Tables
|
Table
6.1:__ Evaluation of Potential Fisheries Impacts during
Construction Phase Table
6.2:__ Evaluation of Potential Fisheries Impacts during Operation Phase |
In accordance with Section 3.4.4 of the EIA Study Brief No.ESB-171/2007, fisheries impact arising from the dredging, laying of pipe and backfilling works for the construction of the submarine gas pipelines were assessed. The potential operation phase impacts on fisheries activities were also addressed.
This Chapter of the EIA Report presents the results of an assessment of the impact of construction and operation of the submarine gas pipelines of the Project on existing fisheries resources, fishing operations and fish culture activities based on the findings of the Water Quality Impact Assessment.
6.2 Environmental Legislation, Standards, Guidelines and Criteria
The following legislations and guidelines are applicable to
the fisheries impact assessment in
¡
Annexes 9
and 17 of the EIAO-TM. Annex 17 of the EIAO-TM prescribes the
general approach and methodology for the assessment of fisheries impacts
arising from 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 evaluating fisheries impacts.
¡
Fisheries
Protection Ordinance (Cap 171). This Ordinance provides for the conservation
of fish and other aquatic life and regulates fishing practices.
¡
Marine
Fish Culture Ordinance (Cap 353). This Ordinance regulates and protects marine
fish culture and other related activities
¡ Water Pollution Control Ordinance (WPCO) (Cap 358). This Ordinance set limits to water quality parameters in various water control zones.
6.3 Fisheries Impact Assessment Methodology
A desktop literature review was conducted in order to
establish the baseline conditions of the physical environment and fisheries
importance of the project area.
As stipulated in clause 3.4.4.1 of the EIA Study Brief No. ESB-171/2007, the importance of fisheries resources and fishing operations
identified within the Study Area and the potential impacts due to the
construction and operation of the submarine
gas pipelines were assessed following the criteria and guidelines for
evaluating and assessing fisheries impact as stated in Annexes 9 and 17 of the
EIAO-TM.
The Study Area is same as that for water quality impact
assessment stipulated in clause
3.4.4.2 of the EIA Study
Brief No. ESB-171/2007, which
covers the Victoria Harbour Water Control Zone (WCZ), Western Buffer WCZ and Eastern Buffer WCZ as designated under the WPCO as
shown in Figure 3.1. The information in
the previous published and unpublished
studies regarding the
Study Area was reviewed and no information gap was identified. No field survey
is considered necessary for the generation of baseline fisheries conditions.
This assessment of fisheries impacts focuses on the fisheries resources and fishing operations within the Study Area. The availability of literature on the fisheries resources of the Study Area comes mainly from the latest Port Survey 2006. Other relevant EIA reports from previous projects at the Study Area have been reviewed. Updated mariculture information was obtained from the Agriculture, Fisheries and Conservation Department (AFCD).
6.4.1 Capture Fisheries
Background
information on capture fisheries within
6.4.1.1
Capture
fisheries in
In 2009, the
estimated fisheries production of Hong
Kong from capture fisheries in
waters both inside and outside
Commercial fish species reproduce throughout the year, although spawning for the majority of species appears to be concentrated during the period from June to September. The findings of literature reviews conducted for AFCD (ERM, 1998) have determined that the marine waters within the proposed works area were not identified as a primary nursery or spawning ground for commercial fisheries.
6.4.1.2
Findings from Port Survey 2006 within
the Study Area
Recent data related
to the waters within the Study Area were extracted from the Port Survey 2006
(AFCD, 2010b). In the survey, a uniform
grid of 720ha cell size overlaid on
Fisheries Production
The survey
results showed that the waters within and in
vicinity of the proposed works area were having medium adult fish
production (100–400kg/ha); and a lower fisheries
production was recorded for waters further west of
The catches at
the waters within the proposed works area were at high
price in
There was no fish fry production recorded within the direct impact grid cells and in waters within the Study Area.
