|
Agreement
No. CE 72/2019 (EP) Environmental
Impact Assessment (EIA) Report for the New Contaminated Sediment Disposal
Facility to the West of Lamma Island July 2022 |
This Section presents the findings of an assessment of potential impacts on capture and culture fisheries associated with the construction and operation activities of the Project.
The criteria for evaluating fisheries impacts are stated in the EIAO-TM. Annex 17 of the EIAO-TM prescribes the general approach and methodology for assessing fisheries impacts caused by a project or proposal, to allow a complete and objective identification, prediction and evaluation of the potential impacts. EIAO-TM Annex 9 recommends the criteria that are to be used for evaluation of fisheries impacts.
Other legislation which applies to
fisheries includes:
n
Fisheries Protection Ordinance (Cap. 171),
which provides for conservation of fish and other aquatic life, regulates
fishing practices and prevents activities detrimental to the fishing industry;
n
Marine Fish Culture Ordinance (Cap. 353), which regulates and protects marine fish
culture and other related activities and requires all marine fish culture
activity to operate under license in designated Fish Culture Zones (FCZs);
n
Water Pollution Control Ordinance (Cap. 358), which aims to control water pollution in Hong
Kong waters. Water Control Zones (WCZs)
are designated with individual water quality objectives to promote the
conservation and best use of those waters in the public interest; and
n
Environmental Impact Assessment Ordinance (Cap.
499), Clause 3.4.5 and Appendix D
of the EIA Study Brief (ESB-328/2019) which outline the key fisheries impacts
to be reviewed and assessed in the EIA report.
In accordance with Clause 3.4.5
of the EIA Study Brief, the Assessment Area for fisheries impact assessment is
the same as that for water quality impact assessment, covering the area within
the Southern WCZ and Western Buffer WCZ.
Detailed description of the physical and
biological characteristics of the marine environment of the Assessment Area are
provided in Sections 3 and 4,
respectively.
A literature review was conducted to review the baseline fisheries conditions within the Assessment Area and to identify information gaps to determine whether field surveys are required to provide sufficient information for the fisheries impact assessment. Findings of the literature review are presented in detail in Annex 5A.
Some of the baseline information was collected very recently in 2016-2018 and is considered to be up-to-date and representative of the existing conditions in the Assessment Area (Figure 1.3 of Annex 5B). Therefore, no information gap within the Assessment Area is identified. Despite this, to better understand the fisheries resources and fishing operations within and in the vicinity of the Study Area, field surveys at selected locations within and in the vicinity of the Study Area where potential impact could occur were conducted between February and May 2021 to update the latest fisheries baseline in these locations. The methodology for the surveys is presented in Annex 5B. Detailed survey findings are presented in detail in Annexes 5C to 5E.
The information from desktop review and field surveys collectively suggested that:
n According to the AFCD Port Survey 2016/17 data, the Study Area falls within an area with moderate to high (>400-600 vessels) level of fishing operations. The Study Area provides low to moderate level of capture fisheries production (>100-300 kg/ha).
n Fisheries surveys conducted from February to May 2021 showed that the catches were generally comprised of low to moderate commercial value fisheries species which accounted for about 75% of total biomass and 65% of total abundance. Some fisheries species of medium to high commercial value were recorded, including prawns, mantis shrimps, porgy and flounder.
n The level of ichthyoplankton and fish post-larvae resources of the Assessment Area varied greatly over time and was low in general with species of low to medium commercial value;
n Vessel surveys recorded an average of four fishing vessels/day operation in the waters within and in the vicinity of the Study Area. The fishing activities were generally undertaken using P4/7 vessels (sampan) and small fishing boats.
Based on the
information reviewed, the importance of the fisheries within the Assessment
Area is evaluated. Findings from the
desktop review and field surveys indicated that the Study Area support low to moderate level of capture fisheries production with generally species of low to medium
commercial value.
According to EIAO-TM
Annex 9, spawning grounds and nursery area can be regarded as an important
habitat type as they are critical to the regeneration and long-term survival of
many organisms and their populations.
The Study Area is located within the recognised spawning ground and
nursery area of commercial fisheries resources.
