Mahseer breeding and conservation and possibilities of commercial culture. The Indian experience. (by Ogale, S.N.)

Tata Power Company Ltd. Lonavla - 410401 Dist.Pune, Maharashtra, India

ABSTRACT

Mahseers (Tor sp.) have been a legendary sport fish of India with a very high table value. Mahseer, at one time considered to be of single species, is now represented by six valid species distributed all over India. Despite their abundance, at one time mahseer were reported to be declining in size and numbers and were feared to be in danger of extinction in some parts of the country. Unfortunately their catches have dwindled considerably due to illegal methods of fishing, habitat deterioration and introduction of exotic species. Studies on their feeding and spawning habits, eggs, larval development and especially the methods of artificial propagation have progressed in recent years. Breeding of four major species of mahseer, T. khudree, T. mussullah, T. tor and T. putitora, by collecting the brooders from the breeding grounds and then stripping them is possible. In the effort to conserve mahseer resources artificial propagation of the fish by stripping the spawners is not always possible unless they are dependably obtainable from natural waters. To overcome this difficulty mahseer fingerlings of all the species can be raised to maturity in captivity (small ponds) by following improved aquacultural practices. Breeding of four major species of mahseer, with and without hypophysation, in brood fish ponds using manipulation of water flow, exercise and high protein palletized diet has also been successful. Stripping the ripe fish becomes necessary and for convenience and surety, two doses of pituitary extract or a single dose of ovaprim/ovatide is desirable. The Tata Power Company's mahaseer hatchery is simple but most successful and can be replicated in remote centers. Approximately 500 000 eggs are collected and fertilized every year by using different methods. Over 8.1 million fry/fingerlings have been produced in the last 30 years. Cross breeding of mahseer species and producing F1 and F2 generations was also successful. Mahseer breeding is no longer in its infancy but the commercial culture is. The breeding successes have raised new hopes for the prospects of mahseer fishery. However there exists the need to intensify these efforts by undertaking large-scale regular cage culture and a mahseer seed ranching programme. Fry and fingerlings of major species are being distributed to many states of India and to angling associations in the country by the Tata Power Company as a measure of rehabilitation and conservation. Transport by air of eggs of mahseer in moist cotton has been successful. There is growing awareness about the need to conserve mahseer and there is ample scope for advancement in certain areas. The technique of cryopreservation of mahseer milt has been successfully developed and gene banking of endangered mahseer is technically feasible. Efforts on the induction of triploidy and gynogenesis in mahseer using heat shock treatment for manipulation of sex ratio are in progress. This paper reviews the present status and potential of further mahseer fishery development.

1. INTRODUCTION

Mahseer is acclaimed as a world famous, outstanding game and food fish of India. As a sport fish, it provides unparalleled recreation to anglers from all over the world, better than salmon. It is known as tiger in waters, because of the fight it musters to wriggle off the hook. In the past mahseer formed a substantial natural fishery in the major riverine and lacustrine ecosystems of India. In commercial fisheries it occupies an important position for its good quality. For the fishermen mahseer is of considerable importance because of its large size. As a food fish, it is highly esteemed and fetches the highest market price in north and northeast of India.

Day (1878) believed that mahseer constituted only one species. Hora (1940) confirmed the validity of six different species. A recent critical study on the subject by Menon (1992) confirmed 6 valid species. He has, however, described a new species from the Darna River (Godavari drainage) at Deolali, Nashik District of Maharashtra, and named it Tor kulkarnii, which he describes as a dwarf cognate of Tor khudree. Preserntly seven valid species are recognized for India:

In addition to the above, three sub-species, viz., Tor mosal mahanadicus, Tor khudree malabaricus and Tor khudree longispinis are considered by Desai (2002) as valid species, with some reservations.

Different species of mahseer occupy different ecosystems ranging from tropical waters where summer temperatures reach 35°C, to sub-Himalayan regions, where the temperatures fall to 6°C. Similarly, they occur in streams hardly above sea level and are also found at an altitude of 2 000 m above sea level. Jhingran and Sehgal (1978) remarked that the occurrence and distribution of mahseer is controlled by the prevailing water temperature of the streams and not by the altitude.

Mahseers were considered as carnivorous and slow growing and thus unsuitable for fish culture. However, a careful study of the feeding habits of mahseer indicating that it is omnivorous has dispelled the notion that mahseer are carnivorous. Studies on the anatomical adaptations of the alimentary canal system also confirm that mahseer are omnivorous. Tripathi (1995) suggested the inclusion of mahseer in polyculture, cage culture and for river ranching and has stated that mahseer would not compete with mrigal (Cirrhinus mrigala) and the common carp.

