Dolphin/Porpoise Sighting Sheet
A baseline marine mammal survey is required
to be conducted before marine construction works for the Permanent Aviation
Fuel Facility commence in accordance with the Environmental Permit
(EP-139/2002/A). The baseline survey was
conducted within 28 days of the construction works. Six, one-day surveys were conducted between
27th October and 1st November 2005. During the surveys, only one type of marine
mammal, the Indo-Pacific Humpback Dolphin (Sousa
chinensis) or Chinese White Dolphin was observed. Sightings occurred
throughout the entire survey area; however, more sightings occurred towards the
north of the Sha Chau and
Contents
1.3 Structure of the Document 2
2 Review
of Baseline Conditions 3
3 Pre-Construction
Survey Methodology and Results 7
4 Conclusion 15
LIST OF TABLES
Table 3.1 Age Classes of Sousa chinensis
Table 3.3 of Dolphin Baseline Survey between 27 October and 1 November 2005
Table 3.4 Age Class of Identified Sousa chinensis Individuals
LIST OF ANNEXES
Annex A Dolphin/Porpoise Sighting Sheet
A Permanent Aviation Fuel Facility (PAFF) is required to ensure a secure means to supply aviation fuel during the operational lifetime of the Hong Kong International Airport (HKIA). The PAFF will eliminate operations at the existing Aviation Fuel Receiving Facility (AFRF) adjacent to Sha Chau and provide the supply to the HKIA. The PAFF must meet the capacity demand for the 2040 planning horizon of the HKIA and must be able to provide the required strategic storage and quality controls. The Airport Authority Hong Kong (AAHK) is committed to expediting the permanent facility, after which the Sha Chau facility will be used for emergency backup purposes only.
The potential environmental impacts of the
Project have been studied in the Environmental Impact Assessment (EIA) Report “Permanent Aviation Fuel Facility for
ERM-Hong Kong, Ltd (ERM) has been
commissioned by Leighton Contractors (
As part of the EM&A programme, pre- and post-construction phase dolphin monitoring are required to evaluate whether there have been any effects on the animals as a result of the construction works. Prior to the commencement of construction works a review of all new available dolphin data for North Lantau waters should be conducted and reported. This report presents the review of baseline conditions and the results of the pre-construction phase dolphin monitoring.
Following this introductory sections, the remainder of the report is presented as follows:
·
Section 2 presents the review of
available dolphin data for
· Section 3 presents the methodology and results of the pre-construction phase dolphin monitoring; and,
· Section 4 presents the summary and conclusions.
This Section
presents a review of all new available dolphin data for
A total of 16 (and possibly up to 18)
species of marine mammals, or cetaceans, have been recorded in Hong Kong waters
(
The distribution, abundance, habitat use, and life history of Indo-Pacific Humpback Dolphins in Hong Kong has been extensively studied since 1995 ([2])(4). The distribution and abundance of dolphins has been studied using line transect methods allowing any patterns to be determined. As sightings are obtained relative to known levels of search effort, corresponding densities have been obtained.
The line transect analysis of vessel
surveys undertaken from 1995 to 2004 for the Indo-Pacific Humpback Dolphin
Monitoring Programme showed that the abundance of dolphins is highest in the
North Lantau area in all four seasons Figure 2.1. North Lantau and West Lantau are considered
to be the major habitats for humpback dolphins in Hong Kong waters where
individuals of humpback dolphins have been consistently recorded throughout the
year in
In spring, almost all sightings of the
Indo-Pacific Humpback Dolphins in Hong Kong have been made in North Lantau with
a seasonal influx of individuals into South Lantau (and to a lesser extent,
Indo-Pacific Humpback Dolphins are present in Hong Kong waters with high densities in summer, autumn and winter and lowest in spring ([4]) ([5]). The proportion of the local population that utilize the North Lantau waters as opposed to other areas of Hong Kong varies from 72% in spring to 92% in winter when the abundance of Indo-Pacific Humpback Dolphins occurring in Hong Kong waters is at its lowest ([6]).
