.
Figure 5.3
Simplified Annual Management Regime of Commercial
Fish Pond Management
employed in Hong Kong (Source: Pers. Comm. HKNTAA)
5.8
Stage 1 - Preparation Stage
5.8.1
Drying out of pond - During harvesting the ponds are drained and
left to dry out over winter. Organic detritus that has accumulated at the base
of the pond during the previous growing season is broken down and consolidated.
This procedure reduces pathogenic bacteria and parasites from the system (Pers.
Comm., HKNTFAA).
5.8.2
Liming - Once the bottom of the pond has dried out,
lime (Calcium oxide) is applied to the bottom of the pond to:
·
neutralise
the acidity of the sediment;
·
increase
the ponds buffering capacity to changes in the pH;
·
accelerate
the decomposition rate of the organic matter; and
·
act as
a sterilising agent to kill bacteria.
5.8.3
Where
adverse pond conditions warrant it, a second application of lime is applied to
the pond later in the year (Pers. Comm. Prichard/Lai).
5.8.4
Elimination of predators - The preferred management techniques adopted
will vary with each aquaculturist. Methods include the application of
traditional teaseed cake to eliminate predators (e.g. eel, snake head or cat fish) that bury into the soft substrate
at the pond bottom, which result in substantial loss of fisheries production
and hence income. No figures are available to substantiate these losses.
5.8.5
Application of fertilisers - The application of lime is sometimes
preceded with dressing the base of the pond with an organic fertiliser. This
may include:
·
poultry
manure;
·
decaying
dead fish left over from last harvest; and
·
peanut
cake is applied to the base of ponds which are stocked predominantly with grey
mullet.
5.8.6
As the
organic fertilisers decompose, inorganic nutrients are released into the water
column which:
·
initiates
a prolific of growth of phytoplankton;
·
provides
a direct organic food supply for small invertebrates, zooplankton and insect
larvae which are a food source for species of fish reared in polyculture
systems.
5.8.7
For
example, midges (Chironomids) lay their eggs into the ponds and subsequently
their larva (blood worms) proliferate, which are consumed by cultured fish.
Blooming of a type of zooplankton (rotifer) is nutritionally important food
source consumed by Bighead.
Re-Watering
of Ponds
5.8.8
Aquaculturists
predominantly depend on rain water to fill the fish ponds, which is
supplemented by water from unpolluted water courses and adjacent fish ponds.
When water is extracted from elsewhere a net is placed over the water inlet to
preclude or minimise the number of predatory fish which enter the fish pond
that could lead loss of stock via predation over the season. Table 5.5
summarises the recommended water quality for initial commencement of culturing
at the beginning of the season (the Water Quality Chapter describes water
quality in the fish ponds). Pond water at pH below 6.5 or higher than 8.0 will
have adverse effect on the growth and reproduction of fish, however, this can
be effectively managed by the application of lime.
Table 5.5
Recommended Water
Quality Standard for Refilling Fish Ponds
|
Parameters |
Units |
|
Ammonia (as nitrogen) |
< 0.1 mg/L |
|
BOD5 |
< 10 mg/L |
|
Chlorine |
< 0.1 mg/L |
|
Chlorophyll a |
< 1 mg/L |
|
Dissolved Oxygen |
> 1 mg/L |
|
Oxidised Nitrogen (as nitrogen) |
< 5 mg/L |
|
pH |
6-8.5 |
|
Phosphate (as phosphorus) |
< 1 mg/L |
|
Salinity |
< 2 0/00 |
|
Suspended solids |
< 20 mg/L |
(Source: AFCD, 1995)
5.9
Step 2 – Fish Fry / fingerlings
·
Historical View – Fish fry are the tiny newly hatched fish less
than <1cm in length. Historically fish ponds in Hong Kong were stocked with
wild fry (e.g. Grey Mullet) caught
from the rapid coastal shores of Hong Kong. However, rapid coastal reclamation
throughout the territory together with deterioration in water quality has led
to the rapid demise of spawning and nursery grounds of commercially important
fish within the territory. These combined factors have led to a rapid decline
of a reliable supply of adequate quantities of fish fry required by local
commercial fish rearing purposes. Consequently, alternative sources are now
sought.
·
Commercial Rearing - Rearing of fish fry/ fingerlings (small
juvenile fish 2-5cm in length) to supply commercial aquaculture ventures
requires comprehensive fish hatchery equipment, intensive management, and an extensive scientific knowledge
of fisheries biology. Whilst a few local aquaculturists breed and rear fry of
Catfish, Common Carp and Snake head, such set-ups are scarce in Hong Kong. No
specific details regarding these establishments and associated costs are
available for inclusion in this report.
·
Importation from Overseas - To meet the high local demand of
commercial fish fry/ fingerlings, local aquaculturists are forced to import
fry/ fingerlings from overseas such as mainland China, Japan, Taiwan and elsewhere in South East Asia e.g. Thailand (AFCD, 1999). Table 5.6
summarises the countries from which specific species of fish fry and
fingerlings are imported.
Table 5.6
Countries from which Fish Fry and Fingerlings are Imported
|
Species of Fish |
Country Supplied
From |
|
Carp
(different species) |
China Taiwan |
|
Grey
Mullet |
China Hong
Kong Japan Taiwan |
|
Sea
Bass |
United
States of America |
|
Yellow
Croaker |
Fujian,
China |
(Source:
Pers. Comm. Prichard/Lai)
5.10
Step 3 – Stocking
·
Time of Year – More recently local aquaculturists have tended
to stock ponds with fingerlings or juvenile fish (15cm in length) since they
have a higher rate of survival and hence ultimately result in a more lucrative
financial returns (Pers. comm. Prichard/Lai). The ponds are stocked with fry or
fingerlings in Spring (February to April) to correspond with the commencement
of the growing season of fish. This provides adequate time for fish to reach a
marketable size by autumn, when they are harvested.
Stocking Regimes
5.10.1
The
stocking density and species composition vary according to the proposed culture
technique, the fry that are available from suppliers and the market demand for
particular species. With respect to the fish ponds within the Study Area ponds
located closer to the sea are used to raise higher value fish (marine species),
whilst ponds further inland are used to raise more hardy species of fish e.g. Catfish and Snakehead (Pers. comm.
Prichard/Lai).
·
Polyculture - Stocking densities of the fingerlings in the
carp polyculture ranges from 10,000-35,000 fingerlings/ha (Wilson, 1992).
Typical species stocked include: Bighead, Grass Carp and Common Carp. In
addition Silver Carp are added to maintain adequate water quality. The market
demand and hence value of Grey Mullet has increased in recent years, hence this
species is frequently reared with Carp.
·
Monoculture - Stocking densities of fingerlings in
monoculture ponds are much higher, in the range of 150,000-300,000 fingerlings/
ha. Species reared include Catfish, Sea Bass, Snakehead (refer to Table 5.4).
