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CONTRACT
NO. HY/2012/07
Tuen
Mun – Chek Lap Kok Link (Southern Connection Viaduct Section)
Impact
Monitoring Report for Land-based Dolphin Behavioural and Movement Monitoring
Prepared by Hong Kong Cetacean
Research Project
(Professor Bernd Würsig,
Dr. David Lundquist and Dr. Samuel Hung)
1.
INTRODUCTION
The Tuen Mun-Chek Lap Kok Link (TM-CLKL)
comprises a 1.6 km long dual 2-lane viaduct section between the Hong Kong
Boundary Crossing Facilities (HKBCF) and the
According to the TM-CLKL EM&A
Manual, a number of environmental monitoring and audit (EM&A) works related
to Chinese white dolphins (a.k.a Indo-Pacific
humpback dolphins, Sousa chinensis) are
to be conducted during baseline, construction and post-construction phases,
including land-based dolphin behavioural and movement monitoring, to record and
note any changes in response of dolphins to the bored piling noise. Such monitoring is being undertaken by
qualified dolphin specialists, who have sufficient relevant post-graduate
experience and publication in the respective aspects. The specialists approved for the
land-based works are Professor Bernd Würsig and Dr. David Lundquist.
This construction monitoring report of
land-based dolphin behaviour and movement monitoring details the methodology
and results, from March 3rd to
2.
METHODS AND MATERIALS
2.1. Monitoring
Location – Pak Mong Station
To conduct the land-based
monitoring on dolphin behaviour and movement near the alignment of TM-CLKL,
HKCRP research team set up a theodolite-tracking station at Pak Mong near Tai Ho Wan in August 2013 with the assistance of
Professor Bernd Würsig and Ms. Sarah Piwetz, following the same methodology
that was used to set up other well-established theodolite tracking stations in
Hong Kong since 2011 (Hung 2012, 2013; Piwetz et al. 2012).
The Pak Mong
station near Tai Ho Wan is located near the northeast coast of Lantau Island
(GPS position: 22o17.86’ N and 113o57.98’
E; Figure 1). The station was selected based on its
height above sea level (minimum requirement of over 20 m; Würsig et al. 1991),
close proximity to shore, and relatively unobstructed views of the TM-CLKL
alignment (see panoramic view from the station in Figure 2). The height of Pak Mong
station established by HKCRP team is 24.88 m high at mean low water (or 24.73 m
relative to mPD) and 170 m from shore. Moreover, the station is only situated 650-780
m from the six bored piling sites of TM-CLKL southern viaduct section that will
be monitored during the present study (i.e. Piers B1-3, B5-7; Figure 1), which is ideal for the purpose of the present
behavioural and movement monitoring in relation to the TM-CLKL bored piling
works. This is the same station
used in the baseline phase of land-based monitoring of TM-CLKL.
2.2. Monitoring
Methodology
The methodology
of the present monitoring programme generally followed the one established
under the Piwetz et al. 2012 study, which was also part of the AFCD long-term
marine mammal monitoring programme (Hung 2012, 2013). On each survey day, observers searched systematically
for Chinese white dolphins using the unaided eye and handheld binoculars (7 x
50) from the Pak Mong Station, overlooking the viaduct
alignment to the northeast coast of Lantau Island, in particular the area
around the six bored pile sites as indicated in Figure 1. Notably, all six bored piling sites were
monitored during baseline phase, while three of these six sites (B1, B2 and B3)
were chosen for construction phase monitoring.
A theodolite tracking
session was initiated when an individual dolphin or group of dolphins was
located, and focal follow methods were used to track the dolphins. Within a group, a focal individual was
selected for the purposes of tracking the behaviour and movement of the group,
based on its distinctive feature such as colouration or severe injury
mark. The focal individual would
then be tracked continuously via the theodolite, with positions recorded
whenever the dolphin surfaces. If
an individual could not be positively distinguished from other members, the
group would be tracked by recording positions based on a central point within
the group when the dolphins surfaced.
Tracking continued until
animals were lost from view, moved beyond the range of reliable visibility
(>5 km), or when environmental conditions obstructed visibility (e.g.
intense haze). Behavioural state
data (Table 1) were also recorded every 5 minutes for
the focal individual or group. This interval is long enough to allow
for determination of the behavioural state, and short enough to capture
behavioural responses to the bored piling activities.
