Fisheries Resources - Spawning and Nursery Areas
Spawning
Areas
The northern and southern Lantau waters were previously identified in 1998 as
fisheries spawning grounds for high value commercial species (Figure 10.1)
().
The key fish and crustacean species recorded in the south Lantau
spawning ground were Leiognathus brevirostris (ponyfish), Johnius belengeri (croaker), Nibea diacanthus (croaker) and Metapenaeus joyneri (prawn)
(). The main commercial fish species reported in
the north Lantau spawning area included Leiognathus brevirostris (ponyfish), Lateolabrax japonicus (sea bass/ perch) and Clupanodon punctatus (gizzard shad).
The majority of commercial species
recorded in Hong Kong aggregate and spawn in the open water during the period
from June to September ().
Some fish species reported for the spawning grounds, including Platycephalus indicus
(flathead) and Clupanodon punctatus
(gizzard shad), spawn in the late winter/early spring (i.e., February to April)
and a few are known to spawn in January.
Caranx kalla (shrimp scad)
spawns in the early summer (around June) whilst Leiognathus brevirostris (ponyfish)
and croakers were found to be reproductive throughout most of the year from May
to December. The spawning period of most
of the crustacean species, including Metapenaeus joyneri was found to be from April to November ().
The proposed LNG terminal at South Soko will occupy a
maximum of approximately 0.6 ha of reclaimed land, which will constitute <
0.003% of the total spawning area (22,000 ha) in south Lantau. A short section (< 3 km) of the proposed
submarine pipeline linking the South Soko
terminal to Black Point is also located within the identified fisheries
spawning ground in south Lantau. As shown in Figure 10.1, the proposed
submarine pipeline alignment will not pass through the north Lantau spawning ground and is > 150 m from the nearest
point of the spawning area.
Nursery Areas
The nursery ground in south Lantau was previously identified in 1998 as an important
habitat area for a number of commercial juvenile fish and crustacean species
including Oratosquilla anomala, Siganus oramin and Collichthys lucida (). Juvenile fish species have been recorded in
all seasons. Oratosquilla anomala (mantis shrimp) has been found to
be the dominant species in the spring, autumn and winter. Collichthys lucida and Siganus oramin were dominant in summer whilst Harpiosquilla harpax is
commonly found in winter. High abundance
of Sciaenid fry has also been reported in south Lantau
waters near the Soko Islands
during the summer ().
The results of recent nearshore
juvenile fish surveys at sandy beaches throughout Hong Kong recorded
comparatively high abundance of nearshore juvenile
fish at the southwestern shores of Hong Kong,
particularly Chi Ma Wan Peninsula, North Soko and
South Soko (a shore at Pak Tso
Wan) ().
The proposed South Soko
LNG terminal is expected to occupy a maximum of approximately 0.6 ha of
reclaimed land which will comprise <0.003% of the total nursery area (22,000
ha) in south Lantau.
A short section (approximately < 3 km) of the proposed submarine
pipeline linking the South Soko
terminal to Black Point is also located within the identified fisheries nursery
ground in south Lantau (Figure 10.1). The reclamation area will not directly impact
the sandy shore at Pak Tso Wan ().
10.3.3
Artificial Reef Deployment
The AFCD is undertaking a
program to enhance existing marine habitats and fisheries resources through the
siting, construction and deployment of artificial
reefs (ARs). ARs provide hard bottom, high profile habitat in areas
without natural cover and potentially act as fish enhancement devices. The ARs in the Sha
Chau & Lung
Kwu Chau Marine
Park, as depicted in Figure 10.1,
were deployed in March 2000 with the primary aim of enhancing the marine
habitat quality and fisheries resources.
Forty-two concrete-coated containers with a total volume of 940 m3
have been deployed. They are located
approximately 850 m away from the proposed submarine pipeline alignment.
10.3.4
Fisheries Importance
The importance of the fisheries resources
within the Study Area is addressed based on the baseline information provided
above. The fishing areas near South Soko are of medium
commercial value. The waters along the
proposed pipeline alignment range from low to medium in terms of commercial
fisheries value. Relatively low
commercial value was recorded around the pipeline landing site at Black Point. The catches from the waters of the Study Area
are composed of juvenile mixed species, which are used as fish feed in mariculture.
The EIAO-TM
(Annex 9) states that spawning and nursery grounds 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. Published literature from a study conducted
in 1998 identifies a spawning area in the north Lantau
waters as well as the majority of the southern waters of Hong Kong as important
for specific commercial species ()
(Figure
10.1). Consequently, these seasonal spawning grounds in
the north and south Lantau waters, as well as the
nursery area in the south Lantau waters could be
considered as important to fisheries.
10.3.5
Sensitive Receivers
Based on the preceding review of the
available information on the capture and culture fisheries of the waters of the
Study Area and its immediate vicinity, the potential sensitive receivers that
may be affected by the proposed works associated with the Project are
identified as follows:
·
Nursery areas of commercial
fisheries resources in south Lantau;
·
Spawning grounds of commercial
fisheries resources in north and south Lantau;
·
Artificial reefs in the Sha
Chau & Lung
Kwu Chau Marine
Park.