It is, however, important to note that the densities of ichthyoplankton
and fish post-larvae resources varied across seasons at the three surveyed
sites from the fisheries surveys. The
level of ichthyoplankton and fish post-larvae resources of the Assessment Area
was low in general with mainly low to moderate value commercial species, which
indicates that the potential for the Assessment Area to function as important
spawning grounds and nursery area is not high.
The waters within the Project’s footprint and its vicinity also do not support mariculture activities. The nearest FCZs are located more than 6.9 km (by sea) from the Project.
Based on the preceding review of the available information on the capture and culture fisheries of the waters in the vicinity of the proposed Project, the potential sensitive receivers that may be affected by the Project activities are identified as follows:
n Recognised spawning ground and nursery area of commercial fisheries resources in southern waters located within the Project;
n FCZs at Cheung Sha Wan (~ 6.9 km away from the Project), Lo Tik Wan (~ 7.0 km away from the Project), Sok Kwu Wan (~ 8.8 km away from the Project) and Ma Wan (~ 14.3 km away from the Project); and
n Artificial reefs within Lo Tik Wan FCZ (located ~ 8.9 km from the Project).
The locations of the sensitive receivers are shown in Figure 5.1.
A review of baseline
fisheries conditions from available literature and field surveys was conducted
for the purpose of establishing the fisheries importance of the waters in the
Assessment Area and its vicinity. Information
from the water quality impact assessment (Section 3) was examined to assess
potentially affected area by perturbations to water quality parameters.
The potential
impacts due to the construction and operation activities of the Project were
then assessed (with reference to the EIAO-TM Annex 17 guidelines) and
the impacts evaluated (with reference to the criteria in EIAO-TM Annex 9).
The key construction and operation activities
of the Project are discussed in Section 2.6.4. Potential sources of impacts to fisheries
resources and fishing operations arising from the Project may occur during both
construction and operation activities, including:
Construction
activities:
§ Dredging of the seabed for the formation of CMP
Operation
activities:
§ Disposal of contaminated sediment in the formed CMP
§ Capping of the exhausted CMP with uncontaminated sediment up to the original seabed level
Note that
the construction activities (dredging) could overlap with operation activities
(backfilling and capping) to maintain uninterrupted disposal service of the
proposed WL Facility. The following key
issues to fisheries have been assessed and discussed in the following sections:
§ Direct disturbances of fisheries habitat and fishing ground;
§ Perturbations to key water quality parameters from marine construction and operation activities; and
§ Underwater sound generated from marine construction activities.
Direct impacts to
fisheries resources, habitats (including spawning ground and nursery area) and
fishing operations include disturbance caused by the dredging, disposal and
capping works of the Project during construction and operation. The
construction and operation activities are expected to cause temporary loss of
access to potential fishing ground of up to 120 ha at the active CMP(s) within
the Key Area at any one time. It should
be noted that a relatively small number of works
vessels (e.g. up to two dredgers,
some tugs/ supporting vessels, some hopper barges for sediment handling at any
one time) will occupy the active CMP areas, and the
frequency/ trip of works vessels would also be relatively low in general
depending on the sediment disposal demand.
It is expected that the disturbance to fisheries habitats will be temporary at discrete work locations of the
active CMPs. Each CMP will be constructed and operated sequentially and will be capped with 3
m layer of uncontaminated sediments to keep the contaminated material beyond the
reach of bioturbation and to protect it against storm erosion. The
work rates for dredging, backfilling and capping works will be controlled and a
maximum of two grab dredgers or one TSHD will be used for the formation of CMP
at any one time. The dredging works for formation of CMP will not be continuous
throughout the service lifetime of the WL Facility and the schedule could be
adjusted in view of the actual sediment disposal demand and the interface with
other concurrent activities / projects to minimise potential environmental
impacts. The disposal activity is
expected to have a much lower working rate throughout the service lifetime of
the WL Facility with reference to the estimated annual average disposal demand
of 0.6 Mm3 (equivalent to ~1,650 m3/day) while the
working rate of capping activity could also be controlled depending on the
availability of uncontaminated sediment.
