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Biologging Helps Endangered Species Research

March 4, 2010

Biologging ““ the use of miniaturized electronic tags to track animals in the wild ““ has revealed previously unknown and suprising behaviors, movements, physiology and environmental preferences of a wide variety of ocean animals.

For instance, biologgers have recorded 5,000 foot (1,550 m) dives by Atlantic bluefin tuna, followed journeys of elephant seals halfway across the Pacific from their breeding beaches, and observed annual 40,000 mile migrations of sooty shearwaters ““ the longest recorded for any animal. Biologging science is showing researchers how animals work in the furthest reaches of the ocean environs and is advancing both basic and applied research.

A special collection of papers from an international conference on Biologging Science held in California and co hosted by the Tagging of Pacific Predators (www.TOPP.org) and the TAG A Giant Foundation (www.tagagiant.org) is being published Wednesday, March 3, 2010 in the scientific journal Endangered Species Research, which features a wide array of cutting-edge biologging research from around the world.

The ability to study animals in the wild using microchips that store on board data or transmit data to Earth-orbiting satellites has revolutionized how we study animals in the most distant parts of the globe. The tags can relay information about the animal’s movements, behavior, physiology or environmental surroundings in “real time,” or “archive” the data for later retrieval. Using this latter approach, researchers have overcome the challenges of studying wild, free-ranging predators that remain submerged beneath the ocean ““ where radio communications are impossible.

Recent biologging studies featured in the theme section fall into one of four major themes. The first are examples of advances in biologging technology, where partnerships between engineers and researchers have resulted in the development of more sophisticated types of tags, allowing new types of studies.

For instance, the use of tri-axial (three-dimensional) accelerometer tags has allowed scientists to study detailed movements of imperial cormorants, and to identify mating events in free-living nurse sharks. One researcher even used this technology to document beak movements of loggerhead turtles ““ enabling detailed analysis of their breathing and feeding patterns in the wild.

A second major theme is that of physiology, behavioral ecology and population structure. The ability to apply instruments to animals and actively record physiological parameters such as body temperature, oxygen utilization or heart rate has provided important net knowledge about how animals function in the wild.

This collection includes papers on Weddell seals in eastern Antarctica, harbor seals, Mediterranean monk seals and Stellar sea lions in the northern Gulf of Alaska. There is also the first biologging study of Blainville’s beaked whales around Hawaii, where they are sometimes exposed to sonar from naval vessels.

The third theme focuses on the ability of a tagged animal to record useful data about its surrounding environments ““ sometimes referred to as, “Animals as ocean sensors.” Elephant seals, for example, can sample the water column up to 60 times per day, reaching depths of 1000 m or more under their own power, across broad expanses of the ocean that are difficult to reach by ship or other conventional means.

Such data are now being incorporated into global ocean databases, and are being used by the oceanographic community to better understand ocean circulation. Specific studies in the collection focus on the data from northern elephant seals, juvenile Stellar sea lions, olive ridley sea turtles and Atlantic bluefin tuna.

The fourth theme is the use of biologging science for the conservation of threatened and endangered species. By providing a detailed understanding of how animals utilize their environment, biologging science offers resource managers and policymakers a valuable tool for identifying critical habitat areas, key for the recovery of such populations.

Several of the papers focus on sea turtles, including hawksbill turtles tagged on the Yucatan Peninsula, Mexico, juvenile green turtles from off the coast of North Carolina, loggerhead turtles in the Mediterranean and leatherback turtles tagged on their nesting grounds in Costa Rica. Other conservation-related studies focused on dolphins, river sharks, European minks and Mohave desert tortises ““ demonstrating the growing importance of this field across a variety of issues and habitats.

On the Net:

Stanford University — Hopkins Marine Station