6. FISHERIES IMPACT

Introduction

6.1 This section identifies and evaluates the potential impacts on capture and culture fisheries in the assessment area resulting from the construction and operation of the Shatin to Central Link – Hung Hom to Admiralty Section (SCL (HUH-ADM)).

6.2 This assessment is based on desktop review of the latest relevant literatures. It includes a description of baseline conditions, identification and evaluation of potential impacts, and recommended mitigation measures, where necessary.

Environmental Legislation, Policies, Plans, Standards and Guidelines

6.3 This fisheries impact assessment was conducted according to criteria and guidelines set out in the Annex 9 and Annex 17 of Technical Memorandum on Environmental Impact Assessment Process (EIAO-TM) in order to provide complete and objective identification, prediction and evaluation of potential fisheries impacts arising from the Project. EIAO-TM Annex 17 sets out the methodology for assessment of fisheries impacts and Annex 9 provides the evaluation criteria.

6.4 Other local legislations that applies to fisheries and are relevant to this fisheries impact assessment include the following:

Ÿ Fisheries Protection Ordinance (Cap. 171) – aims to promote the conservation of fish and other forms of aquatic life within the Hong Kong waters by regulating fishing practices to prevent detrimental activities to the fisheries industry. The Ordinance came into effect on 30 June 1997.

Ÿ Marine Fish Culture Ordinance (Cap. 353) – regulates and protects marine fish culture by designating areas of fish culture zone, granting license, prohibiting unauthorized vessels and any deposition of chemicals or other substance which are likely to cause injury to fish in a fish culture zone. The list of designated fish culture zones was last revised in January 2000.

Ÿ The Water Pollution Control Ordinance (Cap.358) – aims to control water pollution in the waters of Hong Kong. Water control zones are designated with individual water quality objectives to promote the conservation and best use of those waters in the public interest. The most updated water quality objectives for the Victoria Harbour Water Control Zone were revised in June 1997.

Assessment Area

6.5 The assessment area for the fisheries impact is the same as that for water quality impact and includes area within the Victoria Harbour Water Control Zone (WCZ), the Eastern Buffer WCZ, the Western Buffer WCZ, as declared under the Water Pollution Control Ordinance. Areas within a distance of 300 m from the Project boundary, including works sites away from the railway route and other areas such as existing and new drainage system and any associated water system(s) affected by the construction and operation of the Project. Based on the latest design of the Project, the works site away from the railway route includes an immersed tube (IMT) casting basin at Shek O.

Assessment Methodology

6.6 Baseline information on fisheries resources in the assessment area was elucidated via a desktop review of available literatures. This review included relevant fisheries baseline data presented in Port Survey 2006 (AFCD, 2010a) and other relevant information available in other reports and publications. The information available was comprehensive and no information gaps were identified and therefore no field surveys were considered necessary.

6.7 The impact assessment followed the criteria and guidelines for evaluating and assessing fisheries impacts as stated in Annex 9 and 17 of the EIAO-TM.

Description of the Environment

Sites of Fisheries Importance

6.8 There are two mariculture areas identified in the assessment area, Tung Lung Chau Fish Culture Zone (FCZ) and Ma Wan FCZ, which are about 11 km and 14 km away from the proposed alignment of the Project, respectively. The locations of the fisheries resources are shown in Figure No. NEX2213/C/331/ENS/M51/030. Based on the findings of the literature review, no important nursery or spawning area was identified within the assessment area (AFD, 1998a).

Capture Fisheries

6.9 In 2010, the capture fishing industry landed approximately 168,000 tonnes of fisheries product valued at $2,100 million (AFCD, 2011a). The industry consisted of about 3,900 fishing vessels and 8,200 fishermen. Fishing activities were mainly conducted in the waters of the continental shelf in South China Sea. The majority of the fishing vessels were manned by family members with the assistance of hired crew. Main fishing methods included trawling, long-lining, gill-netting and purse-seining, with the majority of the total catch obtained through trawling. Some recent data on local capture fisheries industry are summarized in Table 6.1.

Table 6.1 Recent Hong Kong Capture Fisheries Industry Figures

Parameter	2010	2009	2008	2007	2006	2005	2004	2003	2002	2001
Fishing fleet size (No. of vessels)	3,900	3,700	3,800	4,000	3,950	4,150	4,300	4,600	4,470	5,100
Local fishermen engaged in capture fisheries	8,200	7,600	7,900	8,500	8,500	9,170	9,700	10,100	10,860	11,560
Production (thousand tonnes)	168	159	158	154	155	162	167.5	157.4	169.8	174
Value of produce (HK$ million)	2,100	2,000	1,780	1,530	1,600	1,600	1,600	1,500	1,600	1,700

Source: AFCD 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 and 2011a

6.10 The latest AFCD Port Survey 2006 (AFCD 2011a) provides the most updated information on capture fisheries in Hong Kong waters, including both fishing operation and fisheries production (adult fish and fry). In general, the highest fish yields in Hong Kong were obtained in the eastern waters (e.g. Tolo Harbour, Crooked Haven, Port Shelter, and Po Toi) and the southwestern waters (e.g. Lamma Island, Cheung Chau and Soko Islands).

