Advances in Underwater

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Advances in Underwater Biotelemetry J.
Winter Chapter 19
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Biotelemetry Terms and Definitions
Biotelemetry the study of biological
interactions of organisms based on remotely
sensed signals. Also known as Telemetry. Hertz
a measure of the frequency of the signal, equal
to 1 cycle per second. Transmitter device
attached to an animal that emits a signal. Also
known as a tag. Transponder device which
returns a signal in response to a signal sent to
it. Receiver device that filters input signals,
amplifies them, and converts them to a form
audible to the investigator (or electronic signal
detector). Bandwidth the range of frequencies
than will be passed through the narrowest filter
to the listener or electronic signal detector.
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Biotelemetry More Terms and Definitions
Induction Administration of anaesthesia to the
fish, to induce a state where the fish cannot
move or feel pain during surgery. Implantation
surgically placing the transmitter in the
fish Shielded Needle Technique a type of
antenna placement to reduce transmitter
loss. Diel round-the-clock sampling
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Why Telemetry?

• Telemetry provides a means to
• Collect data on animals not readily visible
• Monitor the biology of animals with a minimal
  influence on the behavior and health of the
  animal
• Collect additional data beyond what is possible
  with mark/recapture studies
• Compare physiological and behavioral data
  collected in the laboratory and in natural
  systems.

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Why NOT Telemetry?

• Telemetry should not be used to look at
  behavioral characteristics of animals without
  careful consideration.
• Just because it sounds like fun does NOT mean
  that telemetry will work in all applications.
• It is VERY IMPORTANT to determine the questions
  you wish to ask FIRST before you start planning
  and buying for a telemetry project.
• Telemetry is time consuming and tedious work,
  and it takes ATTENTION TO DETAIL to be
  successful (I.e., reportable results).
• Telemetry equipment can be quite expensive, and
  you will usually not be able to recover implanted
  tags.

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Biotelemetry
Signal range Ultrasonic Frequency Range
20-300 kHz Radio Frequency Range 27-300
MHz AM Radio 550 - 1660 kHz FM Radio 88-108
MHz WVAQ 101.9 MHz WMNF 90.9 The tags
we will use today 148, 149, 150 MHz
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Biotelemetry
We will focus on two main types of
telemetry Radio telemetry Ultrasonic
Telemetry Features Common to Both
Systems Transmitter signals both either
continuous or pulsed. Pulsed signals most common
in radiotelemetry- pulsing saves
energy. Transmitter encapsulation usually
potted in epoxy, way, urethane, silicone, or
dental acrylic. Most commonly solid clear
epoxy. Batteries usually gt 50 of transmitter
volume and gt80 weight batter choice
determined by energy per unit weight or
volume. Receivers transmitter signal must be
within appropriate bandwidth signals (There
are other types of telemetry but we wont focus
on them today).
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Considerations for telemetry projects

Habitat Characteristics Water depth,
temperature, conductivity (dissolved ions),
current, study area size, plant densities,
presence of structure under/at the water
surface (i. e., dams, weirs, jetties), Animal
Behavior Mobility, activity pattern (diurnal,
nocturnal etc.), grouping tendencies, hardiness
or resistance to disturbance Cost Purchase
price of equipment, personnel costs, lodging
costs, training time/learning curve, sampling
frequency, weather considerations, equipment
mobility/ruggedness, down time. THE MOST
IMPORTANT CONSIDERATIONS ARE Animal mobility (do
your homework on the biology of the study
species) and size of the study area.
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Considerations for telemetry projects

• Selecting A Telemetry Supplier
• Equipment, performance, and service varies.
  Equipment MAY NOT BE compatible between
  manufacturers.
• FIRST, decide on the goals of the project and
  make sure telemetry will answer the questions you
  are asking. Think scientific hypotheses!
• A good telemetry equipment manufacturer will
• Provide technical advice and assistance during
  planning
• Fill your order quickly
• Repair the equipment quickly
• Loan replacement equipment
• Help with problem solving
• Adapt or adopt equipment changes to match your
  project, not make you change to adapt to their
  equipment.
• AVOID contracting equipment development to
  friends, colleagues, or firms not engaged in the
  business of (aquatic) animal tracking.