·
Vulnerability to Predators - Rearing of fry to fingerlings is
the most critical stage of the pond management, as the juvenile fish are very
vulnerable to predation by aquatic predators e.g. dragonfly nymph, catfish and various species of birds, notably
heron, egret and cormorant.
·
Nutrient Enrichment - At this stage of the life cycle juvenile fish
consume plankton, consequently aquaculturists frequently add wheat or soya
flakes to the ponds to enhance the nutrient levels within the pond water and
thereby increase production of plankton which is consumed by the fish.
·
Continuous Stocking – Increasingly aquaculturists that managed ponds
within the Study Area have adopted a continuous stocking management technique
in an effort to increase yields and secure a more reliable income throughout
the year. This entails continuous stocking of juvenile fish into the ponds
through out the year, and correspondingly continuously harvesting of “market
size” fish throughout the year.
5.11
Step 4 - Rearing Stage
Polyculture
·
Feeding Regimes - During February-October when fish grow rapidly
within the polyculture system the fish are fed once to twice a day, once being
the norm (Pers. comm. Prichard/Lai). Feed is typically cereal based products
(Table 5.7). Low protein feeds (e.g. rice barn) are typically added to the pond
at the beginning of the growing season when the fish are small and a large
amount of natural food is available. As the fish grow larger the pond operators
switch to feeding fish higher protein food (e.g. peanut cake). It is uncommon
for commercial feeds to be added to polyculture fish ponds in Hong Kong.
Table 5.7
Feed Types Added to Polyculture Fish Ponds
|
|
Feed |
|
Common Cereal
Based Feed |
Corn
meal Peanut cake Wheat bran Rice bran |
|
Other Types of
Feed |
Biscuit Bread Brewery
waste Instant
noodle Sorghum Soya bean |
|
Ponds in which
Grass Carp are Reared |
Grass
clippings |
·
Monitoring Behaviour of Fish - The appetite of the fish depends on
environmental temperature, oxygen levels in ponds and the quality and quantity
of feed applied. However, temperature is the predominant factor influencing the
appetite of the fish. When the temperature rises, fish consume more feed,
whilst for fish that remain in the ponds over winter their food intake is
considerably less. To avoid the pond becoming over enriched with nutrients he
aquaculturist observes the daily feeding behaviour of fish to determine the
amount of food that fish require. A considerable amount of feed remaining at
the pond bottom eight hours after feed application indicates overfeeding.
Overfeeding should be avoided as left-over feed increases the biological oxygen
demand (BOD) of sediment and result in an anoxic condition at the pond bottom.
This leads to fish dying and hence loss in revenue.
Monoculture
·
Similar
feeding regimes and management principles are applied to monoculture ponds,
with the exception that high protein commercial feeds are applied to these
ponds throughout the year.
5.12
Addition of Fertilisers
·
Requirement for Fertilisers - The dynamics of the polyculture pond system
is dependent upon autotrophic and heterotrophic food production. During the
growing season fertilisers are applied to the ponds approximately every
fortnight to maintain the nutrient content. Organic fertilisers added to the
pond include cattle, pig and poultry manure and peanut cake. Inorganic
fertilisers are rarely applied.
·
Monitoring Water Quality - The amount of fertilisers added to the pond
is critical to maintaining production and hence must be carefully managed.
During day light, plankton (microscopic free floating plants) photosynthesise
and produce oxygen. At night when photosynthesis ceases the oxygen is consumed
by living aquatic organisms including fish within the pond. In ponds where
excessive quantities of fertilizer are added, excess nutrients accumulate at
the bottom of the pond causing prolific growth and multiplication of bacteria
that reside in the detritus. Bacteria will rapidly consume the dissolved oxygen
within the pond water resulting in the production of methane and hydrogen
sulphide which are highly toxic to fish. By dawn high biological oxygen demand
(BOD) caused by bacteria will result in insufficient dissolved oxygen within
the pond to support the fish population and therefore lead to fish mortality.
·
Ammonia (NH3) – Ammonia in the pond water is produced by
fish during excretion and the decomposition of the nitrogenous compounds of the
organic fertilisers. When dissolved oxygen levels are adequate, nitrifying
bacteria convert ammonia to non-toxic nitrites and nitrates (i.e. nitrification). However, in high
density fish culture regimes combined with the addition of large quantities of
feed and organic fertilisers, ammonia concentrations may increase to levels
that are toxic to fish. This causes osmoregulatory imbalance, damage to kidneys
and gill epithelium leading to suffocation. Sub-lethal levels of ammonia cause
poor growth and reduction in tolerance to pathogens and parasites. This problem
can be resolved by continuous aeration.
·
Observation – Daily monitoring of fish behaviour by aquaculturists is the most
effective method to maintain optimum water quality. The gills of fishes are
very sensitive to environmental stresses and infection. Since fish breathe via
their gills, any abnormalities experienced (e.g.
low oxygen levels in the pond), will cause the fish to congregate at the pond
surface where the dissolved oxygen level is highest. By regularly observing the
colour and visibility of the water, and the behaviour of fish, aquaculturists
can implement corresponding treatment. These can include temporary cessation of
feeding and addition of fertilizers, initiating aeration, removal of some water
to be replaced with less nutrient rich water to effectively dilute the
phytoplankton.
5.13
Monitoring Water Levels
·
Flooding – Flooding
periodically occurs in the North West New Territories including within the
Study Area. Elevated water levels can cause the fish ponds to overflow leading
to loss of fish. During flooding episodes attempts may be made to reduce risk
of flooding by pumping water out of ponds. However, this is fruitless if
adjacent water courses also flood. Some aquaculturists place temporary mesh
fences around the perimeter of the pond in effort to retain fish within ponds
during flooding episodes (Pers. Comm., Deacon/Everitt).
·
Low Water Levels – If during the dry season the water levels become unacceptably low in
active ponds, expensive tap water is used to replenish water levels.
5.14
Predation
·
Commercial
fish ponds provide concentrated feeding opportunities for water birds. Species
include ardeids (i.e. Herons,
Egrets), however, as their beak size is relatively small they are only able to
feed on the small fingerlings at the beginning of the season. As the commercial
fish increase in size Ardeids then feed primarily on the ‘trash fish’ which are
of no commercial value. Ardeids therefore do not have significant impact on
predating on commercial species. However, Cormorants frequent the Deep Bay area
including the Study Area between October-April, during which they feed
extensively on fish ponds. In addition many of the birds feed at night or dawn,
and are therefore more difficult to control. The Hong Kong New Territories Fish
Aquaculture Association (HKNTFAA) state that aquaculturists within the Study
Area annually loose 10% of their commercial catch, which accounts for
approximately 120kg per acre to predation by birds. However, the HKNTFAA do not
retain records to account for the financial losses attributed to this loss
(Pers. comm., Prichard/Lai).