The locations of these sensitive receivers
are shown in Figure
10.1. Due to their
distance from the proposed South Soko LNG terminal
and submarine gas pipeline, the oyster production areas (> 4.5 km) and FCZs (> 15 km) are not considered to be sensitive
receivers and therefore not expected to be affected by the Project.
10.4
Fisheries Impact
Assessment Methodology
A desktop literature review was conducted
in order to establish the fisheries importance of the area surrounding the
proposed South Soko LNG terminal, the associated
submarine pipeline connection to the Black Point Power Station and the
utilities connections (water main and power cable) to Shek
Pik.
Information from the water quality assessment (Part 2 Section 6) was used to refine the size of the Study Area as
that potentially affected by perturbations of water quality parameters.
In addition to the desktop literature
review, an extensive Ichthyoplankton and Fish Post-Larvae Survey (the
Survey) was completed with the
primary aim of determining the sensitivity of the fisheries resources
potentially impacted by the construction and operation of the LNG terminal and
associated facilities. To this aim,
abundance, composition and spatial distribution of the early life stages of the
fish was assessed at a total of 20 sampling locations (Figure 1.1 - Annex 10). Two methodologies were adopted:
1. An ichthyoplankton
survey aimed at determining the abundance and species composition of fish
larval assemblages. In this stage, fish
are still in their planktonic phase and are passive
to water currents;
2. Post larval-juvenile survey aimed at
determining the abundance and species composition of post-settlement
stages. In this stage, fish are no
longer planktonic and are actively swimming.
The elaboration and assessment of the
results has allowed for a better understanding of the characteristics (i.e.,
species composition and distribution) of the spawning area identified in the
waters of southern and western Lantau (Figure 10.1). The methodology, results and conclusions of
the Survey is reported in Annex 10.
In brief, the Survey delineates a low
density of fish larvae for the five South Soko stations (SK1-SK5) both in the wet (July
- October) and dry (November -March) season with no significant difference in
vertical distribution within the water column irrespective of the day/night
cycle (Section 2.1.4 – Annex 10). The Survey portrays an overall family
composition dominated by non-commercially important families such as Clupeiform, Engraulidae and Ambassidae.
Furthermore, the Survey concludes that
there is no observable difference in fish density and eggs density between the
non-spawning/non-nursing grounds of western Lantau
and the spawning/nursing grounds of southern Hong Kong Waters allowing for a
reinterpretation of the sensitivity of the identified Sensitive Receivers. These
results will be used in the following sections to help determine the magnitude
of the potential impacts associated with the LNG terminal.
The importance of potentially impacted fishing
resources and fisheries operations identified within the Study Area was
assessed using the approach described in the EIAO-TM. The potential
impacts due to the construction and operation of the Project and associated
developments 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).
10.5
Identification of
Fisheries Impacts
10.5.1
Construction Phase
The construction activities associated
with the proposed Project that have the potential to cause impacts to fisheries
are:
·
Dredging associated with
seawall construction for the preparation of the proposed site at South Soko and the Gas
Receiving Station (GRS) at Black Point;
·
Dredging operations of the
approach channel, turning basin and berthing area for LNG carriers;
·
Dredging associated with the
installation of the submarine pipeline connecting the LNG terminal at South Soko to the power station
at Black Point;
·
Dredging operation for the
installation of a submarine power cable connecting Shek
Pik with the proposed LNG terminal at South Soko;
·
Dredging operation for the
installation of a submarine water main connecting Shek
Pik with the proposed LNG terminal at South Soko.
The activities listed above have been
subdivided in the following two categories:
1. Dredging and reclamation activities
associated with the construction and installation of the proposed LNG terminal
(i.e., site, seawater intake/outfall pipe, approach channel, turning basin and
berthing area) and GRS; and
2. Installation of the connecting gas
pipeline and the utilities (i.e., power cable and water main).
Dredging and Reclamation for the LNG
Terminal and GRS
The construction of the proposed LNG
terminal on South Soko
will involve dredging and reclamation to provide approximately 0.6 ha of
reclaimed land for the terminal and 1.1 ha of seawall modifications. Dredging will be required for those areas
within and along the turning basin, approach channel and berthing area of a
depth less than 15 m to allow the safe navigation and manoeuvring of LNG
carriers. Dredging will also be required
for the installation of the intake and outfall pipes. The GRS will be constructed on
reclaimed land adjacent to the Black Point Power Station.
Construction phase impacts to fisheries
resources and fishing operations arising from the construction works of the
proposed LNG terminal may be divided into those due to direct disturbances to
that habitat and those due to indirect perturbations to key water quality
parameters.
Direct
Impacts
Due to the small area of the marine
habitat permanently lost to reclamation, the adverse impacts to local fisheries
resources are not predicted to be significant.
It is expected that the direct impacts to fisheries resources and
fishing operations include some habitat loss due to the dredging and
reclamation works and the dredging of the approach channel, turning basin and
berthing area. The construction will
lead to the loss of approximately 0.6 ha of marine habitat due to the
reclamation and 1.1 ha of seawall modification, and a temporary interference of
approximately 51 ha due to the dredging of the navigational, manoeuvring and
berthing areas. Temporary interference of fishery habitat will also be associated
with the installation of the intake and outfall pipes.