Despite their abundance at one time, the mahseer population has been declining in number and size in natural waters and is in serious danger of extinction. The National Commission on Agriculture (1976) in its report on fisheries had stated there was a general decline in mahseer fishery in India due to indiscriminate fishing of brood and juvenile fish and the adverse effect of the river valley projects and accordingly suggested extensive survey and detailed biological investigation on this alarming situation.

The biological investigations commenced in 1970 in Tata Power Company's lakes in Pune District of Maharashtra under the guidance of C.V. Kulkarni and eventually yielded very significant information on artificial propagation of mahseer. The downward trend in the commercial and sport fishing catches of mahseer due to various man-made and ecological factors could be obviated by a continuous stocking programme on a large scale and by strictly enforcing the prevailing legislation. This programme would require production of fry and fingerlings of this species on a very large scale and their release in depleted natural perennial waters.

During the last three decades of the 20th century extensive studies on the distribution, biology and fishery of the commercially important mahseers have been made by TPCL. This has led to development of techniques of breeding, larval rearing and cultural practices at TPCL hatchery farm Lonavla, which is now capable of producing fry and fingerlings of all the desired species of mahseer.

The mahseer hatchery technology developed by TPCL may well lead to the revival of mahseer fisheries in Indian waters, provided standardised simple mahseer hatcheries based on TPCL technologies could be set up in the rural areas adjacent to rivers and reservoirs.

Causes of depletion

The exponential increase in human population is the root cause for the loss of biodiversity and the depletion of natural resources. Much has already been said regarding the depletion of mahseer. The major possible factors for the depletion of mahseer stocks are:

• degradation of ecological conditions of aquatic systems,

• indiscriminate fishing of broodstock and juveniles,

• impacts of river valley projects,

• industrial and human pollution,

• the use of explosives, poisons and electrofishing by poachers,

• introduction of exotic species,

• population pressures on resources.

The above- mentioned factors combined with human greed are responsible for the reckless damage to this priceless national heritage.

The declining trend in the populations of mahseer needs immediate attention for its in situ conservation and rejuvenation in natural waters. The reasons for the conservation of this gene pool need no further emphasis. Several measures have been enumerated for their conservation (Kulkarni 1991; Ogale, 1997). The artificial propagation and distribution of resultant fry and fingerlings into different waters constitutes one of the most important steps to rehabilitate the species, as is being done for the well known salmon in American and European waters. However, for dependable and continued results, improved aquacultural practices for the breeding of mahseer under controlled conditions play a vital role.

2. METHODOLOGY

2.1 Artificial propagation

The artificial fertilisation of eggs of the true mahseer (Tor khudree) was successfully carried out on a large scale for the first time in 1970 by Kulkarni (1971) at the Tata Power Company's fish farm at Lonavla, District Pune (Maharashtra). Since then considerable knowledge has been gained and practical knowledge has been achieved in recent years on the spawning season and habits, methods of artificial propagation, hatchery management, rearing of fry, fingerlings and broodstock, and most importantly, on the success of hypophysation (induced breeding) of pond-raised stocks of all the major species, i.e. Tor khudree, Tor mussullah, Tor tor and Tor putitora in that order (Kulkarni and Ogale, 1986; Ogale, 1997).

2.2 Spawning season

Kulkarni (1971) reported that Tor khudree spawn in July and August (peak period) and sometimes in September in Walwhan and Shirwata lakes at Lonavla. This observation has been confirmed over the last 30 years by actually collecting the eggs at TPCL Mahseer Farm. In the case of Tor tor introduced in Walwhan, Shirwata and Telco lakes at Lonavla and Pune, gravid females and males were available for stripping generally in July, August and September and in one exceptional case in April in the Telco Lake, Pune. At Lonavla, Tor putitora, like other species, is observed to spawn naturally in lakes from July to September. Kulkarni and Ogale (1986,) were also able to breed Tor khudree, Tor tor, Tor mussullah and Tor putitora with hypophysation of the pond-raised stock from July to December.

Tor putitora females have responded to stripping, with hypophysation or even without it during ten months in a year. It would be worthwhile to try and breed putitora mahseer in the other two months, i.e. January and December, during which breeding has not been attempted due to shortage of brooders.

From the above observations it could be said that the breeding season of all mahseer species extends from July to September with a peak in July - August and in exceptional cases to October, and even beyond which has been observed by the author at Lonavla from 1997-2001. This has shown the adaptability of the species to different environments.