According to data from the Agriculture,
Fisheries and Conservation Department, which has been collected between 1995
and 2004, it appears that the use of waters by Indo-Pacific Humpback Dolphins
within the Study Area is not uniform (Figure 2.2 and Figure 2.3). In all four seasons, Indo-Pacific Humpback
Dolphins are most abundant in the western waters between Castle Peak and Black Point
in the east and the islands of Sha Chau and Lung Kwu Chau in the west. High densities have also been recorded in
areas to the north of the airport especially near the northeast corner and
around the
The exact status of the
Studies have also revealed several areas of
very low Indo-Pacific Humpback Dolphin density in the
This Section presents the methodology and results of the pre-construction phase dolphin monitoring.
Line transect surveying techniques have now been standardised in Hong Kong Special Administrative Region Waters so that data from all surveys are directly comparable. The study area with line transects is presented in Figure 3.1. In order to provide a suitable long-term dataset for comparison, pre-and post construction phase dolphin monitoring will employ an identical methodology and follow the same line transects as those presented in Figure 3.1.
On each survey day, the survey vessel departed from Tung Chung New Pier. Observation for incidental sighting began immediately on departure from the assigned pier and continued until the vessel reached the survey area.
The survey vessel had an open upper deck, allowing for observer eye heights of 4 to 5m above water level and relatively unobstructed forward visibility between 270° and 90°. When on-effort, the vessel travelled along the survey lines at a speed of approximately 7 to 8 knots (13 to 15 km/hr). The direction of the survey was alternated on different days to avoid possible biases related to the timing of the survey coverage.
Vessel-based transect observations by a three-person team were conducted by searching the 180° swath in front of the survey vessel (270° to 90°). The area behind the vessel was not searched, although dolphins observed here were recorded as off-effort sightings. A primary observer scanned the entire search path (270° to 90°) continuously with Fujinon 7X50 marine binoculars or equivalent as the second member of the team, designated the data “recorder”, scanned the same area with the naked eye and occasional binocular check. The third observer on the boat rotated into the observation team after half an hour, thus relieving one of the initial team. Observers rotated every half an hour. While on-effort, observers were instructed to ignore potential sighting cues that could bias the sighting distance calibration (eg pair-trawl fishing vessels).
A critical consideration in the survey was to ensure a strict timed quantification of “sighting effort” in order to maximise the comparative value of the field survey results. The time and position for the start and end of a period of intensive, uninterrupted effort, and the sighting conditions such as visibility range and Beaufort scale associated with it were recorded. The collection of effort data allowed comparisons within a single study as well as between studies. Strict recording of time and speed travelling along the assigned transect (“on-effort”) was always therefore recorded. Time spent during any deviation from the transect was recorded as “off-effort”.
During periods of poor weather, when visibility is hindered (eg below 1km) or when Beaufort force 5 is reached, the survey would normally be postponed. Such conditions did not occur during the survey.
Sightings distant to 500m perpendicular distance and sightings of single dolphins that were hard to track were not pursued (although those distant to 500m ahead of the vessel were pursued). The initial sighting distance between the dolphin and the survey vessel and sighting angle was recorded in order to estimate the positions of the dolphins. These and other details of the sighting, include the exact location of the sighting, number of individuals were on every occasion discussed among the observation team and recorded immediately. Distances and angles were made as accurately as possible.
A global positioning system was available on board and used during every field survey. A sighting record was filled out at the initial sighting with time, position, distance and angle data filled in immediately and verified between primary observer and recorder. All other information on sea state, weather conditions (Beaufort Scale), as well as notes on dolphin appearance, behaviour, and any other information were completed at the end of the sighting.
The locations of all marine mammals – dolphin and porpoise sighted during the surveys were recorded on a data sheet (Annex A). The species and number of marine mammals, number of sightings and age classes (where possible) were recorded, together with observed behaviours at the times of sightings. The data sheet also included dolphin and boat associations (if any) during the sightings.