6.11 The fishing operation within the assessment area was mainly supported by vessels of less than 15 m in length. Sampans and purse seiners were the dominant fishing vessels but other vessels such as gill netters, stern trawler, shrimp trawler, hang trawler, long liners, hand liners, and miscellaneous crafts were also operated within the assessment area. Nevertheless, no operation of trawlers was recorded within and around the proposed cross harbour section of this Project. The capture fisheries data in the assessment area are summarized in Table 6.2. The proposed dredging area for IMT laying and temporary reclamation are located in the mid Victoria Harbour, whereas the IMT casting basin is located in Tai Tam Bay.

Table 6.2 Summary of Capture Fisheries Data in the Assessment Area

Parameter	Mid Victoria Harbour^(1)	Tai Tam Bay^(1)	Eastern Victoria Harbour^(1)	Lei Yue Mun^(1)	Western Victoria Harbour^(1)	West Harbour^(1)(2)	East Lamma Channel^(1)
No. of vessels	100-400	100-400	100-400	100-400	10-100	10-400	50-400
Adult fish production in terms of weight (kg/ha)	100-400	100-400	100-400	100-400	> 0 and ≤ 100	50 - 200	50-400
Fish fry production in terms of density (tails/ha)	None reported	None reported	None reported	None reported	None reported	None reported	> 0 and ≤ 50
Annual fisheries production (adult and fry) in terms of value (HK$/ha)	5,000 – 10,000	2,000 – 5,000	5,000 – 10,000	2,000 – 10,000	> 0 to 5,000	500 – 5,000	1,000 – 5,000

Source: AFCD 2011a

Note:

(1) Geographic location refers to Figure No. NEX2213/C/331/ENS/M51/030.

(2) West Harbour included waters around Fa Peng, Pa Tau Kwu, Ma Wan, Kau Yi Chau and Sham Tseng.

6.12 The number of fishing vessels operating within the assessment area was generally between 100 and 400 vessels except the western Victoria Harbour (10 – 100 vessels), West Harbour (10 - 400 vessels) and East Lamma Channel (50 – 400 vessels).

6.13 In terms of weight, 100 – 400 kg/ha adult fish was produced in the mid Victoria Harbour, Tai Tam Bay, eastern Victoria Harbour and Lei Yue Mun. Within each water zones, adult fish production could be varied in different regions. In fact, the weight of adult fish production within the proposed cross harbour section of this Project and coastal waters off IMT casting basin ranged from 100 to 200 kg/ha (AFCD, 2010a). In western Victoria Harbour and West Harbour, adult fish productions of less than 100 kg/ha and 50-200 kg/ha were recorded respectively. 50–400 kg/ha of adult fish can be yielded in East Lamma Channel, but the area is located far away (7km) from the proposed marine-based works.

6.14 Important nursery grounds can be identified from the main areas of fry collection for the mariculture industry. Fry collection in Hong Kong has been much reduced in scale in recent years. The latest interview studies reported that fry collection only occurs in a few areas (AFCD, 2010a). The highest fry collection was mainly found in the northeast inshore waters at Three Fathoms Cove, Crooked Harbour, Double Haven and Long Harbour. These areas are all outside the assessment area. Within the assessment area, low fry collection with a density less than 50 tails/ha was identified in the northern waters of East Lamma Channel.

6.15 In terms of capture fishery production values, the mid Victoria Harbour, nearby eastern Victoria Harbour and Lei Yue Mun yielded a production of HK$5,000-10,000 per hectare annually. Whilst, Tai Tam Bay, Western Victoria Harbour, northwestern part of West Harbour and southern part of East Lamma Channel supported lower production value (less than HK5,000 per hectare annually).

6.16 Capture fisheries production of the top ten fish families within the assessment area is summarized in Table 6.3.

Table 6.3 Fisheries Production (kg/ha) of the Top Ten Families in the Assessment Area

