Sharks and Satellite Tagging:
Achieving the Potential
Workshop Report
Michelle R. Heupel and Robert E. Hueter
Center for Shark Research
Mote Marine Laboratory
Sarasota, Florida 34236 USA
April 2004
Mote Marine Laboratory Technical Report No. 962
Table of Contents
Workshop summary….…………………………………………………………....….
1
List of workshop participants and contributors………………………………………...
12
Post-workshop survey and comments………………………………………………….
15
Copy of distributed survey form……………………………………………………….
18
Workshop Vital Statistics………………………………………………………………
19
Table of study species………………………………………………………………….
21
Methods of attachment…………………………………………………………………
23
Duration of deployment………………………………………………………………...
28
Tag reporting…………………………………………………………………………...
30
Tag release data………………………………………………………………………...
31
Major problems with using PAT tags…………………………………………………..
34
Limitations of the current technology: Data……………………………………………
36
Limitations of the current technology: Technical aspects……………………………...
38
Satisfaction with current PAT tag methodology……………………………………….
40
Future thoughts…………………………………………………………………………
41
Workshop Summary
Summary
A workshop to address multiple issues concerning the use of satellite tag technology and its
application to shark research was convened at Mote Marine Laboratory, Sarasota, Florida on
3-5 December 2003. A total of 22 participants attended from four countries and 18
institutions; two other contributors provided information for the workshop but could not
attend the meeting. The main topics of discussion included: an overview of previous
satellite tag meetings and summary of field experience using this technology; the mechanics
of getting tags onto animals and issues of tag retention; electronics and data collection
aspects of tag function; and a listing of recommendations and ideas for future application of
this technology on sharks. The workshop was supported by funding from NOAA/NMFS
through the National Shark Research Consortium (NSRC) and was also sponsored and hosted
by Mote Marine Laboratory’s Center for Shark Research (CSR). In addition to other
participants, all NSRC member institutions were represented.
Prior to convening the workshop, all invitees were requested to complete a comprehensive
survey regarding their experience with satellite tag use and their recommendations for its
application in shark research. The questions posed to the invitees and their responses are
included in this report. Discussions during workshop sessions largely focused on the survey
data, a summary of which was presented by Michelle Heupel of the Mote CSR. In addition
to the plenary discussions, three invited presentations were given by Kim Holland
(University of Hawaii), John Stevens (CSIRO, Tasmania) and Roger Hill (Wildlife
Computers).
The workshop was divided into four sessions:
I)
Overview of the issues
II)
Getting tags to stay on and work better – Mechanics & Electronics
III)
Getting tags to perform – Geolocation
IV)
Thinking forward
Summary of Session I: Overview of the Issues
Kim Holland opened the workshop with an overview of the results of the “Tying One On”
workshop held at the University of Hawaii in December 2002. The report that resulted from
that workshop is available on the UH Pelagic Fisheries Research Program website
(www.soest.hawaii.edu/PFRP/pub_list.html). Kim’s presentation prompted discussion of
several subjects as he raised many questions that are yet to be answered in satellite telemetry
technology. For example, how are “premature releases” of tags defined? How many days of
data need to be collected before the experiment is considered a success if it did not last for
the intended duration? Kim also pointed out the lack of empirical data on tag failure and
listed a range of problems that contribute to tag failure, such as anchor design and material,
tissue rejection and electronic component failure. Several suggestions were presented for
future designs of PAT tags, including: avoiding sharp edges on the tag anchor; maximizing
the load-bearing surface area of the anchor; using materials that reduce infection or rejection;
1
using smooth rather than porous materials; and avoiding vibration and electrolysis. The
perfect tank anchor according to Kim would be one that has rounded edges, a large surface
area and is slightly flexible.
To further improve tagging success, Kim suggested that investigators maximize control of
animals during tagging and consider onboard restraint for precise tag placement. There was
some discussion that onboard restraint, if done rapidly, produces less stress on the animals
than in-the-water procedures that take much longer to apply tags. Kim suggested that
minimizing handling time might improve tag retention, and he recommended using aseptic
procedures in storing and handling instruments, but he indicated that the use of antiseptics
and other “microprocedures” in applying the tags was probably unnecessary for animal
health and not worth the extra animal handling time. Empirical testing of tag design is
required and the use of flume tanks and captive animals was suggested for testing dummy
tags to determine how well the tags perform, how well they tow in the water and what
materials work best. Having conducted preliminary tests on captive sharks in Hawaii and
tested tags in a flume tank, Kim reported that the current PAT tag design “wobbles” when
towed by a shark, causing chafing. Strapping the tag to the body of the shark will stop this
wobble effect and may improve tag retention. In addition, a captive blacktip reef shark
(Carcharhinus melanopterus) removed a PAT tag within a week by jumping out of the water
and rubbing and scraping the tag. Finally, Kim recommended that data be collected from tag
users via surveys and reports of tag recovery to develop an archive of user results that
scientists can access.
After Kim’s presentation the group discussed the need for new tag designs and tag testing.
There was consensus that tank testing of prototypes is a necessary next step. Tank tests
should include examination of tissue response at different tagging locations on the shark,
post-release behavior and healing of sharks, testing of different sizes and styles of tags to
determine tag “swimming behavior” and size limitations, and testing of data signal
transmission from new designs. Several ideas for new tag designs were discussed including
mushroom- and teardrop- (remora-) shaped tags.
John Stevens provided a summary of his experiences using various types of satellite tags on
numerous shark species in Australian waters. John has used multiple attachment methods
ranging from tags directly attached to the animal to models that were towed on a tether.
Tethering experiments involved the use of PTT tags on whale sharks. Tags were embedded
in a foam casing with a winged keel and were attached to a 5 -10 m tether. The longest tag
retention with this method was three months, with tag failure attributed to the tag dart not
holding. Several anchor types were used including Floy tags and speargun tips and all were
shed. Bolting tags directly to the dorsal fin was attempted on whale sharks via a gaspowered applicator for fast attachment. Attachment was successful, but the shark rubbed the
tag off in one day (a similar result occurred with the attachment of a video Crittercam unit).
