Perspectives on the Application of Unmanned Aircraft for Freshwater Fisheries Census

Abstract

This work provides an overview of the use of small unmanned aircraft systems for freshwater fisheries survey and fish identification. As an example, a series of river reaches in Mongolia was surveyed for identification and sizing of the endangered Taimen Hucho taimen, the world's largest salmonid. Using polarized video imagery, Taimen were positively identified in depths of over 2 m. River reaches were chosen for survey to include likely Taimen holding grounds as well as areas that were unlikely Taimen habitat. Large areas of river reaches were quickly surveyed with video imagery stored for analysis. Using land‐based targets for sizing and flying autonomous search patterns, we found that Taimen were easily identifiable based on their swimming patterns and could be remotely sized; furthermore, the fish did not appear to be disturbed by the presence of overhead aircraft. Lessons learned from the experiments and recommendations for future advances are provided. The use of small unmanned aircraft systems for fisheries is shown to be a novel and inexpensive alternative to traditional fisheries survey methods.

Riverine Plastic Litter Monitoring Using Unmanned Aerial Vehicles (UAVs)

“…The easiest way to reduce sun glint is to make use of polarising filters when flying in sunny conditions. This directly reduces the appearance of sun glint [31]. A disadvantage of using polarising filters, however, are that they cannot be "turned off" during flight.…”

Flight elevation and water clarity affect the utility of unmanned aerial vehicles in mapping stream substratum

“…Unmanned aerial vehicles (UAVs or drones) may provide a flexible bridge between remote sensing techniques and on‐the‐ground mapping (Hodgson, Baylis, Mott, Herrod, & Clarke, ). The use of UAVs may be particularly useful when one requires more detailed images than what is available from aerial photography, and across larger spatial extents than is feasible to cover on the ground (Tyler et al, ). UAVs are increasingly being used in studying aquatic organisms and have recently been employed in quantifying jellyfish aggregations in marine habitats (Schaub et al, ) and identifying individual taimen Hucho taimen Pallas in Mongolian rivers (Tyler et al, ).…”

“…Indeed, a rapidly increasing number of available UAVs contribute to lowering the price to the level that their use is no longer cost‐prohibitive (Woodget, Austrums, Maddock, & Habit, ). When used under favourable conditions, UAVs can represent a useful addition to the quiver of tools used in aquatic habitat mapping and may be used to build orthophotos and quantify substrate size distributions (Tyler et al, ). A major strength of this approach is that geo‐referenced footage can be stored for future evaluations (Marcus & Fonstad, ), which may serve as important baseline information in the face of chronic pressures on rivers and riparian ecosystems.…”

Use of Drones in Fishery Science

“…Tyler et al. () described perspectives for collecting freshwater fisheries census data with Taimen Hucho taimen surveys in Mongolia to test the feasibility of species identification (without animal disturbance), size and detection rate estimates, and automated fish recognition. Spawning surveys for Chum Salmon O. keta and Sockeye Salmon O. nerka have been successfully conducted (Kudo et al.…”

“…Outside of megafauna studies, the literature for fisheries population assessments is currently limited, despite the fact that such surveys would be possible, particularly in clear coastal waters or stream ecosystems. Tyler et al (2018) described perspectives for collecting freshwater fisheries census data with Taimen Hucho taimen surveys in Mongolia to test the feasibility of species identification (without animal disturbance), size and detection rate estimates, and automated fish recognition. Spawning surveys for Chum Salmon O. keta and Sockeye Salmon O. nerka have been successfully conducted (Kudo et al 2012;Whitehead et al 2014).…”