LCQ10: Red tides and massive fish deaths
It is learnt that since December last year, severe red tides have repeatedly occurred in Tolo Harbour in Tai Po and neighbouring waters, resulting in massive fish deaths in the marine fish culture farms there. Massive fish deaths were also found along Shing Mun River in Sha Tin. Some mariculturists consider that the Government's current mechanism for monitoring red tides and its investigations into the causes of massive fish deaths are in need of improvement, and the assistance it provided to affected mariculturists is also insufficient. In this connection, will the Government inform this Council:
(1) given that the authorities have merely confirmed after tests that the red tides mainly comprised Karenia mikimotoi without explaining the causes of their formation, and some mariculturists suspect that the occurrence of red tides was related to the use of mosquito control pesticides and the discharge of sewage not properly treated, whether the authorities have studied the relationship between the formation of red tides and sewage discharge as well as mosquito control pesticides; of the monthly average quantities of mosquito control pesticides used along Lam Tsuen River and Shing Mun River for carrying out anti-mosquito operations in the past three years and the composition of such pesticides; how such quantities compare with those used in other watercourses; whether they have assessed the impacts of mosquito control pesticides on the marine ecological environment and the mariculture industry; if they have assessed, of the details; if not, the reasons for that; whether the authorities have obtained any latest investigation result showing that apart from the red tides comprising Karenia mikimotoi, there were other causes for the aforesaid massive fish deaths in waters around Tolo Harbour; if they have, of the details; if not, the reasons for that;
(2) as some mariculturists have relayed to me that this year, mariculturists affected by the massive fish deaths were given only a grant of $6,780 and a special grant of $7,260 under the "Emergency Relief Fund", making a relief fund of only $14,040 in total, which reflects that the assistance provided under the current mechanism is just a drop in the bucket for what is needed for them to resume business, of the date(s) on which the authorities last reviewed the ceilings for the relief fund and the mechanism for providing the fund, and whether they will conduct another review expeditiously, so as to help affected mariculturists to resume business as soon as possible;
(3) whether the authorities will consider setting up a "natural disasters protection mechanism for the agriculture and fisheries industry", which includes (i) an insurance scheme for the mariculture industry, (ii) interest-free loans for post-disaster business resumption and (iii) post-disaster provision of fry or sea fish feed; if they will, of the details; if not, the reasons for that; and
(4) given that although the tests, conducted repeatedly in the past by the Environmental Protection Department and the Agriculture, Fisheries and Conservation Department on the water quality of the waters/watercourses where massive fish deaths occurred, had shown that the water quality there was normal, some mariculturists have queried whether the water quality standards concerned are so low that fish is unable to survive in the river water/sea waters even if the latter meets such standards, how the authorities currently conduct tests on whether the water quality of the marine fish culture zones around Tolo Harbour is suitable for mariculture activities, and of the relevant details; the date(s) on which the authorities last reviewed such water quality standards and the mechanism for conducting the tests; whether they will expeditiously conduct a comprehensive review in this regard and devise appropriate water quality standards for the mariculture industry; if they will, of the details; if not, the reasons for that?
It is the Government's policy to promote the long-term sustainable development of fisheries. We seek to assist the development of the industry and enhance its overall competitiveness through a series of measures including technical support, training, financial assistance and loans, as well as red tide monitoring.
Over the years, the Agriculture, Fisheries and Conservation Department (AFCD) has been collecting samples in different areas of Hong Kong waters to monitor the planktonic algae in water and the water quality in fish culture zones (FCZs). AFCD will collect additional samples for testing and issue timely warnings to mariculturists in case of abnormal increase in the quantity of phytoplankton or irregularities in the water quality. In the cultured fish kill incident happened in the waters of Tolo Harbour to Long Harbour from late December last year to mid-February this year, AFCD had sent red tide forewarnings to mariculturists by telephone short message service. Following the incident, concerned Government departments kept in touch with the mariculturists, fishermen's organisations and local bodies and provided multi-pronged assistance, including the provision of grants under the Emergency Relief Fund (ERF) to the mariculturists concerned. AFCD's surveillance covers all FCZs in Hong Kong, and will study ways to further enhance its red tide monitoring mechanism and technologies, with a view to forewarning mariculturists of red tides as soon as possible and help minimise their losses. The Government is also committed to maintaining the cleanliness of local rivers/watercourses and protecting the local ecological environment. Should pollution occur in rivers/watercourses, the Government will investigate and take appropriate actions to reduce the impact on the community.
My reply to the various parts of the question upon consolidating inputs from concerned bureaux and departments is as follows:
(1) Red tide is a natural phenomenon, caused by rapid growth of algae which led to discolouration of seawater. Its formation and duration are determined by various factors such as sunlight intensity, water temperature, salinity, trace elements in seawater, water flow and whether the seawater is polluted.
In the cultured fish kill incident happened in the waters of Tolo Harbour to Long Harbour from late December last year to mid-February this year, red tides caused by Karenia mikimotoi coincided with the deaths of cultured fish in a few FCZs. In addition, upon conducting field studies on the response of fish to Karenia mikimotoi, and toxicological studies on Karenia mikimotoi as well as pathological analysis on the gill tissues of the affected fish by AFCD and laboratories of three universities, AFCD and the Red Tide Expert Group comprising local and Mainland red tide experts have come to believe that the fish kill was highly likely caused by the red tides formed by Karenia mikimotoi.
