NOAA Fisheries’ Alaska Fisheries Science Center, Marine Mammal Laboratory’s Michael Cameron is leading an innovative project to investigate the use of small uncrewed aerial systems (sUAS) to monitor the body condition of Arctic seals. Monitoring the body condition of seals in Alaska is increasingly important considering the rapid changes in the Arctic environment as a result of a changing climate.
The National Marine Fisheries Service (NMFS) is required to monitor the health and population status of five species of phocids (also known as “true” or earless seals) in Alaska as part of the Polar Ecosystems Program. The species of seals being monitored are bearded (Erignathus barbatus), ringed (Phoca hispida), spotted (Phoca largha), ribbon (Histriophoca fasciata), and harbor (Phoca vitulina). All of these species are NMFS Protected Resources under the Marine Mammal Protection Act, and the bearded and ringed seal are both listed as “threatened” under the Endangered Species Act. Body condition is a key indicator of population health and productivity, but traditional methods of capturing and measuring individuals to assess body condition are challenging, expensive, and often result in small sample sizes. Using sUAS and photogrammetry provides a non-invasive method of monitoring body condition of seals in Alaska with greater efficiency and less disturbance to the seals, greatly increasing the number of seals that can be measured and considered when assessing the health of seal populations in Alaska.
The Office of Research, Transition, and Application (ORTA) works to help accelerate transitions in NOAA and ensure that NOAA receives the best possible return on its research and development (R&D) investments. In some cases, projects require additional support at the final stages of R&D to cross the “valley of death” into use, so ORTA implemented a Bridging Program, which provides funding to high Readiness Level projects to help them across the bridge.
Dr. Cameron and his team participated in ORTA’s Bridging Program to enable their return to University of California Santa Cruz (UCSC) Long Marine Laboratory (LML) to collect additional sUAS images of captive seals to replace the earlier images that could not be used due to equipment issues (Figure 1). The Uncrewed Systems Research Transition Office (UxSRTO) supported the original project to develop a non-invasive method for monitoring body condition of seals in Alaska by using sUAS to collect images of seals in the wild. The sUAS can be flown over seals to collect images with minimal disturbance, and photogrammetry of the images taken with sUAS can be used to estimate body mass and develop an index of body condition.
In order to apply the method to wild animals, researchers must first develop a model that estimates a seal’s body mass based on photogrammetry measurements. Data from seals at captive-care facilities that are of known size serve as the foundation of that model. In 2021 and 2022, sUAS flights were conducted to collect imagery of bearded, ringed, and spotted seals at captive-care facilities at the Alaska SeaLife Center (ASLC) and the UCSC LML. Length, width, and footprint area measurements of the captive seals were taken from the images and will be used to build a model to estimate body mass; known measurements from the captive seals will be used to validate the model.
Over 11,000 images of seals were collected using sUAS. After images were collected, data were reviewed and seals in a subset of the images were measured. During this processing, much of the data collected at LML was found to be compromised due to equipment issues and so could not be used in the analyses. These data included imagery of the only bearded seals available for the study, and this imagery is critical to any efforts to develop a model for estimating body mass for this species. With critical data compromised, the project came to a standstill.
With support from the ORTA Bridging Program, the research team returned to UCSC in June 2023, to use sUAS to collect new images of the seals at the LML captive-care facility. The same sUAS and laser rangefinder was used at LML as had been used in 2022 at ASLC. The team again worked closely with the skilled trainers at UCSC to successfully obtain the full suite of images that are required for the remaining measurements needed for the model development (Figure 2).
The final phase of this project is to develop models to estimate body mass using the complete dataset of measurements from the captive seal images. Once the model has been developed, sUAS will be used to collect imagery of wild seals, such as those captured on a recent Polar Ecosystems Program ice seal research cruise on the NOAA Ship Oscar Dyson. Photogrammetry measurements from those images will be used with the model to estimate body condition (Figure 3).