Once dredging,
backfilling and capping works for a CMP of the Project are completed, the
seabed and hydrodynamic regime is expected to restore to their original
condition. A review of long term
environmental monitoring within and around the capped pits at South Brothers
has shown that there is an increasing trend of macrobenthos infauna in terms of
biomass over time at the capped pits and the faunal diversity at the capped
pits also appears to increase over time and the majority of the infauna species
identified were polychaetes, crustaceans and bivalves, which were similar to
the species found in the adjacent reference stations in North Lantau waters in
a relatively short period of time (about 2 years following the completion of
capping works) ([1]). This
demonstrates that recolonisation of benthos occurs and the habitats are
expected to return to pre-dredged conditions.
Considering the
temporary and reversible nature of the disturbance, small extent of the area at
any one time which is of low to moderate fisheries production and moderate to high level of fishing operation, impacts are considered to be of minor to
moderate significance. Safety /
precautionary measures such as issuance of Marine Department Notice or other
notifications is expected to reduce the risk of collision of increased marine
traffic and fishing vessels to within acceptable levels. During construction and operation of the
CMPs, works area will be established within and in the vicinity of the active
CMP(s) within Key Area only to minimize the actual extent of fisheries
habitats and fishing ground affected at any one time. Fisheries resources are expected to return to
the area following the cessation of dredging, backfilling and capping
works. Overall, unacceptable impacts on fisheries are not expected.
Indirect impacts to
fisheries resources, habitats (including spawning ground and nursery area) and
fishing operations during the construction and operation activities of the
Project include sediment release associated with the dredging, backfilling and
capping works. Potential impacts to water quality from sediment release
due to the construction and operation activities of the Project are described
in the water quality impact assessment (Section
3). These potential impacts are as follows:
n
Suspended
solids (SS) dispersion and sedimentation;
n
Dissolved
oxygen (DO) depletion;
n
Release of
sediment-bounded contaminants into the water column; and
n
Release of
sediment-bounded nutrients into the water column.
Dredging, backfilling and capping works are expected
to generate SS within the water column and result in increased sediment
deposition in close proximity of the works areas. The modelling works have analysed SS
dispersion from concurrent dredging, backfilling and capping works of the CMPs (Section 3.7.1).
Fluxes of SS naturally occur in the
marine environment and as a result, fish have evolved behavioural adaptations
to tolerate changes in SS load (e.g. clearing their gills by flushing water
over them). Concentrations of SS generated by the dredging, backfilling and capping works are expected to be greater, particularly in the Key Area. Beyond the active works areas of the proposed CMPs,
dispersion could be expected so there is a rapid decline in the SS
concentrations.
Compared to adult fish, larvae and post-juvenile fish are relatively more susceptible to variations in SS concentrations as their sensory system is less developed. Adult fish are more likely to move away from area of disturbance when they detect sufficiently elevated SS concentrations and therefore are unlikely to be significantly impacted.
The SS level at which fish move into clearer water is defined as the tolerance threshold which varies among species and different stages of the life cycle. If SS levels exceed tolerance thresholds and the fish are not able to move away from the affected area, fishes are susceptible to be stressed, injured and may eventually die. The rate, timing and duration of SS elevations affect the type and significance of impacts upon fish and potentially crustaceans.
Findings from literature reviews indicated that lethal responses had not been reported in adult fish at SS values below 125 mg L-1 ([2]) and that sub-lethal effects were only observed when levels exceeded 90 mg L-1 ([3]). In the Consultancy Study on Fisheries and Marine Ecological Criteria for Impact Assessment by AFCD, guideline values have been identified for fisheries and selected marine ecological sensitive receivers. The values are based on international marine water quality guidelines for the protection of ecosystems ([4]). The AFCD study recommends a maximum SS concentration of 50 mg L-1 (based on half of the No Observable Effect Concentrations). This criterion has been adopted in previous approved EIA Reports. However, the study cautioned that site-specific data should be considered in environmental assessments on a case-by-case basis. In order to provide a more conservative assessment (i.e. with a lower tolerance criterion), the WQOs for SS elevation are adopted in this study as the assessment criteria for fisheries sensitive receivers.