Fishing Operations
Within and around the project area there
were 100–400 fishing vessels under operation. They included
gill netter, long liner, hand liner, purse seiner, miscellaneous craft and
sampan. All of them were
less than 15m in length. Sampan was the dominant type with 50–100
vessels operating around the project area, while miscellaneous craft and gill
netter (10–50 vessels) followed. Other vessel types were of low numbers, with no
more than 10 vessels for each of them. Operation of trawlers was not recorded
within and around the project area.
In terms of production, both sampans and miscellaneous crafts had annual fisheries production of 50–100kg/ha within the proposed works area, which were the highest among other fishing vessels operated in the region. Productions of each of other fishing vessels were low with not more than 50kg/ha.
6.4.2 Culture Fisheries
Marine fish culture area is not in vicinity to the proposed works area. The closest designated Fish Culture Zone (FCZ) within the Study Area is located at Tung Lung Chau, which is approximately 9km apart from the proposed submarine pipelines within the Eastern Buffer WCZ. As at January 2010, Tung Lung Chau FCZ consisted of 60 licensed rafts with a total licensed area of 13,373m2. No figure is available for production at this FCZ, although the estimated production of mariculture alone in 2009 was about 1,437 tonnes valued at approximately $92 million (AFCD, 2010a). The main species cultured are the Green Grouper (Epinephelus coioides), Brown-spotted Grouper (Epinephelus chlorostigma), Giant Grouper (Epinephelus lanceolatus), Russell’s Snapper (Lutjanus russellii), Mangrove Snapper (Lutjanus argentimaculatus), Star Snapper (Lutjanus stellatus) and Pompano (Trachinotus blochii) (AFCD, 2010a).
The other marine fish culture zone within the Study Area is the Ma Wan FCZ, which is located within the Western Buffer WCZ at approximately 16 km apart from the proposed works area. As at January 2010, Ma Wan FCZ consisted of 107 licensed rafts with a total licensed area of 14,554m2 out of the total gazetted area of 46,300m2. The main species cultured include Spotted Grouper (Epinephelus chlorostigma), Gold-lined Seabream (Rhabdosargus sarba), Mangrove Snapper (Lutjanus argentimaculatus) and Pompano (Trachinotus blochii).
6.5
Identification
of Fisheries Impacts
This Section
identifies and evaluates the potential impacts on fisheries arising from the
construction and operational phases of the Project in accordance with Clause
3.4.4.5 of the EIA Study Brief No. ESB-171/2007.
6.5.1 Construction Phase
The twin submarine pipelines with a width of approximately 450mm diameter will be submerged and embedded in a trench of width approximately 29m in the seabed by using the construction methods stated in Section 2.5 of this EIA including grab dredging, bottom pull and lay barge in various sections. The entire submarine gas pipelines will be backfilled with rock armour cover matching the original seabed level.
Impacts on fishing operation are expected to occur during dredging of the seabed and installation of the submarine gas pipelines. These impacts are predicted to be localised and small-scale and may occur through the following mechanisms:
6.5.1.1
Direct Impact
Temporary Loss
and Damage of Fisheries Resources
Long term direct impact is not expected to occur through the dredging of seabed for installation
of the submarine gas pipelines.
Short term direct impacts including
the temporary loss of fishing ground and direct injury to species (such as
crabs) are predicted to occur during
trenching work for the installation of the pipeline. The submarine pipeline trench will be
approximately 3.1km in length, 29m in width at a depth of approximately 4m to
9m below seabed level. It constitutes to a temporary loss of 8.99ha of seabed
for the installation of pipeline. After backfilling of the trench, the marine
benthos would recolonize the seabed and the associated fisheries resource would
return to the recovered seabed. Therefore, no long term impact is predicted. Besides
the temporary loss of fishery ground of seabed, the construction barge would
also restrict access of vessels for fishery operation and constitute a temporary
loss of fishing ground on sea surface. The assessment on the potential impact
on temporary loss of fishing ground is provided in following sub-section “Obstruction
of Fishing Vessels Operation”.