2.3 Spawning behaviour

Most mahseer species are known to have very similar spawning behaviour and breeding habits. The spawning and breeding habits of the mahseer received specific attention at the Tata Power Company's farm at Lonavla (Kulkarni, 1971). Methods of artificial propagation on large scale were also studied and described (Kulkarni and Ogale, 1978). The natural spawning grounds in the reservoirs were discovered and their peculiarities were described. These habitats usually comprise the marginal lake areas where streams draining the adjoining hills cascade into the lake. The ripe fish in the lake are attracted by the sound and the incoming well oxygenated running water, which also gives the impression of possibilities of migration, and congregate in the area. If the streams are negotiable, the prospective broodfish migrate into them and cannot be captured for stripping and artificial propagation. The configuration of the marginal areas of the lakes has to be of an appropriate nature to enable the successful capturing of spawners. In addition to well oxygenated water, water temperature from 21°C to 26°C proves to be effective for final maturation, leading to a proper response to stripping and the ultimate release of eggs (ova). Mature fish in a ripe condition are useful for artificial fertilisation, proper hatching and further propagation (Kulkarni and Ogale, 1978). It is now known that the eggs are heavy and demersal unlike those of the major Indian carps.

The stripped eggs were then collected in plastic trays and the milt of the male spread over it as is usually done in the case of trout and salmon for fertilising the eggs. The fertilised eggs are demersal, lemon yellow or brownish golden in colour. They measure 2.8 to 3.2 mm in diameter and if kept in proper hatching trays with a direct water sprinkling arrangement, take 60 to 96 hours to hatch or even more, depending on water temperature which may vary from 20°C to 28°C (Kulkarni, 1980; Sehgal, 1991). Incidentally, almost the same size of eggs are reported for Tor khudree, Tor putitora and Tor tor. Since the spawning habits of T. tor and T. putitora are also similar to those of Tor khudree, TPCL's methodology was used to collect spawners in the Kumaon lakes of Uttar Pradesh by the National Research Center for Cold Water Fisheries (NRC-CWF) and Jammu and Kashmir.

The early hatchlings of mahseer are golden yellow and pass through a semi-quiescent stage during which they remain huddled in corners and crevices with their heads tucked away from light, as if they were negatively phototropic. In this condition, they are exposed to heavy predation by other predatory animals. This condition continues for about six days and forms the most critical period of its early life cycle. This mortality can be reduced by artificial fertilisation of eggs, hatching them in trays and nurturing the hatchlings in a protected manner in nursery ponds.

At Lonavla, after the hatchlings are grown into fry and fingerlings in nursery and rearing ponds, the grown-up fingerlings are released into the Tata Power Company's lakes. About 4 to 5 hundred thousand eggs are obtained in the above manner every year. Thousands of fry and fingerlings have also been supplied gratis for some years to different State Governments and Angling Associations in the country wherever there was commitment and opportunity to rehabilitate the fish. A consignment of mahseer fry has been sent to Laos PDR for stocking the Mekong River basin in that country.

2.4 Inherent constraints in natural breeding

While considering large scale propagation of the mahseer, the natural spawning behaviour and the inherent constraints in its early life cycle need to be understood. In nature, the spawners try to reach their favoured spawning grounds which may be in the vicinity or far away, traversing smoothly or ascending the overflowing monsoon streams. The actual spawning area needs to be comparatively calm, having well-oxygenated water and a bed of sand or gravel. The journey to these grounds may be safe or fraught with risks and dangers, but their inner instinct drives the spawners to meet the challenges in order to breed.

Our observations on stripping, hatching and larval growth of the khudree, mussullah, tor and putitora mahseer at Lonavla indicated that Mahseer species have very low fecundity of 10 000 to 15 000 per kg of body weight, though Desai (1970) had estimated a figure ranging from 7 000 to 106 500 from the ova count, depending on the size of the fish. The eggs of the mahseer are demersal and if there is loose mud on the bed instead of sand or gravel, they perish.

The hatching period of different mahseer species is 60 to 96 hours in water temperature of 20°C to 28°C as described by various authors, compared to 18 hours for catla (Catla catla), rohu (Labeo rohita), etc. If water temperature falls below 20°C, the hatching period extends beyond 96 hours. The semi-quiescent stage is three days for catla, rohu, etc. and six to ten days for Tor species. In this stage, the mahseer hatchlings tend to remain at the bottom, huddled in large numbers in corners and crevices as stated earlier. Their heads remain tucked away from light and their tails keep vibrating constantly. In this condition, they are highly vulnerable to all kinds of predators.

2.5 Hatchery management

Several systems of hatching fish eggs are being followed in different parts of the country, but the one developed at Lonavla (Kulkarni and Ogale, 1978) is the simplest. It involves cement cisterns, wooden floating trays and perforated pipes. The pipes have been specially punctured at regular intervals to provide oxygenated water directly into the trays and on the eggs.