As discussed in Section 3.7.1, the water quality
modelling results have indicated that at all fisheries sensitive receivers, SS
elevations as a result of the proposed dredging, backfilling and capping works
are predicted to be compliant with the relevant WQOs for both wet and dry
seasons (Table 3.13). The maximum SS elevation at sensitive
receivers was predicted to be 1.1 mg/L while the maximum SS elevation at the
nearby FCZs was predicted to be 0.2 mg/L.
Elevated levels of SS as a result of these works are expected to be
temporary in nature and localised to the proximity of active works areas of the proposed CMPs. With the implementation of mitigation measures proposed
in the water quality impact assessment in Section
3.8, such as the use of cage-type silt curtain for dredging works by
grab dredgers, control of working rates for dredging, backfilling and capping
works, potential impacts to fisheries would be further reduced. Also,
although larvae and post-juvenile fish are more likely to be impacted as they
may not be able to detect and avoid areas with elevated levels of SS, the
Project area only contributed to <1% of the recognized nursery area and
spawning ground for commercial fisheries resources in Hong Kong waters, and the
level of ichthyoplankton and fish post-larvae resources of the Assessment Area
varied greatly over time and was low in general. Therefore, unacceptable impacts from
dredging, backfilling and capping works on fisheries resources and habitats
(including spawning ground and nursery area) are not anticipated.
The relationships between SS and DO are
complex, with elevated SS in the water column together with a number of other
factors to reduce DO concentrations.
Elevated SS (and turbidity) reduces light penetration, lowers the rate
of photosynthesis by phytoplankton (i.e. primary productivity) and thus lowers
the rate of oxygen production in the water column. Furthermore, the potential release of
sediment contaminants into the water column may consume the DO in the receiving
waters. The resulting overall DO
depletion has the potential to cause an adverse effect on the eggs and larvae
of fish and crustaceans, as at these stages of development high levels of
oxygen in the water are required for growth to support high metabolic growth
rates.
The results of the water quality assessment
have indicated that elevated levels of SS as a result of dredging, backfilling
and capping works are expected to be temporary in nature and localised to the
proximity of active works areas of the proposed CMPs. DO depletion associated with dredging, backfilling
and capping works are predicted to be very low (~0.03 mg/L, see Section
3.7.1.2) and remain compliant with the relevant WQO DO criteria at all
fisheries sensitive receivers for both wet and dry seasons. Therefore, impacts are considered to be of
minor significance and no unacceptable impacts to fisheries from the reduction
of DO concentration are expected to occur.
The potential for
release of contaminants from disturbed sediments has been assessed in Section 3.7.1.3. Sediment samples
collected within the Study Area indicated low levels of sediment contamination
within the Project Site. Therefore, risk
of release of sediment-bounded contaminant from dredging works of the Project
is minimal and impact to fisheries resources due to potential contaminant
release is not expected. On the other
hand, the contamination levels of sediments for backfilling of the Project
could vary and sediment-bounded contaminants from backfilling is more likely to
be released. As a conservative approach
in the water quality modelling, it is assumed that concentration of all
sediment-bounded contaminants are at the corresponding UCEL and release of
sediment-bounded contaminants is instantaneous and 100% loss from the entrained
sediment. In reality, the release of
sediment-bounded contaminants takes time and generally cannot reach its
completion (see Section 3.7).
The modelling results showed that all the levels of contaminants of
concern at sensitive receivers are within the corresponding assessment
criteria. Unacceptable water quality
impacts due to the potential release of heavy metals and organic pollutants
from disturbed sediments into the water column are not expected to
occur. An assessment on bioaccumulation was also conducted for this
study and the results showed that the increase in contaminant concentrations in
fisheries resources is insignificant (see Section 8). In addition, with reference to the long-term
environmental monitoring data from ESC CMPs, the concentrations of contaminants
for tissues/ whole body samples of fisheries resources (including pelagic fish,
molluscs, predatory crabs, predatory fish and predatory shrimps) collected
between reference area (i.e. away from CMPs) and impact area (i.e. closer to
the CMPs) were found to be similar over the years ([5]), indicating there is no evidence of adverse impact to fisheries
resources collected near the CMP area due to the potential release of
sediment-bounded contaminant. Therefore,
impacts on fisheries resources due to bioaccumulation of released contaminants
from disturbed sediments are not expected to occur.