·
Historically
aquaculturists shot birds as a method to control predation, however, new
legislation renders this practice illegal. Since the designation of Mai Po
Nature Reserve in 1994 and implementation of corresponding management
techniques to protect and enhance wetland habitats and minimise disturbance,
members of the HKNTFAA have observed a distinct increase of birds frequenting
ponds within the Study Area. Many ponds are covered with netting to minimise
predation of commercial fish by birds. As an intermediate measure to manage
this issue, the World Wildlife Fund for Nature (WWF) and AFCD currently
purchase fish from members of the HKNTFAA to stock ponds managed by WWF at Mai
Po to alleviate the problem (Pers. Comm, Prichard/Woo). Both WWF and
Agriculture and Fisheries Department are currently investigating longer term
mutually acceptable management regimes to address this issue.
5.15
Step 5 -Harvesting Stage
Factors
Influencing Harvesting
5.15.1
A
number of factors influence the time at which fish are harvested including:
·
Fish reaching a marketable size i.e.
Fish that reach the optimum market size will achieve a higher market rate than
fish which are either too big or too small.
·
Market prices/ market demand – When market prices are high (e.g. around Public Holidays such as
Chinese New Year the market price for fish typically increases) correspondingly
more fish are harvested. If market prices fall aquaculturists will retain fish
in their ponds.
·
Time of Year – Harvesting typically occurs between October and March (autumn -
winter) for several reasons defined in the preceding text. However, many local
aquaculturists have more recently adopted a continuous stocking/harvesting
regime throughout the year hence it is now common practice for fish to be
harvested throughout the year. Table 5.8 summarises the typical production
period and market size of fish commonly reared in polyculture systems. During
winter the water temperature falls causing fish to loose their appetite and
correspondingly growth becomes minimal. With the exception of ponds subjected
to continuous stocking, local aquaculturists believe that there is no merit in
retaining fish in ponds over winter if no significant increase in body size and
hence market revenue is achieved. Thirdly, pond maintenance can only be carried
out during the dry season once the ponds have been drained.
Table 5.8
Production Period and
Typical Market Size of Fish Reared in
Polyculture Systems*
|
Species |
Production
Duration (Months) |
Market
Size Weight (kg) |
|
Bighead Carp |
9 – 14 |
1.0 – 2.0 |
|
Common Carp |
6 – 9 |
0.3 – 0.6 |
|
Grass Carp |
20 – 24 |
1.0 - 2.5 |
|
Grey Mullet |
7 – 12 |
0.2 – 0.6 |
|
Silver Carp |
9 – 14 |
1.0 – 2.0 |
|
Tilapia |
4 – 9 |
0.2 – 0.6 |
|
Yellow Croaker |
24** |
No data available |
(Source:
Wilson, 1992; ** Pers. Comm. Prichard/Lai)
Note: * No
comparable information available for species cultured in monoculture systems
·
Draining Ponds – For ponds that are managed following the
traditional pond management cycle at the commencement of harvesting the ponds
are gradually drained down. Water is either pumped into an adjacent pond or
alternatively discharged it into a nearby water course. The Fish are then
netted off. Ponds are typically drained down during the autumn and early
winter. With the adoption of continuous stocking/harvesting draining of ponds
may occur every two or more years (Pers. comm. Prichard/Lai).
·
Netting - A seine net is inserted into the pond and
dragged by two individuals from either side of the banks along the length of
the pond. The two ends of the net are then pulled together thereby trapping the
fish. The fish are then removed from the pond and placed in holding tanks where
they are transported in lorries to market. All fish are transported live to
market, with the exception of Grey Mullet that die once they are caught (Pers.
comm. Prichard/Lai).
·
Harvesting Duration – Aquaculturists employ temporary staff to assist during harvesting of
the fish. The duration of harvesting varies according to each individual
aquaculturist, whether the pond is stocked annual or continuously, the market
demand for fish and the availability of casual staff. Fish are harvested from
ponds gradually, as an influx of fish to the market will result in a drop in
price. More recently harvesting is being undertaken more gradually over a
duration of between 6-12 months (Pers. Comm, Prichard/Lai).
·
Feeding Opportunities of Birds – As the water is drained out of the ponds,
trash fish are exposed which create excellent feeding opportunities for water
birds (see Chapter 4, Ecology).
5.16
Step 6 - Pond Maintenance
·
Drying Out
- Over the duration that the pond is actively used, a large amount of detritus
accumulates at the base of the pond which significantly reduces both the depth
and volume capacity. Therefore following harvesting during the autumn, the pond
is drained completely. Water is pumped either into adjacent water courses or
alternatively into adjacent ponds. The base and sides of the ponds are then
allowed to dry under the sun, thereby consolidating the bottom detritus.
·
Dredging -
Once dry, these areas are then worked over with a bulldozer to redistribute the
bottom detritus allowing the organic matter to be oxidised completely. Less
frequently the base of the ponds are dredged out to increase the depth of the
pond by 0.30m to increase volume capacity. The dredged material is used to
build up the bunds around the perimeter of the ponds. These works are conducted
on a rotational basis i.e. not all
ponds are dredged in the same year. Works are typically undertaken in September
onwards. Such maintenance works were formerly conducted every two to three
years. However, due to the increased operational costs ponds are now dredged
every 3-5 years (Pers. Comm., Deacon/Everitt).
·
Maintenance Works – Approximately every three years a range of maintenance work of ponds
are carried out which include reconstruction of bunds around the circumference
of ponds using a bulldozer.
5.17
Creation of Feeding Opportunities of
Birds During Draining of Ponds
5.17.1
As
stated above, as ponds are drained down during harvesting, trash fish become
exposed which provide feeding opportunities for birds. Table 5.9 summarises the
common residual trash fish found in both monoculture and polyculture ponds. The
combined average weight per hectare of fish pond is 261.88kg/ha. Under the
current situation, the area of active fish ponds within the Study Area amounts
to 44.1ha. This provides 11,549kg/yr of trash fish. This compares with
19,311.03kg/yr of trash fish produced from the 73.7ha of active ponds within
the study area prior to November 2000. Trash fish provide feeding opportunities
for a variety of species of birds including Ardeids and Cormorants (Aspinwall
& Co, Unpublished data).
Table 5.9
Species of Trash Fish that are Commonly Found
in Fish Ponds
|
Common
Name |
Scientific
Name |
|
Mosquito Fish |
Gambusia affinis |
|
Pawn |
Macrobrachium
nipponense |
|
Tilapia |
Oreochromis
mossambicus |
(Source: Aspinwall & Co., Unpublished data)
5.18
Water Quality & Quantity
5.18.1
Water
quality of fish ponds is principally determined by acidity and alkalinity (pH),
oxygen, nutrients and salinity as described below.
