Risks and benefits of telemetry
techniques in investigating harbour
seal and wind generator construction
interactions

Sea Mammal Research Unit
Report to
The Ministry of Economic Affairs, the Netherlands

March 2013 [Version 700]

Dr Bernie McConnell
Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife.KY16 8LB, UK.

Telemetry techniques and harbour seal investigations

1 Summary

1. In response to a request from the Dutch Ministry of Economic Affairs, Directorate-General
for Nature and Regional Affairs, Regional Affairs and Spatial Economic Policy Department,
this report briefly reviews aspects of the risks and benefits of telemetry techniques in
investigating harbour seal and wind generator construction interactions.
2. The challenge is to quantify the magnitude of any telemetry effect with an appropriate
metric, and then to predict the consequences of such an effect the validity of the
investigation.
3. Seals spend much of their lives underwater any away from ready visual observation. Also it is
at-sea that seals are acoustically coupled to effects of piling noise. Thus some form of
telemetry is essential for both baseline and manipulative applied studies. There is no
alternative method.
4. Whilst necessary for such applied studies, telemetry is unlikely to be sufficient on its own. It
should certainly be undertaken as a compliment to population counts (and other biological
stress-related studies). In this way causal linkages may be inferred / negated from changes in
population trajectory. Also the synergy of these two techniques will permit absolute
population estimates as well as the absolute density of at-sea usage.
5. During the last five years 105 peer-reviewed papers have been published whose data were
obtained using seal telemetry; of these 22 papers were on harbour seals.
6. Harbour seal are difficult to re-catch and so tag data must be relayed ashore by satellite or
GSM (mobile phone) systems. Tags vary greatly in their functionality – and thus also in size.
The functionality must be matched to the question posed. Also, the sample of tagged
individuals must be sufficient to support robust population behavioural responses.
7. Capture risks (chronic disturbance, collision trauma and drowning) are reduced to
acceptable levels primarily by the availability of a skilled and experienced catching team.
Such a team may take many years to assemble.
8. Seal handling (with or without anaesthesia) is unlikely to have significant long-term effects
on individuals.
9. In the past, the excessive use of epoxy glue to attach tags to seals fur occasionally caused
burns. However nowadays the use of minimal glue prevents any such exothermic build up.
Also, the use of flexible edging to the edge of the tag reduces edge abrasion.
10. Seals are well streamlined and so external attachment will have some hydrodynamic effect.
However it should be noted that, as capital breeders, harbour seals (particularly adult
females) naturally undergo rapid and large changes in size and shape every breeding season.
11. Whilst some studies on penguins have shown significant tag effects, two empirical studies of
Antarctic fur seals and elephants seals suggested minimal tag effects. However, caution
must be used in extrapolating to other species and types of tag.
12. Computer Flow Dynamics (CFD) can simulate water flow and predict hydrodynamic
parameters. In one CFD study the addition of a telemetry tag to a harbour seal caused a
12% increase in the coefficient of drag (Cd). However there were no data to assess the
crucial link between this parameter and the real increase in drag in relation to seal activity /
energy budget and the behavioural and fitness consequences.
13. The effect of carrying a tag of the thermal balance of a seal is unlikely to be significant.
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Telemetry techniques and harbour seal investigations
14. The effect of telemetry on harbour seal individual welfare and reproductive fitness is
difficult to estimate with a high degree of certainty. Certainly, more studies are needed.
However an over-zealous application of the precautionary principle would be a dis-service to
the conservation of a species currently facing threats from a variety of anthropogenic
sources.