Though a larger area of the seabed is
impacted by the dredging activities of the approach channel, turning basin and
berthing area, it is expected that the temporary nature of the interference will
not cause significant impacts on the fishery resources and activities of South Soko. The 1.1 ha of seawall modifications can be
expected to have a longer term benefit to the fisheries resources at the site
through provision of habitat that will be colonised by flora and fauna that act
as prey for fish species.
In view of the small area and the short
term nature of the loss of fisheries habitat no significant impacts are
expected to be associated with the installation of the seawater intake and
outfall pipes.
Indirect
Impacts
Indirect impacts to fisheries resources
and fishing operations during the construction phase are primarily associated
with the suspension of sediments due to the marine works. Potential impacts to water quality from
sediment release are listed below:
·
Increased concentrations of
suspended solids (SS);
·
Increased turbidity and a
resulting decrease in dissolved oxygen (DO) concentrations;
·
Increase in nutrient
concentrations in the water column.
Suspended
Solids: Suspended solids (SS) fluxes occur naturally
in the marine environment ();
consequently, fish have evolved behavioural adaptations to tolerate changes in
SS load (e.g., clearing their gills by flushing water over them). However, the increase in suspended solids
concentrations that would arise from the dredging would be uncharacteristic of
the normal variable marine conditions.
Concentrations of SS generated via dredging are expected to be greater,
particularly in the immediate vicinity of the dredger. Beyond the active dredging area, dispersion
will cause a rapid decrease in the suspended solids concentrations.
Larvae and post-juvenile fish are more
susceptible to variations in SS concentrations than more mature fish since
their sensory system is less developed.
Adult fish are more likely to move away when they detect sufficiently
elevated suspended solids concentrations and therefore are unlikely to be
significantly impacted. 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 SS level at which fish move into
clearer water is defined as the tolerance threshold and varies from species to
species at different stages of the life cycle.
If SS levels exceed tolerance thresholds and the fish are unable to move
away from the area, the fish are likely to become stressed, injured and may
ultimately die. Susceptibility to SS
generally decreases with age such that eggs are the most vulnerable and adults
the least sensitive to the effects of high SS concentrations. The rate, timing and duration of SS
elevations will influence the type and extent of impacts upon fish and
potentially crustaceans ()
().
Literature reviews indicate that lethal
responses had not been reported in adult fish at values below 125 mg
L-1 (23) and
that sublethal effects
were only observed when levels exceeded 90 mg L-1 ().(24). However, guideline
values have been identified for fisheries and selected marine ecological
sensitive receivers as part of the study for AFCD, Consultancy Study on Fisheries and Marine Ecological Criteria for
Impact Assessment (25).().
The
values are based on international marine water quality guidelines for the protection of
ecosystems The AFCD study recommends a maximum SS concentration of 50 mg L-1
(based on half of the no observable effect concentration).
Temporarily elevated levels of SS are
likely to occur in the immediate vicinity of the marine works (see Part 2 Section 6 - Water Quality Assessment). There are no predicted exceedances
of the WQO as a result of the terminal construction works. The water quality assessment has also shown that
unacceptable water quality impacts due to the release of heavy metals and
organic micro-pollutants associated with suspended sediments are not expected
to occur (see Part 2 Section 6.6.5).
Dissolved
Oxygen: The relationships between SS and DO are complex,
with increased SS in the water column combining with a number of other effects
to reduce DO concentrations. Elevated SS
(and turbidity) reduces light penetration, lowers the rate of photosynthesis by
phytoplankton (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 has the potential to consume DO in the receiving water. The resulting overall DO depletion may 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 (Part 2 Section 6)
examining the dispersion of sediment plumes associated with all marine works
has shown that the predicted maximum levels are localised. Concentrations within the Study Area as a
whole will remain compliant with the Water Quality Objectives (WQOs). The
subsequent effect on dissolved oxygen within the surrounding waters is,
therefore, predicted to be minimal.
Unacceptable impacts to fisheries from the reduction of DO concentration
are not expected to occur.
Nutrients: High levels of nutrients in seawater can cause rapid increases in
phytoplankton, on occasions to the point where an algal bloom occurs. An intense bloom of algae can lead to sharp
decreases in the levels of dissolved oxygen.
This decrease will initially occur in the surface water, and then deepen
as dead algae fall through the water column and decompose on the seabed. Anoxic conditions may result if DO
concentrations are already low or are not replenished. As discussed above, reduced levels of DO can
impact the eggs and larvae of fish and crustaceans which require high levels of
oxygen for development. Significantly
low levels of DO may also result in mortality to fish.
As with dissolved oxygen, the effect of
the localised increases in suspended solid concentrations on nutrients within
the surrounding waters is expected to be minimal (see Part Section 6).
Unacceptable impacts to fisheries are not, therefore, anticipated.
Impacts on Sensitive Receivers
Seasonal Spawning and Nursery
Grounds: The potential impacts
associated with the construction activities resulting in increased SS
concentrations in the seasonal spawning and nursery grounds in South Soko are likely to occur
in the immediate vicinity of marine works.
