There is an urgent need to manage and conserve riverine fish resources in Malaysia. These resources have largely been ignored, but are an important source of both income and food. Having particularly diverse fish fauna in rivers provides the basis for a fishery, and it has been estimated that there are over 300 species of freshwater fish dwelling in the many riverine ecosystems of Malaysia.

The fishing industry has generated a substantial income in Malaysia, and although the number of anglers visiting riverine habitats is still vague, it has been estimated that most fishermen in Malaysia are freshwater anglers. Consumption of these freshwater fish in inland rural areas is widespread.

There is thus a need to protect the fishery resources and fishery-related habitats, and at the same time promote the enjoyment of fishing as a recreational activity. This paper aims to identify the riverine fish ecosystems in Malaysia, as well as to suggest achievable management and conservation plans in order to preserve this valuable resource.

Introduction

The freshwater habitat is part of Malaysia's vast aquatic ecosystem and consists of both natural and man-made water bodies. It is highly heterogeneous; including riverine, lacustrine (natural lakes, ox-bow lakes, reservoirs and ex-mining pools) and palustrine (freshwater and peat swamps and rice fields) habitats, according to studies done by the World Wide Fund for Nature in Malaysia (WWFM, 2002).

There are over 1,500 rivers stretching over a total length of about 35,000 kilometres in the country, forming over 150 riverine systems (Anon, 1998); 94 being of major importance. Of these 94, 49 are in the Peninsula, 24 in Sabah and 21 in Sarawak (Yap, 1992). Major rivers in East Malaysia tend to be larger than in Peninsular Malaysia. The longest and largest river in Malaysia is located in Sarawak, Rajang River, which has a length of 565 km and catchment of 51,000 km2. In Sabah, Kinabatangan River is the longest river, with a length of 563 km. In Peninsular Malaysia, there are three main rivers, i.e. the Pahang (434 km; 29,137 km2) Perak (427 km; 15,151 km2) and Kelantan (390 km; 12,691 km2) Rivers (Anon, 1987; Hoque et al., 1994; UNESCAP, 1995; Yusoff et al., 1997; Ali, 2000). Many rivers have been extensively modified for drainage purposes and their carrying capacities significantly altered; as an example irrigation canals, which were built decades ago, are now a common sight throughout Malaysia (WWFM, 2002).

Lacustrine and palustrine habitats are comprised of non-flowing or stagnant water bodies (lentic system) and include few natural lakes: (Tasik Bera and Tasik Chini); 63 man-made dams and reservoirs (47 single purpose dams and 16 multi-purpose dams); 16,440 hectares of ex-mining pools and 2.5 million ha of freshwater and peat swamp forests (Hoque et al., 1994; Yusoff et al., 1997; MOSTE, 1997; Le and Facon, 2001). Yet the resources contained in these habitats are all largely ignored.

Fauna

Freshwater fish fauna of Malaysia have received little attention since the earliest days of ichthyological exploration in the region (Roberts, 1989) with work only actually starting in mid-19th century (Zakaria-Ismail, 1991). Most of these studies have been in Peninsular Malaysia.

Published accounts of the freshwater fish fauna of specific streams, drainage areas or certain particular sections of a river are numerous and examples include:

However, work on whole river systems, or even on specific stretches of a river, is still lacking. Most Malaysian river systems have never been studied intensively. Previous studies in the river basin of the Perak and Pahang Rivers were basically concerned with species checklists and fisheries' status (Khan and Yeo, 1993; Ali, 2000). Other studies carried out in different river basins or systems include: ichthyofaunal study of Bernam (Yap et al., 1997) Melaka and Rompin Rivers (Zakaria-Ismail and Aishah Salleh, 1997) and Perai, Juru and Perlis Rivers (Ho and Tan, 1997). Even the available documents are considered incomplete because these studies were only short term, and lack follow-up work to monitor changes in distribution in relation to changes in habitats (Zakaria-Ismail, 1987).

Up to now no researcher has been able to state or list a reliable number of fish present in Malaysian freshwater bodies (Zakaria-Ismail, 1991; Ng et al., 1992; Ali, 2000), not to mention the riverine ecosystem. Thus, based solely on available literature, it has been generally estimated that there are over 300 species of freshwater fish dwelling in the diverse freshwater ecosystems of Malaysia (Bishop, 1973; Ali, 1992; Khan and Yeo, 1993; Zakaria-Ismail, 1997). Kottelat and Whitten (1996) identified a total of 264 freshwater fish species that could be found in Peninsular Malaysia and southern Thailand.

Mohsin and Ambak (1983) listed a total of 382 species of freshwater fish representing 56 families in Peninsular Malaysia based on various sources. However, though their actual fish sampling was undertaken over four years, they only managed to collect 121 species of primary freshwater fish.