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Sonic Telemetry (aka acoustic telemetry)

ADVANTAGES
DISADVANTAGES Works well in high
conductivity Difficult to locate animals from a
distance (hydrophone must be Works well in
deep water submerged) Accurate within 3-4m
Signals affected by boat noise,
submerged plants/structures, high
particulate matter/algae, temperature
gradients Cant be used near
dams/power plants because of air
bubbles Fewer individuals can
be distinguished by frequency Indi
vidual transmitters with pulsed signal
signatures that must be carefully
counted
So, why use sonic? You need sonic telemetry in
areas with high conductivity (i.e., estuaries or
marine systems) or in very deep areas (i.e.,
reservoirs).
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Radio Telemetry

ADVANTAGES
DISADVANTAGES Works well in low
conductivity Cant be used in marine conditions
Works well in shallow water Signals reduced
by increasing depth (gt 5m) and conductivity
Works well in turbulent water (gt 400 µS/cm
) Can be used to search large Radio signals
deflected by metal areas to find mobile
species objects, terrestrial vegetation,
and Radio signals not as affected by mountainous
terrain. Also can be vegetation, algae,
thermoclines affected by boat motor
noise Each tag can transmit on a
different frequency, allowing for ID of many
animals at the same area at once
So, why use radio? Use radio telemetry in
shallow areas with low conductivity or in
turbulent areas. Especially suited for
low-conductivity rivers, lakes, ponds.
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Combined Acoustic-Radio Telemetry aka CART

ADVANTAGES
DISADVANTAGES Can be used in a variety
of Larger size depths, conductivity,
temperature High cost Programmable
(turn sonic portion off and switch to
radio only). Reference Solomon, D. J. and E.
C. E. Potter. 1988. First results with a new
estuarine fish tracking system. J. Fish Biology
33(Suppl A)127-132.
So, why use CART? Well suited for
anadromous/catadromous species where life stage
information is known.
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Satellite Telemetry

ADVANTAGES
DISADVANTAGES Can be used in a variety
of External attachment to fish depths,
conductivities, temperatures (fouling of
transmitters means they cant transmit)
Long-lasting High cost Improved data
capture and download capabilities (lacking in
Difficult to retrieve sonic AND radio
telemetry)
So, why use satellite telemetry? Best available
tracking for highly migratory species.
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Sonic Telemetry

Transmitters Operate between 20-300 kHz.
Frequency determined by vibration of the
transducer. Usually ceramic cylinders with
omnidirectional resonance because this type is
cheapest. Hydrophones The most important
component of acoustic telemetry. The
hydrophones convert the vibrations of the
transmitter into electronic pulses. It is
important that the hydrophone and receiver
specifications MATCH. (In other words, buy them
together from the same company). 2 main types
of hydrophones OMNIDIRECTIONAL best for
searching and for fixed stations. DIRECTIONAL
blocks noise from most directions. Orientation
of hydrophone VERY important. Usually mounted
on rotatable, vertical pipes that are suspended
in the water. Good hydrophones have a shielded,
twisted-pair lead cable, NOT a coaxial cable, and
a low-noise preamplifier near the hydrophone.
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Sonic Telemetry, continued

Signal Transmission Frequency choice depends on
transmitter size, which in turn affects the size
of transmitter and acoustic output. SMALL
transducer higher frequency more power
needed LARGE transducer lower frequency less
power needed Ultrasonic transmission in salt
water (Urick 1975) and deep water (Nelson 1978)
is well known, so transmitter range can be
calculated beforehand. Signals are affected by
spreading, absorption, noise, etc. Sound
spreading is independent of frequency,
temperature, salinity. ABSORPTION with
salinity and temperature. Noise comes
from wind, wave action, boat engines, fish
finders, rain, ice cracking, and biological
sources (e.g., snapping shrimp). Thermoclines,
haloclines also affect refraction and absorption
of signals.
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Sonic Telemetry, the final word...