Only the Indo-Pacific Humpback Dolphin, which is distinguished by its wide-based, slightly falcate dorsal fin, located at mid-back, was observed during the surveys. Humpback dolphins have a long, slender rostrum, with a shallow groove between the melon and the beak. Adults are white to pink in colour, and often have a variable degree of black spotting or mottling.
Age class of humpback dolphins was identified in accordance with the six age classes ([9]). The classification of their age class was mainly based on their body size and length, skin colouring pattern, and density of spotting. Their skin colour pattern changes dramatically throughout their lifespan, whitening increases as age increases. The spot patterns on juveniles and sub-adults disappear gradually as they get older, as presented in Table 3.1.
Table 3.1 Age Classes of Sousa chinensis
|
Age Class |
Body Length (m) |
Colour Pattern |
Spotted Pattern |
Behaviour |
|
Unspotted Calf (UC) |
1 m to 1.3 m (approximately half length of adults); up to 6-8 months of age |
Uniform black to dark gray |
No spots |
Swim dependently of adult, presumably the mother |
|
Unspotted Juvenile (UJ) |
Approximately 1.5 m to 2 m (two-third of the adult length) |
Uniform light gray |
No spots |
Occur in the vicinity of adults |
|
Mottled (SJ) |
Approximately similar length as SAs and UAs |
Light pinkish grey |
Heaving spotting |
Same as SAs and UAs |
|
Speckled (SS) |
With same size as SAs and UAs |
Pale pink to white |
Less spotting pattern than SJ |
Full independence of movement and association; hard to distinguish from SA |
|
Spotted Adult (SA) |
Same as SS |
Purely pink to white |
Less spotting pattern than SJ |
Same as SSs |
|
Unspotted Adult (UA) |
Up to 2.6 m |
Purely pink to white |
Essentially no spotting pattern but may have a few tiny spotting |
Same as SAs and SSs |
Marine mammals exhibit certain behaviour and for the humpback dolphins this has been previously characterised based on ongoing studies. These are presented in Table 3.2.
Table 3.2 A Summary and Description of Specific Types of Behaviour and Activities exhibited by Indo-Pacific Humpback Dolphin Sousa chinensis
|
Type of Social Behaviours and Activities |
Descriptions |
|
Activities |
|
|
Travelling |
Directional motion,
swimming fast, taking regular breaths on water surface. |
|
Feeding |
Long jumping and high-speed
chasing while hunting fish; On sea surface, swimming slowly rising
intermittently before commencing the next dive. They may display certain behaviours such as
feeding rushes, fish whacking, carousels, and fluking dives. |
|
|
|
|
Milling/Resting |
Remaining in one area
without any sign of feeding or social interaction; move slowly with a
drifting or gliding motion, rising slowly, or breathing while circling over
the same area. |
|
Socializing |
Extensive bodily contact,
inverted swimming, somersaulting, leaping and chasing with aerial activity;
group activities centred on animate or inanimate objects; two to three
individuals form a group. |
|
|
|
|
Breaching |
A behavioural pattern also
known as body slamming or a ‘log’ jump.
The animal rises out of the water at an angle between 90° to 45° to the sea surface.
When exiting the water the dolphin’s flippers, its abdomen or peduncle
may clear the surface. |
|
Spyhopping |
Raising the head vertically
out of the water, then sinking below the water without a splash. Used to check an area for hazards. |
|
|
|
|
Porpoising |
Fast, shallow, arching
leaps with the dolphin coming either partially or entirely out of the
water. It was only observed when the
dolphins were boat chasing and allows the animals to combine shallow dives
for fish with a fast rate of travel.
The adults will show noticeable colour changes, turning from white to
a deep pink. This is probably due to
vascular dilation in the blubber layer and is, possibly, a flush response to
prevent overheating. |
|
|
|
There were 38 sighting records of humpback dolphins (a total of 109 individuals), and no sighting records of finless porpoise reported during the surveys. Daily records of marine mammal sightings are presented in Table 3.3. The locations of sightings were plotted and presented in Figure 3.4.