Obstruction of
Fishing Vessels Operation
Direct obstruction
of activities of fishing vessels in the proposed works area is anticipated during the dredging operation, installation of submarine gas
pipelines and backfilling works. The
area to be dredged and backfilled will be enclosed to minimize any uncontrolled
spreading of suspended sediment to other water quality sensitive receivers and to
reduce the chance of head-on collision between vessels and construction
machinery. Thus, fishing vessels will be temporarily restricted to enter the
proposed works area and the vicinity and therefore fisheries activities would
be temporarily affected.
During construction phase, the construction barges would occupy a small working area on sea and restrict access of vessels which in turn obstructs the operation of fishery vessels. However, the potential impact is predicted to be minor as the affected area is relative small and the barges would move progressively along the pipeline alignment so that it will only occupy a small area on the sea in phase. Since a portion of the pipeline alignment is within the Principal Fairways where fishing activity is prohibited, the potential impact on obstruction of fishery operation would be further reduced such that it is predicted to be insignificant.
6.5.1.2 Indirect Impact
Indirect impacts to fisheries resources and fishing operations during the construction phase include sediment release due to the “bottom-pull” or dredging works and the associated deterioration of water quality. Potential impacts on water quality from sediment release will cause an increase in suspended solids (SS) concentrations, and in turn causing a decrease in dissolved oxygen (DO) level and increases in nutrient concentrations in the water column.
Suspended Solids
Elevation
The increase in SS concentration in the water column will cause blockage of fish gills. Some fish may adapt to gradual increase of SS level by clearing their gills with water flushing over them. Where SS levels become excessive and exceed the tolerance threshold of the fish, it will swim to clearer region or becomes stressed. Different sizes and age groups of a fish species may have different tolerance thresholds. Juveniles and eggs are more susceptible to elevated SS concentration than adults. They may become stressed or even die. The effect on fish depends on the sediment releasing rate, season and duration of SS elevations. Higher SS releasing rate, longer duration of SS elevation occurring in breeding season of the fish group will result a higher impact.
No significant elevation of SS concentration for the two fish culture zones within the Study Area was predicted based on the water quality modelling results (Tables 3.18 to 3.21 in Section 3.7). The elevation of SS concentration will be confined to the dredged area. Level of SS concentration in the FCZs will comply with the relevant Water Quality Objectives (WQO) stating that “human activity should neither cause the natural ambient level to be raised by more than 30% nor give rise to accumulation of SS which may adversely affect aquatic communities”. It is also predicted that no exceedance of SS criterion (maximum concentration) will be occurred at the FCZs with reference to the value recommended by AFCD, which was identified for fisheries and selected marine ecological sensitive receivers that have been based on international marine water quality guidelines for the protection of ecosystems under the Consultancy Study on Fisheries and Marine Ecological Criteria for Impact Assessment (CCPC, 2001). The Study recommended a maximum concentration of 50 mg/L (based on half of the no observable effect concentrations).
Levels of Dissolved
Oxygen and Nutrients
Dissolved oxygen (DO) concentration would be reduced with increased SS in the water column combining with other effects. Elevated SS reduces light penetration, lowers the rate of photosynthesis by phytoplankton (primary producers) and thus lowers the rate of oxygen production in the water column. Elevated SS can also cause an increase in energy retention from sunlight, resulting higher water temperature and thus the potential for lower oxygen levels as oxygen is more soluble in cold water. Such condition has particularly an adverse effect on fish eggs and juveniles as these stages of development require high levels of oxygen in water for growth to support high metabolic rates.
High levels of nutrients such as inorganic nitrogen in seawater can cause rapid increases
in abundance of phytoplankton,
on occasions to the point where an algal bloom occurs. An intense bloom of algae can lead to sharp
decrease in the level of DO. This decrease will initially occur in the
surface water, and then deepen as dead algae fall through the water column and being decomposed at the bottom. Anoxic
conditions may result if DO concentrations are initially low or are not
replenished. This may result in the mortality of fish, especially juveniles, due to oxygen depletion.