Sources of noise and reflections can render
ultrasonic systems ineffective. IT IS IMPORTANT
to consider or monitor noise and reflection
BEFORE beginning ultrasonic telemetry projects.
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Radio Telemetry

Transmitters Operate between 27-300 MHz.
Frequency determined by a crystal which controls
production of electromagnetic vibrations.
Signals are transmitted through circular (loop)
or straight wire (whip) antennas. Loop
antennas work on land or in water with no
additional tuning. Signal transmission is more
directional than whip, so signal levels from
moving animals fluctuate. This makes location of
animals difficult. Whip antennas require
tuning in water during construction. The whip
antenna should be straight for maximum efficiency
and range. For a given size battery, whip
antennas result in a longer, narrower footprint
suited for implanting in the body cavity of fish.
Transmitters with whip antennas are easier to
locate than loops. Coded/Sensing Transmitters
the manufacturer can modify signals to provide
information on depth, temperature, movement
(mortality signal) etc. IF A MORTALITY SENSOR
IS AN OPTION, GO FOR IT!
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Radio Telemetry, continued

Receiving Antennas Usually Loop, H-Adcock
(H), Yagi or omnidirectional (whip) antennas
are used. All gain in signal detection the
higher off the water they are. Loop and H
antennas are directional (have a leading or
dominant side). Yagi and Whip receiving antennas
are not. Loop receiving antennas are small,
circular or diamond-shaped metal tubes with a
handle. Signal detection range usually lt 1 km.
Used to pinpoint locations. H antennas have two
cross-directional elements. Good sensitivity and
accuracy (3). One element usually slightly
shorter than the other which provides limited
directionality. Used to pinpoint
locations. Yagi antennas consist of a series of
small metal elements connected to a central metal
boom. The size of the elements and boom
increases with decreasing frequency strength.
Yagis must be mounted with the elements
vertically oriented, and because of their size
must be firmly attached to the tracking boat by
guidewires.
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Radio Telemetry, the final word...

More about Receiving Antennas Whip antennas
are usually straight wire or metal tubing whips.
They often have a tuning ring which allows them
to detect specific frequencies. Whip antennas
are most often attached to vehicles or boats for
large area searching. Short coaxial whip
antennas are used to detect fish passage past
fixed receivers. Antennas are tuned by the
manufacturer for specific frequency ranges. For
best results, buy the receiver and the antenna(s)
at the same time to keep equipment
compatible. Signal Transmission Transmission of
radio signals depends on attenuation from depth,
conductivity, noise, as well as signal frequency.
The affects of high conductivity and depth are
greater for frequencies over 100 MHz. Losses
in signal strength and errors in detection can be
caused by power lines, ignition systems, cellular
phones, and CB radios.
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Telemetry Systems
Ultrasonic Equipment. From L to R
omnidirectional, cone, and linear array
hydrophones. Top R ultrasonic receiver and
headset for underwater. Bottom R traditional
sonic reciever.
H antenna
Radio Equipment. High and low frequency
receivers, loop, and multiple-element
Yagi antennas, headset.
Yagi
Loop
Lo-Tek receiver
ATS receiver
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Transmitter Attachment

• Transmitter attachment depends on
• morphology and behavior of the species
• nature of the aquatic ecosystem
• project objectives
• The most widely used methods of attachment are
• external
• stomach insertion
• surgical implantation
• Before you put transmitters on or in experimental
  animals, do some dissections of similar sized
  dead and captive animals to gain experience.
• It is important to determine where the tag will
  rest on/in the fish, and how the method of
  attachment will affect the internal organs and
  mobility of the fish.