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Telemetry techniques and harbour seal investigations

2 Contents
Table of Contents
1

Summary ......................................................................................................................................... 2

2

Contents .......................................................................................................................................... 4

3

Introduction .................................................................................................................................... 4

4

Seal telemetry systems ................................................................................................................... 5

5

Potential risks .................................................................................................................................. 6

6

5.1

Capture.................................................................................................................................... 6

5.2

Handling .................................................................................................................................. 7

5.3

Attachment ............................................................................................................................. 7

5.4

Tag carrying ............................................................................................................................. 8

5.4.1

Abrasion .......................................................................................................................... 8

5.4.2

Hydrodynamic modification............................................................................................ 8

5.4.3

Thermal balance.............................................................................................................. 9

Wind farm construction and harbour seal interaction ................................................................... 9
6.1

Telemetry techniques ............................................................................................................. 9

6.2

Study types............................................................................................................................ 10

7

Discussion...................................................................................................................................... 11

8

References .................................................................................................................................... 12

3 Introduction
This report reviews the benefits and potential effects of using telemetry systems to investigate the
effect of wind farm construction on harbour seals (Phoca vitulina). Specifically, the remit is to
review and assess:
1. The latest scientific international insights, possible effects of tagging devices on seals
(including the possible effect of hydrodynamic disturbance),
2. Why this method is selected and used for research on possible disturbance effects due to
construction works.
3. Alternative methodology

Telemetry is an observation, or measurement, tool. We start with the premise that measurement in
all fields of scientific investigation is imperfect. Such imperfection may be manifested in the
measurement itself and / or in unwanted effect on the target. For example, a good voltmeter can
both measure potential difference with precision and (due to its high internal resistance) and have
minimal effect on the true potential difference in the circuit. In such cases the effect is sufficiently
trivial that it is of no consequence. Thus the challenge is not to observe that there is effect, but
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Telemetry techniques and harbour seal investigations
1. to quantify the magnitude of the effect with an appropriate metric, and then
2. predict the consequences of such an effect the validity of the investigation.
In this brief review we first describe the telemetry systems (Section 4), specifically their functionality
and design constraints. In Section 5 we consider the potential risk to seals; this includes capture,
handling and the effect of carrying a telemetry device. In Section 6 we consider the role of
telemetry in investigating interactions between harbour seals and piling noise due to offshore wind
energy construction piling. In the Discussion (Section 7) we synthesise these issues.
The brevity of this document precludes a comprehensive treatise; it also limits the depth of
discussion. However we hope that it provides an initial framework, and a common currency, within
which the role of telemetry in seal studies may be rationally debated.
Declaration of Interests
The author is a long-serving biologist within the Sea Mammal Research Unit (SMRU). In addition to
its primary goal of biological investigation, SMRU also designs and sells telemetry tags. Other
organisations also manufacture telemetry tags. This review is based on tag generic function and
effect and does not advocate specific models or manufacturers.

4 Seal telemetry systems
Seals spend much of their lives underwater, and frequently far from land. Their behaviour at sea is
thus seldom directly observable. It is for this reason that telemetry has become such an important
and essential tool in marine mammal science (McConnell et al. 2010). During the last five years 105
peer-reviewed papers have been published whose data were obtained using seal telemetry; of these
22 papers were on harbour seals1.
North Sea harbour seals breed in June/July and then moult in August / September. The standard
telemetry attachment method for seals is to glue the tag glue to the fur (Field et al. 2012). Thus tags
will detach from harbour seals at the moult in August / September. However mean tag longevity for
harbour seal tags is 3-4 month, and so the tag may fail before the moult. Attempting to catch the
same animal twice in order to retrieve an archival tag2 is not practicable. Thus data must be relayed
ashore from tags. Two types of data relay systems are available:

1

Argos satellite

GSM mobile phone

Coverage

Global

Location
determination
Data transfer rates
(Kbytes.day-1)

Inbuilt, but inaccurate
and infrequent
1

=< 35 km from coast. Thus data
store and forward required
None3. Fastloc GPS used:
accurate and frequent
50-100

Based on a search of Web of Science on ‘seal and (telemetry or Argos)’ or ‘seal and (harbor or harbour or
vitulina) and (telemetry or Argos)’, and manually deselecting inappropriate matches.
2
Where data are just stored in memory.
3
Location through base transceiver station (BTS) triangulation is not practicable at sea.