Top ten fish families	Mid Victoria Harbour	Tai Tam Bay	Eastern Victoria Harbour	Lei Yue Mun	Western Victoria Harbour	West Harbour	East Lamma Channel
Scad (Carangidae)	≤ 5	≤ 5	≤ 5	≤ 5	≤ 5	≤ 5	≤ 5 to 40
Shrimp	None reported	≤ 5	None reported	≤ 5	≤ 5	≤ 5 to 10	≤ 5 to 20
Rabbitfish (Siganidae)	> 60	10 - 20	> 60	20 - 60	≤ 5 to 20	≤ 5 to 40	≤ 5 to 60
Squid	≤ 5	≤ 5	≤ 5	≤ 5	≤ 5	≤ 5	≤ 5 to 60
Croaker (Sciaenidae)	≤ 5	≤ 5	≤ 5	5 - 20	≤ 5 to 10	≤ 5 to 20	≤ 5 to 10
Crab	20 -40	≤ 5	20 -40	10 - 20	≤ 5	≤ 5	≤ 5
Mullet (Mugilidae)	≤ 5	≤ 5	≤ 5 to 10	≤ 5	≤ 5 to 10	≤ 5	≤ 5
Sardine (Clupeidae)	≤ 5	≤ 5	≤ 5 to 10	≤ 5 to 10	≤ 5	≤ 5	≤ 5 to 40
Seabream (Sparidae)	10 - 20	5 - 10	10 - 40	10 - 40	≤ 5	≤ 5 to 20	≤ 5
Anchovy (Engraulidae)	None reported	None reported	None reported	20-40	≤ 5	≤ 5	≤ 5

Source: AFCD 2011a

6.17 The most common capture fish along the proposed cross harbour section of the Project was the low-valued Rabbitfish (Siganidae) (AFD, 1998), followed by crab. Rabbitfish was also the most common capture fisheries in the rest of the assessment area. Apart from Rabbitfish, Scad (Carangidae), Squid and Sardine were also commonly captured in the East Lamma Channel.

6.18 According to the “Fisheries Resources and Fishing Operations in Hong Kong Waters” (AFD, 1998a), nursery areas of commercial fisheries resources were identified in Northeast Waters, Port Shelter, Lamma Island and South Lantau; whilst spawning grounds of commercial fisheries resources were identified at Northeast Waters, Eastern Waters, Southeast Hong Kong in Mirs Bay, South Lamma, South Cheung Chau, Northeast and South Lantau. No important spawning or nursery grounds for fish recruitment were identified within the assessment area.

Culture Fisheries

6.19 Marine culture fisheries included marine fish culture and oyster culture. Mariculture areas for marine fish included 26 fish culture zones (FCZs) located in various sheltered coastal areas in Hong Kong marine waters and occupied about 209 ha of marine areas with about 1,035 licensed operators in 2009 (AFCD, 2011b). Majority of the licensed farms are small, family-based and consisting of one to two rafts with average total area of around 280 m². Oyster culture has been practiced on the Deep Bay mudflats for at least 200 years. Production from oyster culture in 2010 was about 120 tonnes (meat only) valued at $8 million (AFCD, 2011b).

6.20 There are two FCZs but no oyster culture present in the assessment area. The Tung Lung Chau FCZ and Ma Wan FCZ are shown in Figure No. NEX2213/C/331/ENS/M51/030.

6.21 Although no figures are available on the individual production of FCZ, it was estimated that culture fisheries of marine fish production in 2010 was about 1,512 tonnes valued at $118 million which catered about 9% of local demand for live marine fish (AFCD, 2011b). Recent figures on marine fish culture are presented in Table 6.4.

Table 6.4 Recent Figures on Hong Kong Marine Culture Fisheries Industry

Parameter	2010	2009	2008	2007	2006	2005	2004	2003	2002	2001
No. Licensed operators	1,035	1,050	1,060	1,070	1,078	1,092	1,125	1,155	1,240	1,370
Production (tonnes)	1,512	1,437	1,370	1,532	1,490	1,540	1,540	1,490	1,211	2,470
Value (HK$ million)	118	92	82	99	89	76	79	76	57	136

Source: AFCD 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 and 2011b

6.22 The species cultured varied depending on the availability of imported fry. Common species under marine culture include green grouper, brown-spotted grouper, giant grouper, Russell's snapper, mangrove snapper, goldlined seabream, star snapper and red drum (AFCD, 2011b).

Identification, Prediction and Evaluation of Environmental Impacts

Construction Phase

6.23 The proposed marine works required under the Project might result in impacts to fisheries resources. The major marine construction activities associated with the Project would include:

Ÿ Temporary reclamation works at Hung Hom Landfall and Causeway Bay Typhoon Shelter (CBTS);

Ÿ Partial demolition and reinstatement of Hung Hom Freight Pier;

Ÿ IMT tunnel laying works within the mid Victoria Harbour between Hung Hom and Causeway Bay involve dredging activities. Provisional underwater blasting might be required at the middle of the Victoria Harbour and south of Hung Hom Landfall;

Ÿ Tunnel formation by cut and cover method from CBTS near the Police Officers’ Club (POC) to the north of the CBTS breakwater; and

Ÿ IMT casting basin at Shek O Quarry.

6.24 The potential impacts to the fisheries resources within the assessment area may include:

Ÿ Temporary loss of fishing ground;

Ÿ Loss of fish stock;

Ÿ Impact to livelihood of fishermen;

Ÿ Indirect impact on fisheries resources due to change in water quality; and

Ÿ Noise disturbance impact to fisheries resources.