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Transmitter Attachment

Regardless of transmitter type, Transmitters
should not exceed 1.25 of the fishs weight
in water (submerged weight) -OR- 2 of the
fishs weight in air. (Think of a loaf of bread
stuffed into your stomach cavity.)
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External Transmitter Attachment (a quick overview)

Advantages Quicker and easier than surgical
implantation. Quick recovery. Useful for
short-term studies. Disadvantages Causes
problems for the fish in terms of balance and
drag. Easily fouled, snagged, or caught. Most
common method of attachment Transmitter attached
alongside the dorsal fin by stainless steel or
teflon wires. Technique A large surgical needle
(catheter) is used to pass the wires through the
adipose tissue and between the pterygiophore
bones. After removing the needles, the wire is
pulled taught so the transmitter is snug against
the fish.
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Stomach-Inserted Transmitter Attachment
Advantages Do not cause drag, less likely to
cause abrasion. Less likely to affect balance
because the weight of the transmitter is below
the fishs center of gravity. Quick, painless
insertion. Disadvantages Transmitters difficult
to insert May result in esophageal or stomach
damage. May be regurgitated. Difficult to
assess external variables. Method of
attachment Transmitter forced into
mouth. Technique Insert through the mouth by
using a tube or balling gun (used by large animal
vets). Tubes should be coated with glycerin to
prevent damage. Antennas protrude from mouth or
gill cavity.

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Surgically-Implanted Transmitters
Advantages Do not cause drag, less likely to
cause abrasion. Less likely to affect balance
because the weight of the transmitter is below
the fishs center of gravity. Best method for
long-term studies. Disadvantages Timing is
important (implant before spawning). Requires
surgical supplies not always available to
non-veterinarians. Takes longer to perform and
has a long recovery period. Method of
attachment Transmitter placed in body cavity
through surgical incision. Technique We will
focus on this method of attachment as the
technique of choice for freshwater telemetry
studies.

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Surgical Implantation Techniques

• Important considerations
• There are NO anaesthetics or antibiotics approved
  by the FDA for use in wild fish. Check with
  local, State, and Federal regulations BEFORE you
  start!
• You will need a recovery tank, an induction tank,
  and a surgical trough before you start. Also,
  find some old terrycloth towels that you can
  wreck. These will be soaked in water and used to
  keep the fish wet, cool, and prevent it from
  seeing (reduces stress).
• Required surgical supplies
• Sutures (monofilament with attached curved
  cutting needle) size 5-0 for fish
  gt300 mm TL 4-0 for 100-300 mm fish.
• Haemostats (surgical stainless steel, with
  cutting area if possible)
• Scalpels disposable, 10 sterile surgical blades
  with plastic handles
• Catheters large animal-sized, 12-16 gauge works
  best
• Scissors surgical stainless steel (to cut suture
  material)

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Surgically-Implanted Transmitters
Suture Material For fish that will be
immediately released to the wild (i.e., no
antibiotics used), your best choice for suture
material is the nonabsorbable monofilament suture
with an attached, curved, cutting needle. Why
Choose This Combination? Absorbable sutures are
made of braided polyglycolic acid. The nature of
the braid design allows bacteria to travel down
the grooves of the braid and into the fishs
abdomen, known as wicking Monofilament does
not allow wicking. Attached needles It is
difficult to attach thread to the needle,
especially monofilament, and doubly hard on a
bouncing boat. Curved, cutting needles Fish
skin (skin in general) is tougher than you think.
The curved cutting needle lets you get the
suture in the right place from the start.

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Surgically-Implanted Transmitters
Methods Before you implant tags in your study
fish, PRACTICE YOUR SUTURES. You will need to
have a veterinarian show you how to tie the
surgeons knot (see Methods For Fish Biology- the
blue book) Where to place the tag The
abdominal wall of fish is thinnest along the
midline, and no major blood vessels pass the
midventral line. Incision length should be the
smallest possible to allow the transmitter to be
placed into the abdomen. On scaled fish, 2 or
more rows of scales will have to be removed
before the incision is made. Care must be taken
to avoid damaging the abdominal organs,
especially during spawning season when gonads are
enlarged.

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Anaesthesia
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Surgically-Implanted Transmitters
Other Considerations You need to develop a
feel for how hard to push on the scalpel to
make one continuous incision- AVOID sawing at the
incision or making lots of small cuts because
this increases t he damage to the surrounding
tissue. It is very important NOT to damage
internal organs. Internal bleeding can cause
organs to adhere, necrosis, and death of
implanted fish. Suturing Pick the method that
works best for you (simple interrupted works
well). Use 3-5 sutures per incision, depending
on the length of the incision. The average
incision length is 1.5 to 2 cm for a 1-year
transmitter for fish gt3 kg. Make sure you do not
suture organs into the incision. Do not pull the
sutures so tight that they pucker. The knot is
the weakest part of any suture, so you dont want
it to be too stretched.