·
Acidity and alkalinity (pH) - The acidity and the alkalinity of
the water is influenced by the underlying geology and soils of the catchment
area, the quantity of rainfall as well as biological activities such as
anaerobic respiration by bacteria in the water. Most organisms including fish
being reared in ponds can only tolerate a limited pH range of 6 - 8.5 (Refer to
Table 5.5) (AFD, 1995).
·
Dissolved Oxygen Level - Photosynthesis by phytoplankton and other submerged aquatic plants
produces oxygen. This is subsequently absorbed by fish via the gills and other
living organisms within the pond during respiration. Dissolved oxygen is
quantified in terms of Biochemical Oxygen
Demand (BOD) which represents the potential oxygen demand due to the
breakdown of organic matter in the water. The breakdown of organic matter
requires oxygen and the higher the level of BOD, the lower the amount of oxygen
available for plants, invertebrates and fish.
Unlike the flowing environment of a
water course where gas exchange occurs, water in fish ponds is quiescent, hence
gas exchange with the water is limited. At night when photosynthesis stops,
oxygen may be depleted as a result of respiration, while the level of oxygen
may only build up slowly during the day time. In addition, the capacity of the
water to hold dissolved oxygen decreases with increasing temperature.
Consequently by carefully monitoring the behaviour of fish aquaculturists can
implement active aeration in ponds to increase the dissolved oxygen levels in
ponds and hence minimise fish kills attributed to oxygen deficits in the pond.
·
Nutrients - The concentration of dissolved nitrogen and
phosphorous in the water column can control the development of living organisms
in ponds. Phosphorus forms insoluble salts which are unavailable to plants and
therefore can restrict growth of organisms in ponds.
Water quality can be classified
according to the concentration of nutrients:
·
Eutrophic
- Nutrient rich water
·
Oligotrophic
- Low nutrient levels
By the addition of nutrients to the
fish pond, the water body is maintained in a eutrophic state resulting in algal blooms which give the water a
green tinge. However, as stated earlier the addition of nutrients to the pond
must be carefully managed otherwise the biomass of algal will become too dense,
resulting in turbidity thereby preventing light from penetrating the water
column. If this occurs other submerged plants such as algae are unable to
photosynthesis, and consequently die and decay. The organic matter rapidly
reduces the dissolved oxygen concentration in the water, leading to fish suffocating.
·
Chemical pollutants - Toxic pollutants include heavy metals (e.g. mercury, lead and cadmium) and inorganic compounds (e.g. ammonia, cyanide, fluoride, acids
and alkalis and organic micropollutants). In sub lethal or lethal
concentrations they can cause negative impacts upon aquatic organisms. In
solution, these chemicals may be absorbed passively by plants and animals
resulting in negative impacts. If various pollutants are present
simultaneously, synergistic effects (combined effects) may occur. In addition,
environmental factors may also influence the impact of chemical pollutants. For
example:
·
the pH
of the water may influence the toxicity;
·
increasing
temperature increases toxicity; and
·
increasing
salinity decreases toxicity.
When organisms at the bottom of the
trophic food web consume contaminated food, the pollutant bioaccumulates
through the food chain. Whilst there may not be obvious evidence of changes
sub-acute impacts may occur. In addition, organisms at the beginning of the
life cycle are more sensitive to pollutants.
·
Saline Intrusion –The potential of saline intrusion was
investigated due to the proximity of ponds to the coastal area of Inner Deep
Bay, however, no saline intrusion was found (Aspinwall & Co, 1997).
·
Groundwater Intrusion – Similarly, monitoring water levels of drained ponds indicated that
ground water intrusion of fish ponds does not occur, hence fish ponds are
effectively a ‘closed loop system’.
·
Water budget – Fish ponds are effectively self-contained entities and therefore are
not subjected to the dynamic water budgets of other open system wetland
habitats. Hence the water levels are dependent on rainfall, the transfer of
water from one pond to another or, in extreme cases, when water levels drop, to
the addition of tap water.
Correspondingly water will be lost
from the fish pond via:
·
evaporation
and evapo-transpiration;
·
filtration
through permeable substrate; and
·
artificial
draining during harvesting.
Water levels will change throughout
the seasons due to rainfall and variable evaporation /evapotranspiration rates.
5.19
Socio Economic Aspects of
Aquaculture Management in Hong Kong
Land
Ownership
5.19.1
All
the fish ponds within the Study Area are located on government land. As
described at the beginning of this chapter, many of the fish ponds in the area
of the proposed Lok Ma Chau station have been vacated by the previous pond
operators. Of these 18 ponds have been drained down and the fish ponds have
been inactive for more than a year. This includes the proposed ecological
mitigation area. To the east of Lok Ma Chau Boundary Crossing, several fish
ponds remain actively managed.
Leasing
5.19.2
Ponds
located on government or privately owned land are typically leased for a 5-10
year contract, the actual duration of the contract is dependent upon each
individual lease holder. Following the expiry of the lease the majority are
renewed. Other than increased annual costs no additional clauses are added to
the lease contract, nor are any specific conditions regarding management regimes,
conduct etc cited in the lease
contract.
Costs
of Leases
5.19.3
Ten
years ago the cost of an annual lease was in the range of $7400 –
11,840/ha/annum, considerably lower than costs today. However, as the demand
for land for development in the region of the Study Area has risen sharply and
during the 1990s the local aquacultural industry was relatively profitable,
lease costs have risen sharply.
5.19.4
During
1999 aquaculturists leased ponds in the Study Area at the cost of
$14,800-16,280/ha/annum. This lease was paid to the appropriate land owner/
agent as a lump sum once a year.
5.19.5
Within
the vicinity of the Study Area ponds range in size from 0.67-2.02ha, with ponds
typically falling within the 1.0-1.35ha size range. The number of hectares of
pond leased by each aquaculturist varies considerably.
5.20
Cost of Pond Management
5.20.1
Figure
5.4 summarises the overall costs, revenue and profit
associated with managing fish ponds within the Study Area (Pers. comm. Prichard/Tam/Lai
(HKNTFAA)). The costs associated with aquaculture practices applicable to
management of ponds that will be effected by the proposed Spur Line, have
been quoted in the proceeding text are essential to demonstrate the annual
costs of operating such pond management practices. All quoted costs have been
provided by members of the Hong Kong New Territories Fish Culture Association,
and were correct in September 1999.
5.20.2
The
actual costs associated with each pond will vary according to the species being
reared and the culture technique. Since marine fish are fed predominantly
artificial feed, costs of rearing marine fish are approximately 60-70% higher
than freshwater and brackish species (refer to Table 5.10).
5.20.3
Table
5.10 summarises the initial costs for stocking ponds. Whilst costs for the
purchase of fry have been cited in Table 5.9, more recently as fish hatchery
techniques improve and suppliers stocks become more reliable and are able to
supply a greater number of fish, local aquaculturists have increasingly chosen
to purchase and stocking fingerlings (approximately 7cm in length) and juvenile
fish (approximately 12-15cm in length) as they have a higher survival rate than
fry and very juvenile fish. In addition, by initially stocking ponds with
larger fish these are less susceptible to predation by birds, hence harvest
yields and profits are proportionally higher.