Moreover, when multiple groups or
individuals were present in the study
area, attempts were made to record the behaviours
of all groups/individuals every 10 minutes, with spotters assisting in
determining behaviour of the dolphins.
Positions
of dolphins, boats and construction activities were measured using a Sokkisha
DT5 digital theodolite with ± 5-sec precision and 30-power magnification
connected to a laptop computer running the program Pythagoras Version 1.2 (Gailey and Ortega-Ortiz 2002). This program calculates a real-time
conversion of horizontal and vertical angles collected by the theodolite into
geographic positions of latitude and longitude each time a fix is
initiated. Pythagoras also displays positions, movements, and distances in
real-time. When possible, the
position of the focal dolphin was recorded at every surfacing with use of Pythagoras. The position, type, and activity of all
vessels within 5 km of the focal dolphin were also recorded. An effort was made to obtain at least
several positions for each vessel, and additional positions were acquired when
vessels changed course or speed.
While
the primary source of human disturbance to dolphins of interest in this study
is bored piling works for the TM-CLKL Project, the presence of vessels may also
have an effect on the behaviour and movement patterns of dolphins. In the baseline phase the HKCRP research
team simultaneously tracked dolphins and boats over time to provide information
on the speed and orientation of dolphins, as well as their movements in
relation to vessel activities. This
data was intended to be used as a baseline for comparison during construction,
but unfortunately too few dolphin groups were seen to properly quantify these
responses. Other construction activities and
vessel movements in relation to the bored piling works were recorded during the
construction phase monitoring, and the same theodolite tracking and behavioural
procedures were followed as during baseline phase.
2.3. Data
Analysis
2.3.1. Assessment
on potential impacts from bored piling activities
To
evaluate if dolphin behaviour or movement patterns varied in the presence of
vessels in the construction phase, it was necessary to determine how many
vessels were present with the focal group at any time. A vessel was considered to be present
with the focal dolphin when the two were within 500 metres of each other. Data
recorded in Pythagoras was used to
calculate dolphin and vessel positions in latitude and longitude for this
comparison. Tracks were required to
have a minimum duration of 10 min. to be included in the analysis. If two consecutive fixes in a track for
one dolphin were more than 300 seconds apart, the track was be split at this
point and analysed separately.
Dolphin and vessel positions were be interpolated every 150 seconds,
assuming linear travel at a constant speed between subsequent positions. Distance between the focal
individual/group and each vessel was calculated to determine how many vessels were
within 500 metres of the group at each point in time.
Using the above calculations, the maximum number
and type of vessels present was calculated for each track. Response
variables, including mean leg speed, mean inter-breath interval, reorientation
rate and linearity, were calculated for each track. These response variables have been
commonly used by many researchers, including the dolphin specialists of the
present project (Lundquist et al. 2012a; Lundquist 2012; Lundquist and
Markowitz 2009). Leg speed (km/hr)
is the displacement between two successive points divided by the time
interval. Inter-breath interval (s)
is the length of time between successive surfacings. Reorientation rate (˚/surfacing) is a
measure of how much the group changed course over time. It is calculated as the sum of the
absolute values of heading changes (defined as 0 to 180 degrees relative to the
current bearing) divided by the number of surfacings in the track. Linearity is a dimensionless index
ranging from 0 (no net movement) to 1 (straight line). It is calculated by dividing net
distance from the first to last fix of a track by the sum of all the distances
for each leg.
The statistical technique originally proposed to be
used in comparison of baseline and construction phase monitoring data
(Generalized Additive Modelling) could not be used because there were few
dolphin groups spotted during the baseline phase and no dolphin groups spotted
during the construction phase.
Instead, data on vessel traffic is presented here and the potential
implications for dolphins discussed.
