第 30 卷 第 6 期 水 生 生 物 学 报 Vol .30 , No .6 2 0 0 6 年 1 1 月 ACTA HYDROBIOLOGICA SINICA Nov ., 2 0 0 6

BIODIVERSITY AND CONSERVATION OF FRESHWATER IN HONG KONG, CHINA

VIRGINIA Laifun Lee , MARIA Lauching Young , TONY Kingtung Chan , SAMUEL Kinsan Lam , FRANCO Kwokyan Ng and JULIA Wingyin Chan (Agriculture , Fisheries and Conservation Department , HKSAR Government Cheung Sha Wan Government Offices, 303 Cheung Sha Wan Road , Hong Kong)

Abstract:We surveyed the distribution , composition and diversity of freshwater fish in Hong Kong , China from 2002 to 2004. Sites surveyed were mainly streams, marshes and estuaries .There are ponds for aquaculture and reservoirs in Hong Kong but no large natural water bodies.From the 220 sites surveyed , 114 of 37 families were found .Gobiidae (with 24 species)and (21 species)were the dominant families.This survey has increased the number of freshwater fish species recorded in Hong Kong to 167 .Among these , 71 (42 .5%)are primary freshwater fish , 44 are brackish and 46 are vagrants .The remaining 6 species are diadromous.In Hong Kong , freshwater fish are conserved by a combination of measures.About 38% of Hong Kong' s land area is designated as country parks and/ or special areas, and is managed for nature conservation and educational purposes .In addition, another 5% of land area is zoned for conservation in the statutory land use zoning system to protect them from develop- ment and incompatible land uses.Major development projects have to go through the statutory environmental impact assessment process to ensure that they will not have adverse impact as far as practicable .There are conservation action plans for important species.For example , captive-bred individuals of the endemic Hong Kong Paradise Fish Macropodus hongkongensis have been re- leased to suitable and secure sites inside country parks and their populations are regularly monitored.Other measures such as wet- land creation , restoration and enhancement programmes are also implemented for freshwater fish conservation.

Key words:Freshwater fish biodiversity ;Family composition ;Species composition;Conservation measures CLC number :X176 Document code:A Article ID:1000-3207(2006)06-0660-07

Hong Kong Special Administrative Region , China , brackish species , diadromous species and marine vagrants . has an area of 1095km2 and is located at the edge of the They can be found in all major freshwater bodies , from northern tropical zone .The landscape is dominated by swift flowing hill streams to trickling lowland streams/rivers hills and ravines with flat land restricted to the low flood- and estuaries , as well as artificial habitats like reservoirs , plains and coastal regions .In this hilly domain , the small fishponds and agricultural wetlands/marshes.Each type of rocky streams are typically fast flowing at their upland freshwater habitat has its own ecological characteristics and sources , and gradually reduce in speed as they wind along each supports specific communities of aquatic organisms . hill cuttings to reach the lowlands .While streams are Likewise , each freshwater fish species has its own niche and commonly found , rivers are very limited in number .The special adaptations to survive in its habitats .Hong Kong may few long and meandering rivers with their floodplains are not have a high diversity of natural freshwater habitats , but located in the northern and northwestern New Territories it is surprisingly rich in freshwater fish species . (Fig .1). From February 2002 to August 2004, we carried out in- Freshwater fish comprises primary freshwater species , tensive and territory-wide surveys on freshwater fish covering

Received date:2004-11-4 ;Accepted date:2006-3-9 Foundation item:the comprehensive ecological baseline survey programme of the Department of Agriculture , Fisheries and Conservation Corresponding author :Virginia Laifun Lee, E-mail:lf [email protected] 6 期 VIRGINIA Laifun Lee et al .:BIODIVERSITY AND CONSERVATION OF FRESHWATER FISH IN HONG KONG , CHIN A 661 over 200 freshwater habitats in Hong Kong .The distribution, with the aim of improving our knowledge of local freshwater composition and diversity of freshwater fish were surveyed fish and formulating action plans for their conservation .

