Indigenous Farming System of NE IndiaNorth Eastern Region of the country is located between 21.570N – 29.300N latitude and 89.460E – 97.300E longitude. The fishery resources of the region fall within all three types of climate i.e. tropical, sub-tropical and temperate and represent a strong biodiversity. The region with two principal rivers Brahmaputra and Barak and their numerous tributaries harbors varieties of fish species. The region has about 19,150 km of rivers; 23,972 ha. of reservoirs; 1,43740 ha.of lakes ;40,809 ha. of ponds and 2,780 ha.of rice-cum-fish culture area. The State Assam which forms about 30% of the North Eastern region has Brahmaputra and Barak river systems and their numerous tributaries (combined length 4820 km), a large number of flood plain wet lands(Beel) and swamps(1.12 lakh ha.).The North East India is considered as one of the hot spots of fresh water fish biodiversity in the world (Kottelat and Whitten, 1996).
Diversity of fish fauna:
The North Eastern Region shares its fish fauna predominantly with that of the Indo-Gangetic fauna and to a small extent with the Burmese and South China fish fauna (Yadav and Chandra 1994). Sarkar & Ponniah, 2000 in a communication listed 197 potential food, sports and aquarium fish species belonging to 27 families under 74 genera.
The National Bureau of Fish Genetics Resources (NBFGR, ICAR), Lucknow in 1992 had identified nine endemic fishes of North East Region as most threatened. These are as follows: Ompok pabda, Ompok pabo ,Labeo dyocheilus, Semiplotus semiplotus, Olyra longicuudata, Psilorhynchus homaloptera, Noemacheilus elongates, Balitora brucci and Barbus dukai. It is reported that out of 600 fresh water fishes identified in India, 320 were assessed through a six-day conservation assessment and management plan (CAMP) workshop under the BCCP jointly organized by the NBFGR and Zoo Outreach Organization of IUCN in 1996. Of the 320 species assessed at the workshop,105 were from the North Eastern Region ; four were catagorised as critically endangered (CR), 17 are endangered, 40 are vulnerable,34 are lower risk near threatened(LR-nt),seven are lower risk least concern etc. The four species under CR category are Garra litanensis Viswanath, G.manipurensis, Aborichthys garoensis Hora and Lepidocephalus goalparensis (Pillai and Yazdani); of these three species are endemic to this region. Of the endangered category, seven are found to be endemic. Some of the important fishes listed under this category are Tor putitora, T. tor, Ompok bimaculatus, O.pabda, Aborichthys elongates, A.tikaderi and Noemacheilus multifasciatus. There has been a wide variation in the number of fishes reported from this region ranging from 172(Ghose & Lipton, 1982) to 267 (Sen,2000). Bhowmik & Ayyappan(2000) reported that so far 172 fish species have been recorded from the entire North eastern Region of which 33 representatives are endemic in their distribution to this region. Over the years, this rich fish fauna has been tremendously degraded.
In Assam so far, 185 species belonging to 98 genera fewer than 34 families have been recorded (Bhattacharjya et al, 2000). The fauna has 33 representatives endemic to the region. There can be many more fish species which are yet to be recorded owing to remoteness of the region. Based on the random field surveys conducted during 1996-98 and available literature, 25 fishes have been identified as threatened species facing dangers at various levels. The tentative check-list includes four endangered species , Tor tor; Labeo dyocheilus; Bengala elanga; Ompok pabda, eight vulnerable, T. putotora, Labeo pungusia, puntius sarana sarana, Mystus vittatus, M.tengara, Pangasius pangasius, clupisoma garua, Anguilla bengalensis, four rare, Chagunius chagunio, Cyprinion semiplotum, Channa barca, Lepidocephalus goalparensis etc.(Bhattacharjya et al,2000). In addition to this list ,the State also harbours several important ornamental fish such as Colisa, Nemacheilus ,Danio ,Botia, Chaca etc. Some of these important ornamental fish species have been recently prioritized under the NATP project for undertaking studies on biology and breeding to facilitate their sustainable utilization.
