1.1.5
To fulfil the abovementioned FEP
conditions,
a “Revised Translocation Proposal for the Endemic Freshwater Crab Somanniathelphusa
zanklon” (NENTX-FUG-RP-E-EM-I01
Revised Translocation Proposal) (the “Proposal”) was prepared and agreed upon
with EPD and Agriculture, Fisheries and Conservation
Department (AFCD).
1.1.6
The
NENTX Design-Build-Operate (DBO) Contractor (the Contractor), on behalf of
EPD/LDG, will be responsible for carrying out the capture surveys and
translocation works in accordance with the Proposal.
1.2.1
This
Translocation Report for the Endemic Freshwater Crab Somanniathelphusa
zanklon (the “Report”) was prepared to detail the findings of the capture
and translocation activities in fulfilment of FEP conditions 2.6 and 2.8 and as
basis to fulfil these aforementioned FEP conditions in addition to EIA Report
Approval Condition no. 4 for the post-translocation monitoring of the
translocated endemic freshwater crab S. zanklon
community in the recipient site.
§
Section 2 details the
methodology of the capture-translocation activities;
§
Section 3 details the survey
results of the capture-translocation activities;
§
Section 4 presents the summary
and conclusion; and
§
Section 5 details the post-translocation
monitoring programme.
2.1.2
Further,
the methodology was in accordance with the approved Proposal..
2.4.1.1
The capture-translocation activities were
conducted in a period close to the actual commencement of the works that affect
the concerned watercourses(s). It started
no earlier than one month prior to the commencement of site clearance works,
with the last day of the capture no earlier than one week before the
commencement of site clearance works. This is to avoid the recolonization of
other S. zanklon individuals in the concerned watercourse(s) after the
capture survey. Site clearance works at the concerned watercourses(s) commenced
last 27 July 2022 (upstream section) and 30 July 2022 (downstream section).
2.4.1.2
The capture-translocation activities were
conducted during wet season when the crabs are more active (Black & Veatch,
2020). Where possible, the activities were conducted at time with lower surface
water, i.e. avoiding period of heavy rainfall and/ or during period of lower
rainfall. The lower surface water in watercourse allowed surveyors to maximise
the survey extent for the translocation survey.
Each translocation survey was conducted in both day time and night time
during the capture-translocation period.
2.4.1.3
Standard survey methodology for aquatic
fauna, including active searching by hand netting and kick sampling was adopted
to search for the presence of S. zanklon. In addition, direct observation was also
conducted along the stream riparian zone, where potential hiding space (e.g.
under rocks and fallen tree branches) will also be checked to search for S.
zanklon. Permit under Cap. 170 was obtained from AFCD before the use of
nets to collect freshwater fauna in the streams (Appendix C).
2.4.1.4
All S. zanklon individuals caught
during the capture-translocation activities were recorded and photographed on
site. The surveyor recorded the individual’s size (see Photo 2.1), sex (see Photo 2.2) and
any other observation such as injuries.
The capture-translocation activities were conducted for at least three
times until new individuals of S. zanklon are not discovered within the
watercourse sections of collection.
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Photo 2.1:
Size measurement of the captured Somanniathelphusa
zanklon individual
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Photo 2.2:
Sex determination of the captured Somanniathelphusa
zanklon individual
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2.4.2.1
Hand netting (see Photo 2.3) was used as a quick search at potential habitats along the
watercourse. As most aquatic species spend majority of their time amongst
vegetation, leaf litter or on the bottom of water body, hand netting was aimed
in these areas. The sweeping motion of the hand netting scraped the layer of
the stream bottom substrate into the net, e.g. soil and leaf litter where
possible, as S. zanklon is likely to be among these substrates.
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Photo 2.3:
Hand netting at a potential habitat (vegetation)
along the watercourse
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2.4.2.2
After taking the hand net out of the water,
it was allowed to drain, and the net content was emptied on to a large sorting
tray (see Photo 2.4). All caught S.
zanklon were carefully moved to a plastic container (see Photo 2.5) for translocation.
