Instruments attached to seals to understand their foraging in the Main Hawaiian Islands

April 28, 2014

To gain insight into the ecology and behavior of seals in the Main Hawaiian Islands (MHI), seals have been instrumented with National Geographic Crittercams (animal borne video cameras) along with a suite of other instruments including GPS tags and three-dimensional inertial motion sensors (OpenTags). The goal is to understand and share images of feeding and underwater behavior, and lay to rest many of the myths and misconceptions regarding monk seals and their impact on the marine environment and its resources.

Adult male RV18 on Kauaʻi with Crittercam, GPS tag, and 3D inertial motion sensor (OpenTag).
Adult male RV18 on Kauaʻi with Crittercam, GPS tag, and 3D inertial motion sensor (OpenTag).

Beginning in August 2010, instrument packs have been deployed on Molokaʻi, Kauaʻi, and Oʻahu, but the seals have taken them to nearly every other island from Niʻihau to the Island of Hawaiʻi. To date, data has been recovered from 11 seals (10 adult males and 1 adult female), and we are now in our final year! Crittercam deployments will be on-going after this project ends, but in the future they will not be paired with the additional location and motion sensors.

Data downloaded from the GPS tags will be used to identify foraging habitat and develop a better understanding of monk seal movements throughout the islands. Data collected from Crittercams and Open Tags (3D inertial motion sensors) will be used to develop 3D dive profiles to help us understand how and where the seals are foraging and how much energy they are spending while at sea. This metric will then be used to model the energetic cost of being a monk seal in Hawaiʻi (how much food a seal must consume to survive). We will use these data to develop analytical models to compare home ranges, habitat use, and behavior of monk seals in the main islands. We want to know if the seals prefer certain habitats over others, where those habitats are, and what the seals are doing when in those areas. Lastly, we will combine all of this information (habitat use and energetic cost) with a study of monk seal diet to look at the impact of monk seals on fisheries in the Main Hawaiian Islands.