of Lower Missouri River physical aquatic References Cited habitat and its use by adult sturgeon ( Scaphirhynchus) 2005–07: U.S. Geological Survey Scientific Investigations DeLonay, A.J., Jacobson, R.B., Papoulias, D.M., Simpkins, Report 2009–5121, 81 p. (Also available at http://pubs. D.G., Wildhaber, M.L., Reuter, J.M., Bonnot, T.W., Cho- er.usgs.gov/usgspubs/sir/sir20095121. jnacki, K.A., Mestl, G.E., and Mac, M.J., 2009, Ecological Wildhaber, M.L., DeLonay, A.J., Papoulias, D.M., Galat, D.L., requirements for pallid sturgeon reproduction and recruitment Jacobson, R.B., Simpkins, D.G., Braaten, P.J., Korschgen, in the Lower Missouri River—A research synthesis 2005–08: C.E., and Mac, M.J., 2007, A conceptual life-history model U.S. Geological Survey Scientific Investigations Report for pallid and shovelnose sturgeon: U.S. Geological Survey 2009–5201, 59 p. (Also available at http://pubs.usgs.gov/ Circular 1315, 18 p. (Also available at http://pubs.er.usgs. sir/2009/5201/. gov/circ/2007/1315. 94°35'30" 94°35'15" 369.8

(! (! EXPLANATION 369.7

(! Depth, in meters (! Deep (! (! (maximumHigh : 10.83 12.6) (! (! 39°08'30" (!(! Shallow 369.6 (! OUTSIDE (minimum,Low : 3.91 2.9) (! (! (! REVETTED (! (! BEND (! (! (! (! (! (! Sturgeon relocation— (! 369.5 (!(!(! Relocations of (!(! (! pallid sturgeon (! (! PLS08-004 (! (acoustic tag 574) (! between May 7 and 369.4 (!(! May 10, 2008 (! (! (! (! (! 369.1 River-mile marker— 39°08'15" !(! ( Number is distance (! 369.3 (! upstream from the Missouri River junction with the ,

(! in miles 369.2 (! (! (!

Discharge on the date of mapping (2008-05.13) at the Kansas City, Mo., 0 75 150 METERS 369.1 streamgaging station: 68,600 cubic

0 300 600 FEET feet per second

Base from U.S. Department of Agriculture River miles from U.S. Army Corps of Engineers, 1960; National Agriculture Imagery Program, digital data, 2006 Sturgeon relocations from U.S. Geological Survey, Universal Transverse Mercator projection DeLonay and others, 2007; Aaron J. DeLonay, Zone 15 unpub. data, 2008

Figure 4. Multibeam bathymetric map showing location of a female pallid sturgeon (Scaphirhynchus albus) during spawning in the Missouri River.

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