Direct bolting of PTT tags to dorsal fins of tiger and white sharks was very effective. Tags
were applied via a pneumatic applicator at the side of the boat. There was a long-term
problem with this method due to damage to the tag antenna, presumably due to the shark
attempting to remove the tag. John alerted the group to a significant problem in using tags
with lithium batteries: battery passivation. Stored tags should be kept in a refrigerator to
2
help avoid passivation of the battery and tags should be tested prior to deployment. John also
examined the location class of hits from PTT tags deployed on sharks and stationary tags
maintained on a rooftop. Of the detected hits from sharks only 21% were considered good
for geolocation. Stationary rooftop tags showed locations ranging from 100 -1000 km from
the actual tag location and revealed that class locations are not as accurate as expected.
Finally, John discussed recent use of PAT tags on white and whale sharks. Tags were
deployed for three- or six-month deployments and three of five tags were shed prematurely.
The whale shark tag shed within two weeks and John received only partial data transmission
from one of the white shark tags. Again John stressed that the animals may be damaging the
antennas on the tags by trying to dislodge them.
Summary of Session II: Getting Tags to Stay on and Work Better – Mechanics & Electronics
This session focused on the results of the workshop survey of tag users, presented by
Michelle Heupel. Questionnaire results are summarized in this document. Responses to the
questionnaire provided valuable information on whether the tags were providing the kind of
results users anticipated from them. Comments from attendees identified the strengths and
weaknesses of the current technology and provided information on what users would like to
see added to the current technology or how they feel it could serve them better. Following
the workshop a brief questionnaire was sent to participants to gauge the usefulness of the
workshop. Those results are also included in this document.
Summary of Session III: Getting Tags to Perform – Geolocation
This session began with a presentation by Roger Hill describing basic geolocation and
celestial geometry. Roger discussed how day length does not alone specify one location on
the earth at any given time, so further interpretation of the data beyond day length is required.
Definition of dusk and dawn is critical to geolocation and can be easily affected by
atmospheric conditions such as cloud cover. Water clarity, depth of the animal and tag
fouling can also compound problems with light level data and how well they can be
interpreted. Current tag technology measures the light curve for the day and the
accompanying software examines the curve and compares it to light curves for all known
locations on a given day to determine potential locations. The tag stores the entire light
curve, but only reports the dusk/dawn points in the summary, so tag recovery greatly
improves the ability to geolocate the animal’s position. Celestial mechanics make it
impossible to accurately geolocate at certain times of the year. The solstice is a problem at
high latitudes (high latitudes have greater longitudinal error) and the equinox causes
problems at low latitudes. Geolocation resolution must be examined by area and season, and
potential error ranges for various locations are illustrated in the images provided by Wildlife
Computers on pages 5 and 6. Some errors can be as large as 8-10° of latitude or greater (as
much as 600 or more north/south miles) during equinoxes in the tropics. Finally, Roger
discussed how animal movement can also confound geolocation by affecting the day length
of the light curve. East-west movement of an animal can corrupt latitude estimates so that
3
other data (e.g. depth) should also be used to refine the location of an individual. Additional
sensors may provide a more accurate position for an animal as they become available.
Following Roger’s presentation the group discussed the limitations of current geolocation
estimates and what can be done to improve those results. The discussion also involved how
animal movement itself can affect the geolocation estimates provided by a tag. This included
movement direction and diving behavior. The group also discussed tag programming and
how setting bin sizes alters the amount of data returned via the satellite. New versions of
satellite tags are coming on line to address many of the concerns of users.
Summary of Session IV: Thinking Forward
The final session of the workshop was a group discussion dedicated to looking towards the
future of this technology and the needs for its application to the study of sharks. The group
compiled a list of features they would like to see on future tags. This included new tag
shapes, new and additional environmental and physical sensors to understand what individual
animals are doing, and more accurate geolocation methodology.
A large portion of the discussion time during this workshop centered around what had been
successful in previous deployments and where the limitations of the technology occurred (i.e.
attachment failure, electronic failure of the tag, failure to transmit, etc). The consensus of the
group was that this technology is very valuable and useful, but needs to be used correctly to
address specific hypotheses. The group also agreed standardized methods should be
developed, and that basic testing of deployment methods, tag design and tag success should
be evaluated.
The session resulted in a list of recommendations for the future, included in this document.
4
Geolocation limitations
Bearing of Dawn or Dusk Lines averaged over sun elevations from
-3º to +5º
Results of geolocation limitations based on the bearing of dawn and dusk lines as presented
by Roger Hill. The following page shows similar diagrams where the data above were used
to present the best expected latitudinal and longitudinal errors associated with geolocation.
5
Geolocation cont.
Best Expected Latitude Error over sun elevations from -3º to +5º
Best Expected Longitude Error over sun elevations from -3º to +5º
Images provided by Wildlife Computers
6
Workshop Conclusions
•
Although satellite tagging provides data on sharks that no other technologies can
currently provide, it does have its limitations and those cannot be overlooked.
•
Tag attachment design is critical since attachment failure appears to be common with
sharks. Therefore, testing of tag designs and attachment methods on captive animals
is needed immediately.
•
In addition to attachment problems, tags fail for many reasons including physical
damage due to depth/pressure, antenna damage (bending), battery failure, electronic
failure (failure to release), and biological issues such as fouling (causing the tag to
sink and decreasing transmission) and predation by other fish.
•
Minimal contact of tags with sharks’ skin is desirable to avoid abrasion and tissue
damage and tags must not act or look like lures.
•
Tag shelf life is an issue due to battery passivation. Tags should be stored in a
refrigerator or freezer whenever possible.
•
Longer tag deployment times typically reduce tag reporting success rate.
•
Recovery of tags is essential whenever possible and it may be important to provide a
reward and launch a campaign to increase public awareness. A means of locating a
floating tag (e.g. radio-tracking) may assist in tag recovery.
•
Comprehensive user’s guides for satellite tags are needed.
•
Validation of geolocation estimates and specification of resolution error are
necessary.
•
Collaboration and communication among users is essential to advancing this field as a
whole.
7
Workshop Recommendations
•
Experimental testing should be conducted to test tag attachment and tag design.
• Tags should be flume-tested to see how they “swim” in the water.
• Strain gauges in the attachment mechanism can provide information on how
much drag the tag is causing.
• Tank testing must be conducted to examine drag effects, tissue
response/necrosis, attachment duration, animal behavioral responses, etc.
•
User manuals for satellite tag use and geolocation software should be developed.
These should include suggestions about setting bin sizes, deployment durations, and
other practical considerations.
•
Standardized methods for tag deployment and use are needed.