Fig.1 The location of surveyed sites within 7 regions in Hong Kong

regions of Hong Kong .The survey sites were divided into 1 Methods 7 regions [ Northeast New Territories (NENT), North- 1.1 Study sites The survey covered 220 sites (Fig .1) west New Territories (NWNT), Sai Kung (SK), Central distributed throughout Hong Kong .They were mainly up- District (C), Hong Kong Island (HKI), Lantau Island land and lowland streams , marshes and estuaries while (LI)and other outlying Islands (Is)] based on their geo- there are ponds for aquaculture and reservoirs , there are graphical locations in Hong Kong .Similar MDS plot was no large natural water bodies in Hong Kong . carried out to study the association between species distri- 1 .2 Sampling methods A combination of sampling bution and habitat types . methods was used to investigate different types of freshwa- The stress values indicate the goodness of ordinations ter fish habitats , including bankside counting , pot trap- in MDS[ 1] .Stress value smaller than 0 .1 means that the ping , hand netting , gill netting , seine netting , cast net- MDS plot given is a meaningful one and stress value ting and angling . smaller than 0 .2 means that the plot is a reasonable one . We selected 3 to 5 sampling points randomly for each For stress value larger than 0 .2 , the plot just gives limit- site depending on site conditions and spent about 30 to 45 ed explanation of the data set . minutes on each sampling point .Sampling was done all 2 Results year round including both wet and dry seasons except after heavy rains . were identified and counted on site 2 .1 Survey sites and then released back to their original habitats . A total of 220 sites were sampled between February 1 .3 Non-metric multi-dimensional scaling Non- 2002 and August 2004 .Among them , 103 (46 .8 %)fell metric multi-dimensional scaling (MDS)was used to in- inside protected areas1 .64 .7 %of the surveyed sites were vestigate the variation of species composition in different upland stream courses while 11 .3 %, 10 .0 % and 7 .3 %

1 Protected areas include Country Parks, Special Areas and Sites of Special Scientific In terest (SSSIs) 6 62 ACTA HYDROBIOLOGICA SINICA 30 卷 were lowland streams , marshes and estuaries respectively . Eight of the ten most common species recorded were The remaining 6 .7 %were fish ponds and reservoirs . native species .Two exotics were Gambusia affinis and 2 .2 Family composition Xiphophorus variatus .G .affinis is believed to have been A total of 114 species from 37 families were recorded deliberately introduced for mosquito control in the past and the relative family composition of the recorded species and X .variatus is believed to be released aquarium fish . is shown in Fig .2 .The Gobiidae and Cyprinidae dominate Both species belong to Poeciliidae and are originated from the freshwater fish community , with 24 species and 21 Central America . species recorded respectively , comprising 21.0% and Tab.1 The 10 most common primary freshwater fish species 18 .4 % of the total number of species recorded .Other rel- recorded in Hong Kong atively important families include Cichlidae , Eleotridae and Species No.of sites recorded Balitoridae with 9 species (7 .9 %), 6 species (5 .3 %) 1 Rhinogobius duospilus 102 and 5 species (4 .4 %)recorded accordingly .The remain- 2 spilurus 86 ing 43 .0%(49 species)is contributed by 32 families . 3 Puntius semifasciolatus 84 4 Gambusia affinis 71 5 Schistura fasciolata 60 6 Rhinogobius giurinus 53 7 Liniparhomaloptera disparis 45 8 Pterocryptis cochinchinensis 38 9 Pseudogastromyzon myersi 31 10 Xiphophorus variatus 31

2 .5 Species composition and distributional pattern The 220 survey sites were divided into 7 regions (Fig .1)and 5 habitat types according to site conditions . Fig.2 Relative family composition of the freshwater fish The sample size for each region and habitat type is shown families recorded in Hong Kong during 2002—2004 in Tab .2a and 2b respectively .

2 .3 Species composition Tab .2a The number of sites surveyed in the 7 regions in Hong Kong

Out of the 114 species recorded , 48 species (42.1 %) Region Number of surveyed sites (n) are primary freshwater species .Secondary freshwater fish Northeast New Territories (NENT) 63 constitutes 57 .9 %of the total number of species recorded Northwest New Territories(NWNT) 36 in which 28 species (24 .6 %)are brackish , 33 species Sai Kung (SK) 37 are vagrants (28 .9 %) and the remaining 5 species Central (C) 35 (4 .4 %)are diadromous .This survey has increased the Lantau Island (LI) 28 number of freshwater fish recorded in Hong Kong to 167 Hong Kong Island (HKI) 17 Other Outlying Islands(Is) 4 representing 46 famili es .Among them , 71 species Total 220 (42 .5 %)are primary freshwater fish , 44 are brackish and 46 are vagrants .The remaining 6 species are diadromous. Tab.2b The number of sites surveyed at the 5 habitat types 2 .4 Common species Habitat type Number of surveyed sites (n) Tab .1 lists the 10 most common freshwater fish Upland stream (U) 84 species recorded in the survey .Rhinogobius duospilus Lowland stream (L) 71 (Gobiidae)had the widest distribution and was recorded at Estuary (E) 29 Marsh (M) 10 46 .4 %(102 sites)of the surveyed sites .It was followed Others, including reservoir and pond (O) 26 by Parazacco spilurus (Cyprinidae)and Puntius semifasci- Total 220 olatus (Cyprinidae)recorded at 39 .1 % (86 sites)and 38 .2 %(84 sites)of the surveyed sites respectively . 6 期 VIRGINIA Laifun Lee et al .:BIODIVERSITY AND CONSERVATION OF FRESHWATER FISH IN HONG KONG , CHIN A 663