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Telemetry techniques and harbour seal investigations
A balance must be achieved between tag functionality and size. The battery is usually the largest
component in a marine mammal tag. Its size can be reduced by maximising energy storage capacity
and minimising use:
maximising storage

minimising use

Use high energy density
chemistry cells (e.g. Li-SOCl2)
Scavenge energy (e.g. solar
cells)

Duty cycling of operation
Intelligent on board processing
of raw data
Efficient data coding
Efficient data relay
Low power hardware

The user can further reduce energy use by reducing tag functionality:




Shortening tag life. For a typical GSM tag on a harbour seal tag attachment seldom exceeds
six months.
Reducing rate of location fix attempts. Note that is will impair the ability to interpolate true
tracks (Lonergan, Fedak & McConnell 2009).
Omitting behavioural data: e.g. dive & haulout events. That is, ‘location only’ tags.

In summary, there is a variety of different telemetry systems, with a variety of functionality and
form. As a guide, the weights of tags currently available may vary from 100 to 370 g. However
within this range there is a large variation in functionality. The functionality (and thus size) of the
tag chosen depends entirely upon the biological question posed. It is universally agreed that
intervention in any wild population under study should be minimised. Thus it would be
unacceptable to fit captured animals with tags that then could not actually provide the both the
quality and quantity of information required for the study.

5 Potential risks
We consider here the potential risks to harbour seals during the capture, attachment and
subsequent carrying of telemetry tags.

5.1 Capture
Unless it is an essential part of the scientific design, harbour seal capture tends to avoid the breeding
periods. The moult follows soon afterwards and thus tag attachment would be brief. Avoiding the
breeding season also minimises interference to nursing pups.
There are no methods available to remotely attach a tag without physical capture. Capture may be
undertaken on shore with hand-held nets. The approach can either be from a fast boat landing, or
covertly overland. Alternatively nets can be shot / set offshore from a haulout site, and act as either
a barrier or a tangling device. Netted seals are then moved into hand held nets and onto land or a
mother boat. If large numbers of seals are caught in one session, seals may remain in a hand net for
up to two hours before tag attachment.
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Telemetry techniques and harbour seal investigations
The following table shows risks associated with harbour seal capture:
risk

comments

Chronic
disturbance

Repeated capture attempts at the
same site may lead to colony
movement to alternative sites.

>30 years’ experience indicates
that hauled out colonies are
robust to revisits. Individual seals
disturbed into the water may
haulout out again within 30
minutes and within 50 m of
tagging operations.

Collision
trauma
Drowning

Fast manoeuvring of boats poses a
risk of collision with hull or propeller.
Unattended nets in the water pose
drowning risk.

The principal risk reduction strategy is to develop a skilled and experienced catching team. Such a
team may take many years to assemble. International coloration is a key to transferring these skills.

5.2 Handling
For tag attachment, a seal may either be physically restrained or chemically anaesthetised. Opinions
differ on the preferred method. Restraint is a simpler process, but the seal is fully aware of the
attachment process. However it may be argued that the short (20 min) period of tag attachment is
no more stressful that the longer capture and holding phase. Harcourt et al. (2010) showed that
Weddell seals (Leptonychotes weddellii) had elevated cortisol during handling, and that his could be
reduced with application of diazepam.
Baker et al. (2002) compared the fate of 549 Hawaiian monk seals (Monachus schauinslandi) that
had been handled against a control group. Handling had no effect on mortality in subsequent years.
Hawaiian monk seals are highly endangered and Baker et al. stated:
‘conservative selection procedures and careful handling techniques have no
deleterious effects on Hawaiian monk seals.’
Anesthetisation has the advantage that the seals are oblivious to the attachment process, but
requires appropriate veterinary skills. As with all veterinary procedures, it carries a very small (< 1%)
risk of an adverse reaction. When such rare reactions do occur > 95% can be successfully managed.

5.3 Attachment
Gluing to the seal fur is the preferred attachment method when moult detachment is acceptable
(Field et al. 2012). This technique was first practically demonstrated in 1983 (Fedak, Anderson &
Curry 1983). A variety of glues may be used. Whilst simple to use in the field, epoxy resins cure
exothermically. Avoiding excess use of resin avoids the risk of heat build-up and burning. In a study
of resighted elephant (Mirounga leonina) and Weddell seals, Field et al. (2012) state :
‘Four of the 508 seals had lesions under the footprint of the instrument that we
suspect were caused by the epoxy getting too hot. All of these deployments
occurred in 1999, and all involved the epoxy being heated (in a water bath
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Telemetry techniques and harbour seal investigations
between 20°C and 30°C) prior to mixing. The practice of preheating the epoxy
has been abandoned.’