The assessment results of dissolved oxygen have shown that
the predicted maximum decrease in DO
concentrations and increase in nutrient
levels are localised in the dredged region around the submarine
pipelines and restricted to the lower layers of the water column (i.e. close to
the seabed). Regarding the potential
impact on culture fisheries, the simulation results of DO level presented in Tables
3.26, 3.28, 3.30 and 3.32 indicate that the predicted DO level in Tung
Lung Chau and Ma Wan FCZs are non-compliance with WQO. The non-compliance of DO
levels during wet season is due to
the non-compliance of the ambient depth-averaged DO levels with the WQO. However
the decrease of DO is considered minimal and the impact due to the change of
water quality is negligible. Therefore impact to the Fish Culture Zones and
fisheries due to water quality in construction phase is not anticipated.
Contaminants
Dredging activities generating
re-suspended sediments may have the potential of the release of contaminants. Potential
indirect impact associated with contaminants to fisheries may arise as a result
of:
¡
accumulation
of contaminants in the tissue of fish and invertebrates resulting in sub-lethal
effects which may affect behaviour, reproduction and increasing susceptibility
to disease; and
¡
increased
mortality and sub-lethal effects to eggs and juvenile species, as these are
particularly sensitive to elevated contaminant concentrations (ERM, 2005).
With reference to the
elutriate test results of sediment samples from the project area (Section
3.7 of this Report), levels of trace organic contaminants (including
PCBs, PAHs, TBT and chlorinated pesticides) would not be higher than the blank results or the water quality
criteria. Moreover, it is expected that any release of heavy metals during
dredging would be quickly diluted by the large volume of marine water within
the dredging site. The release of contaminants will also be minimized by the
use of closed grab dredger. Therefore, indirect impact on the fisheries
resources from the potential release of contaminants would be very limited.
6.5.2
Operation Phase
The backfilled rock armour will not cause any impact on the fishing activities
during the operation phase, as the
seabed will be filled with rock
armour up to the same level of the existing seabed without protruding
above the adjacent seabed level. No trawling activities were identified in the
proposed reinstated region base on the Port Survey 2006 findings. Only gill netter, long liner, hand liner, purse seiner, sampan
and miscellaneous craft of not exceeding 15m in length were operated in the
6.6 Assessment of Fisheries Impacts
The fisheries impacts identified in Section 6.5 during the
construction and operation phases of the proposed submarine gas pipelines were
evaluated in accordance with Annex 9
of the EIAO-TM and presented in Table 6.1 and Table 6.2 respectively.
Table 6.1: Evaluation of Potential Fisheries Impacts during Construction Phase
|
Criteria |
Habitat Loss & Direct Injury to Fisheries Resources |
Impeded of Fishing Vessels Operation |
Indirect Impacts on Fisheries Resources and Fishing Operation |
|
Nature of Impact |
Temporary loss of fishing ground; reversible and
short term during the construction period. |
Temporary and short term in phases. |
Temporary
and short term during the construction phase. |
|
Size of Affected Area |
Seabed
area of the trench to be dredged (i.e. approximately 8.99ha). Sea surface
area of the construction barges and associated sediment curtain. |
Fishing
vessels operation will be obstructed by the construction barges and the
associated sediment curtain but exclude the area in Principle Fairway. |
Localised to the dredged areas and the waters in vicinity; no marine fish culture zone will be affected. |
|
Loss of Fisheries Resources/Production |
Constitutes a small proportion of total fisheries
resources/ production in |
Constitutes a small proportion of total fisheries
production in |
Constitutes a small proportion of total fisheries
resources/ production in |
|
Destruction and disturbance of nursery and spawning grounds |
No important
nursery and spawning grounds are identified in the affected region. |
No important
nursery and spawning grounds are identified in the affected region. |
No important nursery and spawning grounds are identified in the affected region. |
|
Impact on fishing activity |
The area to be affected is of medium to high fisheries production and value, moderate number of fishing vessels lesser than 15m in length will be affected. Impacts to fishing activities in the area due to temporary habitat loss are not expected to be significant due to the small area physically disrupted during the installation of the submarine pipeline, the short time frame of disturbance and the high mobility of the fishes that will move to adjacent waters due to habitat disturbance. |