6.25 As demonstrated in the ecological impact assessment (Section 5.41 to 5.42, 5.54 and 5.65 to 5.66), CBTS supported a very low diversity and abundance of marine fauna. Temporary reclamation, provision of mooring site at CBTS involving dredging activities and relocation of Royal Hong Kong Yacht Club (RHKYC) jetty are not expected to cause any loss of fishing ground or fisheries resources, although indirect impact may affect fisheries resources in nearby waters.

Direct Impact

Temporary Loss of Fishing Grounds

6.26 During construction phase, the marine-based construction works or activities and the associated diversion of the Principal Fairway where fishing is restricted would limit the access of the vessels, causing loss of fishing ground. The potentially affected fishing ground would include:

Table 6.5 Summary of Fisheries Resources Affected by the Proposed Marine-based Activities or Construction Works

Locations of fishing ground	Marine-based construction works/ activities	Size of affected area (ha)	Adult fish production in terms of weight^(^1)	Fisheries production (adult and fry) in terms of value^(^1)
Mid Victoria Harbour	Ÿ Temporary reclamation Ÿ Dredging activities Ÿ Underwater blasting Ÿ IMT laying activities	~1.5 – 5^(2)	100 – 400 kg/ha	$5,000 – 10,000/ha

Note:

(1) Refer to Section 6.13 and 6.14

(2) The construction work in Victoria Harbour would be carried out in different phases. The size of works area at each phase varied from 1.5 to 5 ha.

6.27 As described in Table 6.5, about 1.5 - 5 ha of fishing ground would be temporarily unavailable for fishing at each phase. The adult fish production and fisheries production value in the vicinity of the proposed marine-based works area generally ranged from 100 – 400 ka/ha and $2,000 – 10,000 per hectare annually. The affected areas only support an insignificant portion of the total fisheries production of Hong Kong (< 0.01%)[1]. In view of the low importance of the fishing area affected and the temporary nature of the impact, the impact to fisheries resources is considered to be minor.

Loss of Fish Stock

6.28 Underwater blasting activities might be taken place at two locations along the proposed cross harbour section of the Project to remove bedrock along the alignment: one at sea front off Hung Hom and one at the portion within the navigation channel (Figure No. NEX2213/C/331/ENS/M51/001 refers). Shock waves generated from underwater blasting could kill the fisheries resources, mainly those with air bladders (Aplin, 1946). Air bladder, blood vessels, rib and even all of the content of the body cavity of fish could be exploded. Previous study (Wright, 1982) showed that an overpressure greater than 100 kPa would result in these effects. The area with an overpressure greater than 100 kPa is known as lethal zone. Whilst, the quantity of shellfish and crustaceans including crabs killed by the detonation of explosives is believed to be negligible (Wright & Hopky, 1998).

6.29 The number of fish killed is suggested to be dependent on the fish population within the lethal zone at the time of detonation (Lewis, 1996). The size of the lethal zone, in turns, is determined by the types of explosives, the magnitude of the explosion, the dimensions of the water body (its area and depth), the nature of the seabed, the depth at which the charge is set off, and the nature and sensitivity of potentially impacted organisms (HyD, 1999). It is estimated with the standard “Hong Kong Government M&Q’s vibration empirical formula” that the setback distance (distance where the overpressure is greater than 100 kPa) for the explosives used would be 17 m and 30 m at the sea front off Hung Hom and within the navigation channel, respectively. Therefore, the size of lethal zone would be around 1.7 ha (Figure No. NEX2213/C/331/ENS/M51/001 refers).

6.30 The impact due to underwater blasting activities would be short term in nature. Underwater blasting, if needed, would be carried out tentatively one blast per 5 day cycle and occur within the 12 months excavation period. The size of lethal zone is small and large proportion of captured fish in the direct affected area consists of low-valued Rabbitfish. With a hard shell, crabs are highly resistant to shock (Lewis, 1996). Potential damage to crabs, another fisheries resources common in the affected area, is therefore considered to be minor. Since the area of fisheries habitat affected and the value of fisheries resources lost only constitute a small proportion of the total fisheries resources, the impact is considered to be minor and acceptable.

Impact to Livelihood of Fishermen

6.31 There are about 100 – 400 vessels operating in the affected area compared to 3,700 fishing vessels in Hong Kong. Most of the vessels operating there were small crafts such as sampan and cage trappers. The most common capture fish in the affected area was confined to Rabbitfish which is of relatively low economic value (FMO, 2009). Moreover, no important nursery or spawning area was identified within or in the vicinity of the works area.

6.32 Although some areas would be temporarily unavailable for fishing activities, the size of the affected area would be small. Since the construction work would be carried out in phases, the affected vessels could fish in other alternative areas in nearby waters. The affected area would be re-opened after construction phase. The impact to livelihood of the fishermen would be temporary and minor.