High levels of
nutrients (total inorganic nitrogen and ammonia) released from disturbed
sediments to the water column may potentially cause rapid increase in phytoplankton
population, on occasions to the point that an algal bloom occurs. An intense algal bloom can cause decrease in
the levels of DO. This decrease would
initially occur in the surface water, and then spread to deeper water as dead
algae fall through the water column and decompose on the seabed.
The water quality
modelling results have indicated that elevated levels of SS as a result of
dredging, backfilling and capping works are expected to be temporary in nature
and localised to the proximity of active works areas of the proposed CMPs. The
predicted change is well below 1% of the corresponding WQO and is considered
inconsequential at all fisheries
sensitive receivers for both wet and dry seasons (see Section 3.7.1.4).
Impacts are considered to be of minor significance and unacceptable
impacts to fisheries are thus not expected to occur.
In summary,
predicted levels of SS, DO, contaminant and nutrient concentrations as a result
of dredging, backfilling and capping works of this Project are anticipated to
be in compliance with the relevant assessment criteria. Impacts are
considered to be of minor significance. Impacts are localised with negligible impact on fishing activity. Unacceptable indirect water quality impacts
from sediment release on fisheries resources, habitats, fisheries sensitive
receivers and fishing activity are not expected to occur.
Intermittent sounds,
which occur during construction and operation activities such as dredging and
marine vessel movement, may have an impact on fisheries resources. Potential effects of increased underwater
sound include physiological stress, avoidance and injury (at high pressure
levels). The level of impact is however
dependent upon background sound, number of fish present, type of species
affected, proximity of fish to the sound source, attenuation properties of
seabed sediments and hearing capabilities of the species affected, etc..
Most marine
invertebrates do not possess air-filled space and thus it is generally
considered that sound would have limited physiological or behavioural effects
on marine invertebrates, except if they are located within a few metres of the
sound source. Therefore underwater sound
generated from marine works is expected to have negligible impact on marine
invertebrates in the Assessment Area.
Fish, however, can
detect underwater sound vibrations through two ways, the lateral line system
and the inner ear for species containing air-filled swim bladders. Anthropogenic underwater sounds associated
with vessels for this Project, such as barges, tug boats, dredgers, etc.,
exhibit major energy below 1,000 Hz and sound levels of between 170 and 190 dB
re 1 μPa at 1 m and may be audible to most fish species ([6]).
Waters within the Assessment Area and its vicinity is subject to
relatively high levels of marine traffic by similar types of vessels; therefore
it is reasonable to assume that fish in these waters are habituated to a
relatively high background level of underwater sound, and a small increase in
vessel activity associated with the construction and operation of this Project
is not anticipated to result in unacceptable impacts on fisheries resources,
and hence is expected to have negligible impact on fishing activity.
From the information presented above, the fisheries impacts associated with the Project are not considered to be significant. An evaluation of the impacts according to Annex 9 of the EIAO-TM is presented in Table 5.1.
Table 5.1 Evaluation of Fisheries Impacts in
accordance to the Criteria described in Annex 9 of EIAO-TM
|
Potential Impact |
Nature of Impact |
Size of Affected Area |
Loss of Fisheries Resources / Production |
Destruction and Disturbance
of Nursery and Spawning Grounds |
Impact on Fishing Activity |
Impact on Aquaculture
Activity |
Overall Impact Significance |
Mitigation Measures
Required |
|
Direct
disturbances of fisheries habitat and loss of access to fishing ground |
Temporary and
reversible. |
A total of ~235 ha. Up to 120
ha at active CMP(s) within the Key Area at any one time
during dredging, backfilling and capping operations. |
The Project
area is of low to moderate fisheries production. Fisheries resources are expected to return to the area following the cessation of
dredging, backfilling and capping works.