Lim et al. (1993), who attempted to record all known indigenous freshwater fish of Peninsular Malaysia managed to list a total of 261 species representing 40 families. Lee et al. (1993) did a more comprehensive compilation of freshwater fish found in Peninsular Malaysia based on available literature and preserved fish specimens. They managed to list a total of 292 species of freshwater fish representing 43 families. This list includes thirteen introduced species found in the wild or natural freshwater habitats. This compilation represents not only the valid and revised scientific names of fish, but also described their habitat distribution and conservation status. However, this is not considered to be the complete list since new species are likely to be discovered in the remote and undisturbed areas.

There are other reports that provided the number of freshwater fish species found in Malaysia. World Conservation Monitoring Centre (WCMC, 1992) stated that there are 183 species of freshwater fish in Peninsular Malaysia. NCS (1993) reported 386 freshwater fish in Peninsular Malaysia and over 160 species in East Malaysia. Whereas, MOSTE (1997) mentioned that overall, a total of 449 freshwater fish species are present in Malaysian freshwater bodies. These figures, however, were not substantiated with actual and reliable source of information or references.

For East Malaysia, perhaps the most comprehensive work on freshwater fish was done by Inger and Chin (1962) and Kottelat and Lim (1995). Inger and Chin (1962) had previously done an ichcthyofaunal study of Sabah (North Borneo) in the 1950s. Based on the already available preserved specimens, as well as on field surveys, a total of 137 fish species had been recorded. Eight of them were introduced species brought in for aquaculture. In an updated version, Chin (1990) added 15 more species to the list of which five were introduced. The number of freshwater fish now known from Sabah is 155, which includes three sub-species and 13 introduced species. Out of this, 85 are primary freshwater fish (those which have evolved in freshwater and are unable to tolerate brackish waters (Lowe-McConnell, 1987) and 19 of them are endemic.

Ichthyological surveys and research in Sarawak has not been extensive. Among the earliest ichthyofaunal surveys in Sarawak was carried out by the Department of Agriculture in three major river systems, namely, Sungai Rajang, Sungai Batang Ai and Sungai Baram. A status report was produced in 1985 regarding the inland (freshwater) fish of Sarawak, which listed 59, 31 and 43 fish species found in Sungai Rajang, Sungai Batang Ai and Sungai Baram, respectively.

As the survey was confined to a small geographical area, this study was considered incomplete. The actual number of species was expected to be much higher. In the 1990s, a freshwater fish fauna study of Sarawak as well as Brunei was carried out through literature search, examination of preserved specimens and field surveys. They listed a total 249 freshwater fish species that are found throughout Sarawak and Brunei (Kottelat and Lim, 1995). Given this scenario, a comprehensive study to assess the status of freshwater fish of Malaysia is, therefore important and needs to be carried out immediately.

For both Peninsular Malaysia and Borneo, cyprinids are dominant consisting of 30% of all species. Channidae and Anabantidae comprise a further 26% while the remainder is distributed among nine other families. Among the most common cyprinids are sebarau (Hampala macrolepidota), kelah or Malaysian Mahseer (Tor spp.), temoleh (Probarbus jullieni) and lampam sungai (Barbodes schwanefeldii). The largest of the Malaysian freshwater fish are catfish known as tapah (Wallago spp.), which grow to nearly two metres in length. Other common catfish are baung (Mystus spp.), patin (Pangasius spp.) (Tweedie and Harrison, 1954).

The upper reaches are the least known riverine habitats and there are probably more species that await discovery. The rate of endemism is also high (Kottelat and Whitten, 1996). For example, Poropuntius smedleyi is endemic to Peninsular Malaysia and is the most widely distributed in Peninsular Malaysia and has been recorded in Johor, Pahang, Kelantan and Selangor. This species is confined to montane streams and areas at the foothills (about 100 m a.s.l.) (Zakaria-Ismail, 1991).

Fisheries

Capture fisheries

Having particularly diverse fish fauna in rivers provides the basis for a fishery, which are pursued with a great variety of gear whether for subsistence, income or recreation. Unfortunately, there is little information on total landings and consumption of riverine fish, as until recently, little attention was focused on the riverine capture fisheries in Malaysia. This is due to the fact that most Malaysians prefer to consume marine fish. However, the consumption of freshwater fish in inland rural areas is widespread. The nature of the inland fishery varies according to the target species and character of the river basin in which it is undertaken. Most fishing activity is concentrated in the middle and lower reaches.

The main riverine species harvested are cyprinids and silurid catfish. Among the commercially important riverine fish are tinfoil barb (Barbodes schwanenfeldii), sultan fish (Leptobarbus hoevenii), tenggalan (Punioplites bulu), temoleh (Probarbus juelleni) and kelah (Tor tambroides). Silurids that are equally in demand include the pangasids (Pangasius micronema and P. Pangasius) and bagrids (Mystus spp. and Wallago sp.). Some rivers such as Sungai Selangor also support the catching giant freshwater prawns (Macrobranchium rosenbergii). These species have a niche demand and can be very highly priced (WWFM, 2002).

The fish are caught using a variety of gear, most of which are passive in nature. Common fishing gear includes the cast net, drift net, lift net, pull net, long lines, pole and lines and fish traps. The use of poisons, explosives and mechanical or electrical appliances is banned in Malaysia.