Indirect Impact

Changes in Water Quality

6.33 Indirect impacts on the fisheries resources would be associated with changes of water quality due to temporary reclamation, dredging, IMT tunnel construction, underwater blasting, and site runoff from land-based construction works. Details are described and evaluated below.

Elevation of Suspended Solids (SS)

6.34 SS occur naturally in the marine environment by wave action and vertical flux of water current. Fish have evolved adaptation to tolerate changes in SS, i.e. flushing water through their gills or simply moving to less turbid waters. Marine construction works, such as temporary reclamation, dredging, and blasting activities, would increase the SS level. Concentration of SS generated by dredging is expected to be higher in the immediate vicinity of the dredger. Dispersion would cause rapid decrease in SS level beyond active dredging area.

6.35 Effects of SS on fisheries resources could be lethal or sublethal through reduction in survivorship, growth rate and reproductive potential due to stress incurred by the need to constantly flush out deposited material. High SS level may clog gill structure of fish and cause physical damage and hinder transfer of oxygen. Fish egg and larval fish (fry) are more susceptible to deleterious impacts from sedimentation through smothering and clogging of their respiratory systems. Adult fish are more likely to move away when they detect certain SS level and therefore less sensitive to the effects from SS.

6.36 If SS levels exceed tolerance thresholds and the fish are unable to move away from the area, they may become stressed or even die. The rate, timing and duration of SS elevations will influence the type and extent of impacts on fish and crustaceans (CPPC, 2006). Lethal response had not been observed in adult fish at SS level less than 125 mg/L, and sublethal effects were only reported at levels exceeded 90 mg/L. However, guideline values were identified for fisheries and selected marine ecological sensitive receivers in Consultancy Study on Fisheries and Marine Ecological Criteria for Impact Assessment based on international marine water quality guidelines for the ecosystem protection. The recommended value was 50 mg/L (AFCD, 2001). Besides, the Water Quality Objective (WQO) for SS (i.e. elevation of less than 30% of ambient baseline level) is also generally applicable to fisheries sensitive receivers inside the relevant water control zones.

6.37 From the sediment plume modelling results presented in Table 11.13 and Table 11.14 of this Report, under unmitigated scenario, SS concentrations at most areas within the assessment area were predicted to be less than 50 mg/L. The exceedance would only occur near Provident Centre in North Point (maximum SS concentration: 52.97 mg/L). The affected area was predicted to be small and localized.

6.38 However, non-compliance with the WQO for SS was predicted in the Victoria Harbour (Appendices 11.9 and 11.10). SS exceedance would occur mainly at the coastal area off Hong Kong Island; under worst case scenario, exceedance was also predicted at the coastal area off Tsim Sha Tsui and Hung Hom area. However, the SS concentration is expected to decrease shortly after completion of dredging activities. The impact due to SS elevation is considered to be acceptable.

6.39 Installation of gates at the gate frames of the existing quarry for the construction of the Shek O IMT casting basin would not result in any adverse water quality impact (see Sections 11.45 – 11.47). However, activities relating to the flooding and draining of the casting basin for the removal of the formed tunnel units would have the potential to impact on water quality. It is anticipated that the large volume of water in the casting basin would tend to reduce this impact (see Section 11.180). To further reduce SS level, measures including draining washdown waters (and any concrete curing waters) to the treatment unit, settlement of washed waters prior to discharge to the sea, comply the discharge from the treatment unit with the Technical Memorandum standards for Effluents Discharged into Drains and Sewerage Systems, Inland and Coastal Waters (TM-DSS), placement of cofferdam and skimming of floating debris, would be implemented (Details refer to Sections 11.181 to 11.183). With proper implementation of the above measures, increased SS level is expected to be insignificant. Thus, no unacceptable adverse impact on fisheries resources due to the increase of SS is expected.

6.40 No important spawning or nursery grounds of commercial fish species were identified within and in the vicinity of the proposed marine works areas in Victoria Harbour, with the implementation of the proposed water quality mitigation measures in Sections 11.200 to 11.207, 11.209 to 11.211 and 11.213 of this Report, the SS elevation arising from this Project could be effectively reduced. By reducing the dredging/filling rate for IMT construction in Victoria Harbour to 2,500m³ per day (with other concurrent marine works in Victoria Harbour) or 4,500m³ per day (without other concurrent marine works in Victoria Harbour), non-compliance with the WQO for SS was predicted to be significantly reduced. In view of the temporary nature of such impact, only minor impact on capture fisheries is anticipated.

6.41 Impact to far field fisheries sensitive receivers (i.e. Tung Lung Chau FCZ and Ma Wan FCZ) is not expected as these FCZs are located outside the influence zone of the predicted sediment plumes (Appendices 11.9 and 11.10 of this Report refer). Therefore, no adverse impact at these FCZs would be expected.