Table 3.3 Results of Dolphin Baseline Survey between 27 October and 1 November 2005
|
Date |
Number of Sightings |
Total Number of Individuals |
|
27 October 2005 |
5 |
16 |
|
28 October 2005 |
11 |
36 |
|
29 October 2005 |
3 |
4 |
|
30 October 2005 |
7 |
17 |
|
31 October 2005 |
9 |
25 |
|
1 November 2005 |
3 |
11 |
Humpback dolphins were recorded in all survey days and at different areas of the transect lines, including off shore of Black Point, Sha Chau and Lung Kwu Chau Marine Park and near the Airport platform. The majority of dolphin sightings were recorded towards the north of Lung Kwu Chau.
Effort sightings and number of individuals of marine mammals are presented in Figures 3.2 and 3.3, respectively.
The number of sightings per survey day varied from a minimum of 3 to a maximum of 11 over the entire survey period. The number of individuals ranged from 1 individual to a group size of 8 individuals, however, the majority (over 55%) were in group sizes of 1 to 2 individuals.
Dolphins of all age classes were observed during the survey. For those which could be identified with age classes, the majority of humpback dolphins recorded were identified as Spotted Adults (SA) (27 individuals), Mottled (SJ) (22 individuals) Speckled (SS) (14 individuals), Unspotted Adults (UA) (6 individuals), Unspotted Juvenile (UJ) (3 individuals) and Unspotted Calf (UC) (6 individuals), as presented in Table 3.4.
Table 3.4 Age Class of Identified Sousa chinensis Individuals
|
Date |
Unspotted Calf (UC) |
Unspotted Juvenile (UJ) |
Mottled (SJ) |
Speckled (SS) |
Spotted Adult (SA) |
Unspotted Adult (UA) |
|
27 Oct 2005 |
0 |
1 |
3 |
1 |
4 |
1 |
|
28 Oct 2005 |
1 |
0 |
13 |
3 |
6 |
4 |
|
29 Oct 2005 |
0 |
0 |
0 |
1 |
1 |
0 |
|
30 Oct 2005 |
0 |
1 |
2 |
3 |
5 |
0 |
|
31 Oct 2005 |
4 |
1 |
3 |
3 |
6 |
0 |
|
1 Nov 2005 |
1 |
0 |
1 |
3 |
5 |
1 |
Breaching, Spy-hopping, Feeding, Porpoising and Socialising activities were observed from the sightings. Only 2 sightings had association with shrimp trawlers. No other boat associations were observed during the survey.
This report presents a review of available
dolphin data for
The Indo-Pacific Humpback Dolphin (Sousa chinensis) was the only marine mammal observed during the survey. Sightings were observed on all survey days and were throughout the entire survey area, however, size groups tended to be small. All age classes of humpback dolphins were recorded including calves.
The information presented within this report, along with the data to be collected during the post-construction phase dolphin monitoring, will allow the assessment of the overall efficiency of the project-specific mitigation measures. It is recommended that further monitoring be conducted if the results of dolphin sighting/population from post-construction phase dolphin monitoring is significantly lower than the results from this baseline (pre-construction phase) monitoring. Monitoring should be conducted in a manner that is consistent with the pre- and post-construction phase monitoring to allow direct comparison of results.
([1]) Jefferson TA, Hung SK, Law I,
Torey M and Tregenza N (2002) Distribution and abundance of finless porpoises
in Hong Kong and adjacent waters of China. Raffles Bulletin of Zoology
Supplement 10:43-55.
(2) Jefferson TA (2002) Monitoring of
Indo-Pacific Humpback Dolphins (Sousa chinensis) in Hong Kong waters.
Final Report. For the Agriculture,
Fisheries and Conservation Department,
(3) Jefferson TA (2000) Population
biology of the Indo-Pacific Humpback dolphin in
(4) Jefferson
TA and SK Hung (2004) A review of the status of the Indo-Pacific humpback
dolphin (Sousa chinensis) in Chinese waters. Aquatic Mammals. 30:149-158