Landing from the riverine systems throughout Malaysia are obscure and vague. Based on Department of Fisheries Malaysia annual fisheries statistics, total landings in Peninsular Malaysia in 2000 amounted to only 3,500 tonnes. Approximately 87% of the catch came from five states, namely, Kedah, Perak, Selangor, Johor and Pahang. Production from other states appears to be insignificant (DOF, 1998; WWFM, 2002).

It is unclear how accurate these statistics are as it is likely that there is a good deal of underreporting. Proper statistical collection is only possible where there is a common landing point through which catch is circulated to their respective markets (WWFM, 2002). In addition, the figures do not reflect landings in Sarawak, where inland fisheries are far more widespread and developed compared to Peninsular Malaysia. The annual landing of freshwater fish in Rajang river alone in Sarawak in 1994, for instance, was estimated at 31 tonnes (Anon., 1997). Given the fact there are numerous large rivers in the state and ribbon communities next to them, the total volume caught is likely to be very substantial.

Anecdotal information suggests the riverine fisheries catch has been declining over the past few years. However, the lack of baseline information and formal survey deters concrete understanding on the status of riverine fish resources.

Recreational fisheries

Recreational fishing is one of the most popular outdoor activities in Malaysia. Presently, it has been roughly estimated that there are about two million anglers in Malaysia, more than 150 fishing clubs and associations, together with seven monthly fishing magazines, twelve websites on the Internet and weekly columns in all the newspapers catering to recreational fishing activities all over the country.

Recreational fishery incurred an average spending of about RM500.00 person− 1 yr− 1, or $135.00 US which would roughly amount to RM1 billion yr− 1 or $269 million US (Feisol, 2001). Although the number of anglers visiting riverine habitats is still vague, it has been estimated that 70% of all anglers are freshwater anglers (WWFM, 2002). There is thus a need to protect the fishery resources and fishery-related habitats, and at the same time facilitate the enjoyment of angling as a recreational activity (Hickley et al., 1995).

Resource health

Rivers are one of the most degraded ecosystems in Malaysia. Land clearing and habitat encroachment; reclamation of mangroves, riparian vegetation and wetlands; as well as dam construction have had deleterious impacts on fish populations (Ali, 1992). These not only affect the subsistence fisheries, but also the recreational fishing industry. Due to the lack of baseline information and formal surveys, a concrete understanding of the status of riverine fish populations has not been achieved. But the little that does exist tends to confirm this trend.

A study carried out in Pusu River in the Klang River Basin, showed that more than 40% of the native fish have disappeared due to adjacent development activities over the past few years (Zakaria-Ismail, 1997). Ho (1994) estimated that the Gombak River in Selangor lost about 60% of its indigenous fish species over the last 20 years due to deterioration in water quality.

Perak River lost six out of the nine commercially important fish species over the last 15 years (Khoo et al., 1987) while Ho (1994) reported that the catch of freshwater giant prawns had been reduced to about 25% within a decade on Tanjung Tualang due also to pollution.

The presence of invasive alien species in Malaysian freshwater is also a major threat. Species like Aristichthys nobilis, Barbodes gonionotus, Ctenopharyngodon idellus, Cyprinus carpio, Labeo rohita, Oreochromis mossambicus, O. niloticus, Trichogaster pectoralis and Osphronemus gouramy were introduced into Malaysian waters in the early part of 20th century (Ang et al., 1989) and some of them like Oreochormis spp. and Trichogaster pectoralis have established resident populations.

Other species such as Colossoma brachypomum and Clarias gariepinus are newly introduced species in Malaysia and not much is known about their adaptability in Malaysian water bodies. Species like Hypostomus plecostomus was brought in as an aquarium fish and once they have outgrown the aquarium, they are thrown or released into the natural water bodies. The impact of introduced species on native fish has been sparsely documented (Ang et al., 1989). A main source of concern is the displacement of indigenous fish species from their present habitat.

Policy and legislation governing riverine fisheries

In Malaysia, inland fisheries are a state matter. However, only 11 states have passed the requisite legislation to govern the activity, and only 2 have dedicated management agencies. The others have been content to assign their responsibilities to the Federal Department of Fisheries.

Conclusions

There is an urgent need to manage and conserve freshwater fish resources in the country. In carrying out the management and conservation of fishery resources and fish-related habitats, the general measures that should be carried out are (Zauwiyah Ishak and Alias Man, 1997):

  • To maintain fishing effort at a sufficient level for the fish stock to regenerate itself;

  • To protect, conserve and rehabilitate the fishery-related habitats;

  • To increase enforcement and monitoring;

  • To promote sustainable, well planned, managed land use and human activities; and

  • To establish integrated management among relevant agencies with a holistic approach.

There should be intensification of research programs into freshwater biology, ecology and habitats, as well as education and awareness programs among stakeholders, better regulation of exotic fish species and increased efforts at artificial propagation and restocking.

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