3. RESULTS
3.1. Summary
of Theodolite Tracking Effort
A total of 180 hours and 43 minutes
were spent during the 30 days of impact phase monitoring effort from March 3rd
through
During this 30-day construction phase
monitoring period, no dolphin groups were sighted
or tracked. On
the other hand, a total of 5,725 vessels of
18 different types were tracked (see Figure 3), with the majority being transportation vessels and
construction boats servicing the TM-CLKL, HKBCF and HKLR construction sites (Table 2). Vessels observed in the study area were
typically travelling (88% of observations) or stationary (11% of
observations). All data included in
these analyses are presented in Appendix II.
3.2. Movement
patterns and behavioural state
No dolphin groups were tracked during the construction phase monitoring,
so this analysis was not possible.
4.
DISCUSSION
While it was not possible to
statistically analyse the movement patterns of dolphin groups in this area due
to the absence of sightings, a general comparison can be made to numbers
reported during baseline monitoring and the
There was an
88% increase in vessel traffic in the project area during the construction
phase compared to the baseline phase (5725 vessels vs. 3053 vessels), mostly
attributable to construction traffic.
Based on the results of the HKLR09 project, it is expected that the
presence of so many more vessels would affect the movement and behaviour of any
dolphins in the study area, but it is not possible to determine whether this
increase in vessel traffic resulted in no dolphins being seen during
construction monitoring.
From the
results presented here, it is clear that the study area is not frequently used
by dolphins. In fact, there are
multiple lines of evidence to support that dolphins rarely occur in the area near
TM-CLKL bridge alignment in the past and present:
1) Review
of HKCRP long-term monitoring data on Chinese white dolphins indicated that
very few dolphins have occurred in this area in the past. Out of the 927 dolphin sightings made in
NEL during 2002-2013, fewer than 10 groups were sighted in the proximity to the
bridge alignment (Figure 4).
2) Under
the same bored piling monitoring programme for the TM-CLKL, concurrent
intensive surveys were conducted to examine dolphin acoustic behaviours in NEL
area between March 3rd and
3) For
the same bored piling monitoring programme, passive acoustic monitoring was
also conducted to detect dolphin presence 24 hours a day, by deploying an Ecological
Acoustic Recorder (EAR) adjacent to the bridge alignment from March 5th
and
In summary,
dolphins rarely occur along or near the TM-CLKL bridge alignment in the past
and present, which may be related to the high level of vessel movements. If this area has a naturally low density
of dolphins, then the overall effect of construction activities on dolphins is
likely to be low, which confirm the prediction from the original EIA study for
the TM-CLKL.
5. EVENT
AND ACTION PLAN
According to Section 6.5 of the
EM&A Manual, the Action and Limit Levels as well as the Event and Action Plan
(EAP) for ecology shall be proposed upon the baseline monitoring data, and
agreed by AFCD and EPD. Similar to
the HKLR09 bored piling monitoring programme, the response variables for
dolphin movement patterns (i.e. mean leg speed, mean inter-breath interval,
reorientation rate and linearity) and dolphin behaviours (five different
behavioural states) should be assessed under the EAP, and these variables should
be recorded during both baseline and construction phase monitoring works. Departures of any of these variables between
baseline and construction phases by a certain percentage of difference would
trigger the Action and Limit Levels.
However, due to the paucity of dolphin
sightings and the availability of a single track for analysis from the baseline
shore-based theodolite tracking works, it was impossible to reliably establish
the baseline values for the various response variables. Moreover, as dolphins rarely occur in
this area as discussed in Section 4, it is not unexpected that rare occurrence
of dolphins has persisted during the construction phase of the TM-CLKL
project. Without appropriate
baseline information established for the behaviour and movement of Chinese
white dolphins, it was decided that EAP could not be properly implemented for
the shore-based theodolite tracking study, and therefore would rely on the implementation
of EAP on dolphin acoustic behaviour to safeguard dolphins from the potential
impacts of the bored piling works.
Nevertheless, it is important to conduct the post-construction phase
monitoring on behaviour and movements of Chinese white dolphins through
shore-based theodolite tracking, to confirm that they were not seriously
affected by the construction works.
6. REFERENCES
Bain, D.E., R. Williams, J.C. Smith, and D. Lusseau. 2006. Effects of vessels on the behavior
of southern resident killer whales (Orcinus
spp.) 2003-2005.
NMFS contract report AB133F05SE3965. 65pp.