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Photo 2.4:
Large sorting tray with net contents
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Photo 2.5:
Plastic container for translocation
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2.4.3.1
Kick-netting (see Photo 2.6) was done along the watercourse by moving upstream with the net facing
the water current. The surveyor disturbed
the substrate by kicking the streambed substrate by kicking, such that the S. zanklon
dislodged from the streambed was trapped in the net. In order to maximise the survey effort within
the stream, the surveyor moved up the stream in a zigzag direction to increase
the kick sampling coverage. The net was checked after a maximum of one minute
of kick sampling. However, the net was
checked more frequently if large amount of substrate was kicked into the net.
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Photo 2.6:
Surveyor kick-netting the substrate and checking the
net’s contents
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2.4.3.2
Similar to hand netting, the
net content was emptied on to a large sorting tray. All caught S. zanklon were carefully moved to a plastic
container for translocation.
2.4.4.1
Captured S. zanklon individuals were
marked (see Photo 2.7)
first prior to translocation to the recipient site. The marker was an
epoxy-resin based paint (Jotamastic Wintergrade) which contains a metallic
component and cures in contact with water. Earlier laboratory and field trials
had established that crab survival and behaviour was unaffected by paint marking
on the carapace and that the marks persisted in field conditions (Eaton et.
al., 2001).
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Photo 2.7: Surveyor marking the carapace of the captured Somanniathelphusa
zanklon individual
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2.5.1.1
The recipient site is located at the middle
section of Ping Yuen River tributary, and adjacent to Ping Yuen Road, to the
north of Ping Yeung Village (see Photo 2.8).
In this tributary, S. zanklon was previously recorded during the
approved EIA studies (i.e. EIA-133/2007 and EIA-190/2010) (ERM, 2022)
suggesting that this watercourse is suitable for S. zanklon.
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Photo 2.8:
Recipient site located at the middle section of Ping
Yuen River tributary, and adjacent to Ping Yuen Road (outside NENTX)
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2.5.1.2
While channelisation features (e.g. concrete
bank and gabions) and an inflatable water dam are present about 100m to the
east of this middle stream section, this section is considered largely natural
with a low gradient and low water flow. The streambed is mainly covered by soil
and stream banks are vegetated with grass. This section is generally considered
as a suitable recipient site for the crab considering the stream
characteristics, which meet the habitat requirements of the species. The soft
soil stream substrate and the availability of riparian vegetation would be
ideal for S. zanklon to create microhabitat to inhabit. In addition, the
natural meander would also reduce the water flow, which is preferred by the S.
zanklon. As revealed by up-to-date satellite images, similar habitat is
present over a long distance as the stream stretches west toward Ping Che Road.
It is anticipated that pollution or disturbance would be in a low level in this
section, considering there is limited roads and houses (and therefore human
activities) until the stream reaches Kan Tau Wai and Tong Fong along Ping Che
Road. It is considered that there is approximately 1.2km of relatively
undisturbed habitat for the S. zanklon.
2.5.1.3
The recipient site was resurveyed again to
re-confirm its suitability prior to the start of translocation survey.
2.5.2.1
During the translocation activities, all caught S. zanklon at the collection
sites were moved to a plastic container for translocation. The plastic
container was filled with water from the watercourse where S. zanklon was caught. The
plastic container was placed with small amount of leaf litter to provide
temporary habitat for the caught individuals.
In order to avoid stress and mortality, all S. zanklon individuals were
translocated to the identified recipient site within four
hours after being caught.
2.5.2.2
Upon arrival to the recipient site, the
surveyor gradually mixed the water at recipient site into the plastic container
before releasing all individuals to the recipient site (see Photo
2.9). This acclimatisation process would lower
the risk of mortality due to temperature shock on the translocated individuals.
It was noted that any deceased individuals would not be released into the
recipient site, but it would be reported.
