9. FISHERIES IMPACTS

9.1 Introduction

9.1.1 This section reviews existing information on fisheries within the Assessment Area, describing positive and negative fisheries impacts associated with construction and operation of the proposed project. It also proposes mitigation measures to reduce negative impacts to within acceptable levels, and assesses the need for fisheries monitoring.

9.2 Relevant Legislation and Guidelines

9.2.1 Hong Kong SAR Government ordinances, regulations and guidelines relevant to the consideration of fisheries and mariculture under this study include the following:

9.2.2 The assessment in this chapter is conducted in accordance with the guidelines in the EIA TM, particularly Annexes 9 and 17. The EIA TM guidelines provide a systematic method for fisheries impact assessment.

9.3 Baseline Conditions

9.3.1 A literature review was conducted to determine the baseline conditions within the Assessment Area and to identify areas and species of potential fisheries importance. The review included Government and private sector reports, as well as unpublished information, including the following:

9.3.2 Evaluation of fisheries at Tai O is complicated by the fact that until 1 July 1997 Tai O fishing areas lay outside Hong Kong waters, and no fisheries surveys offshore of Tai O were conducted before that date.

9.3.3 Existing information indicated that a wide variety of fish species are exploited in north Lantau waters and hence probably in the Tai O area. The north Lantau area as a whole is fairly important on an SAR scale in terms of fish production, but is not identified as important for fry production.

9.3.4 The P4/7 became to be the most common type of fishing vessel used at Tai O in the 1990s. This is probably due to its speed, versatility, small size and shallow draft which suit conditions at Tai O.

9.3.5 As no fisheries field data were available prior to 1 July 1997, indirect information was obtained through interviews with fishermen at the port, on-board observations and helicopter surveys (AFD 1998).

9.3.6 Fisheries surveys and interviews were carried out at Tai O and Yi O to define baseline fisheries resources in Tai O Bay for an EIA study (Scott Wilson 2000). Local data on fisheries resources were provided. Fisheries surveys were conducted during spring 1999 by utilizing two fishing techniques commonly used by local fishermen, handlining and gillnetting. Surveys were conducted in Tai O Bay and the neighbouring bay of Yi O for comparison purposes. The handlining sampling resulted in a very low yield (only two fish were caught), and it was attributed to seasonal factors. Local fishermen reported that handlining catches vary significantly between seasons, and handling is not normally practised between late autumn and May. Small catches from handlining in March were thus not unexpected.

9.3.7 A total of 319 individual organisms were collected through gillnetting, representing 26 fish species and 12 crustaceans species. Species caught were common and widespread throughout Pearl River estuary waters. The most abundant species were the Horned anchovy Thrissa mystax and Pony fish Leiognathus daura. The fish Halichoeres nigrescens and the 3-spot crab Portunus sanguinolentus were also well present. The majority of fish caught were sub-adults or adults. Juvenile fish contributed only a small portion of the catches. Examination of gonads on selected fish specimens showed they had not reached the spawning stage. This suggests that Tai O is not significant as a spawning or nursery ground, at least not during the spring season.

9.3.8 Locally based fishermen were also interviewed for the above study. Most fishermen (90%) used vessels less than 30 feet (10m) in length. Gillnetting was the most common fishing method and handlining the second most commonly used. Most Tai O fishing vessels were reported to operate outside Tai O Bay. Preferred fishing sites included Mainland waters and coastal areas of western Lantau Island. Only a small number of fishermen used Tai O Bay as one of their regular fishing sites. Over half did not fish inside Tai O Bay at all, the main reason given was because of the low catches. No fish fry collection was reported in the Tai O area at the time of the study. Some fishermen reported that fish fry were collected in the Tai O area before construction of the new airport.

9.3.9 Fisheries surveys indicated that Tai O Bay is not an important fishing ground. Gillnetting surveys recorded mostly common fish species for the area, and yields were low. Catch size, number of species and species composition of catches from Tai O Bay were generally similar to those from Yi O, but catches from Yi O showed overall higher yields, numbers of individuals and numbers of species. Tai O was not reported to be one of the most popular fishing sites for Tai O based fishermen.

9.4 Sensitive receivers

9.4.1 Sensitive receivers for fisheries impact assessment are the capture fisheries at Tai O and nearby waters. This includes commercial fisheries resources (adult fish and invertebrates harvested for market) and fish and invertebrates serving as prey for commercial species.

9.5 Impact Assessment

9.5.1 The primary EIA requirement is for compilation and analysis of data, followed by assessment of impacts using TM guidelines. Assessment of fisheries impacts will be based on the following criteria described in Annex 9 of the Technical Memorandum on Environmental Impact Assessment Process:

Nature of impact;

Size of affected area;

Loss of fisheries resources/production;

Destruction and disturbance of nursery and spawning grounds;

Impact on fishing activity; and

Impact on aquaculture activity.

9.5.2 Impacts are generally ranked as "minor", "moderate" or "severe". The ranking assigned varies based on the criteria listed above. The major factors giving rise to a given ranking are noted in the text.

Construction Phase Impacts

9.5.3 No marine work or dredging will be carried out for the Project and this will minimise the potential for impacts, and the need for mitigation.

9.5.4 Economically, few or no fishers appear to depend significantly upon Tai O Bay, particularly the inner bay, for their livelihood. The selected option of discharge point is located at the mouth of Tai O Creek, adjacent to the existing stormwater pumping station near the bus terminus on the western side of Tai O, and associated construction phase impacts would be concentrated there.