Considering the temporary and reversible nature
of the disturbance, impacts on loss of fisheries resources / production
are considered minor. |
Although the
Project is located within recognised spawning ground and nursery area, the
level of ichthyoplankton and fish post-larvae was generally low. Impacts on destruction and disturbance of
nursery and spawning grounds are considered minor. |
The Project
area falls within an area with moderate to high level of fishing
operation. Considering
the temporary and reversible nature of the disturbance, as well as the
minimisation of works area to active CMP(s) within Key Area only, impacts on
fishing activity are considered minor to moderate. |
No aquaculture
activities in the Project works areas and hence no impact. |
Minor to
Moderate |
Yes; minimise
works area to active CMP(s) within Key Area only. Issue Marine
Department Notice or other notifications as safety / precautionary measures |
|
Perturbations
to key water quality parameters from marine construction and operation
activities |
Temporary and
reversible. |
Localized to the immediate vicinity of the active works areas of the proposed CMPs. |
Avoidance by fish
is expected, and negligible loss of fisheries resources or production. |
Water quality
compliance expected with minor impact. |
Impacts are
localised with negligible impact on fishing activity. |
Water quality compliance at FCZs expected with no
unacceptable impact. |
Minor |
No, water quality mitigation measures would further
reduce impacts (Section 3.8) |
|
Underwater
sound |
Temporary and
reversible. |
Localized to the immediate vicinity of the active works areas of the proposed CMPs. |
Avoidance and habituation by fish are expected,
and negligible loss of fisheries resources or production. |
Underwater sound is expected to have negligible
impact on spawning ground and nursery area. |
Underwater
sound is expected to have negligible impact on fishing activity. |
Aquaculture activities are too remote to be
affected by underwater sound and hence no impact. |
Minor |
No |
The fisheries impact
assessment has considered the cumulative effects of different activities of
this Project on fisheries resources, habitats and fishing operations. The water quality impact assessment (Section
3) was based on the worst-case scenarios of concurrent construction and
operation activities of this Project as well as relevant concurrent projects
(see Annex 3A for the
detailed consideration) and thus has also incorporated potential cumulative
impacts. The cumulative impacts of the
various construction and operation activities of this Project and other
relevant concurrent projects have been demonstrated in Section 3.9
as not causing unacceptable impacts to water quality. Consequently, unacceptable cumulative impacts
to fisheries resources are not predicted to occur.
Information from
publicly available sources suggested the major projects that may coincide with
the construction/ implementation programmes of this Project (Section
2.8 and Annex 2A). Potential cumulative impacts were evaluated
with other existing and planned major development in the Assessment Area, in
particular South of Cheung Chau Open Sea Sediment Disposal Area, Improvement
Dredging for Lamma Power Station Navigation Channel and Development of an
Offshore Wind Farm in Hong Kong and the Artificial Islands in the Central
Waters located within a few kilometres from the Project. Outcomes of this evaluation are summarised as
follows:
n
Habitat Loss
and Disturbance and Loss of Access to Fishing Grounds: the extent of disturbance of the Project is
expected to be small, temporary and confined to localised works areas at the
active CMP(s) of the Key Area (up to ~120 ha of loss of fishing ground at any
one time for dredging, backfilling and capping activities). The South of Cheung Chau Open Sea Sediment
Disposal Area is expected to result in a temporary disturbance of a maximum of
600 ha seabed habitat at any one time, though the seabed disturbance is
expected to be confined in particular areas where disposal activities would
occur. The Improvement Dredging for
Lamma Power Station Navigation Channel is expected to result in a temporary
disturbance of 262 ha seabed habitat and loss of access to fishing ground. The Development of an Offshore Wind Farm in
Hong Kong is expected to result in a permanent loss of 0.16 ha seabed habitat
and permanent loss of access to ~700 ha fishing ground. The severity of such cumulative habitat loss
is expected to be significantly reduced to acceptable levels by mitigation
measures proposed as part of the EIAs for the Improvement Dredging for Lamma Power
Station Navigation Channel and Development of an Offshore Wind Farm in Hong
Kong. Considering the temporary nature
and relatively small size (up to ~120 ha of loss of fishing ground at any one
time for dredging, backfilling and capping activities) of the Project, it is
not expected to exert an unacceptable cumulative effect. On the other hand, the development of the
Artificial Islands in the Central Waters are expected to result in a permanent
loss of ~1,000 ha seabed. The KYCAI
development is currently in early planning stage and effective and feasible
mitigation measures, including compensation measures, will be investigated
under the CW Study to address the permanent loss of seabed due to the proposed
development ([7]). The acceptability
of residual cumulative impacts on fisheries from the said concurrent projects
will largely depend on the environmental acceptability of the reclamation of
KYCAI and the HKI-NEL Link in the Central Waters.
n
Underwater Sound: the Project is located at sufficient distance
from other projects and only a relatively small number of slow-moving works
vessels would be used for the Project.