The MDS plots by using presence/absence of indi- species in upland stream habitat are separated from those vidual species in the seven regions show that individual in estuary forming two clusters , and between them is an- sites in different regions overlap with each other and no other cluster formed by lowland species (Fig .4).Species distinct separation is noted (Fig .3).On the other hand , groups in marshes and other habitat types (reservoirs and similar analysis for the five habitat types reveals that ponds)are not separated from each other .

Fig .3 Non-metric multidimensional scaling plots of the presence/ absence of individual species in 7 regions of Hong Kong (2-dimensional solution, n=220). NENT-Northeast New Territories ;NWNT-Northwest New Territories;SK-Sai Kung;LI-Lantau Island;HKI-Hong Kong Island;C-Central;Is-Other Outlying Islands

Fig.4 Non-metric multidimensional scaling plots of the presence/ absence of individual species in 5 habitat types(2-dimensional solution, n=220). U-Upland stream ;L-Lowland stream;O-Others;M-Marsh;E-Estuary

water fish community in Hong Kong is dominated by Gobi- 3 Discussion idae instead of Cyprinidae .This may due to the fact that Unlike other regions in Mainland China , the fresh- the freshwater fish habitats in Hong Kong are mainly up- 6 64 ACTA HYDROBIOLOGICA SINICA 30 卷 land streams or relatively polluted lowland streams and veyed sites and P .spilurus was recorded at 40 % of the there is a lack of large rivers and channels . surveyed sites .However , field observation showed that In addition , the dominance of Gobiidae can probably certain species were rather sparsely distributed like M . be explained by their capability to tolerate a wide range of hongkongensis which was only recorded in the northeast- salinities , from purely freshwater environment in up- ern part of Hong Kong .More field surveys are necessary streams to relatively higher salinities especially in estuar- to investigate the distribution range and pattern of differ- ies .The large representation of Gobiidae in the present ent species .Other analytical methods may also be em- survey is also attributed by the diverse nature of this fami- ployed to provide a clearer picture of the distribution of ly with members spanning a wide range of habitat types . individual species as well as the fish community in Hong More than 40 % of the species recorded is primary Kong . freshwater fish .This group of fish in Hong Kong compris- Distribution of freshwater fish is at least partly gov- es mainly of Cyprinidae , Balitoridae and Channidae .A erned by the presence of suitable habitat and different remarkable species in this group is the Macropodus species are associated with specific environment .It is not hongkongensis which was once misidentified as M .con- surprising that upland species and the estuarine formed color but was later considered to be a new species endemic two distinct groups .Marine species such as Terapon jar- to Hong Kong[ 2] . bua and Lutjanus argentimaculatus are incapable to enter It is also worth mentioning that the freshwater com- upland streams and the upstream species like L .disparis munity in Hong Kong is extremely diverse with 167 and S .fasciolata cannot tolerate saline environment on species from 46 families , when compared with the fish the other hand .From field observation , these two groups fauna in South America (more than 2 , 400 species but on- were also found not to share the same niche even juveniles ly 60 families)and West Africa (more than 600 recorded of both groups appear in lowland streams .The juveniles of freshwater fish species of 74 families)[ 3] .Many of the lo- upland species usually feed and hide in rock crevices cal freshwater fish belong to marine families with members while those of the marine species swim freely along lower of brackish species and marine vagrants that enter the stream courses and estuaries . freshwater environment both regularly and sporadically . 3 .3 Threats to freshwater fish and their habitats 3 .1 Species diversity inside protected areas Due to the development of Hong Kong in the past Based on our survey findings and data obtained by three decades , watercourses in new development areas other local researchers , it is noted that only one primary were filled or turned into channels and culverts to make freshwater fish species was not represented inside protect- way for new towns , roads and infrastructures .Human-in- ed areas in Hong Kong .The natural aquatic habitats in duced alterations to the flow of watercourses , including protected areas are mainly natural upland streams of rocky engineering , diversion , blockage or even filling , have led substratum with little marshy areas .It provides favourable to alteration of aquatic habitats .Species composition and habitats for our native upstream species such as Schistura abundance were therefore affected . fasciolata , Pseudogastromyzon myersi and R .duospilus . Another current threat faced by freshwater fish of While the upland streams provide habitats for our native Hong Kong is the introduction of invasive alien species . species , all the 17 man-made reservoirs offer a mixture of Common species of the aquarium trade and locally reared artificial macro and micro-habitats which support a rich species in fish farms have escaped or were released to the diversity of freshwater fish . natural environment .Some of these species , such as 3 .2 Species composition and distributional pattern Tilapias , Mosquito Fish and Swordtails , were able to es- Fig .3 reveals that the species composition does not tablish in our water bodies which are difficult to elimi- differ in different regions of Hong Kong .This may be nate .They may compete for available food resources to contributed by the presence of common species that