9.5.5 The following construction activities are potential sources of negative impacts to fisheries:

Construction site runoff

9.5.6 Construction site runoff may adversely affect water quality in Tai O Bay if uncontrolled. Elevated suspended solids levels caused by site runoff could increase the suspended solids load in the water column, and could decrease dissolved oxygen (DO) levels. A lower DO level would affect stationary species, whilst mobile species would tend to temporarily avoid the area. The result could be a temporary reduction in fish production and fishing activity over the limited area within Tai O Bay. Impacts, however, would be concentrated within the Tai O Creek, and escape of suspended sediments outside the Tai O Bay is predicted to be limited in extent.

9.5.7 The above impacts would be short-term, localised, and temporary, and would arise in an area where seasonal fluctuation in sediment loads is characteristic due to the influence of the Pearl River.

9.5.8 Accidental spillage of chemicals and wastewater from construction activities, though unlikely, could also be classified as part of the construction site runoff. The extent of impacts would be similar to that of the construction site runoff.

9.5.9 Discharge of worker generated sewage from works sites could have negative impacts on local fisheries. Use of temporary toilet facilities would minimise impacts and workers would not be concentrated in key fishing areas.

Operational Phase Impacts

9.5.10 The export effluent will be of high quality (see Table 1.2). The pollution loading discharged from Ngong Ping STW would be small as compared to the background pollution loading, and the potential impacts on the water quality would be localized and minimal.

9.5.11 As shown in the Water Quality Assessment section of this report, the modelling results indicated that all water quality parameters at all sensitive receivers met the water quality objectives for the baseline conditions and during the operational phase. The predicted increases in pollutant levels caused by the Ngong Ping exported effluent would be minimal.

Cumulative Impacts

9.5.12 The construction of the future Tai O Boat Anchorage would involve dredging. No cumulative impacts, however, would result from these two projects as no intertidal or marine works would be required the sewerage project, and the Boat Anchorage project will be commissioned before the construction of the present project according to the available schedule from CED. The Water Quality Assessment has taken into account the boat anchorage project, and indicated that the boat anchorage would not produce significant cumulative impacts.

Mitigation Measures

9.5.13 Mitigation of construction phase and operation phase impacts was proposed according to the ranking of the potential impacts.

9.5.14 As stipulated in water quality assessment section of this report, to minimise the water quality impacts from construction site runoff and various construction activities, the practices outlined in ProPECC PN 1/94 Construction Site Drainage should be adopted.

9.5.15 As stipulated in water quality assessment section of this report, disposal of chemical wastes should be carried out in compliance with the Waste Disposal Ordinance. General requirements include:

9.5.16 As stipulated in water quality assessment section of this report, to avoid introducing additional pollution loads into the nearby waters, chemical toilets for workers sewage are recommended. Wastewater generated from kitchens should be collected in a temporary storage tank. The chemical toilets and temporary storage tank should be cleaned on a regular basis. The sewage and wastewater could be transported to the sewage treatment plants for disposal.

9.5.17 For the operation phase, as stipulated in water quality assessment section, the effluent will be of high quality and the pollution loading discharged from Ngong Ping STW would be very small as compared with the background pollution loading in Tai O Creek and Tai O Bay. It is not anticipated that the proposed discharge from the project would result in significant impacts on the receiving water bodies, including Tai O Bay and the nearby waters. No mitigation measures are required for the water quality during the operational phase.

Residual Impacts

9.5.18 Provided that all the mitigation measures during construction phase for water quality are strictly enforced, no residual impacts would be expected on the fisheries in Tai O Bay and the nearby waters.

9.5.19 Due to the level of treatment and the small additional loading during the operational phase, no impacts would be expected on fisheries.

9.6 Fisheries Monitoring

9.6.1 No marine work will be carried out during the construction phase. The potential fisheries impact will be associated with the construction site runoff. Provided that all the mitigation measures during construction phase for water quality are strictly enforced, no residual impacts would be expected on the fisheries in Tai O Bay and the nearby waters. No fisheries monitoring programme would be needed.

9.7 References Cited

AFCD. 2001. Agriculture and Fisheries Department Annual Report 1999/2000. Agriculture and Fisheries Department, Government of Hong Kong Special Administrative Region.

AFD 1998. Port Survey 1996/1997. Agriculture and Fisheries Department, Government of Hong Kong Special Administrative Region.

Scott Wilson (Hong Kong) Ltd. 1998a. Study on Tonggu Waterway. Working Paper No. 2 Part II: Ecological, Fishery, and Chinese White Dolphin Survey (Draft). Prepared for Civil Engineering Dept., Hong Kong SAR Government. Dated Oct. 1998.

Scott Wilson (Hong Kong) Ltd. 1998b. Study on Tonggu Waterway. Working Paper No. 4: Assessment Report on Chinese White Dolphin, Marine Ecology & Fisheries (Draft). Prepared for Civil Engineering Dept., Hong Kong SAR Government. Dated Oct. 1998.

Scott Wilson (Hong Kong) Ltd. 1998c. Study on Tonggu Waterway. Draft Final Report. Prepared for Civil Engineering Dept., Hong Kong SAR Government. Dated Dec. 1998.

Scott Wilson (Hong Kong) Limited. 2000. Agreement No. CE 41/98 Tai O Sheltered Boat Anchorage Environmental and Drainage Impact Assessment. Final Assessment Report. Prepared for Civil Engineering Department. May 2000