•
A new tag shape or design may work better for sharks. Mushroom-shaped or
teardrop- (remora-) shaped fin tags should be developed as prototypes and tanktested.
•
Additional sensors on tags would provide ancillary data that may help improve
geolocation estimates. Suggested sensors include those detecting direction,
acceleration, speed, heading and magnetic field. Additional suggested sensors that
users would like to take advantage of include those measuring conductivity, salinity,
pH, stomach motility, muscle temperature, and general activity.
•
A review of the currently available literature should be conducted and published to
present the present state of knowledge and technology.
•
An additional, more detailed survey of satellite tag users should be conducted. This
survey should build upon the one developed for this workshop, but be more detailed
in nature and canvas a wider user group.
•
Additional meetings should be hosted to continue these discussions and build upon
current information.
•
Communication among users and tag manufacturers should be encouraged.
8
Satellite Tag Resources
Arnold, G and Dewar, H 2000 Electronic tags in marine fisheries research: A 30 year
perspective. In: J.R. Sibert and J.L. Nielsen (eds.) Electronic Tagging and Tracking in
Marine Fisheries. Kluwer Academic Publishers, Netherlands pp 7-64.
Block, BA, Dewar, H, Farwell, CF and Prince, ED 1999 Novel Satellite Technology for
Tracking the Movements of Atlantic Bluefin Tuna. Proc. Nat. Acad. of Sci. 95, 9384-9389.
Block, BA, Costa, DP, Boehlert, G and Kochevar, R 2000 A Report on the Tagging of
Pacific Pelagics (TOPP) Workshop: A pilot project for the Census of Marine Life. Final
Report. http://www.toppcensus.org/workshop_reports/00001.pdf
Boustany, AM; Davis, SF; Pyle, P; Anderson, SD; Le Boeuf, BJ; Block, BA 2002 Satellite
tagging: Expanded niche for white sharks. Nature 412, 35-36.
Eckert, SA; Stewart, BS 2001 Telemetry and satellite tracking of whale sharks, Rhincodon
typus, in the Sea of Cortez, Mexico, and the north Pacific Ocean. Environmental Biology of
Fishes 60, 299-308.
Eckert, SA; Dolar, LL; Kooyman, GL; Perrin, W; Rahman, RA 2002 Movements of whale
sharks (Rhincodon typus) in Southeast Asian waters as determined by satellite telemetry.
Journal of Zoology 257, 111-115.
Ferrero, RC; Moore, SE; Hobbs, RC 2000 Development of Beluga, Delphinapterus leucas,
Capture and Satellite Tagging Protocol in Cook Inlet, Alaska. Marine Fisheries Review 62,
112-123.
Godley, BJ; Richardson, S; Broderick, AC; Coyne, MS; Glen, F; Hays, GC 2000 Long-term
satellite telemetry of the movements and habitat utilisation by green turtles in the
Mediterranean. Ecography 25, 352-362.
Goulet, A-M; Hammill, MO; Barrette, C 1999 Quality of satellite telemetry locations of
gray seals (Halichoerus grypus). Marine Mammal Science 15, 589-594.
Graves, JE; Luckhurst, BE; Prince, ED 2002 An evaluation of pop-up satellite tags for
estimating postrelease survival of blue marlin (Makaira nigricans) from a recreational
fishery. Fishery Bulletin 100, 134-142.
Heide-Joergensen, MP; Kleivane, L; Oeien, N; Laidre, KL; Jensen, MV 2001 A new
technique for deploying satellite transmitters on baleen whales: Tracking a blue whale
(Balaenoptera musculus) in the North Atlantic. Marine Mammal Science 17, 949-954.
Le Boeuf, BJ; Crocker, DE; Grayson, J; Gedamke, J; Webb, PM; Blackwell, SB; Costa, DP
2000 Respiration and heart rate at the surface between dives in northern elephant seals.
Journal of Experimental Biology 203, 3265-3274.
9
Marcinek, DJ; Blackwell, SB; Dewar, H; Freund, EV; Farwell, C; Dau, D; Seitz, AC; Block,
BA 2001 Depth and muscle temperature of Pacific bluefin tuna examined with acoustic and
pop-up satellite archival tags. Marine Biology 138, 869-885.
Musyl, MK; Brill, RW; Boggs, CH; Curran, DS; Kazama, TK and Seki, MP 2003 Vertical
movements of bigeye tuna (Thunnus obesus ) associated with islands, buoys, and seamounts
near the main Hawaiian Islands from archival tagging data. Fisheries Oceanography Vol. 12,
152-169.
Nichols, WJ; Resendiz, A; Seminoff, JA; Resendiz, B 2000 Transpacific migration of a
loggerhead turtle monitored by satellite telemetry. Bulletin of Marine Science 67, 937-947.
Priede, IG; French, J 1991 Tracking of marine animals by satellite. International Journal of
Remote Sensing 12, 667-680.
Priede, IG 1986 Limitations of fish tracking systems: Acoustic and satellite techniques.
National Marine Fisheries Service Southwest Fisheries Center NOAA TECH. MEMO.,
1986, 21 pp.
Sedberry, GR; Loefer, JK 2001 Satellite telemetry tracking of swordfish, Xiphias gladius,
off the eastern United States. Marine Biology 139, 355-360.
Silbert, JR and Nielsen, JL (eds.) 2001 Electronic tagging and Tracking in Marine Fisheries.
Kluwer Academic Publishers 468 pp.
Sibert, JR; Musyl, MK and Brill, RW 2003 Horizontal movements of bigeye tuna (Thunnus
obesus) near Hawaii determined by Kalman filter analysis of archival tagging data. Fisheries
Oceanography 12, 141-151.
Sims, DW and Quayle, VA 1998 Selective foraging behaviour of basking sharks on
zooplankton in a small-scale front. Nature 393, 460-464.
Stevens, JD; Norman, BM; Gunn, JS; Davis, TLO 1998 Movement and behavioural patterns
of whale sharks at Ningaloo Reef: the implications for tourism. CSIRO Marine Research,
Hobart, Tasmania (Australia). 35 pp.
Stone, G, and Kraus, SD (eds.) 1998 Marine animal telemetry tags: what we learn and how
we learn it. Marine Technology Society Journal. 32(1).