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Photo 2.9:
Recipient site during the actual translocation
activity located at the middle section of Ping Yuen River tributary, and
adjacent to Ping Yuen Road (outside NENTX)
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3.1.1
A
total of eight S. zanklon individuals
(Appendix D) were captured, marked,
and translocated during the survey from 21-24 July 2022. All these individuals
were captured from the watercourse section adjacent to the truck water filling
station within the Survey Area, particularly from the soft silty-muddy substrate
with adjacent riparian vegetation of the water section. No other individual was
present nor captured from other collection sites. Additionally, no other
aquatic fauna of conservation importance was noted within the Survey Area.
3.1.2
All
the individuals were collected on 21 July 2022. Succeeding this collection
date, no individuals of S. zanklon were collected for the next three
consecutive capture surveys.
3.2.1
Sizes
of the eight S. zanklon individuals
ranged from 0.36 cm to 1.36 cm. Majority of the individuals were below 1 cm in
carapace width which indicated that these individuals were still juveniles
relative to the sizes of several recorded individuals which range from 3.04 cm
to 4.2 cm (Huang et. al, 2018).
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Photo 3.1: Size of one captured Somanniathelphusa
zanklon individual
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3.3.1
Majority
of the captured S. zanklon individuals
were males (7 individuals) while there was only one recorded female in the area.
Current survey findings that showed sex ratio as skewed towards males were similar
with observations by Huang et. al (2018) which noted the dominance of males within
the community.
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Photo 3.2: Captured male Somanniathelphusa zanklon
individual showing its abdominal segments
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4.1.1
A
total of eight S. zanklon individuals
were captured, marked and translocated throughout the survey period from 21-24
July 2022. These individuals were translocated to the recipient site specified
on the approved Revised Translocation Proposal for the Endemic Freshwater Crab S. zanklon. Further, these individuals
were all juveniles relative to their sizes; and male crabs dominated the
community within the Survey Area.
4.1.2
No
other aquatic fauna of conservation importance was noted within the Survey Area
throughout the survey period.
Table 5.1: Data sheet for Somanniathelphusa zanklon post-translocation
monitoring
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Information
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Description
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Date:
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Capture
Site1:
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Weather:
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Capture
Site2:
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Start
Time:
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Capture
Site3:
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Finish
Time:
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Recipient
Site:
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Remarks:
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Qualified
Ecologists:
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Individual Number
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Abundance
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Size (Carapace width, cm)
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Sex (M/F)
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Remarks
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Bell, M.C., D.R. Eaton, R.C.A. Bannister, J.T.
Addison. 2003. A mark-recapture approach to estimating population density from
continuous trapping data: application to edible crabs, Cancer pagurus, on the east coast of England. Fisheries Research
(65):361–378.
Black & Veatch. 2020. Approved
Environmental Monitoring and Audit Manual 198172/B&V/034 for the
Development at San Hing Road and Hong Po Road, Tuen Mun accessed at https://www.epd.gov.hk/eia/register/report/eiareport/eia_2632020/EM&A/02%20PDF/EMA_2.pdf
Eaton, D.R., J.T. Addison, S.P. Milligan, J.
Brown and L.J. Fernand. 2001. Larvae surveys of edible crab (Cancer pagurus) off the east coast of
England: implications for stock structure and management. ICES CM 2001/J:14.
10pp.
Huang, C., K.C. Wong, S.T. Ahyong. 2018. The
freshwater crabs of Macau, with the description of a new species of Nanhaipotamon Bott, 1968 and the
redescription of Nanhaipotamon wupingense
Cheng, Yang, Zhong & Li, 2003 (Crustacea, Decapoda, Potamidae). ZooKeys
810: 91–111. https://doi.org/10.3897/zookeys.810.30726.
Lettink, M. and D.P. Armstrong. 2003. An
introduction to using mark-recapture analysis for monitoring threatened
species. Pp. 5-32 in: Department of Conservation 2003: Using mark-recapture
analysis for monitoring threatened species: introduction and case study.
Department of Conservation Technical Series 28, 63 p.
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