Release of Contaminant from Marine Sediment

6.42 Dredging activities can potentially cause the release of contaminants from marine mud. Potential impacts on fisheries resources include the accumulation of contaminants in the tissues of fish, resulting in sublethal effects which may alter behaviour, reproduction and increase susceptibility to disease. Eggs, larvae and juveniles are particularly susceptible to the sublethal effects of contaminants, and elevated levels may lead to increased mortality. Bioaccumulation in commercially important fish species may ultimately impact human health. 

6.43 The elutriate tests have been conducted to test for heavy metals, nutrients and organic compounds, including silver, cadmium, copper, nickel, lead, chromium, arsenic, mercury, tributyltin and chlorinated pesticides in the sediment. Exceedance of water quality assessment criteria of cadmium, copper, nickel, lead, chromium, arsenic and tributyltin was found at several locations along the cross harbour section (details refer to Sections 11.164 to 11.165). Whilst, the Delft3D-WAQ model was used to determine the maximum dimensions of mixing zones for zinc, total PCBs and PAHs. Exceedance of water quality assessment criteria of zinc was found at coastal area off Hung Hom and outside CBTS (details refer to Appendices 11.11 and 11.12). Contaminants released due to the marine works could cause lethal or sublethal effects, such as growth inhibition, enzyme alteration and changes in physiological activities to fisheries resources (USEPA, 1980a, 1980b, 1980c, 1987). These could eventually lead to decreased population. Many contaminants are able to be bioaccumulated in organisms’ body and biomagnified up the food chain. Fish, as at high tropic level of the food chain, is susceptible to biomagnification. However, as discussed in Section 11.164 of this Report, it is expected that any release of heavy metals during dredging would quickly be diluted by the large volume of marine water. Chlorinated pesticides were not detected in any of the sediment and elutriate samples (Section 11.165).

6.44 In the view that mobile subtidal fauna like fish and crab is likely to avoid the dredging area and recolonize after construction works and refuge habitats would be available in nearby coastal waters for the affected resources, adverse impact due to the release of contaminant on fisheries resources would be minimal.

6.45 Wash-down, oil, grease, and concrete curing waters are considered as potential contaminants arising from flooding and draining of the casting basin. To reduce or eliminate these potential contaminants, measures including draining washdown waters (and any concrete curing waters) to the treatment unit, settlement of washed waters and oil removal prior to discharge to the sea, comply the discharge from the treatment unit with the TM-DSS, placement of cofferdam and skimming of floating debris and any oil, would be implemented (Details refer to Sections 11.180 to 11.183). With proper implementation of the above measures, the water quality impact and thus impact on fisheries resources due to the washdown, flooding and draining of the casting basin is considered acceptable.

Release of Nutrients from Marine Sediment

6.46 High nutrient levels in marine water can trigger rapid increase in phytoplankton, resulting in algal bloom. As the algae die, it will be degraded, depleting dissolved oxygen. When a large number of algae die, sudden drop in dissolved oxygen leads to suffocation of fish and other organisms. Sometimes, algal blooms are caused by phytoplankton which produces biotoxin. When degraded, toxin released could be lethal to fish.

6.47 Based on the assessment in relation to the sediment quality results, assuming that all contaminants contained in the sediments that lost to the water environment during dredging would instantaneously be released into the water column. The maximum elevations for unionized ammonia (UIA) and total inorganic nitrogen (TIN) were 0.0024 mg/L and 0.055 mg/L, respectively. All maximum elevations for UIA and TIN were small as compared to the WQO of 0.021mg/L and 0.4mg/L. Thus, it is anticipated that the dredging work would be unlikely to cause any unacceptable nutrient impact upon the receiving water and any elevations of nutrients caused by the dredging works would be transient only.

6.48 Since insignificant change in nutrient levels is expected, impact on fisheries resources would be unlikely.

Oxygen Depletion

6.49 Increase in SS in water column combining with a number of other physical or biotic factors would reduce DO in water column. Elevated SS reduces light penetration, lowers the photosynthetic rate of phytoplankton and so lowers the rate of oxygen production in water column. Also, the release of inorganic substances from the dredged sediments may cause eutrophication and algal bloom. Oxidation of dead algae may use up some of the oxygen in the water. If oxygen levels are depleted to low levels, fish, especially those in early life stages may be unable to tolerate such conditions and suffer hypoxia-induced mortality and / or stress including reduced feeding and growth rate.

6.50 Based on the results of water quality assessment (refer to Sections 11.173 to 11.174 of this Report), it is predicted that the DO level within the Harbour area would be similar to that of the baseline condition. The results comply with the WQO standard. No adverse impact on fisheries resources due to DO depletion is expected from the construction activities.

