Objectives
The main objective of the MINTAG project is to develop smaller and lighter tags for long-term deployment, than the ones existing on the market today.
The large fast-swimming rorquals are typically too big to be captured alive and many are too skittish to be approached at close distance. So far, it has been difficult to successfully deploy satellite transmitter tags from a long-distance on these species. The goal of the MINTAG project is to develop new satellite telemetry tags and optimise the deployment of new long-lasting satellite tags and optimise the deployment methods to allow for the collection of year-round datasets of geographic positions for these species.
To tag fast-swimming whales, it is necessary to develop satellite transmitters that are small and can be shot into the skin and blubber from distances of over 20 m. This is often the closest that a well-trained whale-tagger can approach these whales. The whales show the back of their body for only a few seconds before the next dive, so a projectile tag must fly along a fairly straight trajectory across distances up to 30 m.
The new tags can also be used on smaller whale species (smaller diameter) and fast swimming species (as implantable tags generate less drag and vibration). Their longevity will be extended, as the retention time should be increased (reduced impact meaning reduced rejection risk) and the technology will be improved further by a reduced battery consumption compared to existing tags.
Satellite Telemetry
Satellite telemetry allows researchers to track the movement of an animal by using orbiting satellites that detect signals emitted from a transmitter attached to the animal. It is a widely used technology for tracking everything from sea turtles to birds and mammals. It has also been used extensively on marine mammals, including some groups of larger whales that are easier to approach, such as the humpback, bowhead and sperm whales.
Different satellite tracking systems are currently used in the four NAMMCO member countries and Japan for studying the movement of several species of baleen whales, including minke, fin and blue whales at Svalbard and Norway, minke and humpback whales in Iceland, minke, fin, humpback and bowhead whales in Greenland, fin whales in the Faroe Islands and fin, sei, bryde’s and minke whales in Japan. A high level of investment in terms of both effort and funding has been spent on scattered attempts to acquire data on the whales. However, to make significant progress in tagging studies, a joint effort is required to refine the methods in a way that will eventually benefit the cetacean research in all five countries as well as beyond. Reliable and well-performing satellite transmitter systems are currently available for birds, terrestrial mammals, seals, small cetaceans and some species of large cetaceans that can be relatively easily approached for short-range tagging. There is therefore an opportunity to refine these systems to address the need to develop effective satellite tracking systems for baleen whales, and especially for more cryptic species like minke and fin whales.
Tag Design
MINTAG develops miniaturised satellite tags to study fast-swimming, understudied species such as rorquals and pilot whales. Traditional tags have often been rejected within weeks, but MINTAG aims to improve attachment duration and data quality by developing a smaller an less intrusive tag.
The MINTAG project has developed the V0c tags (also referred to as SPOT-415), building on the earlier V0b design that was successfully tested in 2023. In parallel, the project introduced the SPOT-416 tags, which follow a similar design but are slightly larger.
These tags are specifically designed for deployment on fin, minke, sei, and pilot whales in both the North Atlantic and North Pacific. Since the initial prototypes, the tag designs have undergone multiple refinements, resulting in the improved and more robust V0c configuration.
In addition to tag development, the MINTAG Steering Group, working in collaboration first with Wildlife Computers and later also with O3ST, has designed and tested carrier systems tailored to these tags. These carriers enhance deployment efficiency and ensure optimal performance in the field.
One of MINTAG’s primary goals is to develop a miniaturised tracking tag capable of lasting long enough to provide meaningful insights into the winter migration patterns of target species. Through different designs and testing, the team refined multiple prototypes and arrived at an improved version, V0c. Building on these successful designs, the SPOT-416 tags now offer sufficient space to incorporate a double-battery system, significantly extending operational lifespan and enabling the MINTAG Steering Group to capture more data on interseasonal migration.
In keeping with MINTAG’s experimental approach, the SPOT-416 tags are available in three distinct variants: a petal design (SPOT-416B), a cone design with a broadhead tip (SPOT-416A), and a cone design with a standard MINTAG cutting tip (SPOT-416C). This diversity allows the MINTAG Steering Group to continue evaluating retention performance across different configurations, helping identify the most effective and reliable tagging mechanism.
The MINTAG tagging teams faced numerous challenges during its first year likely related to the low retention (i.e., the time the tag remains inside the whale) of the tags in the whales. These challenges limited the ability to adequately evaluate the MINTAG’s mechanical designs.
Consequently, the Steering Group and Wildlife Computers decided to further test the tags that be better retained in the whales during the 2024 and 2025 deployments by developing two variants of the V0b minke whale tags: one with petals and one with a retention cone. Both variants have distinct features, while other developments remain the same for both, such as the addition of flies in the carrier and the splitable stop plate.