5.4 Tag carrying
Tags are attached to harbour seals by gluing to the fur. Thus a seal will only carry the tag up to a
maximum of the next annual moult. We consider here three risks to carrying a tag: abrasion,
hydrodynamic drag and thermal balance.
5.4.1 Abrasion
In the study quoted above, Field et al. (2012) observed wounds from the edges of tag
attachment on 7% of all animals. However they observed that ‘All the abrasions observed in
this study were healed following the first molt after’. It is now common practice to surround
the edge of a tag with a silicone rubber bead to remove concentrated flexure at the edge of
the tag.
5.4.2 Hydrodynamic modification
Seals are well adapted to an aquatic lifestyle. Therefore it is likely that any external attachment will
have some hydrodynamic affect. The fact that any effect (e.g. drag) will have an energetic
consequence of the individual is not in debate. What is important though is to quantify the
energetic cost, and to do so within in the context of the life history of the individual.
In relation to drag, Wilson et al. (Wilson & McMahon 2006) stated that two measurements were
required: the increased power (energy per time) output required to move, and the percentage of
time spent moving. In fact, since drag is related exponentially to velocity, these two parameters
should be considered over a range of velocities.
Drag (and other hydrodynamic forces) can either be estimated empirically or by simulation using
Computer Flow Dynamics (CFD).
5.4.2.1 Empirical studies
McMahon et al (2008) demonstrated that elephants seals that were fitted with data-loggers showed
no difference in mass gain during their at-sea foraging bouts compared with un-instrumented
controls. They showed that this finding held in years of contrasting prey availability.
Boyd et al. (1997) studied the effect of tag drag on Antarctic fur seals (Arctocephalus gazella). They
glued additional false tags (cross sectional area of 21 cm2) onto lactating females and compared
these with a control group. Whilst there was a reduction in the mean swimming speed (from 1.23
to 0.98 m/s) the experimental females used no extra body reserves in foraging and there was no
difference in the pup growth rate compared with the control group.
However in laboratory experiments on a model, Wilson et al. (2004) suggested that the rigid
antennae of some types of penguin tag can lead to a five-fold decrease in penguin foraging
efficiency. The effect was reduced when the rigid antennae were replaced with (more modern)
flexible types.

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Telemetry techniques and harbour seal investigations
It is unwise to generalise too much from theses empirical findings. Different species (indeed
different age classes) will respond differently to carrying a telemetry tag of a given absolute (or
relative) size. A small, fast-moving animal will be effected more than a large slow-moving one.
5.4.2.2 Computer simulation
Pavlov (2007) used CFD to model the flow of water past a dolphin dorsal fin and then modified a tag
design to minimise drag. Hazencamp et al. (2010) used CFD to model the change in coefficient of
drag (Cd)4 of a satellite relay data logger tag on a grey seal. Cd is a dimensionless quantity that is
used to quantify the drag of an object in a fluid environment. They concluded that the increase in Cd
was about 12%. But, crucially, they did not relate this to increase in power requirements and
swimming budgets (Wilson & McMahon 2006). Their discussion of the biological consequences is
thus speculation. Furthermore we note that the tag model used in this study has now been
superseded by a smaller version.
5.4.3 Thermal balance
McCafferty et al. (2007) raised the possibility of tag attachment affecting thermal balance. However
from their studies on grey seal (Halichoerus grypus) they concluded that tags ‘will produce localised
effects on heat transfer in air but will not significantly change the total heat exchange of grey seals
on land or at sea‘.

6 Wind farm construction and harbour seal interaction
The proliferation of offshore wind farms raises the possibility of deleterious interactions with marine
life (Gill 2005). Whilst it is unlikely that the operational phase has significant effect on local harbour
seal behaviour (Edren et al. 2010; McConnell 2012), the acoustic energy generated by piling
operations during construction may have significant effect (Diederichs et al. 2008; Skeate, Perrow &
Gilroy 2012).