were the disadvantage of our local freshwater fish . found across the whole territory of Hong Kong .For in- 3 .4 Conservation of freshwater fish and their habitats stance , R .duospilus was found at nearly half of the sur- In Hong Kong , freshwater fish are protected and 6 期 VIRGINIA Laifun Lee et al .:BIODIVERSITY AND CONSERVATION OF FRESHWATER FISH IN HONG KONG , CHIN A 665 conserved by a combination of measures including the grasscreting)and habitat provision along channel embank- habitat and species approaches .It is important to protect ments (e .g .tree planting along embankment as well as existing freshwater habitats against water pollution and un- preservation and enhancement of isolated meanders). necessary destruction , especially those natural freshwater 3 .5 Important species for freshwater fish conservation habitats with high conservation value .Besides , conserva- Making reference to the conservation status listed in tion action plans are implemented to secure populations of World Conservation Union (IUCN), China Red Data rare species inside protected areas . Book[ 4—6] , we have selected several fish species as hav- (a)Protecting freshwater habitats-Country Parks ing conservation concern . Hong Kong is small and highly urbanized and about To conserve these rarer fish species , action plans 41 , 600 hectares or 38 % of Hong Kong' s land area is have been formulated according to the individual species' designated as country parks and/or special areas , which needs .We have prepared specific conservation action plans are managed for nature conservation and educational pur- for 7 primary freshwater species , namely Acrossocheilus poses .Hundreds of pristine natural stream courses and all beijiangensis , A .parallens , Macropodus hongkongensis , freshwater reservoirs as well as the fauna and flora there Oryzias curvinotus , Pseudobagrus trilineatus , Rasbora are protected by this protected area system from incompat- steineri and Rhodeus ocellatus and appropriate conservation ible activities and developments . actions are being carried out accordingly . (b)Conservation zonings-statutory land use zoning system 3 .6 Conservation action plans for selected species Freshwater habitats in Hong Kong are also protected (a)Hong Kong Paradise Fish Macropodus hongkongensis under the statutory land use zoning system .Conservation To better conserve the important species and their zonings including sites of special scientific interest (SS- habitats, conservation action plans were formulated and SIs), conservation areas and coastal protection areas at implemented according to the needs of individual species . present cover another 5 % of the land area and freshwater For example , captive-bred individuals of the endemic habitats there are also protected from development and in- Hong Kong Paradise Fish M .hongkongensis had been re- compatible land uses . leased to several confined ponds in country parks.Hun- (c)Minimizing and mitigating the impacts of develop- dreds individuals were found in each pond and the re- ments leased populations are regularly monitored . Major development projects in Hong Kong have to go (b)Chinese Rasbora Rasbora steineri and the Rice Fish through the statutory environmental impact assessment Oryzias curvinotus . process to ensure that they would not have adverse impact With regard to habitat provision , we have created as far as practicable .The project proponent is required to and enhanced wetland habitats inside country parks for the collect the relevant ecological information , predict and as- Chinese Rasbora R .steineri and the Rice Fish O . sess potential impacts of the project on the environment , curvinotus .As different fish species have a variety of propose remedial works and formulate suitable mitigation physical habitat requirements throughout their life cycles , measures to avoid , minimize and/or compensate any ad- specific habitat enhancement and improvement works were verse impacts identified .Under the current legislation , carried out so that the re-created habitats would have project proponents of all major river training works and compatible habitat structure and function to those of the other designated projects are required to avoid causing ad- existing habitats .For example , habitats with riffles and verse environmental impact , including impact on freshwa- deep water pools were created while riparian re-vegetation ter fish and natural watercourses .If total avoidance is not and bank stabilization were enhanced .Overflow structures practicable , the project proponents are required to miti- in the form of dams or weirs were also constructed .Ripar- gate the adverse impact to an acceptable level .Some of ian re-vegetation served to increase shading , provide cover the ecological mitigation measures on natural watercourses for fish and input of detritus to the created habitats . include improvement of in-stream environment (e .g .pro- For the Chinese Rasbora , densely wooded wetland vision of microhabitats for fish , aquatic planting bays , covering an area of about 0 .25 hectare inside a country 6 66 ACTA HYDROBIOLOGICA SINICA 30 卷 park was created to establish a system of interconnecting the stream through pipes beneath the ponds .The released ponds (Plates 1 &2).The excavated materials from the populations of 20 individuals of the Chinese Rasbora have area were used for profiling works and formation of pond successfully bred in the wetland .Further enhancement in- bunds .Water for the system was diverted from a nearby cluding replanting of the riparian zone (planting of native stream and routed through underground pipes into the trees and shrubs as well as aquatic plants)would be im- ponds , and subsequently returned to the lower course of plemented with a view to further enhance the habitat .

