The Reality of Dart Tagging the Southern Resident Killer Whales – it is Invasive and Disruptive

Please follow and like us:
Pin Share

(2012) This is an edited repost of a previous two part series.
Southern Resident orcas often come close to shore.
The orcas which ply the inland waterways of Puget Sound and the Salish Sea are not random wild animals – we know them by name, we know their families and their histories. We know some of their quirks and personalities, we’ve watched some of them from the time of their birth to the time that they have had calves of their own.

Dart tag embeds in the dorsal fin.

For decades we have offered them protection from intentional harm, and there are individual whales in this population who have never experienced being shot, harassed, or netted.
They are amazingly tolerant of our activities and interest in them, and never harm us. So the question is, can we now justify applying painful tags to their dorsal fins in order to acquire data? Is it not a breach of the trust we offer them?
There are several things that need to be considered in order to understand the potential effects of tagging these orcas.
Here are the research goals as stated by the principle investigator of the research team:

In accordance with USGP #2, “Procedures involving animals should be designed and performed with due consideration of their relevance to human or animal health, the advancement of knowledge, or the good of society.”
1 Research Goals:
a. What are the scientific issues addressed by the research?
The purpose of this research is to improve information to meet Agency mandates on stock structure, movement patterns, and habitat use of cetacean species on various spatial and temporal scales in the eastern North Pacific Ocean.
Specifically, how will this research improve human or animal health or advance knowledge?
These type of data are required to meet specific Agency objectives under the ESA and MMPA.
b. What are the specific goals of the animal studies described in this protocol?
To maximize data gained while minimizing impacts to individuals and stocks.
c. Explain why animal studies are preferred to non-animal alternatives in achieving these research goals.
There are no non-invasive procedures available that can provide the same spatial and temporal resolution, or adequate sample size for this type of movement data.

If those goals seem broad and general to you, you are right – the application to tag the Southern Resident orcas is just a small part of a larger tagging effort, involving 16 to 23 species of dolphins and whales, the goal of which is to “meet Agency mandates on stock structure, movement patterns, and habitat use”. Essentially, over the next several years the Fisheries Service wants to learn more about how the cetaceans utilize the ocean resources, with management goals in mind.
Of course the scientists themselves will be asking many more questions and will have specific research goals of their own, but the problem is that none of that is spelled out in the application. The only limits mandated by the application as it pertains to the Southern Resident orcas are: 6 dart (satellite) tags per year, adult males and females only. For the more benign suction cup tags, any whale can be tagged except calves less than six months old and their mothers.
The researchers have publicly stated that they will only dart tag adult males and post-reproductive females – but there is nothing to bind them to that agreement. And even if they do only select those categories, are the old animals really the best choice to withstand the possible side effects of invasive tagging (tissue damage and infection)? Also the post-reproductive females play an important role in the care of calves – the last thing they need is a painful tag that can get pulled or bumped by the young animals.

Calf L-117

The fact that a  calf may have been born to 46 year old Tanya (L – 5) brings up the question of how it is determined when a female is considered to be post-reproductive, and the idea of tagging an older whale that could be pregnant doesn’t make any sense whatsoever.
So which orcas would the researchers target? (Based on 2010 figures when the permit application was open to public comment).

  • In J-pod the only options among the females (over 40, although clearly that is too young to be guaranteed post-reproductive) would be Granny, nearly 100 years old, or 77 year old Spiden who wheezes when she breathes. In K-pod it would be just Raggedy, named for her dorsal fin which is already a mess, (40 year old Sequim who had a calf last year). L-pod has seven in the category, from 82 year old Ocean Sun (believed to be the captive Lolita’s mother) down to 45 year old Ophelia – all of whom participate in family care.
  • In terms of the adult males (over 15 years old), J-pod has four: the venerable 60 year old Ruffles (J-1)(named for his striking wavy fin){note, J-1 is now deceased}, Mike and the playful Blackberry, both 19 and Riptide, just 15. K-pod has just three: Cappuccino, Scoter, and Lobo. L-pod has eight, Mega, the oldest, is only 33 years old and the next oldest is 21.

The final fact to consider is that the process of tagging involves harassing the whole population repeatedly. The individual whales need to be identified, located, and successfully darted (even a large whale can be hard to tag, they are moving targets with rubbery (although thin) skin), it can take many tries. Certain orcas will be picked out and pursued – which the whales will figure out right away.