10
Satellite Tag Manufacturers
Wildlife Computers
http://www.wildlifecomputers.com/
Microwave Telemetry
http://www.microwavetelemetry.com/
Lotek
http://www.lotek.com
11
Workshop Participants
&
Contributors
Ramón Bonfil
Wildlife Conservation Society
New York, NY
[email protected]
Greg Cailliet
Moss Landing Marine Laboratories
Moss Landing, CA
[email protected]
Melinda Braun
Wildlife Computers
Redmond, WA
[email protected]
Geremy Cliff
Natal Sharks Board
Umhlanga
South Africa
[email protected]
George Burgess
Florida Museum of Natural History
University of Florida
Gainesville, FL
[email protected]
Christina Conrath
Virginia Institute of Marine Science
Gloucester Point, VA
[email protected]
12
Ray Davis
Georgia Aquarium
Atlanta, Georgia
[email protected]
Roger Hill
Wildlife Computers
Redmond, WA
[email protected]
Heidi Dewar
Tagging of Pacific Pelagics/ CoML
c/o Inter-American Tropical Tuna
Commission
La Jolla, CA
[email protected]
Kim Holland
Hawaii Institute of Marine Biology
University of Hawaii
Kaneohe, HI
[email protected]
Dave Holts
NMFS Southwest Fisheries Science
Center
La Jolla, CA
[email protected]
Ken Goldman
Department of Biology
Jackson State University
Jackson, MS
[email protected]
Robert Hueter
Mote Marine Laboratory
Center for Shark Research
Sarasota, FL
[email protected]
Rachel Graham
Environment Department
University of York
York, UK
Belize address:
61 Front Street
Punta Gorda, Belize
[email protected]
Suzanne Kohin
NMFS Southwest Fisheries Science
Center
La Jolla, CA
[email protected]
Mike Heithaus
Dept. of Biology
Florida International University
Miami, FL
[email protected]
Josh Loefer
Marine Resources Research Institute
SC Dept. of Natural Resources
Charleston, SC
[email protected]
Michelle Heupel
Mote Marine Laboratory
Center for Shark Research
Sarasota, FL
[email protected]
Chris Lowe
Dept. of Biological Sciences
California State University, Long Beach
Long Beach, CA
[email protected]
13
Wes Pratt
Mote Marine Laboratory
Center for Shark Research
Summerland Key Lab
Summerland Key, FL
[email protected]
John Stevens
CSIRO Marine Research
Hobart Tasmania
Australia
[email protected]
Brad Wetherbee
Dept. of Biological Sciences
University of Rhode Island
Kingston, RI
[email protected]
Eric Prince
NOAA Fisheries, Southeast Fisheries
Science Center
Miami, FL
[email protected]
Colin Simpfendorfer
Mote Marine Laboratory
Center for Shark Research
Sarasota, FL
[email protected]
14
Post-Workshop Survey
&
Comments
Post-Workshop Comments
Attendees were asked four questions after attending the workshop. Results follow along with
selected written comments from respondents.
1. Did you find the meeting useful and did you learn anything from participating?
Response
Yes
No
Number of users
16
0
2. Would you participate in future meetings of this sort/on this topic?
Response
Yes
No
Number of users
13
0
Comments:
I found this meeting to be very useful. In particular it should help in avoiding some of the
problems that other people have come across. It was also useful to see how successful (or
unsuccessful) others had been. This technology is so expensive that any advantage towards
getting transmitters to stay on the proper time and to function after popping off is a big
savings and added amount of data. It was also informative to see how little the shark group
knows about this technology and how far we have to progress.
I found the workshop extremely helpful. I learned a lot about some of the more technical
aspects of the transmitters as well as the attachment problems. I would like to participate in
future meetings on this topic. That said however, having gone to the Tying One On workshop
in Hawaii a year prior to the Mote workshop, I am not sure how much progress was made
during that year. While this meeting was more useful in that it was much more narrowly
focused I do not think a lot of progress has been made on the attachment and other issues
that are causing problems with the use of this technology. Without some progress being
made to address these issues, continuing to meet to discuss the problems and not the
solutions may not be overwhelmingly useful.
I thought it was very valuable having (some) of the vendors there. It was good to hear about
the technical limitation and their perceptions of reasonable application and expectations of
the technology. I think it was particularly important to establish dialog with the vendors in
regards to tag design and modifications. Attempting to do this on a one-on-one level is
rarely successful, since the vendor cannot see the profit. However, have a number of users
complaining about the same problems help galvanize the cause.
15
The meeting was a good forum of present users who were able to share experiences and
suggest future directions. I learned many useful things, especially from the tag
manufacturers. Yes I would participate in future meetings as there is still a lot to learn
about.
This meeting was very useful. I think the discussions of tag design and capabilities were
most useful as were the discussions of potential collaborations on testing tag designs. I
would definitely attend a future meeting on this type of topic.
Yes, I found the meeting useful and learned more from other peoples’ experiences, and also
from having Roger and Melinda there talking about some of the technical aspects.
The meeting was extremely useful and I took a great deal of good information away from it.
I believe it is invaluable when you have a group of people who are pushing a relatively new
field forward get together and have constructive conversations (one of the keys to the success
of this conference) about how to make the application of a new tool better for our research
purposes. It is extremely beneficial to hear first hand about success and failure, new
attachment methods, potential tag design and veterinary aspects of tagging. Additionally,
having Roger and Melinda there was paramount to the success of the meeting (unfortunate
other manufacturers declined or could not attend). I would most definitely be willing to
participate in any future meeting on this topic and I’m sure that in time, another such
meeting will be warranted.
The meeting was very useful to find out what which tags work best, under what conditions
and what aspects still require much testing. Good to know what will/will not be acceptable in
publications. Nice to get reality check on the incorporation of the various sensors that we
would all like to see in the tags.
These forums are very valuable to keep researchers at the state of the science and share info,
pubs, what works and what fails. I learned a lot from the meeting and particularly from the
manufacturers (Wildlife Computers folks). Their candor and openness made it very
worthwhile. The development of a better tag is what we all learned about and brainstorming
ideas for the 'mushroom tag' was one of the highlights and holds great promise. I would hope
to see a symposium at AES and a specialist meeting like this every 4 years at a minimum.
16
3. Did participating in the workshop alter your thoughts about using satellite tags in your
research?
Response
Yes
No
Number of users
5
10
4. If so, did it improve or degrade your opinion about the technology?
Response
Improve
Degrade
Number of users
2
3
Comments:
I am more aware of the limitations of the technology than I was prior to the meeting, though
I would not say my opinion has been either degraded or improved.