Fig .1 Wetland before pond creation Fig.2 The created pond

(c)Rose Bitterling Rhodeus ocellatus [ 2 ] Freyhof , J.&F.Herder , 2002 .Review of the paradise fishes of the The Rose Bitterling R .ocellatus is restricted to two genus Macropodus in Vietnam , with description of two species from Vietnam and southern China (Perciformes:Osphronemidae).Ichthy- localities in Hong Kong with slow-flowing water and sandy ological Exploration of Freshwaters 13:147 —167 to silty bottoms in the central New Territories .As this [ 3 ] Kottelat , M., A .J.Whitten , S .N.Kartikasari &S .Wirjoatmod- species is restricted to habitats containing its egg host jo , 1993 .Freshwater Fishes of Western Indonesia and Sulawesi . freshwater mussel Anodonta woodiana which it relies upon Periplus Editions (HK)Limited , Indonesia:pp 293 for reproduction , and that both the fish and mussels are [ 4 ] Wang , S ., P .Q.Yue & Y.Y.Chen , 1998 .China Red Data [ 7] Book of Endangered .Science Press, Beijing (in Chinese) sensitive to water pollution , the Rose Bitterling is of [ 5 ] Chong , D.H .&D.Dudgeon , 1992 .Hong Kong stream fishes:an particular conservation interest .In this connection , labo- annotated checklist with remarks on conservation status.In Hodgkiss, ratory trials were conducted for the breeding of the fish I .J.(editor), Memoirs of the Hong Kong Natural History Society . with reared mussels collected from the wild .Preliminary The Hong Kong Natural History Society , No .19 , Hong Kong :79 — results revealed that breeding and hatching of fish fry from 112 the reared mussels under laboratory controlled conditions [ 6 ] Fellows, J.R., M.W .N.Lau , D.Dudgeon , G .T .Reels, G . W .J.Ades, G.J.Carey , B.P .L .Chan , R.C .Kendrick , K . were successful .Breeding programmes will continue and S .Lee , M.R.Leven , K.D.P .Wilson &Y.T .Yu , 2002 .Wild captive-bred individuals will be released to suitable re- animals to watch :terrestrial and freshwater fauna of conservation con- ceipt sites in protected areas to secure their populations . cern in Hong Kong .In Hodgkiss, I .J.(editor)Memoirs of the Hong Kong Natural History Society .The Hong Kong Natural History Soci- References : ety , No .25 , Hong Kong:123 —159 [ 1 ] Clarke, K.R.& R.M .Warwick , 1994 .Changes in marine com- [ 7 ] Lam, K .S ., 2002 .Freshwater Fish in Hong Kong .Agriculture , munities:an approach to statistical analysis and interpretation .Natu- Fisheries and Conservation Department.Friends of the Country ral Environment Research Council, U.K Parks.Cosmos Books Ltd .:pp 76