‘Underwater Drones’ May Enhance Marine Animal Monitoring

In recent years, concern has grown about the effects of human-caused sound on marine life. Regulators often require monitoring before, during, or after an industrial project to assess or mitigate the impact of noise such as that created by pile driving on the ocean floor. New, unmanned vehicle technologies can improve the offshore monitoring of marine animals by industry. Unmanned surveys are safer for personnel, can be of longer duration, have greater range, and can be less costly than traditional survey methods.

Marine animal monitoring falls into three categories: population, mitigation, and focal animal monitoring. Population monitoring measures the abundance, density, and distribution of animals. Mitigation monitoring is meant to trigger a response to the detection of target animals within an area. Focal animal monitoring investigates a specific animal’s responses to human-caused sound.

Three types of unmanned vehicles are currently in use for marine monitoring. They are:

1. Unmanned Aerial Systems (UAS) – powered aircraft (fixed wing and vertical takeoff and landing aircraft), kites, and lighter-than-air aircraft (blimps and balloons);
2. Autonomous Underwater Vehicles (AUV) – power-driven craft controlled by a propeller and underwater buoyancy gliders, and;
3. Autonomous Surface Vehicles (ASV) – boats, catamarans and semi-submersibles that are conventionally powered or self-powered using wind or waves.

Depending on the job, people determine the best equipment and sensor combination for a project. The types of data gathered can include images, acoustic information, and location data, as well as other information related to the animals or the environment. Cameras, either still or video, can track and record animals. Acoustic monitoring with hydrophones can be either passive or active. Passive systems capture sounds from the environment and can sometimes enable species identification. Animal-borne transponder tags may improve the reliability of data collected from passive systems. Active systems send out sound waves and measure the reflection from whatever the waves encounter. Most data collected, regardless of type, requires human review to confirm the findings.

What’s more, the range of available vehicles and sensor packages is expanding. As a result, unmanned vehicles will play an increasing role in future marine animal monitoring.

The authors recommend that, before putting too much emphasis on “underwater drones,” they should be compared to traditional monitoring methods, outcome-by-outcome to confirm their suitability. They also suggest that testing unmanned vehicles where species of high importance are currently not well monitored may be particularly beneficial. Finally, they advocate the development of computerized models that can simulate species behavior and environmental conditions. These models could test vehicle/sensor packages to determine their efficacy for a given monitoring task.

The emergence of these safer and more cost-effective technologies for marine animal monitoring should be welcome news to animal advocates. Improved monitoring capabilities will allow industry to better gauge the impacts of human activity in marine environments and respond accordingly.