It seems premature to tag this fragile population of orcas at this point, particularly since research has been funded to improve the tagging process over the next three years:

Improving Attachments of Remotely-deployed Dorsal Fin-mounted Tags: Tissue Structure, Hydrodynamics, In Situ Performance, and Tagged-animal Follow-up
Lead PI: Dr. Russell Andrews, Alaska SeaLife Center
The researchers have recently developed small satellite-linked telemetry tags that are anchored to the dorsal fin with small attachment darts. They propose to improve upon their existing tagging methodology to achieve longer, less variable attachment durations by carefully examining the factors that affect attachment success. The researchers will design an improved barnacle-style shape for remote-deployment by assessing the hydrodynamic properties of the current tag shape and determine new candidates that may reduce the drag force.
Number of Years: 3
Requested Funds: $735,000
* Belle Quant Engineering
* Cartesian Flow Solutions, Inc.
* Cascadia Research Collective
* NOAA Northwest Fisheries Science Center

The following information shows what the tagging involves, and is taken directly from the National Marine Fisheries Service Assurance of Animal Care and Use Form:
IACUC Use Only
IACUC Number:A/NW 2010- 6

Satellite tag in dorsal fin of an orca (NOAA)
X-ray of tag in deceased orca’s dorsal fin (NOAA)

“Figure 4. A: Current configuration of the dart used for larger odontocetes and mysticetes with two rows of backward facing petals. B: X-ray image showing a dart (with one row of petals only) in a killer whale dorsal fin (collected from a stranded individual unrelated to any tagging activities) after dart penetration.
Note the backward facing petals are tight against the dart shaft, indicating that they were compressed upon entry into the fin which will minimize tissue damage upon entry. C: X-ray image of the same dart in B, after 11.4 kg of outward pull was exerted on the dart shaft. Note the petals have splayed outward from the dart shaft as they cut through tissue and moved into the holding position as designed (note the tips of two other darts visible in this x-ray). D: X-ray image of the same dart after 22.7 kg of outward pull. The petals have more fully splayed outward from the dart shaft and are now presenting a flat surface nearly perpendicular to the axis of outward force.”

Dart tag

“Limpet” tag (NOAA)

“Based on follow-up observations of more than 40 tagged individuals, in most cases the release appears to be a result of tissue breakdown immediately adjacent to the dart penetration site. This tissue breakdown is most likely associated with a foreign body response to the dart but the process may be accelerated by the additional tension put on the tissue adjacent to the darts by drag forces acting on the tag body.”

Wounds from tag (Marine Stewardship)

There is also the possibility of vascular disruption if a dart intersects with an artery in the dorsal fin. This could lead to a lessening or loss of blood flow distal from the tag site. Most cetacean fins have ample cross-current circulation, so it is thought that this type of disruption would not result in a complete loss of blood flow to the distal areas of the dorsal fin. Only one animal from our re-sighting history has shown any type of tissue loss distal to the tag site. However, no other individuals with similar sized dorsal fins have been sighted post-tagging showing anything other than small white scars and/or small depression or raised area.”

Orcas are highly tactile (Photo by Dave Ellifrit)

“It is also possible that the tag might be dislodged by a conspecific–we have seen suction cup tags pulled off with one species–or by the tagged animal rubbing on other animals or against an inanimate object. However, we have seen no behaviors or evidence to suggest this occurrence with LIMPET tags.
Because the dart tags penetrate the skin, connective tissue and/or blubber, and remain attached for up to several months, a risk of infection is a potential long-term effect. It should be noted however that odontocetes inhabiting warmer tropical waters are regularly bitten by cookie-cutter sharks, which create wounds up to several cm deep and 5-10 cm in diameter, and thus the injury associated with tag attachment may not be particularly unusual for these species. The findings by Hanson et al. (2008) indicate that no major long-term impacts have been associated with attachment of dart-style tags and no tagging-related mortalities have ever been documented.
If, during the course of follow up studies, an unusual wound or healing process is noted, the information will be brought to the attention of a vet.” (Good luck with that one…).
In contrast, the suction type tags are relatively non-invasive, but remain in place for just a few hours, yielding less information:

The suction cup tags are less invasive (Photo by Ari Friedlaender, Duke University).
Example of a suction cup tag (data logging).

For more information and to make comments:

Permits, Conservation and Education Division, Office of Protected
Resources, NMFS, 1315 East-West Highway, Room 13705, Silver Spring, MD
20910; phone (301) 713-2289; fax (301) 713-0376; and
Northwest Region, NMFS, 7600 Sand Point Way NE, BIN C15700, Bldg.
1, Seattle, WA 98115-0700; phone (206) 526-6150; fax (206) 526-6426.
Written comments on this application should be submitted to the
Chief, Permits, Conservation and Education Division, at the address
listed above. Comments may also be submitted by facsimile to (301) 713-
0376, or by e-mail to Please include File
No. 781-1824 in the subject line of the e-mail comment.

Playing with mom! (Photo by Ken Balcomb)
Please follow and like us:
Pin Share

Leave a Reply