Given the similarity in underwater acoustic profiles generated by works
vessels of this Project and other projects (e.g. by the use of large vessels
generating low-frequency sound), cumulative effects of works vessels
operational sound, if any, are anticipated to be negligible.
n
Marine Traffic: this Project is located at sufficient
distance from other projects in the vicinity. It is expected to involve a
relatively small number of works vessels at any one time at the works areas of
the proposed CMPs, and the frequency/ trip of vessel would also be low. Given
the waters off southern Hong Kong have some levels of existing marine traffic,
the cumulative effects of marine traffic disturbance to the nearby fishing
operations, if any, are anticipated to be negligible.
Other projects
either do not have a marine element or are at more than a few kilometres from
this Project, and so no unacceptable cumulative impact on disturbance to
fisheries resources, habitats (including spawning or nursery grounds) and
fishing operation is expected.
In accordance with
the guidelines in the EIAO-TM on fisheries impact assessment, the
approach adopted in this EIA for mitigating impacts to fisheries includes:
n
Avoidance:
Potential impacts should be avoided to the maximum extent practicable by
adopting suitable alternatives;
n
Minimisation: Unavoidable impacts should be minimised by taking appropriate and
practicable measures such as confining works in specific area or season; and
n
Compensation: When all possible mitigation measures have been exhausted and there are
still significant residual impacts or when the impacts are permanent and
irreversible, consideration shall be given to off-site compensation. It may include enhancement of fisheries
resources and habitats elsewhere.
Impacts to fisheries resources, habitats and fishing operations have
largely been avoided (i.e. avoid areas of high fisheries importance through
site selection) and reduced through proper planning and design of the CMPs
(e.g. CMPs to be developed within Key Area, CMPs to be
constructed and operated sequentially, no
more than three pits will be active (dredging / backfilling / capping) at any
one time and works area within and in the vicinity of the active pit(s) only). Issuance of Marine Department
Notice or other notifications is expected to reduce the risk of collision of
increased marine traffic and fishing vessels to within acceptable levels as safety
/ precautionary measures. During
construction and operation of the CMPs, works area will be established within
and in the vicinity of the active CMP(s) within
Key Area only to minimize the actual extent of
fisheries habitats and fishing ground affected at any one time. Appropriate notification, communications,
site protection and marking would be adopted to reduce navigation risks with
fishing vessels. The construction and
operation activities have been designed (e.g. appropriate work rates for
dredging, backfilling and capping) to confirm compliance with the assessment
criteria at sensitive receivers and control water quality impacts to within
acceptable levels and water quality mitigation measures (e.g. deployment of
cage-type silt curtain during dredging works by grab dredgers, good site
practices) will be implemented to further avoid/reduce potential impacts (see Section
3). These measures are expected
to control and reduce potential impacts to fisheries resources as well, and no
other fisheries-specific mitigation measures are thus required during
construction and operation of the Project.
Recolonisation of
benthos is expected after capping of the CMPs and the habitats are expected to
return to pre-dredged conditions.
Fisheries resources are expected to return to the area following the
cessation of dredging, backfilling and capping works. With the implementation of water quality
mitigation measures during construction and operation activities of the
Project, potential impacts on fisheries habitats and resources will be further
minimised. No adverse residual fisheries impacts due to the
dredging, backfilling and capping works of the Project are expected.
While no
unacceptable impacts have been predicted to occur during construction and
operation of the Project, monitoring of fisheries resources and biomonitoring
programme are recommended to address stakeholders’ concerns on the level of
fisheries resources and contamination of seafood in the vicinity of the
Project. The details of the fisheries
resources monitoring and biomonitoring programme will be presented in the
EM&A Manual attached to this EIA Report.
In addition,
monitoring activities designed to detect and mitigate impacts to water quality
during construction and operation activities are also expected to serve to
protect against impacts to fisheries.