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Petal version (Fig. 1) |
Cone version (Fig. 2) |
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Content |
A short sharpened triangular style tip with concave sides. The difference lays on the space between the shaft and the housing of the retention mechanis |
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Retention feature |
Rounded, somewhat flexible, fairly wide and fairly short petals. This version has two sets of petals, one on the shaft near the tip and one near the base of the housing. |
34 mm diameter cone, ridges to be parallel to the shaft, similar to the V0b minke whale tag version. |
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Housing |
Housing to be the same for both versions and nearly the same as the V0b housing |
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The V0b tag prototype consist in two different tags: the fin whale tag (Figure 1) and the minke whale tag (Figure 2). The two tag designs are based on differences in blubber thickness and distance to fascia (Figure 3) between the two target species: the fin and the minke whale. Both tags would ideally penetrate with the tip embedded below fascia, with the minke whale tags in some circumstance only penetrating the blubber. For more information consult our glossary.
The tags are composed of four main components, including:
- The dart tip, which cuts through the skin and blubber of the whale to ensure successful implantation.
- The tag housing, which contains the battery and transmitter.
- Retention cones that act as stoppers below the dermis or fascia to facilitate encapsulation and improve tag retention.
- The antenna, which transmits the tag signal
The ‘retention cones’ of the V0b tags have been redesigned
based on tests conducted on fin whale carcasses in Iceland during
the summer of 2022. To improve the retention properties, an improvised
‘blob-like’ feature was added to the V0b prototype (Figure 4). During testing,
this modification showed promising results, as it required considerable
strength to pull the tag out of the carcass. Consequently, the StG and Wildlife
Computers decided to refine the design and incorporate it into the final V0b
design. The retention cones in the current design have a rough surface to
provide a better grip, and they are perforated to allow tissue growth inside
the cone, thus increasing the retention time of the tags.
The V0b carrier is an aluminum tube equipped with stiff flights fixed with flexible glue, which is suitable for both tag designs (Figure 5). The tag with transmitter is located at the tip of the carrier and is released from the carrier upon impact with the whale.4
Developments on V0b during the tagging season
After the test shootings of five fin whale tags in Japan in June 2023, and test shootings of Greenland with Wildlife Computers, the Steering Group decided to change the fin whale tag design for the next tests in August 2023.
Kenji Konishi as well as Greenland with Wildlife Computers observed during the deployment that there were difficulties in hitting the target position accurately and achieving sufficient penetration, both of which are crucial for the initial testing of transmitters and deployment performance.
Therefore, the fin whale tag 2.0 is shorter than the previous one only measuring 21 cm and has a single front retention cone (Figure 6). Additionally, to ensure that the tag can effectively penetrate and cut through the skin without bouncing back due to the elasticity of the skin layers the tag has a three-blade cutting tip instead of the dart tip.
The transmitter
The MINTAG will be the first tag of a generation of Wildlife Computers tags that will utilise a new transmitter capable of transmitting to older Argos 2 and Argos 3 satellites, as well as to newer Argos 4 satellites. The transmitter is smaller, more efficient, and requires less power, enabling use in smaller tags such as the MINTAG. The Steering Group has experimented with different set ups of the duty-cycling to ensure that the tags are capable of transmitting for up to one year.
Technical Details
Further information on technical details will be displayed when the tag has been optimally developed and has proven to be reliable after successful deployment on fast-swimming rorquals, i.e., demonstrated a longer retention time and life time that what has been achieved today. The first trials of the new tags will be conducted in 2023.
Glossary
Some of the terms used in satellite telemetry methods are specific to this field and will be explained in this glossary. Some terms may not have been used on the website yet, but will be under Tag Design and Technical Design.| ARTS | Air Rocket Transmitter System - same as launcher | |
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Attachment cup |
Part of the carrier to which the tag is attached during deployment |
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Biobsy tip |
A hollow steel cylinder that collects and retains a skin/blubber biopsy |
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Broadhead |
The three bladed tip used for the fin whale version 2. Originally developed for crossbow hunting |
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Carrier |
Device that is used for carrying the tag from the launcher to the whale, also called ‘launching tube’ or ‘rocket’. Will detach and be recovered for re-use after a tag deployment. |
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Cutting tip |
A tip with 2-3 sharp cutting blades |
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Dart tip |
Sharp end of the tag that cuts through whale skin and blubber to ensure entry and successful implantation of the tag |
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Fascia |
Dense layer of connective tissue that separates blubber from muscle
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Flight |
The feather on the carrier that helps maintain a stable and controlled flight trajectory. |
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Launcher |
Device used for deploying tags, in this case the ARTS system |
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Retention cone |
Roughly doughnut-shaped widening around the tag shaft that acts as a stopper below the dermis or fascia to facilitate encapsulation and thereby retention of the tag |
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Retention line |
A monofilament line that can hold the tag to the carrier in case of misses |
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Retention petals |
Leaf-like metal pieces that swing out into the blubber to resist expulsion of the tag |
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Shaft |
The element in front of the tag housing, also called ‘spear’ and ‘anchor’ |
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Skin |
Epidermis and dermis |
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Stopper |
Triangular plate at the distal end of the tag that assist in stopping the tag from penetrating too deep under the skin |
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Stopplate |
Round plate in front of the triangular stopper on the tag. Its purpose is to prevent penetration the top of the tag and the antenna below the skin surface |
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Tag housing |
The part of the tag that includes the battery and the transmitter |
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TTL |
Total tag length: length of tag housing + shaft + tip |
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Umbrella petals |
A collection of petals mounted as an umbrella around the tag, either one or two umbrellas will be used |
