This research is being conducted under permit #881-1668-05 by the NMFS.
Life History Transmitters (LHX) in Steller sea lions: assessing the effects of health status, foraging ability, and environmental variability on juvenile survival and population trends.
PROJECT UPDATES
April 28th, 2006
On April 19th, four juvenile Steller sea lions were released in Resurrection
Bay, AK, that received dual Life History Transmitter (LHX) implants. The animals
are now being tracked via externally attached satellite transmitters. This brings
the number of Steller sea lions that have been successfully released with LHX
tag implants, to six. The external transmitters on the first two implanted animals
have recently fallen off, though the animals have been resighted since.
A new publication is now available describing the development and technical details of the Life History Transmitters:
A new publication describing the 'Transient Juvenile Steller Sea Lion Program' will be available shortly:
The following contributions about aspects of the LHX project and the Transient Juvenile Project were given at the XVI Biennial Conference on the Biology of Marine Mammals held Dec. 12-16 at San Diego, CA. For abstracts see the <PUBLICATIONS> section of the LABB website.
December 1st, 2005
We have reached an exciting new milestone in the LHX project:
The two very first juvenile Steller sea lions with Life History Transmitter
implants were successfully released back into the wild in Resurrection Bay,
Alaska, on November 22nd, 2005. The image below shows the two animals with LHX
tags swimming in the water immediately after their release. On one of the two
animals, the external satellite transmitter that is used for post-release tracking
is visible. A third juvenile that had not received an LHX implant, was also
released at that time.
This research is being conducted under permit
#881-1668-05 by the NMFS.
A new publication describing technical aspects of the LHX tags and their development will shortly be available:
April 5th, 2005
We are continuing to monitor all LHX transmittters deployed in 2004. To date,
we have not received any signals from any of the six transmitters released in
four animals, and we are assuming that these animals are continuing to do well.
We will be giving the following two presentations at conferences, on aspects
of the LHX project:
October 18th, 2004
On October 13th, Eisenhower, the second rehabilitated California sea
lion to have received dual Life History Transmitter implants at The Marine Mammal
Center, was released into the Ocean after completing the mandatory 6-week post-procedure
observation period. The release went well, and 'Howie' is now being tracked
via an externally attached satellite data transmitter. This successful release
brings the total number of rehabilitated sea lions with Life History Transmitters
that have been released, to four. The first two animals were released with single
LHX tag implants, the second two with dual LHX tag implants. (October 18th,
2004)
September 30th, 2004
On September 16th, D-Day was released into the
Pacific Ocean, and is now the first rehabilitated California sea lion to be
released into the wild with dual Life History Transmitter implants. Eisenhower
as the second animal to have received dual implants is currently undergoing
the mandatory 6 week observation period following the procedure, and is continuing
to do well.
September 1st, 2004
As of Sept. 1st we have
implanted LHX tags into four animals, Rory and Pia both received single tag
implants. Both were released and tracked with external tags after their release.
They were diving well for as long as their external tags lasted. As is typical
for such external tags, we were able to track them for one month or less, one
reason for developing the LHX tags! D-Day and Eisenhower both received dual
LHX tag implants. Both are still at The Marine Mammal Center for their extended
post-procedure observation period, and both are continuing to do well. They
will eventually be released just like Rory and Pia, and will be tracked by means
of external satellite tracking units. We are of course monitoring the ARGOS
frequencies of the LHX tags for Rory and Pia, and will do the same for all other
animals that will be released.
August 26th, 2004
On August 26th Eisenhower was the second animal to receive two LHX tag
implants. His procedure also went very well, and he is recovering well.
July 12th, 2004
Pia was released on July
9th. Pia is the second animal to carry a Life History Transmitter in the wild.
In the image below, you can see Pia carrying an external Satellite-linked Data
Recorder. This instrument allows us to obtain data about the diving behavior
and locations of the animal for the next 4 - 8 weeks.
July 7th, 2004
On July 7th, D-Day was the first animal to receive two LHX implants. D-Day
is a large male California sea lion of about 195 kg. The procedure went well,
and D-Day has recovered very well. He is currently at The Marine Mammal Center
for the extended post-procedure observation period mandated by our MMPA permit.
The image below shows an x-ray radiograph of the two implants, taken after the
procedure. One can see the vertebral column, the last few ribs on the left side
of the image, the hip and two femurs towards the right, and the two LHX tags,
of a size comparable to two vertebrae each:
July 1st, 2004:
Rory was released on June
29th, and is once again roaming the oceans. She is the first animal to carry
a Life History Transmitter in the wild.
May 25th, 2004:
On May 25th, we performed the second implant procedure at The Marine
Mammal Center, on a larger male California sea lion from the rehabilitation
program - Pia. The image below shows a radiograph of the intraperitoneally implanted
transmitter, taken at the end of the implant procedure. Pia is also doing very
well.