In addition, increases in nutrient levels and dissolved oxygen depletion
(Part Section 6.6.3) as a consequence
of SS elevations are anticipated to be small and compliant with the WQOs. It is
therefore expected that the potential impacts associated with the marine
construction activities on the seasonal spawning and nursing grounds of South Soko will be localised,
of a low severity and of a short duration.
Installation of Gas Pipeline and Utilities
As described in Section 3, the Project will include the installation of approximately
38 km of a 30” submarine gas pipeline connecting the LNG terminal at South Soko with the power
station at Black Point (Part 2 Section
3.2.6). In addition, power and water
supplies will be provided to the LNG terminal through the installation of a
submarine power cable (approximately 8 km long) and water main (approximately
7.5 km long) from south Lantau Island
(Shek Pik).
·
Gas Pipeline:
The installation of the submarine gas pipeline will involve dredging in
order to bury the pipeline to at least 3 m below the seabed. At present the design intention is that all
sections of the pipeline route will be protected to a degree. The type of protection depends on the actual
section of the route and is presently envisaged to be comprised of rock armour. The protection will not protrude above the
seabed and therefore is not expected to interfere with fishing operations.
·
Power Cable:
The majority of the submarine cable will be laid by jetting with the
exception of pre-dredged trenches at each landing point. Depending on design requirements, the burial
depth will vary. Where the burial depth
of the submarine cable is less than 5 m, a concrete slab will be used to
protect the cable. In case the burial
depth is less than 2 m, split cast iron tubes will be used together with the
concrete slab for cable protection. In
both cases the protection cover of the cable will be level with the seafloor.
·
Water Main:
The installation of the submarine water pipe will involve dredging or
jetting operations. The
dredged sections will be protected by mechanical backfilling or rock armour
will be level with the seafloor.
Direct
Impacts
No long-term direct impacts on the
fisheries resources or activities are expected to occur as a result of the installation
of the gas pipeline, the power cable and the water main.
Short-term impacts are predicted to occur
as a result of the habitat loss caused by jetting and dredging operations
associated with the installation of the lines.
It is expected that the benthic species will recolonise
the impacted areas once the marine operations have ceased and therefore,
potential impacts on the fisheries resources will be at acceptable level.
Indirect
Impacts
Indirect impacts to fisheries resources
and fishing operations during the construction phase include sediment release
associated with the jetting/dredging works.
Similar to the dredging and reclamation activities, potential impacts to
water quality from sediment release due to pipeline, power cable and water main
installation are listed below:
·
Increased concentrations of
suspended solids (SS);
·
Decrease in dissolved oxygen
(DO) concentrations; and
·
Increase in nutrient
concentrations in the water column.
The results of the water quality
assessment have shown that the predicted maximum sediment concentrations are
localised to the work area and are restricted to the lower layers of the water
column. Consequently the effects of SS on
DO and nutrient concentrations are estimated to be localised and minimal.
Impacts on Sensitive Receivers
·
Seasonal Spawning and Nursery
Grounds: The results of the water
quality assessment (Part 2 Section 6)
examining the dispersion of sediment plumes associated with the construction activities
of the pipeline, power cable and water main have shown that the predicted
maximum levels of SS are localised and of short duration. Exceedance of the
WQO for SS was predicted at Pak Tso Wan during the
dredging of the submarine gas pipeline (Part
2 Section 6.6). The SS
concentrations will be reduced through the application of silt curtains. There will be a minor temporary residual
impact which is within the fisheries tolerance criteria and hence impacts are
expected to be temporary, therefore unacceptable impacts to fisheries resources
as a result of potential elevations of SS are not expected to occur. The water quality assessment has also shown
that unacceptable water quality impacts due to the release of heavy metals and
organic micro-pollutants associated with suspended sediments are not expected
to occur (see Part 2 Section 6.6.5). Reductions in DO as well as increases in
nutrient levels are anticipated to be small and compliant with the WQO. Based on the above, no significant adverse impacts
associated with the construction of the pipeline, power cable and water main
are foreseen within the seasonal spawning and nursery grounds of Southern Lantau.
·
Artificial Reefs (ARs) in Marine Park: Impacts
to the ARs in the Sha Chau & Lung Kwu Chau Marine
Park (located
approximately 830 m from the proposed gas pipeline) are not expected to occur
as elevated levels of suspended solids meet the ecological impact assessment
criterion.
Contaminant Release
Another potential impact on fisheries
resources associated with disturbance of bottom sediment that require
assessment in accordance with Clause
3.4.6.5 of the Study Brief, are release of potential toxic
contaminants. The potential for release
of contaminants from dredged sediments has been assessed in Part 2 Section 6, whereas, a
comprehensive set of data on the quality of marine sediment is provided in Part 2 Section 7 – Waste Management.
As discussed in Part 2 Section 6 and Part 2 Section 9.7.1, unacceptable water quality
impacts due to the potential release of heavy metals and micro-organic
pollutants from the dredged sediment are not expected to occur, impacts on
fisheries resources due to bioaccumulation of released contaminants from
dredged sediments are also not expected to occur.
