BAYESIAN MARK-RECAPTURE MODELS FOR FISH SURVIVAL AND POPULATION ESTIMATION FOR USE IN MULTI-SCALE MODELING OF RIVERINE ECOSYSTEMS AND RESPONSES OF FISH POPULATIONS

Population Viability Analyses (PVA) are used to manage recovery or maintenance of fish populations. Such models typically contain parameters for each age class that include number of individuals, probability of survival to next age class, and reproductive rate among others. Using PVA models and inclusion of environmental variables, future population trends and most critical model parameters can be predicted. Wildhaber and others (2007) presented a conceptual life-history model for pallid and shovelnose sturgeon that illustrates how transition (for example, survival) probabilities of sturgeon life stages determine sturgeon population structure. Concurrently, Bajer and Wildhaber (2007) developed initial age-structured models for shovelnose and pallid sturgeon populations in the Lower Missouri River (LMOR). These models are based on the current state of knowledge for these sturgeon species, including critical assumptions of survival estimates. One purpose of this research is to further develop and improve the age-structured demographic models through better survival and population estimates with separate estimates for wild and stocked pallid sturgeon and inclusion of environmental variables.

Whether stocking of geographically distinct pallid sturgeon groups will have an effect on long-term survival or how these fish will disperse into different geographically distinct segments of LMOR and Middle Mississippi River are unknown. Progeny of locally stocked hatchery fish stocked 15 years ago have reached sexual maturity (Wildhaber and Bryan, 2006) and have begun to spawn in the LMOR (DeLonay and others, 2007). The survival of these genetically or geographically distinct fish will have ramifications for the stocking program throughout the LMOR. Additionally, the potential change in population as a result of the currently spawning hatchery progeny in the LMOR could drastically alter the need for additional hatchery fish. Models to estimate survival by size and origin of fish and dispersal patterns is important to becoming more efficient with the limited resources available for the recovery program.

Modeling the growth and survival of endangered species such as the pallid sturgeon is a difficult task due to limited information. Utilization of the more readily available information on the closely related shovelnose sturgeon will aid in development of population and survival estimate models for pallid sturgeon. This borrowing of strength across related species will come in one form through informative priors for a Bayesian analysis.

Bajer, P.G., and Wildhaber, M.L., 2007, Population viability analysis of Lower Missouri River shovelnose sturgeon with initial application to the pallid sturgeon: Journal of Applied Ichthyology, v. 23, no. 4, p. 457-464.

DeLonay, A.J., Papoulias, D.M., Wildhaber, M.L., Annis, M.L., Bryan, J.L., Griffith, S.A., Holan, S.H., and Tillitt, D.E., 2007, Use of behavioral and physiological indicators to evaluate Scaphirhynchus sturgeon spawning success: Journal of Applied Ichthyology, v. 23, no. 4, p. 428-435.

Wildhaber, M.L., and Bryan, J.L., 2006, Ultrasonic and endoscopic examination of lower Missouri and lower Mississippi pallid sturgeon to determine sex and 2006 broodstock potential: U.S. Geological Survey, p. 10.

Wildhaber, M.L., DeLonay, A.J., Papoulias, D.M., Galat, D.L., Jacobson, R., Simpkins, D.G., Braaten, P.J., Korschgen, C.E., and Mac, M.J., 2007, A Conceptual Life-History Model for Pallid and Shovelnose Sturgeon: US Geological Survey, p. 189.