Did you know that an elephant seal holds the record for the deepest dive of any marine mammal? They are true deep divers and have been recorded at depths of OVER 2 KM – 2,388 m to be exact! Southern elephant seals are the largest seals in the world and have a unique life history spending the majority of their time at sea, only coming ashore for 1 – 2 months every year to breed and molt. They have an impressive track record for the amount of ocean that they can cover in their foraging trips – up to 21,000 km in one year during a double migration – and researchers, including SMRU’s Dr. Mike Fedak, have taken a recent interest in using elephant seals to determine oceanographic conditions in hard-to-reach places like Antarctica.
Fedak and his team have been tagging Southern elephant seals for over 25 years and have joined forces with numerous marine biologists as part of the Southern Elephant Seals as Oceanographic Explorers (SEaOS) program. The aim of this collaborative effort is to collect data on both the animals and the ocean that they’re swimming through – a task that is otherwise tricky in the cold, deep and remote waters of the Southern Ocean.
Fedak’s team primarily uses SMRU Instrumentation’s Conductivity/Temperature/Depth Satellite Relay Data Loggers (CTD-SRDLs), which are essentially small computers housed in a waterproof casing. The tags are attached harmlessly with glue where they cause the least amount of disruption to the animal’s hydrodynamics, typically on their head; when it molts, the tag falls off (hopefully on land!) and can be recovered by the research team. SRDL tags include sensors for animal movement, depth, salinity, and water temperature. The information is stored on the tag during each dive, and once the animal surfaces, the information is transmitted to the ARGOS satellite and transferred back to the labs of technicians tasked with analyzing these complex datasets. Over the years and as technology has improved, the tags have become smaller, lighter, and able to house more sophisticated software to manage data and communications. Fedak has used this information to study everything from elephant seal foraging behaviour to body condition and sleep patterns; anecdotes abound from his many tagging studies.
The Marine Mammals Exploring the Oceans Pole to Pole (MEOP) portal is a large database where much of this data is stored, along with the output of numerous other tagging studies. The marine mammal and oceanographic tag data is made available online and can be publicly accessed by scientists around the world. MEOP stemmed from the SEaOS program and is now a sizeable consortium linking field biologists to the teams of researchers using the data. This database has become a key source of information for many oceanographers and marine mammal biologists alike, and has been particularly useful for studies on climate change in polar regions.
Our team has worked with SMRU on several tagging and telemetry studies. If you’d like to learn more about the many applications of tag data, check our some of our projects below. For example, we’re currently using harbour seal tag data to determine their potential collision risk with tidal turbines.
- Telemetry to describe the abundance and distribution of seals in the Firths of Forth and Tay
- Modelling seal telemetry data to predict seal density for MORL and BOWL
- Telemetry data to derive seal abundance estimates at Triton Knoll R2 Wind Farm
- Seal tagging studies at the world’s first large scale commercial tidal stream generator SeaGen