5.20.4
The
costs of purchase of fish fingerlings from fish hatcheries are dependent upon
the species of fish and the length available. General costs are cited below.
·
Marine Fish - $2-2.5/fish (7.5cm in length)
·
Grey Mullet - $0.05-1.0/fish (2.5cm in length)
·
Other freshwater fish - $0.5/2.5cm of fish
5.20.5
As stated earlier, approximately
10% of the fish annually stocked in ponds are subsequently eaten by birds.
The last column of Table 5.10 equates the approximate annual financial losses
per hectare attributed to bird predation. As stated in Figure
5.4, the typical annual profit achieved following the annual harvest of
a fish pond (per hectare) is HK$44,400, consequently the losses attributed
to predation by birds and other losses e.g.
flooding are relatively high. Poaching of cultured fish does not occur in
the Lok Ma Chau area (Pers. comm. Prichard/Lai).
Figure 5.4
Breakdown of Major Costs and Associated Profits from the Management
of Fish Ponds in the Lok Ma Cha Area (Source: Pers. Comm. Tam/Prichard/HKNTFAA)
* cost of labour is not included
Table 5.10
Summary of the
Potential Financial Loss per Hectare due to
Predation by Birds
|
|
Cost Stocking
Pond/Ha (HK$) |
Equivalent 10% in Revenue/Ha
(HK$) |
|
Fry* |
20,000 |
2000 |
|
Grey Mullet
(fingerlings)** |
10,000 – 35,000 |
1000 – 3500 |
|
Marine Fish
(fingerlings) |
25000 – 87,5000 |
2500 – 8750 |
|
Other Fresh Water
Fish (Fingerlings |
60,000 – 210,000 |
6000 – 21,000 |
* Species
specific information is currently not available
** Costs
are based on the higher value previously quoted
(Source: Pers.
Comm. Prichard/Lai)
5.21
Annual Production of Fish
5.21.1
In
1994, 5000 tonnes of fresh fish were produced from fish ponds in Hong Kong.
More up to date information is currently not available (Aspinwall & Co.,
1997). Competition with other suppliers who can raise fish at far lower costs
than in Hong Kong, notably in mainland China, has resulted in local
aquaculturists’ profits declining rapidly. In the early 1990s local
aquaculturists where making 60% more profit on harvested fish than they in
1999.
5.21.2
Table
5.11 summarises the typical weight of fish harvested per acre of fish pond and
the corresponding market value. The variation in values of typical live weight
of fish harvested in the polyculture environment varies according to the amount
of fish initially stocked in the pond, management factors (e.g. feeding) and other factors that account for losses (e.g. flooding, predation by birds). The
HKNTFAA state that for the last three years market prices have been relatively
stable.
5.21.3
From
the values shown in Table 5.11 and the current area of active fish ponds within
the study area (43.3ha), the annual production of fish can be calculated to be
between 775-1,550 tonnes. This compares with 1,320-2,640 tonnes of fish from
73.74ha of active fish ponds within the Study Area, prior to November 2000.[1]
Whilst no up-to-date figures are currently available for the total fisheries
production within Hong Kong, for comparative purposes in 1994, 5,500 tonnes of
fish were produced from all fish ponds within Hong Kong.
Table 5.11
Typical Weight of Fish Harvested per hectare of Fish Pond and
Corresponding Market Value of Fish
|
Common
Species Name |
Typical
Annual Harvest Live Weight of Fish (kg/ha/yr) |
Typical
Market Wholesale Value (HK$/kg/yr) |
|
SPECIES REARED IN
POLYCULTURE SYSTEMS |
||
|
Big Head |
13,430 – 17,902 |
4.8 - 6.0 |
|
Common Carp |
13,430 – 17,902 |
4.8 - 6.0 |
|
Grass Carp |
13,430 – 17,902 |
4.8 - 6.0 |
|
Grey Mullet |
13,430 – 17,902 |
4.8 - 6.0 |
|
Mud Carp |
13,430 – 17,902 |
4.8 - 6.0 |
|
Silver Carp |
13,430 – 17,902 |
4.8 - 6.0 |
|
Tilapia |
13,430 – 17,902 |
4.8 - 6.0 |
|
SPECIES REARED IN
MONOCULTURE SYSTEMS |
||
|
Catfish |
26853 – 35,804 |
12.1 |
|
Snakehead |
35,804 |
6.1 – 9.1 |
|
Sea Bass |
17,902 |
12.1 – 18.1 |
(Source:
Pers. Comm. Prichard/Tam/Lai, HKFNTAA)
5.22
Social Aspects of Aquaculture
5.22.1
The
majority of the aquaculturists who manage the ponds present within the Study
Area:
·
Have
received no formal education
·
Do not
possess any other marketable skills
·
Choose
to work as an aquaculturists due to the traditional subsistence way of life
which is relatively unique to Hong Kong
·
Many
aquaculturists are at least 50-60 years old
·
They
do not receive either a private or state pension or government subsidy
5.22.2
As a
component of the Wetland Compensation Study (WCS) currently being undertaken on
behalf of the Agriculture, Fisheries and Conservation Department, several
community consultation sessions have been undertaken to facilitate the public
and other interested parties to contribute ideas regarding the future
management of wetland habitats (including fish ponds) in Hong Kong. During a
recent consultation exercise it was stated that aquaculture management in Hong
Kong is a traditional way of life which historically has been practiced in Hong
Kong since circa 1900s. Local aquaculturists purposely choose to pursue this
profession as they wish to follow the traditional lifestyle and would like to
continue do so.
5.22.3
As
demonstrated by the figures in Table 5.3, during a seven year period between
1987 and 1994 a total of 530ha of fish ponds were lost. In addition, as
education is now available to all of the younger generation in Hong Kong,
employment and career prospects have improved considerably. Consequently, very
few young people choose to work as aquaculturists, particularly as typical
overall annual income is relatively low (approximately $3700/month/ha of active
pond[2]).
This has led to permanent loss of this lifestyle for numerous local
aquaculturists and the rapid demise of this traditional unique cultural way of
life.
5.22.4
Local
aquaculturists do not possess any formal qualifications or alternative skills,
are of the older generation and have purposely chosen this profession as they
enjoy the traditional lifestyle and do not want to work in other professions.
If they are no longer able to practice their livelihood, due to their age, lack
of academic qualifications and skills, they may encounter difficulties in
finding alternative jobs.