6.1 Telemetry techniques
For there to be any interactions it is necessary, though not sufficient, for disturbance and seals to
overlap both temporally and spatially. The intrinsic spatial basis of telemetry makes it the only
available tool.
Studies in relation to offshore wind energy are on-going in the UK. The importance of both
detecting biological effect and the development of appropriate mitigation systems is recognised by
the UK Department of Energy and Climate Change (DECC5) who have commissioned (2012) a major
harbour seal telemetry / audiometry study during nearby piling operations. In the past five years
DECC has also commissioned the tagging over 80 UK seals as an essential part of its maritime
Strategic Environmental Assessment6. Data from these seals filled in region al gaps in an extensive
UK telemetry database (> 200 seals) to estimate at-sea usage (Matthiopoulos et al. 2004) for grey
and harbour seals.
4

Coefficients of lift and pitching moment were also calculated. Comments of the consequence of C d apply also
to these parameters.
5
https://www.gov.uk/government/organisations/department-of-energy-climate-change
6
http://www.offshore-sea.org.uk/consultations/Offshore_Energy_SEA_2/index.php

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Telemetry techniques and harbour seal investigations
Telemetry techniques compliment other measurements. Seal population numbers are usually
assessed through a time series of aerial counts of seals hauled out on land. In this way trends of
population and abundance can be assessed. However, such techniques must be seen as a
compliment, rather than an alternative to the study of individual behaviour from telemetry studies
for the following reasons:

1. There may be a many drivers of population change (e.g. climate, prey availability,
disturbance and disease) and so attributing change to, say, renewable energy construction is
difficult. The use of space at sea by seals can indicate whether there is spatial overlap
between animals and the extent of a stressor. The extent of such overlap will aid
acceptance or rejection of a causal relationship. Note that the limited visibility of seals’
heads at sea, and thus low sighting rate, precludes ship-borne ‘distance’ survey methods to
quantitatively assess at-sea usage.
2. To assess the population size from haulout counts we need to know the proportion of time
spend hauled out ashore – the correction factor. This is usually derived from telemetry
studies (for example Ries, Hiby & Reijnders 1998).
3. If there are biological effects of construction noise, then the problem is then, which haulout
sites would we expect to be affected? Where would the signal appear? Telemetry provides
the crucial link between onshore abundance and off-shore distribution (Matthiopoulos et al.
2004).

6.2 Study types
In relation to offshore renewables there are two types of information that are generally required to
fulfil licencing requirements:
1. Baseline information on the presence, movements and behaviour of seals in the region of
interest.
2. Model changes in behaviour to relation to potential construction / operation stressors.
McConnell et al. (2012) provide an example of a telemetry study that investigated harbour seal
behaviour in relation to wind turbine activity in Denmark.
For baseline studies (1) it important that there is minimal effect of tagging on the parameters of
interest. However for the detection change ((2) before/after, or gradient) this assumption is not
strictly required since it is very unlikely any change of behaviour would be influenced by whether a
seal bears a tag. For example, it is unlikely that the degree to which an individual may react (e.g.
suspend its foraging activity) to nearby piling activity is affected by a tag.
For most telemetry studies the aim is to detect change in the behaviour in the population of animals.
We thus require a sufficient sample size of tagged individuals to provide statistical power. Tagging
an insufficient number of individual results in data which are anecdotal. The power analysis depends
upon the biological question posed, the variability between individuals, and the degree of a priori
knowledge.
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Telemetry techniques and harbour seal investigations