Small number of vessels of length lesser than 15m will be affected, as the confinement of works area will be in phases and in short term. |
The area to be affected is of medium to high fisheries production and
value. Moderate
number of fishing vessels lesser than 15m in length will be affected. Impacts
to fishing activities in the area due to indirect disturbance of water
quality are expected to be localised and in short term. Impact to the pollution tolerant species
(i.e. Rabbitfish) and the high mobility fish are minor. |
|
Impact on aquaculture activity |
No direct impact on culture fisheries is anticipated as no fisheries culture zone is within the proposed works area. |
No impact on culture fisheries activity is identified for the Ma Wan and Tung Lung Chau FCZs since they far away from the proposed works area. |
No impact on culture fisheries activity is identified for the Ma Wan and Tung Lung Chau FCZs since they are far away from the proposed works area. |
Table 6.2: Evaluation of Potential Fisheries Impacts during Operation Phase
|
Criteria |
Backfilling of Seabed with Rock Armour and Disturbance Impact due to Maintenance and Repair of the Pipelines |
|
Nature of Impact |
No impact on the
fisheries is anticipated after the reinstatement of the seabed by rock
armour; no maintenance dredging is
required. |
|
Size of Affected Area |
Only the section of broken pipeline (which is anticipated to be short) will be affected |
|
Loss of Fisheries Resources/Production |
Loss of fisheries resources/production will be negligible due to the small area to be affected |
|
Destruction and disturbance of nursery and spawning grounds |
No important nursery and spawning grounds are identified in the affected region |
|
Impact on fishing activity |
Impact on future fishing operation is not anticipated as the rock armour will not protrude above the original seabed level. No operational impact is predicted since
no maintenance dredging is required. |
|
Impact on aquaculture activity |
No impact on culture fisheries is anticipated for the minor works and long distances from the Ma Wan and Tung Lung Chau FCZs. |
6.7 Mitigation of Adverse Environmental Impacts
In accordance with the guidelines in the EIAO-TM on fisheries impact assessment the general policy for mitigating impacts to fisheries, in order of priority are avoidance, minimization and compensation.
Significant Impacts
to fisheries resources and fishing operations have largely been avoided during
construction through constraints on the works operations for installation of
the submarine gas pipelines. The confinement of works area for dredging
works and pipelines installation will be in phases to minimize the impact on
marine traffic as well as fishing activities in the
To avoid accidental breakage of pipelines during the operation phase, precautionary measure will be implemented by backfilling of the pipeline trench with rock armour to the seabed level. This measure not only protects the pipelines from frequent maintenance and repairing, it also allows the recolonization of benthic fauna to the region to support the local fisheries.
6.8 Evaluation of Residual Fisheries Impacts
With the implementation of the proposed mitigation measures, the residual impact is expected to be environmentally acceptable.
6.9
Evaluation of Cumulative Fisheries Impacts
The
major marine works include trench dredging is scheduled to take place from in
April 2012. Referring to the latest construction programme of other project
within the Study Area, it is noted that construction period of other projects
listed below might overlap with this Project.
¡ Stage 1 dredging within existing seawall for berth construction for Proposed Cruise Terminal at Kai Tak
¡ Stage 1 dredging for manoeuvre basin for Phase I Berth for Proposed Cruise Terminal at Kai Tak
¡ Dredging
for seawall foundation at the former
¡ Dredging
for
¡ Dredging for providing mooring space at south-east corner of Causeway Bay Typhoon Shelter deepening the seabed level at Kai Tak Barging Point for Shatin-Central Link
¡ Dredging and sand filling for construction of immersed tube sections of Trunk Road T2
¡ Dredging
for providing Sufficient Water Depth for
With
reference to the construction programme and likely concurrent projects,
representative worst case scenario has been adopted for water quality modelling
(refer to Chapter 3 -
Water Quality Impact Assessment), including all the potentially concurrent
dredging activities envisaged during the proposed dredging works for
installation of submarine gas pipelines.
