Hart Kristen M, Guzy Jacquelyn C, Smith Brian J
U.S. Geological Survey, Wetland and Aquatic Research Center, 3321 College Avenue, Davie, FL, 33314, USA.
Department of Wildland Resources, Utah State University, Logan, UT, 84322, USA.
Mov Ecol. 2021 Jan 5;9(1):1. doi: 10.1186/s40462-020-00237-3.
Satellite tags have revolutionized our understanding of marine animal movements. However, tags may stop transmitting for many reasons and little research has rigorously examined tag failure. Using a long-term, large-scale, multi-species dataset, we evaluated factors influencing tracking duration of satellite tags to inform study design for future tracking studies.
We leveraged data on battery status transmitted with location data, recapture events, and number of transmission days to probabilistically quantify multiple potential causes of failure (i.e., battery failure, premature detachment, and tag damage/fouling). We used a combination of logistic regressions and an ordinary linear model including several predictor variables (i.e., tag type, battery life, species, sex, size, and foraging region).
We examined subsets of data from 360 satellite tags encompassing 86,889 tracking days deployed on four species of marine turtles throughout the Gulf of Mexico, Caribbean, and Bahamas from 2008 to 2019. Only 4.1% of batteries died before failure due to other causes. We observed species-specific variation in how long tags remain attached: hawksbills retained 50% of their tags for 1649 days (95% CI 995-1800), loggerheads for 584 days (95% CI 400-690), and green turtles for 294 days (95% CI 198-450). Estimated tracking duration varied by foraging region (Caribbean: 385 days; Bahamas: 356; southern Gulf of Mexico [SGOM]: 276, northern Gulf of Mexico [NGOM]: 177). Additionally, we documented species-specific variation in estimated tracking duration among foraging regions. Based on sensor data, within the Gulf of Mexico, across species, we estimated that 50% of tags began to foul after 83 95% CI (70-120) days.
The main factor that limited tracking duration was tag damage (i.e., fouling and/or antenna breakage). Turtles that spent most of their time in the Gulf of Mexico had shorter tracking durations than those in the Bahamas and Caribbean, with shortest durations observed in the NGOM. Additionally, tracking duration varied by species, likely as a result of behaviors that damage tags. This information will help researchers, tag companies, permitting agencies, and funders better predict expected tracking durations, improving study designs for imperiled marine turtles. Our results highlight the heterogeneity in telemetry device longevity, and we provide a framework for researchers to evaluate telemetry devices with respect to their study objectives.
卫星标签彻底改变了我们对海洋动物活动的理解。然而，标签可能由于多种原因停止传输，而很少有研究对标签故障进行严格检验。我们利用一个长期、大规模、多物种的数据集，评估影响卫星标签跟踪持续时间的因素，为未来的跟踪研究提供研究设计参考。
我们利用与位置数据一同传输的电池状态数据、重新捕获事件以及传输天数，以概率方式量化多种潜在的故障原因（即电池故障、过早脱落以及标签损坏/污损）。我们结合使用了逻辑回归和一个普通线性模型，该模型包含几个预测变量（即标签类型、电池寿命、物种、性别、大小和觅食区域）。
我们研究了2008年至2019年期间在墨西哥湾、加勒比海和巴哈马群岛四个海龟物种上部署的360个卫星标签的数据子集，涵盖86889个跟踪日。只有4.1%的电池在因其他原因出现故障之前耗尽电量。我们观察到不同物种在标签附着时间长短上存在差异：玳瑁的50%的标签附着了1649天（95%置信区间995 - 1800），蠵龟为584天（95%置信区间400 - 690），绿海龟为294天（95%置信区间198 - 450）。估计的跟踪持续时间因觅食区域而异（加勒比海：385天；巴哈马群岛：356天；墨西哥湾南部[SGOM]：276天；墨西哥湾北部[NGOM]：177天）。此外，我们记录了不同觅食区域之间估计跟踪持续时间的物种特异性差异。根据传感器数据，在墨西哥湾内，跨物种来看，我们估计50%的标签在83天（95%置信区间70 - 120）后开始出现污损。
限制跟踪持续时间的主要因素是标签损坏（即污损和/或天线断裂）。大部分时间在墨西哥湾活动的海龟的跟踪持续时间比在巴哈马群岛和加勒比海的海龟短，在墨西哥湾北部观察到的持续时间最短。此外，跟踪持续时间因物种而异，这可能是由于不同行为导致标签损坏所致。这些信息将帮助研究人员、标签公司、许可机构和资助者更好地预测预期的跟踪持续时间，改进针对濒危海龟的研究设计。我们的结果突出了遥测设备寿命的异质性，并且我们为研究人员提供了一个框架，以便根据他们的研究目标评估遥测设备。
