邻近油砂活动的鱼类性能指标：对邻近油砂开采活动的阿尔伯塔省Steepbank河中粘杜父鱼性能指标的响应

自2009年以来,加拿大和阿尔伯塔省政府一直在制定Athabasca河下游及其支流（2010-2013年）地表水质量和水量的监测计划。这项对鱼类监测计划的贡献的目标是1）评估该河支流中鱼类的当前状态,2）识别上游参考物和油砂沉积物暴露位点之间存在的差异,和3）识别鱼类性能指标相对于历史研究的趋势和变化。本研究考察了阿尔伯塔省Steepbank河中粘杜父鱼（Cottus cognatus）在生长、性腺大小、生长状况和肝脏7-乙氧基甲氧基甲酰胺基脱氢酶（EROD）活性方面的鱼类性能指标,以此作为暴露于油砂相关化合物的指标。采样程序遵循历史采样方法（1999-2000年）,随着开发的进展,随着时间的推移提供可比数据,同时增加一个上游参考位点（n=2）。2010年至2013年,从油砂矿床（n=2）内的Steepbank河下游收集的杜父鱼中记录到了一致的变化。杜父鱼的数据显示,肝脏增大的同时相应的EROD活性诱导与历史数据一致,与生殖发育和性腺类固醇生产能力相关的能量投资减少。没有一致的证据表明,随着露天采矿开发的增加使得鱼类性能指标发生了变化,特别是在Steepbank河中段附近。尽管在过去15年里,Steepbank河流域的物理开发有所增加,但这些结果与历史数据一致,表明开发区附近的水环境的响应程度没有改变。     

Assessing conservation status with extensive but low-resolution data: Application of frequentist and Bayesian models to endangered Athabasca River rainbow trout

Use of extensive but low-resolution abundance data is common in the assessment of species at-risk status based on quantitative decline criteria under International Union for Conservation of Nature (IUCN) and national endangered species legislation. Such data can be problematic for 3 reasons. First, statistical power to reject the null hypothesis of no change is often low because of small sample size and high sampling uncertainty leading to a high frequency of type II errors. Second, range-wide assessments composed of multiple site-specific observations do not effectively weight site-specific trends into global trends. Third, uncertainty in site-specific temporal trends and relative abundance are not propagated at the appropriate spatial scale. A common result is the propensity to underestimate the magnitude of declines and therefore fail to identify the appropriate at-risk status for a species. We used 3 statistical approaches, from simple to more complex, to estimate temporal decline rates for a designatable unit (DU) of rainbow trout in the Athabasca River watershed in western Canada. This DU is considered a native species for purposes of listing because of its genetic composition characterized as >0.95 indigenous origin in the face of continuing introgressive hybridization with introduced populations in the watershed. Analysis of abundance trends from 57 time series with a fixed-effects model identified 33 sites with negative trends, but only 2 were statistically significant. By contrast, a hierarchical linear mixed model weighted by site-specific abundance provided a DU-wide decline estimate of 16.4% per year and a 3-generation decline of 93.2%. A hierarchical Bayesian mixed model yielded a similar 3-generation decline trend of 91.3% and the posterior distribution showed that the estimate had a >99% probability of exceeding thresholds for an endangered listing. We conclude that the Bayesian approach was the most useful because it provided a probabilistic statement of threshold exceedance in support of an at-risk status recommendation.