6.51 Surface runoff from land based construction activities near the coastal waters, including construction of the railway and IMT casting basin, may also lead to a deterioration of marine water quality (i.e. increased loads of suspended solid, contaminants and nutrient level) which could in turn adversely affect fisheries resources. Standard good site practice and management, and the implementation of mitigation measures, proposed in Sections 11.216 and 11.219 to 11.256 of this Report, such as the use of silt/sediment and grease traps, and effective site drainage would minimize any impacts to the marine environment resulting from land based construction activities. No adverse fisheries impact associated with the surface runoff is expected.

Noise Disturbance Impact

6.52 Apart from shock waves, underwater blasting would also generate noise. Many fishes are known to be sensitive to sounds (Tavolga, 1964; Würsig, 2000). They would minimize the use of areas affected by underwater noise. Similarly, underwater blasting, if needed, would be carried out tentatively one blast per 5 day cycle and occur within the 12 months excavation period. After the construction phase, fishes are likely to recruit the affected area. Therefore, the impact would be short term and reversible in nature. Moreover, the fisheries habitat has been subject to noisy environment due to heavy marine traffic within the Victoria Harbour. Fishes have probably been adapted to the noisy environment. Since the area of fisheries habitat affected constitutes a small proportion of the total fisheries resources, the impact is considered to be minor and acceptable.

6.53 The overall evaluation of construction phase fisheries impacts for the proposed marine works are summarized in Table 6.6 below.

Table 6.6 Summary of Potential Fisheries Impacts during Construction Phase

Criteria	Construction Phase Impact
Nature of impact	Direct impact Loss of fishing ground due to the proposed marine-based works is temporary and reversible in nature. The works areas would be re-opened for fishing after the construction phase. Loss of fisheries resources due to underwater blasting activities is reversible. Fisheries resources would recolonize the lethal zone and regenerated after the construction phase. Impact to the livelihood of fishermen is temporary and reversible. The works areas would be re-opened for fishing after the construction phase. Indirect impact Indirect impact due to change in water quality is temporary and reversible. The level of SS and DO would return to normal shortly after construction phase. The contaminants and nutrients would be diluted by large volume of water. The effect would be transient. Noise disturbance due to underwater blasting activities is temporary and reversible. Blasting activities would be intermittent.
Size of affected area	Direct impact Small. A maximum of about 5 ha of fishing ground would be temporary occupied by the construction activities. Total size of the lethal zones due to underwater blasting is predicted to be 1.7 ha. Indirect impact Small. Only very localised SS level exceedance is expected (near Provident Centre in North Point).
Loss of fisheries resources / production	Small. Temporary loss to an insignificant portion of the total fisheries production in Hong Kong is expected.
Destruction and disturbance of nursery and spawning grounds	No destruction and disturbance of important nursery and spawning grounds for commercial fisheries species.
Impact on fishing activity	Low impact. The fishing ground in Victoria Harbour where the cross harbour section of this Project is proposed supported 100 – 400 vessels and adult fish production with a weight of 100 – 400 kg/ha and valued HK$ 5,000 – 10,000/ha. Whilst, the IMT casting basin in Shek O (Tai Tam Bay) supported 100 – 400 vessels, and adult fish production with a weight of 100 – 400 kg/ha and valued HK$ 2,000 – 5,000/ha. The size of fishing ground loss is insignificant. The affected areas only support an insignificant portion of fisheries production in Hong Kong. The affected vessel could fish in other areas in nearby waters. The construction work may last for around 4 years in Victoria Harbour, but would be taken place in phase and reopen after construction.
Impact on aquaculture activity	No impact to 2 fish culture zones (Tung Lung Chau FCZ and Ma Wan FCZ) within the assessment area.
Overall fisheries Impact	Low

Operation Phase

6.54 No direct or indirect impact to the fisheries resources would be expected during operation phase. Since protective armour rock layers will be installed to prevent or minimize accidental damages of tunnel, repair works would be unlikely. The only operation impact arising from the Project would be anticipated if repair works were required, such as repairing and maintenance works for accidental damage of the tunnel.

6.55 The protective armour rock layer would protrude above the natural seabed, however, it would be kept at level below the existing Cross Harbour Tunnel except a section close to CBTS. This section would be located to the north of the CBTS breakwater and about 100 m in length. It is predicted that the armoured IMT within this section would be approximately 0.5 m higher than the existing Cross Harbour Tunnel. Graphical comparison between the levels of the top of rock armour protection of IMT and the existing Cross Harbour Tunnel and the adjacent seabed levels is shown in Appendix 6.1. The presence of the protective armour rock layers might obstruct fish trawling activities in the area. Nevertheless, since no trawling activities were identified within the footprint of the proposed cross harbour section of the Project and its vicinity based on the findings of the Port Survey 2006, the protrusion is not expected to significantly affect fishing operation in central Victoria Harbour. Therefore, impacts on fisheries resources would not be expected in the operation phase.

Mitigation of Environmental Impacts

6.56 According to the guidelines in Annex 17 of the EIAO-TM, the general policy for alleviating fisheries impacts in order of priority are avoidance, minimization and compensation.