This workshop didn't really affect my plans on using satellite transmitters in my research. I
was aware of the success rate of some of the studies that had been conducted, I just wasn't
aware of the causes for failure. I have a certain amount of faith in this technology, but since
I had spoken with a number of people that have used it, I didn't have an overly optimistic
attitude toward what they can deliver, which seems like an attitude that many people have
with many types of telemetry methodology prior to their actually getting into doing the actual
study.
Through the workshop I became aware of some of the problems with longer term
deployments, like the fouling problem. My opinion of the technology has not changed, but I
have become more aware of some of the problems to watch out for, and hopefully how to
avoid some of them.
I’ve been pretty enthusiastic about the use of satellite telemetry since it first started being
used to track fishes, and I wouldn’t say I’m any more or less encouraged to use satellite
telemetry, but that I came away better grounded in how and where I might want to apply this
tool. Similarly, the meeting did not degrade or improve my opinion, but left me with a better
realization of the pros and cons of using this technology. We all understand (and agreed)
that any scientific tool must be applied appropriately to answer the question(s) at hand. The
meeting left me with a better understanding of what the technology is currently capable of
doing and what lies ahead with its potential.
17
Survey Summary
&
Results
Satellite Telemetry Workshop Survey
All participants are asked to complete the following questionnaire. Information from the
questionnaire will be used to complete a booklet to be provided to all participants upon
arrival at the workshop and will be used in our discussions. All responses and documentation
will only be used for the purposes of this workshop and will not be published or distributed
beyond meeting participants.
Your name and institution:
Contact information:
Study species:
Study area:
Number of PAT tags deployed and the manufacturers used:
Description of your method of attachment (i.e. dart tag, fin tag, etc.):
Please include a photo (electronic if possible) of your attachment method for inclusion in the
documentation.
Durations of tag deployment: (i.e. 3 mos, 6 mos, etc.)
Any relationship between tag success rate and deployment duration?
Number of reports from PAT tags:
• Pop-off only
• Pop-off with partial data report
• Pop-off with full data report
Number of PAT tags recovered:
How many tags have remained on animals for the programmed amount of time – any
premature removal/releases?
What have been your major problems (if any) with using PAT tags (!):
• Attachment issues
• Pop-off issues
• Data reporting issues
• Costs
• Other – please explain
What do you see as the limitations of the current technology in the following categories:
• Data (e.g. geo-location estimates, sampling regime, etc)
• Technical aspects of the tag (e.g. sensors, depth limit, size/shape of tag, etc)
Where would you like to see the technology go/what additional options would you like tags to
have?
On a scale of 1 to 5, how satisfied are you with current PAT tag methodology (5 = extremely
satisfied)?
18
Workshop Vital Statistics:
Number of meeting participants: 21
Number of survey forms returned: 13
Species fitted with PAT tags based on survey results:
! At least 19 shark species
! 5 shark species are being investigated by three or more research groups (bull,
sandbar, tiger, whale and white sharks)
! 2 ray species
! At least 7 teleost species including three species being examined by multiple research
groups (marlin, swordfish, tuna)
! 1 report of using satellite technology on marine turtles
Total number of PAT tags deployed: Greater than 289
Total number of PTT tags deployed: At least 25.
Methods of attachment:
! 9 different methods of attaching PAT tags have been described
! 2 methods of attaching PTT tags were described
Durations of programmed deployment ranged from weeks to 12 months. At least one
investigator intentionally used short time periods and is testing PAT tags and tag retention on
captive animals.
Tag reporting was variable with nearly equal numbers of pop-off with full report, pop-off
with partial report and did not report.
Tag retention on the animal appeared to be effective in 55% of deployments, but 43% of tags
deployed resulted in a premature release. This result was consistent both within and across
studies.
Major problems with using PAT tags:
! Attachment issues
! Data reporting
19
Limitations of the current technology:
! Geolocation
! Tag size (too large)
Satisfaction with current PAT tag methodology:
! No users were completely dissatisfied
! No users were extremely satisfied
! Most ranked the current technology a 3 on a scale of 1-5
Future thoughts
Almost every respondent provided comments on how they would like to see this technology
improve in the next generation(s) of tags.
Suggestions included:
! Additional sensors
! Reduced size
! Use of cell phone or GPS technology
! ‘Smart’ programming
! Flexibility in data summarization
20
Table of study species
Species
Bignose shark
Investigator
Josh Loefer
Blacktip reef shark
Kim Holland
Blacktip shark
Common thresher shark
Galapagos shark
Great hammerhead shark
Manta ray
Night shark
Colin Simpfendorfer and
Bob Hueter
Dave Holts and Suzy Kohin
Rachel Graham
George Burgess
Mike Heithaus
Colin Simpfendorfer and
Bob Hueter
Dave Holts and Suzy Kohin
Chris Lowe
Mike Heithaus
Heidi Dewar
Josh Loefer
Salmon shark
Sandbar shark
Ken Goldman
Christina Conrath
Blue shark
Bull shark
Scalloped hammerhead
shark
Shortfin mako shark
Ken Goldman
Colin Simpfendorfer and
Bob Hueter
Josh Loefer
Dave Holts and Suzy Kohin
Josh Loefer
Silky shark
Josh Loefer
Smalltooth sawfish
Spinner shark
Colin Simpfendorfer
Josh Loefer
Tiger shark
Mike Heithaus
Kim Holland
Chris Lowe
John Stevens
21
Region
South Carolina – Charleston
Bump
Central tropical Pacific
Ocean
Gulf of Mexico
Southern California Bight
Meso American Barrier
Reef
Florida Keys
Gulf of Mexico
Southern California Bight
Hawaii
Florida Keys
Pacific Ocean
South Carolina – Charleston
Bump
Alaska
Virginia and Carolina
coasts
Gulf of Mexico
Gulf of Mexico
South Carolina – Charleston
Bump
Southern California Bight
South Carolina – Charleston
Bump
South Carolina – Charleston
Bump
Florida Everglades
South Carolina – Charleston
Bump
Florida Keys
Central tropical Pacific
Ocean
Hawaii
Northern Australia
Species Table (cont.)