As
the above projects would also involve dredging and backfilling works, potential
cumulative impacts on fisheries would include direct impact related to loss of
fishing grounds and indirect impacts related to obstruction of fishing
operation and deterioration of water quality in the
Potential
cumulative loss of fishing grounds would be temporary and localised within the
works areas of this Project and the above projects. Obstruction of fishing
operations due to activities of dredgers for this Project and the above
projects would not be significant, as the number of fishing vessels would
constitute only a small proportion of total fishing operations in
With
the implementation of proper water quality mitigation measures stated in this
Report and the previously approved EIA reports of the above projects, potential
cumulative impact on fisheries associated with concurrent projects would be
effectively minimized. The resultant cumulative impact is expected to be
environmentally acceptable.
6.10 Environmental Monitoring and Audit
The implementation of the water quality mitigation measures stated in Section 3.8 should be checked as part of the environmental monitoring and audit procedures during the construction period as presented in the Environmental Monitoring and Audit Manual. No other fisheries-specific measures are considered necessary.
Review of existing information on fisheries resources and fishing operations located within the Study Area have been undertaken. Although the submarine pipeline trench to be formed at the seabed is relatively long, the affected area of fisheries resources is predicted to be temporary and localised to the works associated with formation of submarine pipeline trench at the seabed as a result of the “bottom-pull”, “float and sink” and dredging operations. Since there was no records of fish fry production and operation of trawlers within the proposed works area of the project, impact to fishing activities in the area are not expected to be significant owing to the small affected area and short period of disturbance during the phasing of works for dredging and installation of the submarine pipeline. Impact on future fishing operation is not anticipated as the rock armour will not protrude above the original seabed level. Ma Wan Fish Culture Zone (approximately 16km apart) and Tung Lung Chau Fish Culture Zone (approximately 9km apart) are not predicted to be impacted by either suspended solids elevation, dissolved oxygen depletion or nutrient elevation as a result of the Project. Impact to the Fish Culture Zones and fisheries due to water quality in construction phase is not anticipated.
As potential impacts to fisheries resources and fishing
operations arising from the formation
of the submarine pipeline trench at the seabed are predicted to be temporary
and localised, they are not expected to cause significant adverse impacts to any fishing grounds or species of
importance to the fishery. While no special mitigation measures are required
for fisheries resources and fishing activities, mitigation measures recommended
to control impacts to water quality to within acceptable levels are also
expected to mitigate impacts to fisheries resources and fishing activities.
AFCD. (2010a). Fisheries.
Retrieved March 22, 2010, from http://www.afcd.gov.hk
AFCD. (2010b). Port Survey 2006. Retrieved
March 22, 2010, from http://www.afcd.gov.hk
CCPC. (2001). Consultancy Study on
Fisheries and Marine Ecological Criteria for Impact Assessment: Final Report. Submitted
to AFCD of HKSAR Government.
ERM. (1998). Fisheries Resources
and Fishing Operations in Hong Kong Waters. Submitted to AFCD, HKSAR.
ERM. (2005). New Contaminated Mud
Marine Disposal Facility at Airport East/ East Sha Chau Area: EIA Report. Prepared for Civil Engineering
and Development Department of HKSAR Government.
Maunsell. (2007). Dredging Works for Proposed Cruise Terminal
at Kai Tak: Environmental Impact Assessment Report. Prepared for Civil
Engineering and Development Department of HKSAR Government.
Mott Connell.
(2005). Drainage Improvement in Tsuen Wan
and Kwai Chung – Tsuen Wan Drainage Tunnel: Environmental Impact Assessment
Report. Prepared for Drainage Services Department of HKSAR Government.