Improvement of CTD satellite tags for use on large baleen and odontocete whales
Abstract
Sampling of oceanographic data, including salinity (conductivity), temperature and depth, by instrumented marine mammals is a valuab le technique that has been used widely with seals, and to a lesser extent with cetaceans. The additional spatial coverage of data fr om animal-borne instruments adds to the understanding of ocean water masses and biological oceanography and provides data streams fo r long-term monitoring in the face of changing environmental conditions. Development of a reliable oceanographic sensor for use on m arine mammals must be considered of outmost importance as it, besides informing about animal behavior, contributes crucial informati on on ocean climate change and its link to animal distributions, soundscapes and ocean sound propagation properties. In a previous O NR-funded project, a CTD tag for baleen whales was developed and tested, the Wildlife Computers Scout-CTD; however, problems with er ratic conductivity/salinity measurements appeared some days or weeks after the tags were deployed on bowhead whales. These problems were absent in Scout-CTD tags deployed on narwhals for up to ten months and on elephant seals for up to four months, which indicates that the problem is not the tag but more likely the attachment and placement of the tags on bowhead whales. Some improvements to th e electronics from 2018 to 2019 were made, but they did not solve the problem. We therefore hypothesize that the conductivity senso r is sitting too close to where the tag penetrates the skin of the whale, allowing oil from the blubber to contaminate the sensor. T his will eventually result in an irretrievable loss of sensor accuracy. We propose to redesign the Scout-CTD tag attachment and depl oyment system for baleen whales in a way that should solve the conductivity sensor problems and make a commercially viable solution for other scientists. The modified Scout-CTD tag will be tested on bowhead whales and southern right whales over two field seasons p roviding the opportunity to optimize the design. In addition, we will modify the attachment used on narwhals in an effort to obtain deployments of one year to test the long-term reliability of the conductivity sensor. The results will confirm the efficacy of the instrument on different whale species under different environmental conditions - in Arctic ice-covered waters and the temperate ope n ocean.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 20, 2021
- Source ID
- N000142112632
Entities
People
- Melinda Holland
Organizations
- Office of Naval Research
- United States Navy
- Wildlife Computers (United States)