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Shielded Needle Technique
Transmitters can be expelled through the
incision. To reduce the effects of the antenna
wire abrading the incision, we use a shielded
needle technique. This technique allows the
antenna wire to protrude from the fish in a
different area than the trailing edge of the
incision. The shielded needle consists of a
large-gauge catheter inserted from the outside of
the fish into the peritoneum, and exiting through
the surgical incision. The antenna is threaded
through the catheter. The catheter is then
withdrawn. This technique has been shown to
reduce the chance of transmitter expulsion from
antenna movement and abrasion of the incision.

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Suturing
Simple Interrupted
Suturing a buffalo (note haemostats, gloves)
Continuous
Locking (blanket)
Closing on a carp
Mattress (interrupted horizontal)
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Implanting Techniques
Step 2 make incision put in tag
Step 1 remove 2 rows of scales
Step 4 Thread antenna thru catheter.
Step 3 prepare catheter for shielded needle
technique (antenna placement)
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Suturing Techniques
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Surgically-Implanted Transmitters
Stress It is imperative that you take as many
precautions as possible to reduce stress to the
fish during the holding, induction, surgery, and
recovery process. Complications from surgery
include Electrolyte losses, haemorrhage,
localized inflammation and infection,
peritonitis, systemic infections, gut stasis
(impaired peristalsis and fecal retention) and
internal adhesions. Trauma is another major
problem resulting from surgery. Transient
Posttraumatic Physiological Syndrome (TPPS)
symptoms may be similar to those of stress or
shock Oxygen debt, loss of plasma/blood volume,
ion imbalances, inability to synthesize proteins,
etc. Most implanted fish are returned
immediately to the wild, so the researcher has no
idea how they are coping with postsurgical
stress. This is probably the biggest killer of
surgically instrumented fish.

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Shielded Needle Technique
Transmitters can be expelled through the
incision. To reduce the effects of the antenna
wire abrading the incision, we use a shielded
needle technique. This technique allows the
antenna wire to protrude from the fish in a
different area than the trailing edge of the
incision. The shielded needle consists of a
large-gauge catheter inserted from the outside of
the fish into the peritoneum, and exiting through
the surgical incision. The antenna is threaded
through the catheter. The catheter is then
withdrawn. This technique has been shown to
reduce the chance of transmitter expulsion from
antenna movement and abrasion of the incision.