10.5.2
Operational Phase
The potential impacts of the Operational
Phase of the Project on the fisheries of the Study Area and the sensitive
receivers can be divided into three main categories:
·
Impacts arising from the
altered land use due to the presence of the LNG terminal, mainly loss of
fisheries habitat and the alteration of the natural marine hydrodynamic regime;
·
Impacts arising from the
alteration of the benthic habitat due to the maintenance dredging of the
approach channel and periodic disturbance caused by the LNG carrier’s passage;
·
Impacts arising from the
uptake, treatment and discharge of the seawater used in the vaporization
process, mainly physical damage to marine organisms and the alteration of the
physical and chemical parameters of the seawater.
Land Use
Habitat
Loss
The estimated overall permanent loss of
natural rocky shoreline will be approximately 265 m which is deemed to be too
small to cause any significant adverse impacts on the local fisheries. Furthermore, the artificial seawalls which
will replace the natural rocky environment will limit the impacts to the local
fish populations since the rocky boulders will counteract the initial loss of
the natural environment and provide shelter for juvenile fish.
Hydrodynamic
Regime
Impacts to fisheries
resources could potentially occur if the shape of the reclamation causes a
change to the hydrodynamic regime of the South Soko coastline. The hydrodynamic modelling (Part 2 Section 6) has indicated that the
reclamation on South Soko
will have little effect on current velocity.
Adverse impacts from changes to the hydrodynamic regime and
consequential impact to water quality are, therefore not expected to occur.
Benthic Habitat
Maintenance
Dredging
To the extent practical, the selection of
the fairway transit and approach channel for the LNG carrier was based on the
availability of the required charted water depth (approximately -15mPD). The intent is to reduce the dredging
quantities and hence impacts to water quality which will in turn serve to
reduce impacts to fisheries resources.
Maintenance dredging is anticipated to be
required at a frequency of once every ten years. No long-term direct impacts are expected to
occur from the maintenance dredging works. As a result, it is anticipated that the
fisheries resources are unlikely to be adversely affected by the maintenance dredging operations.
Carrier Passage
Carrier passage
in the dredged approach channel can potentially lead to sediment re-suspension
due to the turbulence created by the carrier’s propellers and thrusters. The disturbance of the substrate may
potentially increase the recovery time of the benthic communities which
colonize the channel, reducing their productivity.
Due to the short
term nature of the event, the small size of the area potentially impacted by
the resuspended sediments and the low frequency of
the LNG carriers passage (approximately once a week) it is expected that the
overall impact due to reduced productivity of the channel’s benthic community
will be minimal (see Marine Ecology
Impact Assessment, Part 2 Section 9).
Water Intake, Treatment and Discharge
Stored LNG will need to be re-gasified in order for it to be transported by pipeline to
the point of use. This will be accomplished
via vaporisers, which will either utilise piped seawater (in open rack
vaporisers) or hot combustion gases (referred to as submerged combined
vaporisers) to raise the temperature of the LNG to its gaseous state.
·
Open Rack Vaporisers - Open-rack vaporisers (ORVs)
are heat exchangers where seawater flows downward over the exterior vaporizer
panels while high-pressure LNG flows internally upwards. This counter current flow between the warm
seawater and cold LNG results in the vaporization or heating of the LNG. The seawater falls over the external panels
to a trough and is then discharged back to the sea. The seawater will pass through a series of
screens to remove debris to prevent blockage or damage to the seawater
pumps. Upon leaving the vaporisers, the
(cooled) seawater will be collected in a sump and discharged back to the sea
via a submarine outfall. The design
seawater temperature drop is -12.5°C at the discharge point.
·
Submerged Combined Vaporisers - In Submerged Combined Vaporisers (SCVs), the LNG is heated by flowing through tubes that are
submerged in a heated water bath.
The present design for the LNG terminal calls for ORVs as the primary vaporization method with a SCV unit as
back-up.
The intake volume and velocity of the ORV
system may have potential impacts, namely:
·
Physical alterations of the
seawater due to the heat exchange process which delivers cooler water at the
outfall location. Cooler water
potentially can impact the physiology of marine organisms (e.g. changes to
natural development and growth rates),
·
Potential physical damage to
marine organisms, particularly fish eggs and larvae, due to impingement on the
intake pipe’s protection screen and entrainment into the vaporizing system;
and,
·
Chemical alteration of seawater
due to the antifouling additives (e.g., sodium hypochlorite) which can cause
stress and potentially death to marine organisms, particularly fish eggs and
larvae, zooplankton and phytoplankton.
The potential fisheries impacts of the ORV
process are discussed in the following sections.
Discharge
of Cooled Water
Induced temperature changes to natural
aquatic habitats have been proven to have detrimental effects on the physiology
of fishes. The decline in temperature
has the potential to alter the rate of development of fish embryos, larvae and
gonad maturation. A slower growth rate
means that fish larvae remain longer in the delicate early development stages,
potentially increasing mortality (). The altered development of gonad maturation
could ultimately reduce the spawning success of fish species and the altered
mechanism of muscle development ()
could potentially reduce the chance of survival of juvenile fish.