6.57 Potential impacts on fisheries resources and fishing operations have been avoided or minimized during construction phase by minimizing the size of the dredging and underwater blasting. The dredging works will be in phases in order to minimize the impact on marine traffic as well as fishing activities in the Victoria Harbour. The mitigation measures recommended in the water quality assessment (Sections 11.200 to 11.207, 11.209 to 11.211 and 11.213 to 11.256 refers) for controlling water quality impact would serve also to protect fisheries from indirect impacts and ensure no unacceptable impact on fisheries resources and operations.

6.58 To isolate the fisheries resources away from the lethal zone, silt curtain would be deployed at near-shore to fence off fish from entering the lethal zone during underwater blasting. It should be noted that it is not feasible to deploy silt curtain or bubble curtain at offshore area particularly at Principal Fairways due to heavy marine traffic.

6.59 After completion of armour rock filling, the final surfaces of the protective armour rock layer shall be checked by ultrasonic sounding survey. Measures such as removing the rock or breaking the rock into pieces shall be implemented in case of non-compliance.

Evaluation of Cumulative Environmental Impacts

6.60 Based on the latest available information, the construction of the following projects within the assessment area would likely overlap with the construction of this Project:

· Reclamation for WDII and CWB projects (2009 – 2017);

· Dredging works for Proposed Cruise Terminal at Kai Tak (2013 – 2016);

· Marine construction works for Kai Tak Development Project (2014 – unknown);

· Installation of Submarine Gas Pipelines from Ma Tau Kok to North Point for Former Kai Tak Airport Development (New Submarine Gas Main) (2012);

· Road T2 and Central Kowloon Route (2012 – 2016);

· Laying of Western Cross Harbour Water Mains and Associated Land Mains (2010 – 2012);

· Dredging at Kwai Tsing Container Basin and its Approach Channel (unknown);

· Lei Yue Mun Waterfront Enhancement (unknown); and

· Container Terminal 10 (CT10) (unknown).

6.61 As dredging and filling activities would be required in the above projects, key issue of concern would be the cumulative effect on the deterioration of water quality in the Victoria Harbour. The worst-case scenarios of concurrent construction of other projects have been assessed in the water quality impact assessment (Section 11) and thus the cumulative impacts of this Project have been accounted for. It is predicted that, with the implementation of the recommended mitigation measures, there would be no unacceptable water quality impacts due to of the Project construction works and due to the cumulative effects from other concurrent marine construction activities (Section 11.264). As such, indirect impact on fisheries resources due to deterioration of water quality is not anticipated.

Evaluation of Residual Environmental Impacts

6.62 The identified residual impact would be the temporary occupy of approximately 1.5 to 5 ha of fishing ground in the Victoria Harbour during the construction of Project. In view of the small size and low fisheries importance of the area being temporarily occupied, the residual impact is considered acceptable.

Environmental Monitoring and Audit

6.63 As no unacceptable impacts have been predicted to occur during the construction and operation of the Project, monitoring of fisheries resources is considered not necessary. Nevertheless, the implementation of the water quality mitigation measures stated in Sections 11.200 to 11.207, 11.209 to 11.211 and 11.213 to 11.256 should be checked as part of the environmental monitoring and audit procedures during the construction phase as presented in the standalone Environmental Monitoring and Audit Manual.

Conclusion

6.64 No fish culture zones and important spawning or nursery grounds were identified within or in the vicinity of the proposed marine works area.

6.65 The Project would temporarily occupy a maximum of about 5 ha of fishing area at mid Victoria Harbour due to the immersed tube tunnel (IMT) construction works. When rockhead or boulder is encountered during tunnel laying, underwater blasting would be required and the fisheries resource within the 1.7 ha lethal zones might be affected. Silt curtain would be deployed at near-shore to minimize damage on any fisheries resource by fencing off fish from entering the lethal zone in the course of blasting. Given the temporary nature of the proposed works and low fisheries importance of the affected area, fisheries impacts is considered as minor and acceptable.

6.66 Indirect impacts due to change of water quality resulting from dredging and reclamation would be temporary and localized. Mitigation measures, such as installation of silt curtain, use of closed grab dredger and reduction of dredging rate, would be implemented to protect fisheries resources. With the proper implementation of the mitigation measures recommended, the impact due to water quality deterioration is considered to be acceptable.

6.67 No major operational phase impacts are expected. The protective armour rock layer covering the surface of the finished IMT would protrude above the natural seabed but it would largely be kept at a level below the existing Cross Harbour Tunnel to minimize impact on any potential trawling activities in Victoria Harbour.

6.68 No adverse impact on fisheries resources or activities is expected from the construction and operation phases of the Project, and therefore fisheries-specific mitigation measures and monitoring programme would not be required.

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[1]

Portion of fisheries production affected due to temporary loss of fishing ground	=	Sum of fisheries production in terms of value x Size of affected area
		Overall value of produce