5.22.5
Where
ponds are to be lost or partially lost to accommodate the construction of the
Spur Line and associated wetland compensation area, local aquaculturists
expect:
·
financial
compensation for current and future projected loss of earnings;
·
loss
of livelihood;
·
potential
forthcoming changes to their traditional way of life which is considered by
many as an important component of the cultural heritage of Hong Kong and
therefore every effort should be made to retain it; and
·
the
aquaculturists that operate in the Sheung Shui to Lok Ma Chau area wish to
continue working as aquaculturist and would welcome the opportunity of
continuing practicing their profession elsewhere in the vicinity of the Study
Area if they are forced to permanently vacate their leased land within the
Study Area.
5.23
Evaluation of Importance of Fish Pond
Aquaculture
5.23.1
On the
basis of the information cited in this chapter regarding fish pond management
and associated socio-economic issues, an overall evaluation has been prepared
in Table 5.12 using the criteria listed in Annex 9 of the EIA Ordinance Technical Memorandum as guidance.
Table 5.12
Evaluation of the Environmental and Socio-Economic Importance of Fish
Pond Aquaculture Practices in the Sheung Shui – Lok Ma Chau Area
|
Criteria |
Evaluation |
|
Size
|
44ha active fish ponds
(Prior to November 2000 area was 73.74ha) 48ha inactive fish ponds
(prior to November 2000 area was 12.04ha) |
|
Typical
Aquaculture Resources/ Production within Study Area |
Typical annual revenue
generated by fish pond is circa $192,400ha/yr whilst profit is in the range
of $44,400/ha/yr. Average
production and financial value of fisheries in the area varies according to
the species. For polyculture species live weight ranges from
13,430-17,902kg/ha/yr, whilst the market value ranges between
HK$4.8-6.0kg/ha/yr Depending on the species
reared in the monoculture system corresponding values range from 17,902 –
35,804kg/ha/yr; typical market values range from HK$6.1-18.1kg/ha/yr. Sea
Bass account for the higher market prices. The current area of 44ha
will generate between 775 and 1,550 tonnes fish annually within the study
area. Prior to November 2000, between 1100-2640 tonnes of fish were produced
annually from the 73.74ha active fish ponds within the study area. |
|
Typical
Aquaculture Production in Hong Kong as a whole |
In 1994 the 5,500,000kg (5,500
tonnes) of freshwater fish were produced in Hong Kong from fish ponds. |
|
Number
of Operating Aquaculturists with Study Area |
At
this stage of the study no specific information is currently available
regarding the number of aquaculturists who are currently actively operating
ponds within the boundaries of the study area. |
|
Impact
on Aquaculture Activity |
At present 44ha active fish
ponds and 48ha inactive fish ponds exist within the study area. Prior to
November 2000, these areas were 73.74 and 12.04ha respectively. The area of fish ponds
directly impacted amounts to 9.1ha inactive fish ponds (below the Lok Ma Chau
station footprint) and 0.4ha active and 0.1ha inactive fish ponds (primarily
under the viaduct section of the alignment). Prior to November 2000, these
areas were 0.66ha inactive fish ponds and 9.5ha of active fish ponds.
Ecological mitigation for these losses will be achieved through the formation
of an ecological compensation area comprising 27.1ha of fish ponds to the
south and west of the future Lok Ma Chau station. The ponds will be managed
for wildlife purposes, following fish farming management techniques. This
will provide an opportunity for fish pond operators within the area to return
to their profession but for a different end purpose. |
|
Overall
Evaluation |
Low to Moderate |
5.24
Identification of Potential Impacts
5.24.1
The area of fish ponds to
be lost due to the proposed development was calculated by superimposing the
construction phase footprint (i.e.
land directly and permanently altered by the project) over the habitat map.
GIS software was utilized to calculate the area of fish pond to be lost (refer
to Table 5.13). Figure 5.1 illustrates
the location of fish ponds to be lost to accommodate construction of the station
at Lok Ma Chau and supporting viaduct structures. As shown in Figure
5.1 the fish ponds located at Lok Ma Chau and San Tin are located within
the boundaries of the WCA.
5.24.2
Table
5.13 summarises the direct loss of habitats including active and inactive fish
ponds within the study area. The only location where the alignment directly
impacts fish ponds is at Lok Ma Chau/San Tin area. At Lok Ma Chau, 9.2 ha of
inactive fish ponds and 0.4 ha of active fish ponds will be lost to accommodate
construction of the station, vertical columns to support the viaduct and a
temporary works area.
Table 5.13
Long-term Estimated Direct Habitat Loss (ha) as
a Result of the
Construction of the Spur Line
|
Section |
Sheung Shui |
|
Kwu Tung/Pak
Shek Au |
Chau Tau |
Lok Ma Chau |
Total loss |
Total present
within 500 m*1 |
% Loss within
500 m |
|
Fung shui wood |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.0
|
17.81 |
2.29 |
|
Lowland secondary forest |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
15.11 |
1.94 |
|
|
0.00 |
0.00 |
0.08 |
0.00 |
0.06 |
0.14 |
32.89 |
4.22 |
|
Orchard |
0.00 |
0.00 |
0.52 |
0.00 |
0.00 |
0.52 |
10.91 |
1.40 |
|
Active dry agric. land |
0.00 |
0.00 |
0.09 |
0.00 |
0.00 |
0.09 |
34.41 |
4.42 |
|
Active wet agric. land |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
14.25 |
1.83 |
|
Inactive wet agric. land |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.64 |
0.08 |
|
Inactive dry agric. land |
0.00 |
0.00 |
0.28 |
0.27 |
0.00 |
0.55 |
19.42 |
2.49 |
|
Managed wetland |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
2.36 |
0.30 |
|
Active fish
pond |
0.00 |
0.00 |
0.00 |
0.00 |
0.40 |
0.40 |
44.12 |
5.66 |
|
Inactive fish
pond |
0.00 |
0.00 |
0.00 |
0.13 |
9.10 |
9.23 |
48.03 |
6.17 |
|
Pond |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
2.72 |
0.35 |
|
Marsh |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
1.67 |
0.21 |
|
Water courses |
0.00 |
0.00 |
0.00 |
0.04 |
0.00 |
0.04 |
56.97 |
7.31 |
|
Grass/shrub mosaic |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
0.00 |
8.05 |
1.03 |
|
Wasteland |
0.00 |
0.00 |
0.00 |
0.06 |
0.00 |
0.06 |
43.52 |
5.59 |
|
Developed areas |
0.20 |
0.00 |
1.85 |
1.10 |
0.02 |
3.17 |
426.22 |
54.71 |
Note: All values are in ha.
5.24.3
An
ecological impact assessment has previously been undertaken for fish ponds in
terms of ecology (Chapter 4 of this report). Consequently this impact
assessment focuses on the socio-economic impacts attributed to the impacted and
loss of fish ponds within the study area. For the purposes of this assessment,
the loss of fish ponds and fisheries production was calculated in two ways.
5.24.4
Under
the current circumstances, with the majority of the fish ponds within the Lok
Ma Chau area being inactive, the following impacts occur.