7 Discussion
Seal telemetry has developed and matured since its first use in the mid 1980’s. Capture and
handling techniques have become less invasive and more efficient – driven mainly by the cultivation
of experienced field teams. In parallel, telemetry tags themselves have reduced in size, whilst
functionality has increased. Whilst it is likely that these trends will continue, both physics and
information theory ultimately limit how much information can be obtained from a given size of tag.
Telemetry has a scientifically justified and established role in investigating both the natural history of
seals, and also interactions with potential anthropogenic stressors. To investigate the consequences
of renewable offshore developments – there is no alternative.
However, this does not absolve the researcher from their moral, scientific, and frequently legal,
obligation to minimise any threat to the target species. This obligation entails active responsibility to
quantify any credible telemetry effect. As such, there is a need for more published studies that
investigate the biological consequences (not just the physical consequences) of carrying a tag.
Indeed these studies should extend from proximate consequences through to individual fitness and
population consequences. However it would be misleading to suggest that the scientific community
is either unaware of, or unconcerned with, these issues (for example: Wilson & McMahon 2006;
McMahon et al. 2012; McMahon, Hindell & Harcourt 2012).
There is a growing scientific literature on the effects of tagging a variety of aquatic species. This has
been illustrated above with three examples. The two seal studies suggested minimal effect. Yet the
penguin study showed a significant effect. But it is not surprising that there is no one single result
since the studies encompass a large range of




species sizes and swimming speeds,
tag weights, shapes and attachment techniques, and
measurement metrics

Therefore the study should be based as closely as possible on the target species and tag. To this
extent the simulation study of Hazekamp et al (2010) is a valuable contribution. However their
extrapolation from physical drag coefficients to biological effects is unjustified. In summary, whilst
more studies should be encouraged, currently there is no evidence that tag devices on seals have
significant biological consequences.
It is important to be aware that the body shape of harbour seals changes seasonally. Being ‘capital
feeders’ they spend most of the year foraging to attain sufficient condition to give birth to a viable
pup and/or mate. During the breeding season, foraging is greatly reduced, and adults’ fat reserves
are rapidly depleted. Over a three week period a lactating female may lose 33 % (30 kg) of mass,
17% (16 kg) of its body fat (with consequential changes in density and thus buoyancy lift) and 32%
(92 cm2) of its cross-sectional area (Bowen, Oftedal & Boness 1992). A typical seal tag weighs
between 100 and 370 g and has a cross sectional area of 28 cm2. Typical figures for an adult prepartum harbour seal are 87kg and 295 cm2 respectively (Bowen, Oftedal & Boness 1992). It would
be naïve and misleading to infer just from these facts alone that the effect of a tag is within the
natural seasonal variation of an individual adult seal. For example, the drag effects are influenced by

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Telemetry techniques and harbour seal investigations
far more than just cross sectional area. However these figures do put the morphological alteration
due to tag attachment into a realistic perspective.
Biological systems are invariably complex. They are also often data sparse. Thus effects and
consequences are difficult to estimate with a reasonable degree of certainty. In terms of practical
wildlife science, a balance thus has to be achieved in an ‘uncertain’ world. On one hand, effort must
be (and is) directed to estimating the magnitude and consequences of tag effects. In an ideal world
this would precede large-scale data collection. In practice the two may continue in parallel and the
data obtained must carry any caveats regarding the effect of tagging, until such time as the issues
are clarified.
The issue is well articulated by McMahon et al. (2012) whose final paragraph is copied below:
‘At a time when science in general is being subject to unprecedented levels of
public scepticism, it is clear that as a society, we have moved beyond accepting
that the scientists/researchers know best. Now society demands that scientists
use evidence-based approaches when informing conservation and animal
welfare authorities about research methods. Ensuring that animal research is
allowed to continue is important because we are currently experiencing a
biodiversity crisis whereby species are being lost at alarmingly high rates.
Without research we cannot conserve the animals or the ecosystems on which
we all rely for our wellbeing. The challenge then is to bring the biological,
ethical and legal components of biodiversity conservation into some form of
jurisdictional harmony before the initiation of research projects that attempt to
address species declines. Providing the basic information to inform this debate
and to stimulate this debate publically must necessarily be a priority for wildlife
researchers‘.

