Data from: Evaluation of an acoustic telemetry transmitter designed to identify predation events

The field of acoustic telemetry has evolved rapidly and now permits the remote sensing of animal behaviour, movement, physiology and survival in environments and species not previously possible. However, an inability to detect when a telemetered animal is consumed by a predator can complicate accurate interpretation of telemetry data. Here, we describe efforts to test two generations of a novel prototype acoustic telemetry transmitter designed specifically to detect predation.
Testing involved either staged predation events where tagged prey (Rainbow Trout Oncorhynchus mykiss and Yellow Perch Perca flavescens) were fed to captive Largemouth Bass Micropterus salmoides, or false positive testing where prey fish were tagged and held without risk of predation. Metrics of interest were (a) the rate of correctly identifying predation events, (b) signal lag (i.e. the time required to detect a predation event), (c) tag retention time in the predator's gut, and (d) the rate of false positive triggering in both live and dead prey fishes.
Staged predation events were successfully identified in 61/65 and 52/55 trials for generation 1 and 2 tags, respectively. Signal lag time was reduced in generation 1 tags (generally between 1 - 9 hours) relative to generation 2 (3 - 29 hours); although signal lag was highly variable. A generalized linear mixed model indicated strong evidence that signal lag and tag retention were both negatively correlated with water temperature, but were not affected by prey species and only slightly by individual predator traits. There was preliminary evidence that prey size may be an important determinant of both signal lag and tag retention. False positives in live fish were absent after 120 days for generation 1 tags (n=31), however rates were significantly higher (10/44) after only 66 days for generation 2 tags. False positives in dead fish suggested that 20% of generation 2 predation tags would falsely trigger 2-3 days post-mortem.
Testing of the novel predation tags was encouraging however further testing is recommended. Predation tags will be an important contribution to the field of acoustic telemetry; permitting improved data interpretation and less subjective estimates of predation rates in biotelemetry studies.

声学遥测领域发展迅猛，如今已可在此前难以实现的环境与物种中，对动物的行为、移动、生理状态及存活情况开展遥感监测。但无法识别遥测标记动物被捕食者捕食的节点，会给遥测数据的精准解读带来诸多困扰。本文详述了针对两代专为捕食事件检测设计的新型声学遥测发射机原型的测试工作。
测试分为两类：一是模拟捕食实验，将携带标记发射器的猎物（虹鳟 *Oncorhynchus mykiss* 与黄鲈 *Perca flavescens*）投喂给圈养的大口黑鲈 *Micropterus salmoides*；二是假阳性测试，即对猎物鱼进行标记后饲养，使其无被捕食风险。本次测试关注的核心指标包括：(a) 捕食事件的正确识别率；(b) 信号延迟（即检测到捕食事件所需的时长）；(c) 发射器在捕食者消化道内的留存时间；(d) 活体与死体猎物触发假阳性信号的概率。
测试结果显示：第1代标签在65次模拟捕食测试中成功识别61次，第2代标签则在55次测试中成功识别52次。与第2代标签（信号延迟为3~29小时）相比，第1代标签的信号延迟更短（通常为1~9小时），但延迟波动幅度较大。广义线性混合模型分析结果表明，有充分证据显示信号延迟与标签留存时间均与水温呈负相关，不受猎物物种影响，仅受捕食者个体特征的微弱影响。另有初步证据表明，猎物体型可能是影响信号延迟与标签留存时间的重要因素。对于第1代标签，31尾活体猎物在120天后未出现假阳性触发情况；而第2代标签的44尾活体猎物仅在66天后便出现10次假阳性触发，比例显著更高。死体猎物的假阳性测试结果显示，20%的第2代捕食检测标签会在猎物死亡后2~3天触发假阳性信号。
本次新型捕食检测标签的测试结果令人振奋，但仍建议开展进一步验证测试。此类捕食检测标签将为声学遥测领域带来重要价值，能够提升生物遥测研究中数据解读的精度，并减少捕食率估算的主观性。