Aquaculture and Fisheries (Jan 2021)
Underwater video cameras allow for detection of North American giant salamanders (Cryptobranchus alleganiensis alleganiensis) in both captive and wild streams
Abstract
Captive propagation and translocation are becoming vital components of conservation and management strategies for Eastern hellbender (Cryptobranchus a. alleganiensis) populations. Zoos, aquaria, universities, and state and federal agencies are concomitantly collaborating on the protection, education, and maintenance of captive populations of this unusual, cryptic salamander. Conservation strategies include the use of artificial nesting structures, collection of eggs from the wild, and head-starting individuals in zoos or hatcheries. The effects of these strategies need to be monitored, however, traditional survey and monitoring methods for the species in the wild involves rock-lifting, which has the potential to both harm habitat and alter reproductive behavior. Therefore, there is a need to develop effective, non-invasive and non-destructive methods of monitoring both wild and captive populations of Eastern hellbenders. Herein, we compare two simple, affordable, underwater video and camera systems (borescope and Aqua-Vu cameras) in their ability to 1) facilitate detection of adults under potential cover items and 2) facilitate nest detection and monitoring in both wild and captive environments. Both cameras were successful in detecting individual hellbender presence, albeit with different resolutions and detection times. The borescope was better at accessing deep cavities given its large flexible attachment which allowed for greater flexibility of scanning crevices of adult shelters. However, search time increased and even low levels of suspended sediment reduced visibility with the borescope. The Aqua-Vu camera provided greater overall visibility and faster detection of individuals under both natural and artificial shelters. There was a significant difference in the amount of time required to detect hellbenders with each camera design when searching under natural rocks (borescope: median = 67.8 s, Aqua-Vu: median = 39.1 s; Kruskal Wallis Test H = 15.62, p < 0.001) and artificial shelters (borescope: median = 30.9 s, Aqua-Vu: median = 13 s; Kruskal Wallis Test H = 25.23, p < 0.0001). We detected 8 natural nests with actively guarding males and only one individual using a wild artificial shelter. We recommend hellbender researchers utilize a combination of underwater video cameras to suit their specific survey goals in both captive and field settings. Moreover, we recommend zoo staff incorporate these methods to not only monitor captive populations but also to potentially record breeding behavior in zoos and aquariums.
