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.

Satellite tagging of a common minke whale in summer 2014 off Norway. The carrier for the satellite tag, that can be seen on the back of the whale, will fall of quite soon after the tag is implanted into the whale and leave the tag inside. © K.A. Fagerheim, IMR, Norway.

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

The MINTAG project aims to develop miniaturized satellite tags that can be used to track the movements and stock structure of lesser-known, under-studied rorquals and pilot whales that are fast swimmers. Previous attempts to tag these species have been limited in duration (weeks) due to the premature rejection of relatively large tags. Tagging these species is particularly challenging due to their high speeds, which make them difficult to approach and properly tag.

The MINTAG project has developed the V0b tags, the first generation of miniaturized satellite tags, which are specifically designed for fin, minke, and pilot whales in the North Atlantic and North Pacific. The tags and have undergone several modifications since the first prototypes (see Figure 1) to arrive at the V0b tag design, which will be deployed for the first time with 25 tags in the summer of 2023. This is a testing phase, which is highly experimental, as these tags will be used for the first time ever this year.  

For more information about the testing of the tags that led to the decisions made for the V0b design, click here

Figure 1. Different prototypes of carriers and tags used in the trials in Iceland 2022

Two different tags have been developed: the fin whale tag (Figure 2) and the minke whale tag (Figure 3). The two tag designs are based on differences in blubber thickness and distance to fascia between the two target species: the fin and the minke whale. Both tags will ideally penetrate with the tip embedded below fascia but the minke whale tags may in some circumstance only penetrate 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
Structure of whale skin
Figure 2. V0b Fin whale tag, TTL 290 mm, 216 g
Figure 3. V0b Minke whale tag, TTL 150 mm, 148 g

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.

Figure 4. The infamous “blob” which started the design of the V0b retention cone
Figure 5. V0b carrier
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.  With duty-cycling, the tag should be capable of transmitting for up to one year.

After the deployment of the 25 V0b tags in summer 2023, and once the scientists have studied the transmission duration from the tags, the design will be re-evaluated and potentially adjusted for the creation of the V1a tags that will be deployed in spring-summer 2024. The adjustments will be based on the experiences and findings from the 2023 field tests, including deployment success, retention time, and the quality of transmissions.

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
Biobsy tip
A hollow steel cylinder that collects and retains a skin/blubber biopsy
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.
Dart tip
Sharp end of the tag that cuts through whale skin and blubber to ensure entry and successful implantation of the tag
Fascia

Dense layer of connective tissue that separates blubber from muscle
Flight
The feather on the carrier that helps maintain a stable and controlled flight trajectory.
Launcher
Device used for deploying tags, in this case the ARTS system
Mounting bracket
Part of the carrier to which the tag is attached during deployment
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
Retention petals
Leaf-like metal pieces that swing out into the blubber to resist expulsion of the tag
Shaft

The element in front of the tag housing, also called ‘spear’ and ‘anchor’
Skin
Epidermis and dermis
Stopper
Triangular plate at the distal end of the tag that assist in stopping the tag from penetrating too deep under the skin
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

Tag housing
The part of the tag that includes the battery and the transmitter
TTL
Total tag length: length of tag housing + shaft + tip
Umbrella petals
A collection of petals mounted as an umbrella around the tag, either one or two umbrellas will be used