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Tracking Methods
Depending on the tag used, instrumented animals
can be located by Boat Airplane Triangulation
Appearance at fixed stations Automatic tracking
systems Satellites Data can be recorded
manually (data sheets) or automatically The
choice of tracking method depends on Habitat
characteristics and size Animal Behavior Animal
mobility Number of animals tracked Amount of
information required
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Tracking Methods Boat
Usual method boat is run at low RPMs (lt1500)
and a scanning receiver is used. Antenna
type scanning large area whip or
yagi precise fish locations loop or H Once
fish are detected using the large antenna, the
loop or H antenna is used to pinpoint the
location. Unlike terrestrial wildlife telemetry,
with most species of fish you can determine
exactly where the fish is and drive the boat
right to them. This is the technique most often
used in fisheries telemetry for mobile tracking
of fish.
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Triangulation
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Triangulation Part 2
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Tracking Methods Plane
Usual method plane is flown at low altitude
with yagi or loop antennas fixed to the
plane. Stringent FAA regulations exist for
attaching antennas (and other equipment to
planes. Different State and Federal
regulations may also limit who may conduct
aerial surveys. Tracking by plane allows for
the greatest detection range for radio
signals Triangulation Animals can be located
from a distance by taking bearings from two or
more locations (triangulation). This is
difficult to do on the water, and not really
necessary unless the study species is skittish
or cannot be approached by boat.
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Fixed Stations
Receiving systems and recording units can be set
up at certain locations. The receiver records
presence/absence of transmitter frequencies near
the hydrophone or antenna. Often used in fish
ladders or in small areas where signals can be
captured between stations. Automatic Tracking
Systems Ultrasonic transmitters can be located
automatically by measuring the time that it takes
for the signal to travel through water. Relies
on an array of hydrophones. Extremely expensive
and most are not easily relocated.
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Automatic Data Recording (data loggers)
Signals from transmitters can be automatically
decoded and recorded Timers can be used to
turn the receiver on and off Multiple
frequencies can be entered in a scanning
receiver Also have a high expense related to the
purchase of scanning receivers, computers, and
related gear. Best idea for practical
applications Weekly or semiweekly tracking in
the entire study area. Timing depends on study
goals (seasonal movement vs. diel movement)
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Error Associated with receiving systems
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Sampling
Field Considerations Waterproof storage for
receivers, GPS units, etc Spares for everything-
antennas, antenna wire, data sheets Receivers
dont like water/moisture if you get caught in
the rain, cover them as best you can, and let
them dry out well afterwards. Test each
transmitter BEFORE implanting If necessary, get
a padded case for the receiver (Lo-tek receivers
come with a padded case for ATS a small
soft-sided lunch cooler works Sample Size The
number of tagged animals depends on cost, labor
availability of animals, type of data desired,
statistical analysis, distribution of
animals The number of locations/data points
collected depends on study type, difficulty in
locating animals, transmitter life
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Sampling
When to sample? Time of day if you sample the
same time every day you will end up with a
biased view of fish habitat preferences, activity
periods, etc. A good method is to divide the day
into equal sampling periods and try to sample an
equal number of periods per unit time. Can also
combine diel sampling with weekly sampling to get
a complete picture. Search Methods The best
method is to use equally spaced transects equal
in duration and area covered is the best
plan. By varying the starting point you can
avoid location the same fish at the same time
of day and avoid making false conclusions
about fish behavior patterns.
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Data Handling
Location Data To get accurate position data, a
Global Positioning System (GPS) unit must be
used. Important GPS considerations Accurate
(DGPS not a consideration any longer) Ability to
log data points Ability to move between
coordinate systems and units Portable Easily
rechargeable or easy to change batteries in the
field The best way to handle location data is to
incorporate a Geographical Information System
(GIS) such as Arc/View or Arc/Info Most GIS are
based in the Universal Transverse Mercator (UTM)
projection. When recording data in the field,
set the GPS units to UTM.
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Coordinate Systems
West Virginia is UTM Zone 17
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Paint Creek
London Dam
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Paint Creek
London Dam
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Data Handling
Location Data There are Arc/View programs
already written that will examine location (point
pattern) data for discernable patterns. The
easiest of these is the Animal Movement Extension
but there are other programs available within the
Arc platform(s). What to Record in the
Field For each location, you want to record all
the habitat variables possible. This
includes vegetation, substrate, location in the
channel, presence of structure or large woody
debris, cloud cover, wind, rain etc. Especially
important WATER QUALITY. (temperature, DO,
pH, conductivity, salinity, turbidity,
chlorophyll etc). MOST IMPORTANT write down the
coordinates for EACH location in case the GPS
data are lost.
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GIS Data Analysis We use the ArcView extension
Animal Movement (USGS, 2000) to look at the
entire group of telemetry points and for each
species by season. http//www.absc.usgs.gov/glba/
gistools/animal_mvmt.htm
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Data Handling
Analysis Face it you will need a GOOD computer
to analyze the large amount of data that
telemetry generates! Arc/View and other GIS
incorporate spatial statistics into them but
you will still need traditional nonspatial
statistical techniques to look for patterns in
habitat use. Statistical software includes SAS
(Statistical Analysis System), S-Plus, Systat,
etc. Of course, you decided on your hypotheses
BEFORE you started your data collection (and
talked to a statistician first) so you wont
have any problems with the analyses. Right??
Hopefully so! I recommend the following book
White and Garrott 1990. Analysis of Wildlife
Radio Tracking Data. Academic Press. ISBN
0-12-746725-4.