The details of the water quality monitoring programme will be presented
in the EM&A Manual attached to this EIA Report.
A review of baseline
information on commercial fisheries resources, habitats and fishing operations
surrounding the waters of the proposed Project from available literature and
field surveys has been undertaken.
Results from the review indicate that the Study Area falls
within an area with moderate to high level of fishing operations and provides low to
moderate capture fisheries production. Sensitive receivers, including
spawning ground and nursery area of commercial fisheries resources in southern
waters, FCZs in Sok Kwu Wan, Lo Tik Wan, Cheung Sha Wan
and Ma Wan, and artificial reefs
in the Lo Tik Wan FCZ have been identified, and the water quality
impact assessment demonstrated that these sensitive receivers would not be
affected unacceptably.
During construction
and operation activities of the Project, direct impacts arising from the
proposed dredging, backfilling and capping works include temporary disturbance
to fisheries habitats and loss of access to potential fishing ground within an
area of approximately Key Area. Considering the temporary and
reversible nature of the disturbance, small extent of the area at any one time
which is of low to moderate fisheries production and moderate
to high level of fishing operation,
impacts are considered to be of minor to moderate significance and unacceptable
impacts on the fisheries resources, habitats and fishing activities are not
expected. Indirect impacts to fisheries
resources related to perturbations to key water quality parameters from
construction and operation activities are expected to be insignificant as the
predicted changes in water quality are temporary, localised to immediate
vicinity of the active works areas of the proposed CMPs and in compliance with
the corresponding WQOs and assessment criteria. Potential impacts of
elevated levels of underwater sound as a result of construction and operation
activities are also not expected to be unacceptable. The
construction and operation of the Project have been designed to reduce
potential impacts on water quality which will, in turn, reduce impacts on
fisheries resources. Water quality mitigation measures (e.g.
deployment of cage-type silt curtain during dredging works by grab dredgers,
good site practices) will be implemented to further avoid/reduce potential
impacts. Safety / precautionary measures such as issuance of Marine Department
Notice or other notifications is expected to reduce the risk of collision of
increased marine traffic and fishing vessels to within acceptable levels. During construction and operation of the
CMPs, works area will be established within and in the vicinity of the active
CMP(s) within Key Area only to minimize the actual extent of fisheries
habitats and fishing ground affected at any one time.
No unacceptable impacts to fisheries are expected to occur. All of the potential construction and operational fisheries impacts identified are deemed acceptable. Recolonisation of benthos is expected after capping of the CMPs and the habitats are expected to return to pre-dredged conditions. Fisheries resources are expected to return to the area following the cessation of dredging, backfilling and capping works.
([1]) ERM (2019). Quarterly EM&A Report for Contaminated
Mud Pits to the East of Sha Chau and the South of The Brothers – October to
December 2018. Submitted under Agreement
No. CE 63/2016 (EP)
([2]) References
cited in BCL (1994) Marine Ecology of the Ninepin Islands including Peddicord R
and McFarland V (1996) Effects of suspended dredged material on the commercial
crab, Cancer magister. in PA Krenkel, J Harrison and JC Burdick
(Eds) Dredging and its Environmental Effects. Proc. Speciality Conference.
American Society of Engineers.
([3]) Alabaster JS
& Lloyd R (1984) Water Quality Criteria for Freshwater Fisheries.
Butterworths, London
([4]) City
University of Hong Kong (2001). Agreement No. CE 62/98, Consultancy
Study on Fisheries and Marine Ecological Criteria for Impact Assessment,
AFCD, Final Report July 2001.
([5]) ERM (2021). Annual Risk Assessment Report for the
Contaminated Mud Pits to the East of Sha Chau - April 2020 to March 2021. Submitted under Agreement No. CE 63/2016
(EP).
([6]) Richardson WJ, Greene CRG, Malme CI, Thomson DH (1995) Marine
Mammals and Noise. Academic Press, San Diego, 576 pp
([7]) Subject to further
investigation on the details of the proposed KYCAI development under the CW
Study, the detailed cumulative impacts to fisheries due to habitat loss and
disturbance and loss of access to fishing grounds, increase in underwater sound
and increase in marine traffic, if any, will be addressed under the EIAs for
the CW Study.