Whale shark
Rachel Graham
Ramón Bonfil
Chris Lowe
John Stevens
Meso American Barrier
Reef and the Seychelles
Caribbean Sea
NW Australia – Ningaloo
Reef
South Africa
California
Southern Australia
Heidi Dewar
Pacific Ocean
Josh Loefer
South Carolina – Charleston
Bump
Northwest Atlantic, Pacific
side of Central America
Northwest Atlantic, Pacific
side of Central America
Pacific Ocean
Northwest Atlantic, Pacific
side of Central America
Northwest Atlantic, Pacific
side of Central America
Pacific Ocean
Southern California Bight
Northwest Atlantic, Pacific
side of Central America
Pacific Ocean
Northwest Atlantic, Pacific
side of Central America
Bob Hueter
John Stevens
White shark
Other species
Shark (no species
specification)
Billfish
Escolar
Eric Prince
Marlin(s)
Eric Prince
Mola mola
Sailfish
Heidi Dewar
Eric Prince
Swordfish
Eric Prince
Striped marlin
Tuna
Heidi Dewar
Dave Holts and Suzy Kohin
Eric Prince
Turtles
Heidi Dewar
Eric Prince
22
Methods of Attachment
Type of PAT attachment
Titanium dart tag
Plastic double-barb (billfish) tag
Plate mount or fin mount via cable ties
Custom-made plastic dart
Jumbo Rototag
Double (2) metal dart tags
Stainless dart tags
Stainless spearfishing tip
Fin saddle
Number of users
10
5
3
2
1
1
1
1
1
Type of PTT attachment
Towed tag
Fin mount
1
2
Photographs of tag attachment methods are included on the following pages.
23
Tag types
Dart tag attachment. Photo courtesy of John Stevens
Double-barb plastic tag.
Photo courtesy of Dave Holts
and Suzy Kohin
Titanium dart tag. Photos courtesy of Rachel Graham
Titanium and custom-made plastic dart tags. Photos courtesy of
Ramón Bonfil
24
Tag types (cont.)
Photo courtesy of Christina Conrath
Photo courtesy of Colin Simpfendorfer
Photo courtesy of Colin Simpfendorfer
Photo courtesy of Chris Lowe
(photographed by Darin Topping)
Photo courtesy of Colin Simpfendorfer
25
Tagging procedure
Tagging procedure of staff at the NMFS
Southwest Fisheries Science Center
Photos courtesy of Dave Holts and Suzy
Kohin
26
Tag placement
Photo courtesy of Mike Heithaus
Photo courtesy of Josh Loefer
Photos courtesy of Eric Prince
27
Workshop Conclusions
•
Although satellite tagging provides data on sharks that no other technologies can
currently provide, it does have its limitations and those cannot be overlooked.
•
Tag attachment design is critical since attachment failure appears to be common
with sharks. Therefore, testing of tag designs and attachment methods on captive
animals is needed immediately.
•
In addition to attachment problems, tags fail for many reasons including physical
damage due to depth/pressure, antenna damage (bending), battery failure,
electronic failure (failure to release), and biological issues such as fouling
(causing the tag to sink and decreasing transmission) and predation by other fish.
•
Minimal contact of tags with sharks’ skin is desirable to avoid abrasion and tissue
damage and tags must not act or look like lures.
•
Tag shelf life is an issue due to battery passivation. Tags should be stored in a
refrigerator or freezer whenever possible.
•
Longer tag deployment times typically reduce tag reporting success rate.
•
Recovery of tags is essential whenever possible and it may be important to
provide a reward and launch a campaign to increase public awareness. A means
of locating a floating tag (e.g. radio-tracking) may assist in tag recovery.
•
Comprehensive user’s guides for satellite tags are needed.
•
Validation of geolocation estimates and specification of resolution error are
necessary.
•
Collaboration and communication among users is essential to advancing this field
as a whole.
28
Workshop Recommendations
• Experimental testing should be conducted to test tag attachment and tag design.
• Tags should be flume-tested to see how they “swim” in the water.
• Strain gauges in the attachment mechanism can provide information on
how much drag the tag is causing.
• Tank testing must be conducted to examine drag effects, tissue
response/necrosis, attachment duration, animal behavioral responses, etc.
• User manuals for satellite tag use and geolocation software should be developed.
These should include suggestions about setting bin sizes, deployment durations,
and other practical considerations.
• Standardized methods for tag deployment and use are needed.
• A new tag shape or design may work better for sharks. Mushroom-shaped or
teardrop- (remora-) shaped fin tags should be developed as prototypes and tanktested.
• Additional sensors on tags would provide ancillary data that may help improve
geolocation estimates. Suggested sensors include those detecting direction,
acceleration, speed, heading and magnetic field. Additional suggested sensors
that users would like to take advantage of include those measuring conductivity,
salinity, pH, stomach motility, muscle temperature, and general activity.
• A review of the currently available literature should be conducted and published
to present the present state of knowledge and technology.
• An additional, more detailed survey of satellite tag users should be conducted.
This survey should build upon the one developed for this workshop, but be more
detailed in nature and canvas a wider user group.
• Additional meetings should be hosted to continue these discussions and build
upon current information.
• Communication among users and tag manufacturers should be encouraged.
29
Satellite Tag Resources
Arnold, G and Dewar, H 2000 Electronic tags in marine fisheries research: A 30 year
perspective. In: J.R. Sibert and J.L. Nielsen (eds.) Electronic Tagging and Tracking in
Marine Fisheries. Kluwer Academic Publishers, Netherlands pp 7-64.
Block, BA, Dewar, H, Farwell, CF and Prince, ED 1999 Novel Satellite Technology for
Tracking the Movements of Atlantic Bluefin Tuna. Proc. Nat. Acad. of Sci. 95, 93849389.
Block, BA, Costa, DP, Boehlert, G and Kochevar, R 2000 A Report on the Tagging of
Pacific Pelagics (TOPP) Workshop: A pilot project for the Census of Marine Life. Final
Report. http://www.toppcensus.org/workshop_reports/00001.pdf
Boustany, AM; Davis, SF; Pyle, P; Anderson, SD; Le Boeuf, BJ; Block, BA 2002
Satellite tagging: Expanded niche for white sharks. Nature 412, 35-36.
Eckert, SA; Stewart, BS 2001 Telemetry and satellite tracking of whale sharks,
Rhincodon typus, in the Sea of Cortez, Mexico, and the north Pacific Ocean.
Environmental Biology of Fishes 60, 299-308.
Eckert, SA; Dolar, LL; Kooyman, GL; Perrin, W; Rahman, RA 2002 Movements of
whale sharks (Rhincodon typus) in Southeast Asian waters as determined by satellite
telemetry. Journal of Zoology 257, 111-115.