In recent years there has been drastic reduction in abundance of the fresh water fishes in the region. The large –scale destruction of habitat, feeding and breeding grounds, obstructions to the regular migratory routes, indiscriminate fishing of brood fish & juveniles, reduction in size of flood plains, alteration in river flow velocities, competition with exotic fish species ,use of explosive & poisons, dumping of industrial effluents & agricultural wastes (pesticides etc.) and ingression of human population etc. seem to have caused the decline in the number.
Aquaculture for conservation:
Use of aquaculture for conservation and recovery of endangered fish populations is highlighted by many scientists. Captive breeding for conservation and recovery of endangered fish population is gradually finding importance (Das, 2000). Conservation aquaculture involves working adaptively with the local gene pool and allowing sufficient migration of genes to allow allelic representation. It requires careful selective breeding programs to provide sufficient diversity within a fish population of interest. It necessitates eliminating as much artificial conditioning as possible. Conservation aquaculture by no means presents the same risks associated with letting nature take its course when nature is no longer able to sustain a wild, native fish population. Aquaculture for conservation should be viewed as one component of multifaceted fish restoration and recovery programmes, many of which include important habitat improvements. The conservation aquaculture in an attempt to address the lost fish habitat should be designed to be implemented simultaneously with habitat improvement and watershed or ecosystem restoration activities. The goal of conservation aquaculture is to conserve wild fish populations along with their locally adapted gene pools and characteristic phenotypes and behaviors. Concerns and risks associated with aquaculture, including inbreeding fitness depression, domestication selection, manifestation of disease, hybridization and introgression are often readily observable and have been well documented (Allendorf and Ryman 1987; Waples 1991). Brannon (1993) further suggested that if hatchery programmes neglect the requirements of natural population and, therefore, the traits they possess that allow them to synchronize their life history with specific environmental constraints, failure is certain. Conservation aquaculture is by no means proposed as a panacea for recovering endangered fish population. However, in certain situations it may be the only viable, immediate solution for maintaining adequate effective population size (Ne) and preserving within-population genetic diversity (Paul 1998). Aquaculture has been used with varying degrees of success to conserve endangered fish population. In particular a management policy that considers aquaculture as a last resort for conserving threatened and endangered fish populations can be counterproductive when it allows a population to dwindle to near –extinction in order to keep it wild.
In Assam, lack of adequate attention to identify and develop appropriate aquaculture techniques for suitable local species appears to have resulted in the dominance of exotics. A preliminary study conducted recently reports that the pure strains of Indian major carps viz: Catla, Rohu & Mrigal are also being threatened gradually as a result of mixed spawning of several major and minor carps by the hatchery operators of the State of Assam and suggests to establish live gene bank (– an ex-situ method) to conserve these native species (Das, 2000).
| Serial No. | Family | Name of fish species | Conservation status |
| 1. | Cyprindae | Semiplotus semiplotus Tor tor Tor putitora Labeo pungusia Labeo dyocheilus Garra litanensis Garra manipurensis Chagunius chagunio Puntius sarana sarana Barbus dukai |
Most threatened Endangered Endangered Vulnerable Most threatened Critically endangered Critically endangered Rare Vulnerable Most threatened |
| 2. | Siluridae | Ompok pabo Ompok pabda Ompok bimaculatus |
Most threatened Most threatened Endangered |
| 3. | Balitoridae | Balitora brucci Noemacheilus multifasciatus Noemacheilus elongates Aborichthys garoensis Aborichthys elongatus Aborichthys tikaderi |
Most threatened Endangered Most threatened Critically endangered Endangered Endangered |
| 4. | Bagridae | Mystus vittatus Mystus tengara Mystus cavasius Mystus bleekeri |
Vulnerable Vulnerable Lower risk near threatened Vulnerable |
| 5. | Olyridae | Olyra longicaudata | Most threatened |
| 6. | Channidae | Channa barca Channa orientalis |
Rare Vulnerable |
| 7. | Schilbeidae | Clupisoma garua | Vulnerable |
| 8. | Psilorhynchidae | Psilorhynchus homaloptera | Most threatened |
| 9. | Amblycipitidae | Pangasius pangasius | Vulnerable |
| 10. | Anguillidae | Anguilla bengalensi | Vulnerable |
| 11. | Cobitidae | Lepidocephalus goalparensis | Critically endangered |