8 References
Baker, J.D. & Johanos, T.C. (2002) Effects of research handling on the endangered Hawaiian monk
seal. Marine Mammal Science, 18, 500-512.
Bowen, W.D., Oftedal, O.T. & Boness, D.J. (1992) Mass and Energy Transfer during Lactation in a
Small Phocid, the Harbor Seal (Phoca vitulina). Physiological Zoology, 65, 844-866.
Boyd, I.L., McCafferty, D.J. & Walker, T.R. (1997) Variation in foraging effort by lactating Antarctic fur
seals: response to simulated increased foraging costs. Behavioral Ecology and Sociobiology,
40, 135-144.
Diederichs, A., G. Nehls, M. Dähne, S. Adler, S. Koschinski & Verfuß, U. (2008) Methodologies for
measuring and assessing potential changes in marine mammal behaviour, abundance or
distribution arising from the construction, operation and decommissioning of offshore
windfarms. . BioConsult SH report to COWRIE Ltd. .
Edren, S.M.C., Andersen, S.M., Teilmann, J., Carstensen, J., Harders, P.B., Dietz, R. & Miller, L.A.
(2010) The effect of a large Danish offshore wind farm on harbor and gray seal haul-out
behavior. Marine Mammal Science, 26, 614-634.
Fedak, M.A., Anderson, S.S. & Curry, M.G. (1983) Attachment of a radio tag to the fur of seals.
Journal of Zoology, 200, 298-300.

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Field, I.C., Harcourt, R.G., Boehme, L., Bruyn, P.J.N.d., Charrassin, J.-B., McMahon, C.R., Bester, M.N.,
Fedak, M.A. & Hindell, M.A. (2012) Refining instrument attachment on phocid seals. Marine
Mammal Science, 28, E325-E332.
Gill, A.B. (2005) Offshore renewable energy: ecological implications of generating electricity in the
coastal zone. Journal of Applied Ecology, 42, 605-615.
Harcourt, R.G., Turner, E., Hall, A., Waas, J.R. & Hindell, M. (2010) Effects of capture stress on freeranging, reproductively active male Weddell seals. Journal of Comparative Physiology aNeuroethology Sensory Neural and Behavioral Physiology, 196, 147-154.
Hazekamp, A.A.H., Mayer, R. & Osinga, N. (2010) Flow simulation along a seal: the impact of an
external device. European Journal of Wildlife Research, 56, 131-140.
Lonergan, M., Fedak, M. & McConnell, B. (2009) The effects of interpolation error and location
quality on animal track reconstruction. Marine Mammal Science, 25, 275-282.
Matthiopoulos, J., McConnell, B., Duck, C. & Fedak, M. (2004) Using satellite telemetry and aerial
counts to estimate space use by grey seals around the British Isles. Journal of Applied
Ecology, 41, 476-491.
McCafferty, D.J., Currie, J. & Sparling, C.E. (2007) The effect of instrument attachment on the surface
temperature of juvenile grey seals (Halichoerus grypus) as measured by infrared
thermography. Deep-Sea Research Part Ii-Topical Studies in Oceanography, 54, 424-436.
McConnell, B., Fedak, M., Hooker, S.K. & Patterson, T. (2010) Telemetry. Marine Mammal Ecology
and Conservation (eds I.L. Boyd, W.D. Bowen & S.J. Iverson), pp. 222-262. Oxford University
Press, Oxford.
McConnell, B., Lonergan, M., Dietz, R. (2012) Interactions between seals and offshore wind farms.
pp. 41. The Crown Estates.
McMahon, C.R., Field, I.C., Bradshaw, C.J.A., White, G.C. & Hindell, M.A. (2008) Tracking and datalogging devices attached to elephant seals do not affect individual mass gain or survival.
Journal of Experimental Marine Biology and Ecology, 360, 71-77.
McMahon, C.R., Harcourt, R., Bateson, P. & Hindell, M.A. (2012) Animal welfare and decision making
in wildlife research. Biological Conservation, 153, 254-256.
McMahon, C.R., Hindell, M.A. & Harcourt, R.G. (2012) Publish or perish: why it's important to
publicise how, and if, research activities affect animals. Wildlife Research, 39, 375-377.
Pavlov, V.V., Wilson, R.P. & Lucke, K. (2007) A new approach to tag design in dolphin telemetry:
Computer simulations to minimise deleterious effects. Deep-Sea Research Part Ii-Topical
Studies in Oceanography, 54, 404-414.
Ries, E.H., Hiby, L.R. & Reijnders, P.J.H. (1998) Maximum likelihood population size estimation of
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