Ferrero, RC; Moore, SE; Hobbs, RC 2000 Development of Beluga, Delphinapterus
leucas, Capture and Satellite Tagging Protocol in Cook Inlet, Alaska. Marine Fisheries
Review 62, 112-123.
Godley, BJ; Richardson, S; Broderick, AC; Coyne, MS; Glen, F; Hays, GC 2000 Longterm satellite telemetry of the movements and habitat utilisation by green turtles in the
Mediterranean. Ecography 25, 352-362.
Goulet, A-M; Hammill, MO; Barrette, C 1999 Quality of satellite telemetry locations of
gray seals (Halichoerus grypus). Marine Mammal Science 15, 589-594.
Graves, JE; Luckhurst, BE; Prince, ED 2002 An evaluation of pop-up satellite tags for
estimating postrelease survival of blue marlin (Makaira nigricans) from a recreational
fishery. Fishery Bulletin 100, 134-142.
Heide-Joergensen, MP; Kleivane, L; Oeien, N; Laidre, KL; Jensen, MV 2001 A new
technique for deploying satellite transmitters on baleen whales: Tracking a blue whale
(Balaenoptera musculus) in the North Atlantic. Marine Mammal Science 17, 949-954.
30
Le Boeuf, BJ; Crocker, DE; Grayson, J; Gedamke, J; Webb, PM; Blackwell, SB; Costa,
DP 2000 Respiration and heart rate at the surface between dives in northern elephant
seals. Journal of Experimental Biology 203, 3265-3274.
Marcinek, DJ; Blackwell, SB; Dewar, H; Freund, EV; Farwell, C; Dau, D; Seitz, AC;
Block, BA 2001 Depth and muscle temperature of Pacific bluefin tuna examined with
acoustic and pop-up satellite archival tags. Marine Biology 138, 869-885.
Musyl, MK; Brill, RW; Boggs, CH; Curran, DS; Kazama, TK and Seki, MP 2003
Vertical movements of bigeye tuna (Thunnus obesus ) associated with islands, buoys, and
seamounts near the main Hawaiian Islands from archival tagging data. Fisheries
Oceanography Vol. 12, 152-169.
Nichols, WJ; Resendiz, A; Seminoff, JA; Resendiz, B 2000 Transpacific migration of a
loggerhead turtle monitored by satellite telemetry. Bulletin of Marine Science 67, 937947.
Priede, IG; French, J 1991 Tracking of marine animals by satellite. International
Journal of Remote Sensing 12, 667-680.
Priede, IG 1986 Limitations of fish tracking systems: Acoustic and satellite techniques.
National Marine Fisheries Service Southwest Fisheries Center NOAA TECH. MEMO.,
1986, 21 pp.
Sedberry, GR; Loefer, JK 2001 Satellite telemetry tracking of swordfish, Xiphias
gladius, off the eastern United States. Marine Biology 139, 355-360.
Silbert, JR and Nielsen, JL (eds.) 2001 Electronic tagging and Tracking in Marine
Fisheries. Kluwer Academic Publishers 468 pp.
Sibert, JR; Musyl, MK and Brill, RW 2003 Horizontal movements of bigeye tuna
(Thunnus obesus) near Hawaii determined by Kalman filter analysis of archival tagging
data. Fisheries Oceanography 12, 141-151.
Sims, DW and Quayle, VA 1998 Selective foraging behaviour of basking sharks on
zooplankton in a small-scale front. Nature 393, 460-464.
Stevens, JD; Norman, BM; Gunn, JS; Davis, TLO 1998 Movement and behavioural
patterns of whale sharks at Ningaloo Reef: the implications for tourism. CSIRO Marine
Research, Hobart, Tasmania (Australia). 35 pp.
Stone, G, and Kraus, SD (eds.) 1998 Marine animal telemetry tags: what we learn and
how we learn it. Marine Technology Society Journal. 32(1).
31
Satellite Tag Manufacturers
Wildlife Computers
http://www.wildlifecomputers.com/
Microwave Telemetry
http://www.microwavetelemetry.com/
Lotek
http://www.lotek.com
32
Tagging results
Examples of results obtained from satellite
tracking of mako, blue and thresher sharks by
NMFS Southwest Fisheries Science Center
staff.
Data and graphics courtesy of Dave Hotls and
Suzy Kohin
33
Major problems with using PAT tags
Problem area
Attachment issues
Pop-off issues
Data reporting
Cost
Other – see below
Number of users
11
6
8
6
Other:
•
No transmission
•
For some fish, the dive patterns tend to occlude light levels needed for
geolocation. Also the structure of the data precludes addressing more diverse
questions. It would be nice to opt for high res data one day a week for example,
either in the form of raw data or short interval histograms. There may also be
other parameters that one could extract.
•
Unsatisfactory customer service, especially in terms of timely, complete, and
accurate documentation of the different products (accurate descriptions of actual
capabilities and characteristics of products, manuals for their use, software
documentation, etc.); response to customer suggestions/needs, response time in
communication, outdated and poorly managed website.
•
We would prefer if quality control were better and that we are kept informed of
potential tag and software problems. For example, we deployed some tags which
had a programming bug in them and they were supposed to report temperature,
but did not. Also there was another bug that caused some tags to report the
wrong date. A third problem was some kind of problem with the PTT numbers
that Argos uses, in that the tag data were not decoded properly by Argos because
the numbers assigned were for the wrong type of data that the tag was reporting.
I may have the details wrong, but the effect was the same: no data. Also we
would like to be informed as soon as software is updated so that we don’t waste
our time using an outdated program. We have received Argos reports, gone
ahead with analysis using the programs we believed to be that latest, and then
upon noticing that something in the spreadsheet didn’t make sense, we were
informed that there had been an update and we were not supposed to use the old
program.
34
Other comments:
•
Of course, cheaper would be better, but not at the expense of quality and features.
•
I have used three types of darts and have found through trial and expensive error
that the modified Floy works best for me. But I have attachment issues with
SPOTs that I would like to discuss.
•
Pop-off issues are primarily related to function at depth and the need to make a
tag that can withstand greater pressures, e.g., >2000 m.
35
Limitations of the current technology:
Data
Data category
Geolocation
Sampling regime
Number of users
9
1
Comments:
•
We need much better geolocation estimators.