·
Loss of fish ponds – 9.2 ha of inactive ponds and 0.4ha of active fish ponds will be
lost from the study area.
·
Fisheries Production – the area of 0.4ha of active fish ponds results in a loss of fish
production in the area as shown in Table 5.14a and summarised below.
·
Polyculture ponds – 5.3 - 7.1 tonnes of live weight of fish
·
Monoculture ponds – 10.7 - 14.3 tonnes for Catfish, 14.3 tonnes for Snakehead, 7.1 for
Sea Bass.
5.24.5
Since
the status of abandoned ponds can change to active during the year and vice
versa, and the fish ponds within the Lok Ma Chau area became inactive due to
clearance in preparation for the ecological compensation for the Spur Line
project in November 2000, an assessment of the potential loss of fish
production was carried out. Table 5.14b summarises the estimated annual loss of
production of fisheries from the impacted area that amounts to:
·
Polyculture ponds – 129 - 172 tonnes of live weight of fish
·
Monoculture ponds – 258 - 344 tonnes for Catfish, 344 tonnes for Snakehead, 172 for Sea
Bass.
5.24.6
The
actual loss will be dependant upon species reared in particular ponds, ponds
which are managed under a monoculture system will result in a substantially
higher loss of revenue than ponds that are reared under a polyculture system.
Since specific information is currently not available as to what species,
stocking densities and cultured systems are practiced in the proposed impacted
ponds, detailed estimates can not be provided.
·
Compensation Area - As stated in the Ecology Chapter of this report, to mitigate for the
loss of habitats to accommodate construction of the proposed Spur Line and
associated works, a total of approximately 27.1 ha of fish ponds in the
Lok Ma Chau area located to the south west area of the proposed station have
been proposed to compensate for habitat lost. As a component of the proposed
management regime a number of management regimes have been recommended that
include enlarging the ponds, re-profiling bunds, planting of marginal emergent
plants, reducing the water depth, increased drain down periods and manipulating
aquaculture management regimes to optimise food availability for birds. The
proposed compensation area is currently not leased out for fish farming
activities. For effective management of the compensation habitat, the
specialist contractor contracted by KCRC to manage the fish ponds within the
compensation area (until the wetland management organisation is established) is
likely to employ local aquaculturists to implement the proposed management
regime. As stated in the Ecology Chapter, the proposed modification of
aquaculture management practices are not anticipated to cause any significant
detrimental effects on fish production or financial viability of aquaculture
management. However, more specific details are currently not available, hence
an estimate of potential socio economic impacts for the proposed compensation
area cannot be fully evaluated.
·
Loss of Livelihood – The number of aquaculturists who currently manage the scheduled
impacted ponds along the Spur Line route is currently not known, therefore it
is not feasible to assess how many local aquaculturists will be affected by the
development.
·
Decline in Availability of Seasonal Work – As shown in Figure 5.4,
during harvest time approximately 8 casual staff are hired over a 10 day duration
to assist in harvesting each pond. With a potential fishpond production area
of 9.6ha within the study area this will result in a decline in the availability
of casual seasonal work within the Lok Ma Chau area.
Table 5.14
Summary of the Potential loss of Production and Revenue Attributed to
the
Loss of Fish Ponds within the Study Area.
(a)
Loss of fisheries
production from 0.4ha actively managed fish ponds to be impacted by the Spur
Line project
|
Common
Species Name |
Typical
Annual Harvest Live Weight of Fish (kg/ha/yr) |
Approximate
Loss in Production of Live Weight Fish (tonnes)[3]
|
Typical
Market WholesaleValue(HK$/kg/yr) |
Indicative
Market Wholesale Values for the 0.4ha of Impacted Fish Ponds (HK$) |
|
POLYCULTURE
MANAGEMENT SYSTEM |
||||
|
Big Head |
13,430 – 17,902 |
5.3 – 7.1 |
4.8 - 6.0 |
32,000 – 43,000 |
|
Common Carp |
13,430 – 17,902 |
5.3 – 7.1 |
4.8 - 6.0 |
32,000 – 43,000 |
|
Grass Carp |
13,430 – 17,902 |
5.3 – 7.1 |
4.8 - 6.0 |
32,000 – 43,000 |
|
Grey Mullet |
13,430 – 17,902 |
5.3 – 7.1 |
4.8 - 6.0 |
32,000 – 43,000 |
|
Mud Carp |
13,430 – 17,902 |
5.3 – 7.1 |
4.8 - 6.0 |
32,000 – 43,000 |
|
Silver Carp |
13,430 – 17,902 |
5.3 – 7.1 |
4.8 - 6.0 |
32,000 – 43,000 |
|
Tilapia |
13,430 – 17,902 |
5.3 – 7.1 |
4.8 - 6.0 |
32,000 – 43,000 |
|
MONOCULTURE
MANAGEMENT SYSTEMS |
||||
|
Catfish |
26853 – 35,804 |
10.7 – 14.3 |
12.1 |
325,000 – 433,000 |
|
Snakehead |
35,804 |
14.3 |
6.1 – 9.1 |
218,000 – 326,000 |
|
Sea Bass |
17,902 |
7.1 |
12.1 – 18.1 |
87,000 – 130,000 |
(Source: Pers.
Comm. Prichard/Tam/Lai, HKFNTAA)
(b)
Loss of fisheries
production from 9.6ha potentially active fish ponds to be impacted by the Spur
Line project
|
Common
Species Name |
Typical
Annual Harvest Live Weight of Fish (kg/ha/yr) |
Approximate
Loss in Production of Live Weight Fish (tonnes)[4]
|
Typical
Market WholesaleValue(HK$/kg/yr) |
Indicative
Market Wholesale Value for the 9.6ha of Impacted Fish Ponds (HK$) |
|
POLYCULTURE
MANAGEMENT SYSTEM |
||||
|
Big Head |
13,430 – 17,902 |
129 – 172 |
4.8 - 6.0 |
619,200 |
|
Common Carp |
13,430 – 17,902 |
129 – 172 |
4.8 - 6.0 |
619,200 |
|
Grass Carp |
13,430 – 17,902 |
129 – 172 |
4.8 - 6.0 |
619,200 |
|
Grey Mullet |
13,430 – 17,902 |
129 – 172 |
4.8 - 6.0 |
- |
|
Mud Carp |
13,430 – 17,902 |
129 – 172 |
4.8 - 6.0 |
1,032,000 |
|
Silver Carp |
13,430 – 17,902 |
129 – 172 |
4.8 - 6.0 |
1,032,000 |
|
Tilapia |
13,430 – 17,902 |
129 – 172 |
4.8 - 6.0 |
1,032,000 |
|
MONOCULTURE
MANAGEMENT SYSTEMS |
||||
|
Catfish |
26,853 – 35,804 |
258 – 344 |
12.1 |
3,121,800 – 4,162,400 |
|
Snakehead |
35,804 |
344 |
6.1 – 9.1 |
2,098,400 – 3,130,400 |
|
Sea Bass |
17,902 |
172 |
12.1 – 18.1 |
2,081,000 – 3,113,200 |
(Source: Pers. Comm. Prichard/Tam/Lai, HKFNTAA)
5.25
Construction Phase Impacts
5.25.1
Under
the present conditions of fishpond status in the Study Area, particularly at
Lok Ma Chau, the predicted short term impacts of the construction phase of the
Spur Line project are likely to be:
·
Permanent
loss of 9.2 ha of inactive fish ponds and 0.4ha active fish ponds. Some
fish ponds to the east of the Lok Ma Chau Boundary Crossing will be temporarily
used for works and will be reinstated at a later stage.;
·
Loss
in production of fisheries and associated live weight (refer to Table 5.14a);
and
·
Temporary use of a strip
of land within actively managed fishponds beneath the viaduct as shown in
Figure 5.1. This impact is considered
to be minimal, as it is temporary and in the case of the large ponds, will
only involve removal from use of part of the pond. These ponds will be reinstated
after completion of construction.