Cooled water with a temperature of
approximately 12.5°C below ambient will be discharged from
the LNG terminal’s seawater outfall located near the bed layer of the water
column. The results of the water quality
modelling in Part 2 Section 6 have
predicted that a temperature change exceeding the WQO of +/-2°C will remain in the bed layer within
approximately 200m of the outfall in the dry season and approximately 70m in
the wet season.
The results presented in Part 2 Section 6 indicate that the
impacts to seawater temperature caused by the open circuit process are
predicted to be localised. Furthermore,
from a review of the results of the Ichthyoplankton and Fish Post-Larvae Survey presented
in Annex 10 it emerges that the
sensitivity of the fisheries resources in the proximity of the proposed LNG
terminal is medium-low due to the comparatively low density of fish larvae and
post larvae recorded, thus further reducing any potential adverse effects of
the localised temperature change.
It is therefore expected that the cooler
water discharge will not cause unacceptable impacts to the fisheries resources.
Impingement
and Entrainment
The discharge and intake points for the
seawater to be used in the proposed open circuit system will be separated to
reduce the re-circulation of the cooled water and therefore maximise the efficiency
of the heat exchange process.
In order to draw in the warmest water to
the vaporisers for optimum efficiency in the regasification
process, the seawater intake will be designed to be as high as possible within
the water column. The intake structure
is made up of a concrete tower ballasted with mass concrete connected to the
onshore seawater pump house by a submarine pipeline. The intake will be appropriately screened to
reduce the uptake of marine organisms and suspended material. From a fisheries perspective the high volume
and velocity of inflowing seawater may have negative effects on fish, fish eggs
and crustaceans due to the physical damage caused by collisions with the screen
(impingement) and due to their uptake and exposure to the vaporization process
(entrainment).
The swimming speeds of juvenile and larval
fishes vary greatly but are generally slower than the water velocity of the
intake pipe. Owing to their larger size
juvenile fish are generally more susceptible to impingement, whilst fish and
crustacean larvae and eggs, zooplankton and phytoplankton are more exposed to
entrainment, as their small size enables them to pass through the screen ()().
Whilst it is acknowledged that the uptake
of seawater for the open circuit vaporization process may minimally increase
the natural mortality rate of fish larvae, crustaceans and fish eggs due to
impingement and entrainment, it has to be noted that the significance of such
impacts is strongly dependent on the ecological sensitivity and the productivity
of the impacted area.
From a review of the results of the Ichthyoplankton and Fish Post-Larvae Survey (Annex 10) it is evident that the
sensitivity and productivity of the impacted area is medium-low due to the
comparatively low mean fish density characteristic of the South
Soko sampling stations. Furthermore, the Survey concluded that:
·
There is no significant
difference in the spatial or diurnal/nocturnal distribution of fish density and
fish egg density at the South Soko
sampling stations (Annex 10);
·
There is no significant
difference in fish density and eggs density between the identified sensitive
spawning/nursing grounds of southern Hong Kong
waters and the non spawning/nursing grounds of western Lantau.
Based on these results, it is estimated
that the sensitivity of the spawning area in correspondence of the five
sampling locations (including the sampling station at the future intake
position – SK1) is medium-low and it is predicted that no unacceptable adverse
impacts to the fisheries resources caused by impingement and entrainment will
occur.
Antifoulants
There
are potential operational issues caused by the growth or encrustation of marine
organisms on the open loop vaporization system (i.e., pipes, valves etc.). Operationally, the colonization of marine
organisms such as algae, bryozoans, molluscs and cirripedes
within cooled water circuits could result in losses in thermal efficiency and
reduced reliability of the system (including total shutdown). To counteract
settling and growth of marine organisms, cooled water circuits are typically
dosed with chemicals (usually sodium hypochlorite). Such chemicals are known as antifoulants and they inhibit the growth of organisms
within the circuit by creating unsuitable living conditions. A secondary consequence of this form of
treatment is associated with the discharge of the treated seawater into the
marine environment.
Research has been conducted
internationally on the effects of chlorine discharges on marine ecological and fisheries
resources. The
international review provides data which can be used as a benchmark to evaluate
potential impacts. Work
on the toxic effects of chlorine on fish eggs and larvae has indicated that
abnormal development may occur at concentrations of 0.31 to 0.38 mg L-1 (). (30). However, behavioural studies have indicated
that adult fish will avoid areas where concentrations of free residual chlorine
in the water exceed 0.035 mg L-1 ().(31).
The proposed LNG terminal is predicted to discharge
residual free chlorine at a concentration of < 0.30 mg L-1. This concentration is below EPD’s discharge limit of 1.0 mg L-1 ().(32).
Concentrations of residual chlorine have
been shown to diminish rapidly with time and distance from the discharge point
(). A concentration of residual chlorine of 0.01
mg L-1 (daily maximum) at the edge of the mixing zone is the
criterion used in the Water Quality
Assessment (Part 2 Section 6). The modelling exercise conducted in the assessment
indicates that maximum residual chlorine concentrations exceeding 0.01 mg L-1
are only likely to occur within 300 m of the outfall and are mainly confined to
lower layers of the water column. These
predicted increases do not exceed tolerance thresholds established in the
literature (0.02 mg L-1) and are consistent with levels recommended
in previous studies in Hong Kong (0.01 mg L-1).
