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Traditional analyses (e.g., Schnabel 1938 or Chapman 1954 of sequential mark-recapture experiments (Petersen and Schnabel type) yield population estimates with substantial negative bias and overly large confidence intervals if the combination of the number of animals marked and examined falls too low. To address these problems, sequential mark-recapture experiments are cast into a Bayesian framework using a "noninformative" discrete uniform improper prior (a priori theoretical) distribution. Some properties of the posterior distribution (probability of each population size given the data) are briefly and informally discussed (inference, convergence, mean, mode, median, and treatment of nuisance parameters). A sequential Bayes computational algorithm, suitable for microcomputers, is given. Several examples are presented as a practical guide to computing estimates.For relatively small sample sizes, the Bayesian approach yields larger mean abundance estimates than traditional methods. There is little difference in these estimates for larger sampling efforts. Advantages of the approach include the following: the probability of observing the data at all feasible population sizes is calculated exactly; the method works for all cases regardless of sample size or sampling procedure; a plot of successive posterior distributions can be used as a visual diagnostic of conformity with basic assumptions; and finally, inferences can be made directly, since the end product completely describes the uncertainty of the population size given the data.

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We developed a Kemp's ridley (Lepidochelys kempii) stock assessment model to evaluate the relative contributions of conservation efforts and other factors toward this critically endangered species' recovery. The Kemp's ridley demographic model developed by the Turtle Expert Working Group (TEWG) in 1998 and 2000 and updated for the binational recovery plan in 2011 was modified for use as our base model. The TEWG model uses indices of the annual reproductive population (number of nests) and hatchling recruitment to predict future annual numbers of nests on the basis of a series of assumptions regarding age and maturity, remigration interval, sex ratios, nests per female, juvenile mortality, and a putative ''turtle excluder device effect'' multiplier starting in 1990. This multiplier was necessary to fit the number of nests observed in 1990 and later. We added the effects of shrimping effort directly, modified by habitat weightings, as a proxy for all sources of anthropogenic mortality. Additional data included in our model were incremental growth of Kemp's ridleys marked and recaptured in the Gulf of Mexico, and the length frequency of stranded Kemp's ridleys. We also added a 2010 mortality factor that was necessary to fit the number of nests for 2010 and later (2011 and 2012). Last, we used an empirical basis for estimating natural mortality, on the basis of a Lorenzen mortality curve and growth estimates. Although our model generated reasonable estimates of annual total turtle deaths attributable to shrimp trawling, as well as additional deaths due to undetermined anthropogenic causes in 2010, we were unable to provide a clear explanation for the observed increase in the number of stranded Kemp's ridleys in recent years, and subsequent disruption of the species' exponential growth since the 2009 nesting season. Our consensus is that expanded data collection at the nesting beaches is needed and of high priority, and that 2015 be targeted for the next stock assessment to evaluate the 2010 event using more recent nesting and in-water data.

Sturgeon (Acipenseridae) stocks worldwide are generally in decline, with many populations close to extirpation. One prominent species, the White Sturgeon (Acipenser transmontanus) with spawning populations distributed throughout three large, western North American watersheds (the Sacramento, Columbia, and Fraser rivers), has experienced population declines in the past decade. In 2003, the Committee on the Status of Endangered Wildlife in Canada designated all six populations of White Sturgeon in Canada “endangered.” To assist sturgeon recovery initiatives in the lower Fraser River (British Columbia), a stewardship‐based monitoring and assessment program was developed by the Fraser River Sturgeon Conservation Society. A descriptive population model was developed to provide reliable annual population estimates by size/age group and location, based on tag release and recapture data collected by trained volunteers. As of January 2011, the population estimate (from 40‐ to 279‐cm fork length) was 44,713 (95% confidence level 42, 634–46, 792). Group size analyses suggest that abundance decreases have been greatest for juvenile sturgeon under 100‐cm fork length. Recruitment decline may be the result of several factors, including destruction of important spawning and early life history rearing habitats; fewer successful adult spawners due to in‐river fisheries; and/or impacts of reduced food supply and ecological imbalances on both early life and adult stages.