·
Loss
of permanent employment and livelihood of full time aquaculturists and
temporary casual work.
·
Potential
impacts from site run-off on the inactive fishpond at Ho Sheung Heung during
construction of the EAP and mitigation measures to be implemented have been
described in the Water Chapter of this EIA. No impact to fisheries production
will occur.
5.26
Operation Phase
5.26.1
The
predicted long term impacts associated with the operation of the Spur Line
project are likely to be:
·
Permanent
loss of fish ponds (i.e. for works
access and storage areas);
·
Permanent
loss of fisheries production; and
·
Permanent
loss of livelihood and hence contribute to the demise of traditional of this
local cultural heritage and way of life.
5.27
Mitigation
5.27.1
A
number of measures could be implemented to mitigate for the anticipated loss of
fish ponds and socio-economic fisheries impacts which will be the
responsibility of KCRC. These are described below.
Habitat Loss
·
To
minimise habitat loss and for compatible engineering reasons, slight
realignment of the proposed track route has already been taken into
consideration as described in Chapter 2. Further adjustments to the alignment
to reduce remaining loss of fish ponds are not feasible.
·
Several
fishponds along the east side of Lok Ma Chau Boundary Crossing will be drained
and part of the pond filled to provide a working area for the contractor for
viaduct construction. The contractor access will be limited to the strip of
land through the fishpond that is required for the construction works. After
completion of construction, the contractor will reinstate the fishpond to its
original state. Temporary works areas along the remainder of the alignment do
not contain any fish ponds.
·
A
total of 9.6ha of fish ponds are scheduled to be permanently lost or disturbed
within the study area. These have been compensated for through provision of an
area to the southwest of the proposed station terminus at Lok Ma Chau. Details
of the mechanism of implementation of this compensation area are described in
the Ecology Chapter of this EIA report. As this compensation area is currently
not licensed for fish farming activities, the socio-economic impacts on the
fisheries of the area cannot be specified.
Fisheries Production & Loss of
Revenue
·
The
loss of fisheries production and associated income will be dealt with during
the resumption of temporary land during the Spur Line construction. The fish
ponds which are within the Spur Line Scheme Boundary and which are not required
for compensation at a later stage, will be reinstated and returned to the
original owners after construction is complete.
Involvement
in Management of Compensation Area
·
To
gain community support and hence a higher success of the proposed management
regime planned for the wetland compensation area, local aquaculturists should
be actively involved in the modification of the fish ponds and offered the
first choice of managing these fish ponds.
·
As
stated earlier in this chapter, currently 10% of the annual stocks are lost to
predation by birds. Mitigation measures could be developed in conjunction with
WWF (managing the nearby Ramsar Site at Mai Po) and the HKNTFAA, to integrate
management techniques that optimise feeding opportunities for birds within the
proposed wetland compensation area. Management techniques to enhance feeding
opportunities at specific times could include stocking of commercial ponds with additional fingerlings, and reducing water levels to expose more
fish. Such management regimes could be manipulated to coincide when other local
commercial aquaculturists are stocking ponds with fingerlings, to encourage
birds to feed in the compensation area and thereby lessen predation on
commercial ponds.
5.28
Summary
5.28.1
This
chapter describes fish pond aquacultural practices undertaken within the Study
Area, including current aquacultural locations, practices and quantification of
resources, and related socio-economic issues. An assessment of impacts from the
Spur Line is followed by appropriate mitigation measures. A total of 43.3ha of
active fish ponds and 48ha of inactive ponds occur within the 1km corridor of
the study area.
5.28.2
Anticipated
impacts attributed to the construction phase of the proposed works include the
permanent loss of 9.2 ha of inactive ponds and 0.4ha of active ponds. From
this small area of actively managed fish ponds, the anticipated loss of annual
fish production is in the range of 5.3 – 7.1 tonnes using the polyculture
system, or between 7.1 – 14.3 tonnes for monoculture. The equivalent commercial
market value for fisheries resources cultured using the polyculture technique
in this 0.4ha fishpond area ranges from HK$32,000 – 43,000, whilst for those
cultured under the monoculture system, the market value ranges from HK$87,000 –
433,000 depending on the species reared. The ponds in the proposed Lok Ma Chau
station area are currently inactive, as a result of clearance by DLO during the
initial proposals for The ecological compensation area. The area proposed for
compensation area is currently not licensed for fish farming activities and
therefore no socio-economic impacts can be specified.
5.28.3
Mitigation
measures include reinstatement of fish ponds temporarily impacted during works
on the viaduct. The contractor access will be limited to the area required for
the works during the contract, to minimise impacts to the fishponds.
References
AFD (1999) Website:
http://www.info.gov.hk/afd/fish/aquac.htm
Anon., (1995) Focus on Fish Ponds : VI Porcupine ! 18:19-26.
Everitt, S.. & Cook, J. (1997) Regional
Study and Workshops on Aquaculture: Sustainability and the Environment. Hong Kong Study Report. Asian
Development Bank
Personal Communication Susannah Everitt (Au Tau
Fisheries Dept. AFD)/ Richard Deacon (BBV)
Personal Communication Anna Prichard (Ecoscope)
/ Mr Lai Loy Chau (Hong Kong New Territories Fish Culture Association)
Personal
Communication Kenneth Tam (BBV) / Mr Lai Loy Chau (Hong Kong New Territories
Fish Aquaculture Association)
Wilson, K.D. (1992) Pond Fish Culture in Hong Kong. Unpublished AFD Paper.
Bibliography
Aspinwall & Co. (1997) Study on the Ecological Value of Fish Ponds in Deep Bay. Executive
Summary/ Final Report. Planning Department Hong Kong.