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Satellite Tags For Managing Dynamic Threats To Sea Turtles And A Real-Time 

Ocean Dashboard
For
Sea Turtle Programs

 

Amongst the COVID-19 crisis we are learning that near real-time data is key to containing this pandemic. And many of us are consulting dashboards like worldometer to inform our professional and personal decisions.

In the management of sea turtles and other at risk species however, we are suffering from a sparsity of sensors. And this leaves our wildlife and fisheries managers often guessing and at pains to make decisions that effectively mitigate risk to animals while limiting impact on fishing, shipping and other activities at sea.

Argos satellite tags can be a powerful tool to inform decision making. For example, John H. Roe et al tagged 135 leatherback turtles with Argos tags, publishing maps including the one below showing risk of turtle bycatch throughout the Pacific (see map). Yet, given the high cost of tags and tagging, often ranging from $2K to $4K each, such studies have tended to be episodic and results consequently providing a snapshot in time rather than reflecting dynamic changes as they occur.    

At Desert Star, we introduced our first Argos satellite reporting tags in 2011. But with many such devices already on the market and recognizing the need to support timely decision making by wildlife and fisheries managers, we aimed to offer something new. Tags that would be suitable not just for individual studies, but for the routine and ongoing tagging of species at risk or of interest. Tags that could underpin real-time ocean dashboards, showing the here and now, to inform decision making. 

If you are in the sea turtle community, we were looking forward to seeing you at ISTS 2020 in Columbia recently. But with this symposium necessarily delayed, let's have a look at what our users achieved with these tags as it relates to dashboard like capabilities and dynamic monitoring. You can also download a brochure discussing SeaTag devices for sea turtles here. 

Tag Endurance

Tag endurance is of course a key parameter for routine tagging. Fundamentally, the use of 'stored solar power' means that SeaTag has no hard endurance limit, providing both energy for sensor data acquisition and archiving even in darkness and for Argos. In practice however, marine fouling of the solar panel, tag shedding and various cumulative tagging risks such as predation and grounding impose limits. As it relates to sea turtles, Van Houtan et al deployed SeaTag-LOT tags as ocean drifters to test the ocean current drift hypothesis for hawksbill hatchlings. His drifters satellite reported for 3.3 to 14.3 months,with the longest reporter still active at the time of publication. Using SeaTag-TT on loggerhead post-hatchlings, Abalo-Morla et al observed reporting to 123 days, with the limit thought to be by tag shedding from the rapidly growing carapace at this early life stage. Overall, the longest reported SeaTag endurance, by Klimley, Hammerschlag et al, stands at three years and belongs to a SeaTag-MOD that first tracked a tiger shark for one year and then drifted across the Atlantic for two more. 

Tag Reusability

If you can recover a tag, you can retrieve its high-resolution archived dataset. And, with SeaTag devices, you may wash it and then use it again, reducing the effective cost of tagging. We are not aware of recovery and reuse among our turtle users, but the concept is practiced by other researchers.   In particular, Rick Goetz et al  have engaged in ongoing tagging of sablefish with SeaTag-MOD. The team has recovered tags from the Pacific in a targeted fashion, achieving 50% recovery rates and access to large datasets. Re-use has reached four deployments for some of the tags!

Large, Satellite Reported Datasets

Argos satellite is bandwidth limited, but with solar powered reporting over months and sometimes years, substantial datasets can nonetheless be remote retrieved. Pohlot et al demonstrated this for activity studies of sailfish, using compressed accelerometer reading transmissions that detailed speed bursts down to the sub-second duration.

Small Size and Tagging At Early Life Stages

While Abalo Morla et al demonstrated successful tagging of post-hatchling loggerheads, Kelly et al ran simulations that showed that the small SeaTag-TT/17g increases the drag experienced by a 30cm carapace green sea turtle by just 1.66%. It was the least drag for any of the tested tag models, and is a side benefit for a stored solar powered tag that doesn't require a battery.

Cost and Sample Size

To support routine tagging in meaningful numbers, tags must be affordably priced.   Designing for affordability is a complex matter. For Desert Star product affordability is baked into our business model.  As a broad based ocean sensing company, we offer many product categories.  And these products are based on a strict modular architecture that yields economies of scale in design, manufacturing, servicing and support alike.  As a result, you can buy a SeaTag-TT satellite tracking tag for sea turtles for $549 in high quantities, a basic pop-up tag for $499 and even our high-capability SeaTag-MOD tops out at $2500 at single quantity.  Meanwhile, satellite data return and therefore sample size can be assured against the various risks of tagging by our ST-GOLD tag replacement policy. 

Ocean Dashboard Beyond Sea Turtles

On the occasion of the originally scheduled ISTS 2020 symposium and recent publications, this newsletter was focused on sea turtles.   But, the need for real-time situational awareness in the oceans transcends individual communities and encompasses maritime security, fisheries management, wildlife conservation, offshore energy exploration and impact mitigation and many other concerns. The use of plentiful sensors at sea informing an ocean dashboard is also not an idea unique to our company.  Rather DARPA's Ocean of Things and Liquid Robotics Digital Ocean concepts pursue similar objectives.  While all these concepts may seem revolutionary, they are also ultimately inevitable and mirroring similar needs to sense and monitor conditions on land, from traffic conditions to air quality, life stock management, forest management and more.  Within the ocean environment, we think of SeaTag as the rough equivalent of smartphones, very versatile globally reporting multi-sensors devices that can be applied to many jobs.   If this broader picture is of interest to you, have a look at Marco Flagg's article on the Ocean Dashboard as published in Sea Technology magazine here.   You might be surprised by the unexpected discoveries of a tiny ocean explorer.
 
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