Gailey, G. A. and
Ortega-Ortiz J. 2002. A note on a computer-based system for theodolite
tracking of cetaceans. Journal of
Cetacean Research and Management 4: 213-218.
Hung, S. K. 2012. Monitoring of Marine Mammals in Hong Kong
waters: final report (2011-12). An unpublished report submitted to the Agriculture,
Fisheries and Conservation Department, 171 pp.
Hung, S. K. 2013. Monitoring of Marine Mammals in Hong
Kong waters: final report (2012-13).
An unpublished report submitted to the
Agriculture, Fisheries and Conservation Department, 168 pp.
Lundquist, D. 2012. Behaviour and movement patterns of
dusky dolphins (Lagenorhynchus obscurus)
off Kaikoura, New Zealand: Effects of tourism. Ph.D. Thesis,
Lundquist, D., Sironi, M., Würsig,
B., Rowntree, V., Martino, J. and Lundquist, L. 2012a. Response of southern right whales
to simulated swim-with-whale tourism at Península Valdés, Argentina. Marine Mammal Science. DOI:
10.1111/j.1748-7692.2012.00583.x
Lundquist,
D., Gemmell, N. and Würsig, B.
2012b.
Behavioural responses of dusky dolphin groups to tour vessels off
Lundquist,
D.J. and Markowitz, T. M. 2009. Effects of tourism on behaviour and
movement patterns of dusky dolphin groups monitored from shore stations. Pp 9-22 in T.M. Markowitz, S. DuFresne, and B.
Würsig (eds.) Tourism effects on dusky dolphins at
Lusseau, D. 2003. Effects of tour boats on the behavior of
bottlenose dolphins: using Markov chains to model anthropogenic impacts. Conservation Biology 17:1785-1793.
Piwetz, S., Hung, S. K., Wang J. Y.,
Lundquist, D. and Würsig, B.
2012. Influence of vessel traffic
on movements of Indo-Pacific humpback dolphins (Sousa chinensis) off
Würsig, B., Cipriano, F.,
and Würsig, M. 1991. Dolphin movement patterns: Information
from radio and theodolite tracking studies. In: K. Pryor and K. S. Norris (editors),
Dolphin Societies: Discoveries and Puzzles, pp. 79-112,
Table 1. Definitions of
group behavioural states of dolphins.
|
State |
Definition |
|
Resting |
Dolphins close to the
surface and each other, surfacing at regular intervals and in a coordinated
fashion. Movement very slow. |
|
Traveling |
All individuals oriented
and moving in the same direction.
This behavioural state includes all high-speed, directional behaviours
(e.g. porpoising). |
|
Milling |
Individuals within the
group simultaneously moving in different directions, with no overall clear
direction of travel. |
|
Socialising |
Physical interactions
taking place among members of the group, including chasing, high levels of
body contact, coordinated clean leaps and noisy leaps. |
|
Feeding |
Dolphins observed either
capturing or pursuing fish at the surface. High number of non-coordinated
re-entry leaps, rapid changes in direction and long dives. Dolphin rostrum or body covered with
mud. Associations with operating
fishing boats. |
Table 2. Number and type of vessels
tracked in study area.
|
Vessel Type |
Count |
|
Construction
Boat |
1074 |
|
Construction
Platform |
15 |
|
Container
Boat |
97 |
|
Fishing
Boat |
39 |
|
Fuel
Boat |
14 |
|
Government
Boat |
86 |
|
Guide
Boat |
4 |
|
HSF
High Speed Ferry |
152 |
|
Marine
Department Boat |
3 |
|
Research
Vessel |
43 |
|
Sand
barge |
247 |
|
Speed
Boat |
194 |
|
Survey
Boat |
32 |
|
Tour Boat |
15 |
|
Transportation
Boat* |
3332 |
|
Tug
Boat |
374 |
|
Waterboat |
1 |
|
Yacht |
3 |
|
|
|
|
TOTAL |
5725 |
* Transportation boats denote the one that
carry passengers to and from the construction sites of TM-CLKL/HKBCF/HKLR03 and
Tung Chung Public Pier, as well as the regular ferries that serve between Tung
Chung and Tune Mun
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