Consequentially, significant impacts to
fisheries resources as a result of the discharge of chlorinated water are not
expected to occur.
Sewage
Impacts due to operational sewage
discharge on fisheries resources would not be expected as the discharge should
satisfy the requirement of WPCO-TM
effluent discharge standard (details refer to Part 2 Section 6.7.5).
Gas Pipeline
The pipeline is designed to be maintenance
free and should it require inspection this will be done internally using a
remotely operated intelligent pipe inspection gauge (PIG). Consequently, there will be no need to
disturb the seabed sediments during inspection and therefore water quality will
not be affected.
The only operational impacts from the gas
pipeline would be if repairs were required.
The impacts from this would be at a lower level than during the
construction phase, as the work would take place in a confined area. Significant impacts to fisheries resources
during the operational phase of the Project are not envisaged. Maintenance of the protection of the gas
pipeline is not required.
10.6
Assessment of
Environmental Impacts
From the
information presented above, the fisheries impact associated with the Project
is not considered to be significant. An
evaluation of the impact according to Annex
9 of the EIAO-TM is presented
below.
·
Nature of Impact: Permanent impacts will occur as a result
of the loss of approximately 0.6 ha of seabed in the area to be reclaimed for
the proposed LNG terminal in Sai Wan. 1.1 ha of seawall modifications will take
place along the shorelines in Tung Wan and Sai
Wan. Short-term impacts will occur to
fisheries resources in the vicinity of the works area as a result of the
jetting and dredging activities for the pipeline, power cable and water main
installation, dredging of seawall trenches and dredging of the navigation
channel, turning basin and berthing area.
Temporary and localised impacts to pelagic and demersal
fisheries resources as a result of perturbations to water quality are predicted
to occur only in the immediate vicinity of the works areas. Discharge of cooled water is not predicted to
pose adverse impacts to fisheries resources and discharges of residual free
chlorine will be in compliance with the EPD’s
allowable discharge limit. No
significant adverse impacts to fisheries resources are expected from the
impingement and entrainment of fish and shrimp larvae or eggs in the open
circuit vaporization system.
·
Size of Affected Area:
The main areas affected by the construction of the LNG terminal and
associated developments are a maximum of approximately 0.6 ha of marine habitat
within the south Lantau commercial fisheries spawning
and nursery areas around South Soko. 1.1 ha of seawall modifications will take
place along the shorelines in Tung Wan and Sai
Wan. The size of the area affected by
the reclamation works comprises approximately < 0.003% of the spawning area
(< 0.003% of nursery area).
Operational impacts are predicted to be within acceptable levels and
located within the immediate vicinity of the proposed LNG terminal. Adverse impacts to fisheries resulting from
the operation of the pipeline, water main and power cable are not anticipated.
·
Size of Fisheries
Resources/Production: Fisheries resources and production rates
within the Study Area range from low to medium in terms of catch weight and
value, when compared to other areas in Hong Kong.
·
Destruction and Disturbance of
Nursery and Spawning Grounds: The proposed location of the
LNG terminal at South Soko,
the short section of the submarine pipeline (< 3 km) and the full length of
the power cable and the water main are within the recognised spawning and
nursery grounds to the south of Lantau. Due to the short term temporary nature of the
disturbance, the impacts on the spawning/nursing area are not expected to be
significant. Moreover, the water quality
modelling predicts localised and short term impacts due to localised loads of
SS, DO and Nutrients in the spawning/nursing area.
·
Impact on Fishing Activity:
Due to the temporary nature of the construction activities and the small
size of the reclamation works at the proposed LNG terminal site, the impacts on
fishing activities are expected to be minimal.
Furthermore the mechanical backfill or rock armour of the pipeline,
power cable and water main will not protrude above seabed level and therefore
will not interfere with future fishing operations.
·
Impact on Aquaculture Activity:
No impact has been identified on the fish and oyster culture activity,
as temporary SS elevations are compliant with the assessment criteria, and the
fish culture zones and oyster production areas are too remote to be affected by
the works (at respective distances of > 15 km and 4.5 km).
10.7
Mitigation Measures
In accordance with the guidelines in the EIAO-TM on fisheries impact assessment, the
policy adopted in this EIA for mitigating impacts to fisheries, are:
·
Avoidance:
Potential impacts should be avoided to the maximum extent practicable by
adopting suitable alternatives;
·
Minimisation: Unavoidable
impacts should be minimised by taking appropriate and practicable measures such
as confining works in specific area or season, restoration (and possibly
enhancement) of disturbed fisheries resources and habitats;
·
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.
Construction impacts to fisheries
resources and fishing operations have largely been avoided and minimised
through the planning and design of the works; in particular those associated
with backfilling and dredging. Reclamation
impacts have been substantially reduced in the design process from
approximately 13 ha through to the adoption of two small reclamation areas at
South Soko Island totalling approximately 0.6
ha. By locating the LNG jetty along the
south coast of South Soko Island
dredging volumes have been substantially reduced from more than 5 Mm3
to less than 1.4 Mm3 at the terminal and consequently impacts to
fisheries resources have been reduced.