•
You’ve hit the big two on the head – geolocation and sampling regime. We all
know that it takes getting the tag back to get “all of the data”. While
understandable, the extension of battery life would allow the data to be more
finely binned if/when desired.
•
Failure by some manufacturers to provide raw data and error estimates of
geolocation fixes.
•
Light-based geolocations for latitude! Biggest problem for sure.
•
Geolocation estimates are notoriously poor in low latitudes, investigation into
improving the light algorithm or finding another geolocation method would be
optima,. e.g., finding a way to combine a PAT with a SPOT so that you get full
sensor data, locations and it detaches from the animal after a period of time.
•
Wish we could get down to an hourly sampling regime that would provide better
estimates of animal behavior particularly with reference to the dawn/dusk
periods.
•
Geolocation software needs more development. CheckSum validation is poorly
described and not transparent to user.
•
I think that the biggest limitation is estimating location accurately. I also think if
there were some way to track the tag once it has popped up or a way to get the
location closer to real time, that would be extremely useful. We have six tags that
popped up in areas we frequently traverse in the course of field season, but we
have not been able to locate any of them.
•
Geolocation is proprietary so results are open to question. Inflexibility in form of
summarized data.
36
•
We are not satisfied with the geo-location estimates, although we realize that
much of the problem is due to the inherent nature of the Earth’s position and
behavior relative to the sun. We like the idea of using SST as another factor in
fine tuning the location estimates, but is this something the tag manufacturers are
trying to incorporate into their algorithms? Also the amount of data we’ve been
receiving from PAT tags is around 30% of the whole record. This seems like a
low percentage. More would be preferable. On some occasions we get a single
block of data which has been transmitted 3, 4, or 5 times. Is there a way to erase
data from the tag once it has been transmitted so that new data will always be
transmitted in subsequent uplinks and thus help maximize the number of data
blocks we get?
•
The transmission rates of the Argos satellites, the accuracy of light based
geolocation and the need for calibration experiments for both tags. The flexibility
of data synthesis and the number of variables that can be measured.
•
Data ‘binning’ is a bit of a problem for analytical assumptions and statistical
analyses.
37
Limitations of the current technology:
Technical Aspects
Technical aspects
Reduce tag size
Better or additional sensors
Better release/attachment
mechanisms
Greater depth limit
Longer battery life
Number of users
7
3
3
2
1
Comments:
•
Battery life seems to be one of the biggest problems now.
•
Smaller tags and better geolocation sensors.
•
Tag anchor tissue compatibility. Inappropriate use by inexperienced researchers.
•
I am very interested in seeing if certain sensors can be added to the tags. My
desire is to have a tag that can have external leads send data to the tag from
inside the musculature of the shark (e.g. temperature).
•
As mentioned previously, I would like to see tags pressure-tested to a greater
depth, e.g. min of 2,000 m, to avoid depth-induced malfunction and/or use of the
guillotine device and subsequent loss of a tag on a repeatedly deep-diving animal.
•
An additional sensor that may be of interest particularly in looking at diving
behavior with respect to stratification of water is conductivity. This variable may
have some impact on fish buoyancy and behavior.
•
The size and shape of the tag are fine for the animals that I am working with.
However it would be great to have a smaller PAT for deployment on large fish
e.g., serranids or carangids or small scombrids. May also be worthwhile
investigating the development and use of a fin-mounted PAT-tag for the pelagic
predatory sharks as this may minimize pressure on the tag and possible
detachments from rapid bursts of speed.
38
•
One of the biggest problems I see is that the release wire is too fragile. I think
that the majority of the failures that I have encountered with premature release
have been due to this wire breaking early. In one case this happened at the time
of tag application. My other problem has been poor data reporting, even with
tags that released after a week
•
Large size and lure shape of the tag are a problem.
39
Satisfaction with current PAT tag
methodology
Satisfaction score
1 – dissatisfied
2
2.5
3
3.5
4
5 – extremely satisfied
Number of users
0
2
2
4
2
3
0
Comments:
•
The costs and size limit its use to large commercially important species only.
•
Size of the package is a concern.
•
If I could avoid non-reporting tags I would have scored closer to 4.
•
I give the current tags a “3” but I bear in mind that some data is better than no
data and that the costs of tracking these animals day and night through inclement
weather far surpass the costs of tags and the occasional lack of data stemming
from malfunctions, etc.
•
I think the technology is far outstripping our ability to take it and use it (tag
retention, etc.).
•
Despite their problems, the PAT tags are still an incredible tool if properly used.
40
Future thoughts –
Where would we like to see the technology
go
•
Real time uplink when animal is at surface.
•
Smaller tags with a wider array of sensors.
•
Smaller packages to be used on smaller sharks, particularly neonates as well as
smaller skate and ray species.
•
I’d like to have a dissolved oxygen as well as pressure and temperature sensors
on the next generation of tags.
•
Would like to see if we can use cellular phone technology on tags as is being done
with juvenile seals or the GPS collars used on elephants. This would obviously
work best on surface swimming sharks. It may also provide better data returns for
tropical sharks in areas where Argos coverage is poor.
•
Besides tag prices coming down, the major area of improvement should be in
release mechanisms and reliability.
•
Greater user flexibility in the way data are presented and summarized. Use of
‘Smart’ programming allowing the tag to make decisions on how data are stored
and summarized. Greater capacity to transmit raw, rather than binned data.
Reduced size.
•
Smaller tags, better location data both while tag is deployed and once the tag
pops off.
•
Conductivity sensor, built in GPS to gather accurate locations when animal is at
surface (would only work for certain species, of course), sensor readings that are
not ‘binned’.
•
A PAT tag that could communicate with the satellite 3-5 times during the
deployment, just to obtain a good position and correct estimates from
geolocation.
•
I would like more flexibility in the data summarization software and the option for
obtaining raw data. Also, it would be nice to have sensor modules that
transmitted data to the PAT tag. For example, you could implant a temperature
sensor in the body cavity or a pH sensor in the stomach and have it transmit data
41
to the PAT tag, these sensors would be left behind when the tag releases and
floats to the surface and would be freed of some of the size constraints of PAT
tags.
•
Smaller is always better and allows a wider variety of animals to be tagged.
•
Directionality sensor. This would help with reconciling the geolocation
estimates.
•
Orientation sensor (or maybe acceleration sensor) to determine when animals are
stationary.
•
Different premature release algorithms.
42