In the prevention and control of mosquitoes, the Food and Environmental Hygiene Department (FEHD) has been using the methods recommended by the World Health Organization (WHO). If there are potential mosquito breeding grounds that are unlikely to be cleared within days, FEHD will apply larvicides according to recommendations of WHO in the water to prevent their breeding.
The common breeding grounds of mosquitoes are water contained in abandoned tyres, broken bamboo stems, tree holes, puddles on rocks, disused fountains, man-made containers, uneven ground surface, uneven canvas covering, clogged drains and sand filters of drains etc. Their distribution is wide and changes all the time. In other words, FEHD will only use larvicides in stagnant water. Since flowing rivers or moving water bodies are not breeding grounds of mosquitoes, FEHD does not apply larvicides directly in them.
The larvicides used by FEHD include Bacillus thuringiensis (Bt) granules, Temephos sand granules and larvicidal oil as recommended by the WHO. Bt is a natural bacteria that can kill mosquito larvae quickly. To a small number of hosts such as mosquitoes, it works effectively against such specific targets. However, it is safe to other non-targeted aquatic vertebrates and invertebrates. It is mainly used in waters that are suitable for mosquito breeding and not heavily polluted. Temephos is a chemical compound of sulphur and phosphorus which can kill mosquito larvae. It is mainly applied in mosquito-breeding waste water. Larvicidal oil, a mineral oil, works primarily in suffocating the larvae in water within a short period of time.
FEHD makes every effort to avoid bringing adverse effects on the ecological environment in its work of mosquito prevention and control. Under normal circumstances, only very small quantities of larvicides are applied by FEHD. For Bt granules, Temephos sand granules and larvicidal oil, the recommended usage level is just 0.25–1 gramme, 0.55–2.2 gramme, and 4 millitres respectively per square metre of stagnant water surface. FEHD does not maintain breakdowns on the methods and types of larvicides used in the vicinity of Lam Tsuen River and Shing Mun River.
Regarding water quality, following the implementation of sewage management and water quality improvement measures, including the discharge of treated water that meets the stringent standards in waters outside the district after the sewage has been treated by Sha Tin and Tai Po Sewage Treatment Works, the total pollution load in Tolo Harbour has drastically reduced by 80 per cent from mid-1980s to the present. As shown in the surveillance of the Environmental Protection Department (EPD), the pollutants and nutrients in waters, including 5-day biochemical oxygen demand, total inorganic nitrogen, ammonia nitrogen and orthophosphate phosphorus, have substantially decreased, resulting in significant improvement in water quality.
(2) Mariculturists who are affected by natural disasters may apply for Primary Producers Grants under ERF. The grants are used to provide prompt assistance for persons who are in need of relief as a result of fire, flooding, tempest, typhoon or other natural disasters. The grants are meant for relief but not compensation. The Government adjusts the amounts of the grants annually, taking into account the operational situation of the industry as well as changes in wages and other expenditure items. We believe that the existing grants provided to mariculturists can already serve the purpose of providing a certain degree of financial relief during emergencies. The Government will examine the current mechanism for providing grants to see whether there is room for adjustment to better suit the needs of fishermen and fish farmers affected by natural disasters.
(3) As the scale of operation of the mariculture industry is relatively small, there is a lack of commercially viable insurance scheme in the market. However, apart from ERF, mariculturists, affected by natural disasters and in need of capital to re-establish their business, may also apply to AFCD for loans under the Kadoorie Agricultural Aid Loan Fund. It is intended to provide low-interest loans to individual farmers, pond fish farmers and mariculturists for development and general operating purposes, including purchasing fry and feed and improvement to farm facilities. The suggestion of provision of Government-purchased fish fry or feed to mariculturists affected by disasters may not be able to meet the needs of mariculturists since the types and quantities of fish fry or feed required as well as their plans and timetables for business resumption vary from one to another. The ERF and the Kadoorie Agricultural Aid Loan Fund mentioned above would be more effective in providing assistance to the mariculturists concerned.
(4) The water quality objectives relevant to seafood and fish culturing include dissolved oxygen, pH level, temperature, salinity and ammonia concentration. According to EPD, Hong Kong's water quality objectives comply with the international standards for tropical and subtropical areas. In addition, AFCD has over the years been collecting samples in different areas of Hong Kong waters to monitor the planktonic algae in water and the water quality in FCZs. About 10 000 marine water samples have been tested this year, with over 5 000 samples coming from Tolo Harbour and the vicinity. AFCD is conducting 24-hour real-time monitoring of water quality of seven FCZs and monitors the remaining FCZs on a regular basis. The monitoring results show that all FCZs in Hong Kong, including those in Tolo Harbour, meet the water quality objectives and are suitable for fish culture.
Ends/Wednesday, November 23, 2016
Issued at HKT 14:45
Issued at HKT 14:45