The main works have been designed to control water quality impacts to
within acceptable levels and are hence are also expected to control and
minimise impacts to fisheries resources.
No fisheries-specific mitigation measures or compensation are required
during construction.
Significant
operational phase impacts to fisheries resources and fishing operations are not
expected to occur. Compliance with the
relevant discharge standards to control water quality impacts to within
acceptable levels is also expected to control impacts to fisheries resources. Furthermore, entrainment of fisheries
resources will be reduced through the appropriate design of the intake screens
on the seawater intake. No additional
fisheries-specific mitigation measures or compensation are required during
operation.
10.8
Environmental
Monitoring and Audit (EM&A)
10.8.1
Construction Phase
As no unacceptable impacts have been predicted to
occur during the construction of the LNG terminal at South
Soko, monitoring of fisheries resources
during the construction phase is not considered necessary. In order to ensure that the seabed affected
by the pipeline works has restored to its original configuration to prevent
impacts from occurring to fishing operations due to changes in seabed profile,
a geophysical survey will be conducted in the post-construction phase of the
pipeline works.
10.8.2
Operation Phase
As no unacceptable impacts have been
predicted to occur during the operation of the LNG terminal at South Soko, monitoring of
fisheries resources during the operation phase is not considered necessary.
10.9
Residual Environmental
Impacts
The identified residual impact occurring
during the construction phase is the permanent loss of approximately 0.6 ha of
seabed associated with the LNG terminal reclamation. Although not implemented specifically to mitigate
the loss of fishing grounds, the construction of 1.1 ha of rubble mound
seawalls on the edges of the LNG terminal’s reclaimed land has the potential to
provide habitat and shelter for juveniles or adult fisheries resources as
ecological assemblages may eventually colonise and grow on the boulders. The enhancement effect of the seawalls will
reduce the potential impacts of the reclamation works on the local fishing
community or their individual economic losses and will not adversely affect the
fishery as a whole.
The limited habitat loss, the small-scale
nature of fishing operations and the potential environmental benefits of the
seawall combine to reduce the magnitude of this residual impact to within
acceptable levels.
10.10
Cumulative
Impacts
At present there are no committed projects
that could have cumulative impacts with the construction of the terminal at South Soko. No projects are planned to be constructed in
sufficient proximity to the Project to cause cumulative effects and hence, cumulative
impacts are not expected to occur.
10.11
Conclusions
Reviews of existing information on
commercial fisheries resources and fishing operations surrounding the waters
adjacent to the proposed South Soko LNG terminal and
along the proposed submarine pipeline, water main and cable routes have been
undertaken. Information from a study on
fishing operations in Hong Kong and the AFCD
Port Survey 2001/2002 indicate that fisheries production values in the vicinity
of the assessment area are low to medium.
Sensitive receivers including the marine waters within the Study Area,
spawning and nursery grounds in the north and south of Lantau,
ARs in the Sha Chau & Lung Kwu Chau Marine
Park have been
identified. Fish culture zones and
oyster production areas are too remote to be affected by the construction and
operation of the LNG terminal.
In addition to the desktop literature
review, an Ichthyoplankton and Fish Post-Larvae Survey (Annex 10) was completed in order to
determine the sensitivity of the fisheries resources potentially impacted. The abundance, distribution and family
composition of the early life stages of the fish were assessed at a total of 20
sampling locations. The results show a
low density of fish larvae for the five South Soko stations (SK1-SK5), both in the wet and
dry season and no significant difference in vertical distribution within the
water column irrespective of the day/night cycle. Furthermore the Ichthyoplankton and Fish Post-Larvae Survey portrays an
overall family composition dominated by non-commercially important fish (i.e., Clupeiform, Engraulidae, and Ambassidae).
Potential impacts to fisheries resources
and fishing operations, as well as impacts to fish fry, may arise from the
permanent loss of habitat due to reclamation, disturbances to benthic habitats
on which the fisheries resources depend for food, or through changes to key
water quality parameters, as a result of the marine works. Impacts arising from the proposed dredging or
jetting works are predicted to be largely confined to the specific works areas
and the predicted elevations in suspended sediment concentrations are not
predicted to cause large areal exceedances
of the assessment criterion. Adverse
impacts to water quality are not predicted and neither are consequential impacts
to any fishing grounds or species of importance to the fishery.
Significant operational phase impacts to fisheries
resources and fishing operations are not expected to occur. Entrainment of fisheries resources will be mitigated
through the appropriate design of the intake screens. Unacceptable impacts from discharges of
cooled water are not anticipated to occur as the effects from these discharges
will be localised to the lower layers of the water column in direct vicinity of
the outfall. Compliance with the
relevant discharge standards to control water quality impacts to within
acceptable levels is also expected to control impacts to fisheries resources. No additional fisheries-specific mitigation
measures are required during operation.
In order to ensure that the seabed affected by the
pipeline works has restored to its original configuration to prevent impacts
from occurring to fishing operations due to changes in seabed profile, a
geophysical survey will be conducted in the post-construction phase of the
pipeline works.