May 11th, 2004:
On May 11th, we performed the first ever LHX tag implant procedure on
Rory, a female California sea lion that had recently undergone a rehabilitation
program for stranded animals at The
Marine Mammal Center, and under funding from the Pollock
Conservation Cooperative Research Center. The image below shows Rory one
week after the procedure. She is continuing to do very well.
Earlier Updates:
In 2001 under funding from the North Pacific Marine Research Program, we completed the development of the first generation LHX tags at Wildlife Computers. These early standard LHX tags consisted of the Wildlife Computers controller board, piggybacked onto an Argos-compatible transmitter board. We used a helical antenna instead of the standard whip antenna, to reduce the size of the LHX tag. This first functional transmitter operated at a power output level of 1 Watt. The helical antenna intrinsically has a reduced efficiency compared to the straight whip. This results in an actual transmission power comparable to a 1/2 Watt transmitter with a straight whip antenna. A single large battery and a float with a large waist that served as the antenna cover completed the package.
The composite image below shows the very first functional prototype LHX tag housed in a positively buoyant package in the upper part of the image, above a pocket knife for size comparison.
This first functional tag was used for extensive simulation and uplink testing, but was still too large to use in an animal. In addition, our goal was to produce a different shape more suitable for implantation. We accomplished that in 2003 and now have a fully functional LHX tag that meets all our size, shape and design criteria, and has passed all simulation testing. This tag is shown in the above image below the pocket knife, but to a different scale than the first functional tag. The actual size of our final tag design is outlined above the first functional tag, for comparison. While the first functional prototype was still over 190mm long and 50mm in diameter, the final design of the LHX tag is housed in a significantly smaller package of 42mm diameter and 120mm in length. This tag has a single integrated controller and transmitter board, a different type of helical antenna, two batteries, and the floatation properties are a function of the entire tag. The tag is coated in a class VI USP certified physiological resin compatible with implantation.
For the health assessments that are part of the LHX project, we are using our new portable hematology and clinical chemistry analyzers to collect baseline data on blood values for healthy animals. These same units will later be used in the field to determine the health status of juvenile Steller sea lions that will receive LHX implants, based on small blood samples.
The unit shown in the image below is a VetScan HMT hematology analyzer by Abaxis. The unit determines a large variety of hematological parameters including hematocrit, RBC count, hemoglobin concentrations and many more from a 10-microliter sample of whole blood, in just a few minutes. The unit uses a separate package of test reagents in the cardboard box to the left. Check out our GLOSSARY in the TECHNOLOGY section for definitions of hematological parameters.
In addition to the HMT hematology analyzer, we use a small, portable VetScan Clinical Chemistry Analyzer by Abaxis. This machine uses a 90 micro-liter sample of whole blood to determine up to 29 different parameters such as glucose, BUN (Blood Urea Nitrogen) and bilirubin, in just a few minutes.
To determine the thickness of the subcutaneous blubber layer and body condition of the sea lions, we use a portable, high resolution ultrasound imaging system by SonoSite (Veterinary SonoSite products are distributed by Products Group International):
One of the images recorded by the SonoSite 180. This is a scan of Sugar, an 8 year old female Steller sea lion at the Alaska Sea Life Center at Seward, AK. At the top of the image is the skin with subdermal tissue. The blubber layer is highlighted by the dotted white line, and in this image is about 17 mm thick. Embedded in the blubber layer are strands of muscle tissue. This makes the application of non-visual ultrasonic blubber thickness probes such as the ScanProbe problematic, a visual control of the blubber layer delivers more reliable results.
Publications resulting from or related to the LHX project:
Check out this publication resulting from our initial validation study on the use of ultrasound to determine blubber thickness:
Permits
Please be aware that this project, like any projects on vertebrate animals and on protected and/or endangered species in particular requires numerous permits to carry out. Please see our permits page for more information. The California sea lion portion of the LHX project is carried out under Permit No. 1034-1685-00 to M. Horning, under the Marine Mammal Protection Act, as well as under AUP # 2/02 issed by the Institutional Animal Care and Use Committee of the Marine Mammal Center. The initial stage of the LHX work on juvenile Steller sea lions is carried out under permit #881-1668-05 to the Alaska Sea Life center.
The LHX project is funded through grants from a variety of sponsors, including:
The North
Pacific Marine Research Program
The Pollock Conservation
Cooperative Research Center
The
Steller Sea Lion Research Initiative of the National Marine Fisheries Service
(NOAA)
The Alaska Sea Life
Center
The Texas Institute
of Oceanography (cost share participation)
Check back with us soon for further updates on this project.
(February 2006)
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![This is a composite image showing the older prototype of an LHX tag in the upper part of the image, next to a small red swiss army pocket knife. In the lower part of the image a new type of LHX tag is visible. The actual size of the new tag is shown by superimposing it's outline over the older tag. See the detailed description of the image through the [D] link.](LHX-tag-design-04-4.gif)