The wooden hatchery trays used at Lonavla are 56 x 56 x 10 cm deep, with a suitable (1mm) plastic or velon mesh properly stretched and fixed to form the bottom of the tray. Eight such trays can be arranged and kept floating in a rectangular cement tank (hatchery), 2.5 x 1.2 x 0.75 m. deep. About 30 000 eggs can be conveniently accommodated in each tray, thus making a total of 240 000 for each hatching tank. More hatching tanks and trays can be arranged according to the requirement and the quantity of water available. TPCL Mahseer Hatchery at Lonavla has a capacity to hatch one million eggs at a time.

2.6 Water requirements for hatching

As mentioned earlier, water is sprinkled over the eggs placed in the hatchery tanks through perforated plastic pipes fixed on top of the sidewalls of the hatchery tank. The perforations are 1mm wide giving rise to jets falling directly but slowly into trays containing the eggs. Four such jets supply water to each tray at a rate of one litre per minute per tray. Thus, if eight trays are used at a time, 480 litres of water will be required per hour and 11 520 litres per day, the total quantity depending on the number of hatching trays being used.

The overhead tank supplying clean, silt-free water can be about three meters tall with a capacity of 10 000 litres. Water is drawn at a level of about 100 mm from the bottom to allow sedimentation of silt, if any. The tank is usually kept full to maintain pressure of water from the sprinkling jets. The outflow from the hatching tank is so arranged that only the bottom water is removed first by a siphon pipe system commencing near the bottom. Adjustments can be made depending on the local conditions prevailing at a given place, the quality of water being the most important. The dead eggs are constantly removed with a pipette or an ordinary ink-filler having a wide aperture.

3. BREEDING POND-RAISED MAHSEER

3.1 Hypophysation (induced breeding)

Efforts to propagate mahseer, especially Tor khudree, Tor tor and Tor mussullah at Lonavla lakes (Maharashtra) by Kulkarni (1971) and Tor putitora and Tor tor in Kumaon lakes by Tripathi (1978) consisted of procuring the spawners and stripping them for artificial fertilisation. Although this is a sure method and has been successful at Lonavla fish farm producing half a million fertilised eggs annually for the past 30 years, it has its own drawbacks. The method of collecting spawners for stripping has limitations in the open hilly terrain or rivers. Since the conditions for the collection of spawners are unlikely to be encountered in many other places, the only reliable method to obtain fry and fingerlings is to grow mahseer juveniles in ponds and breed the resultant adults with the help of hormones. This step ensures proper growth of gonads in ponds. Following this, Kulkarni and Ogale (1986) demonstrated that pond-raised Tor khudree and Tor tor can be successfully bred through hypophysation after growing them for three years in ponds. Stripping was done after administrating the second dose pituitary extract to the female, the male requiring only one dose. This success obviated the difficulty of obtaining spawners from widely spread spawning grounds.

Attempts to breed Tor putitora by hypophysation were first made by Sehgal and Kumar (1977) at Baintwali Mandi, Dehra Dun with little success. Pathani and Das (1978) also tried the induced breeding of Tor putitora without any success. Since the use of pond-reared brood stock of Tor putitora met with little success in induced spawning the induced breeding of natural stocks was resorted to. All efforts however remained unsatisfactory. Sehgal (1991) and Das (1992) reported that among the various species of mahseer, the golden mahseer was most affected and hence acquired the status of an endangered species. Kulkarni and Ogale introduced Tor putitora into the Lonavla lakes of the TPCL in January 1992 with the objective to breed the species both naturally and by hypophysation. Five hundred fingerlings were released and are thriving as evidenced by the catches of anglers in the lakes. However, no mature female was collected till 1997. As expected the golden mahseer adapted to the captive pond conditions and males started oozing in 1993 and were freely oozing by 1994. The females matured in 1995 (3 yrs) as could be seen from external features. The very first attempt to breed two pairs of golden mahseer at Lonavla with a single dose of Ovaprim was successful. Brooders were released in circular spawning tanks after injecting them with ovaprim. In both the experiments, stripping had to be done after 12 hours (Ogale, 1997). During the 1997 breeding season, Tor khudree and Tor mussullah were also bred with a single dose of ovaprim. Since then there has been a steady progress in the development of technique and the TPCL farm has produced 217 000 fry/fingerlings from 281 000 eggs of Tor putitora at Lonavla till May 2001. Hatching success has been over 90%.

3.2 Natural breeding in ponds

Success in breeding pond-raised mahseer and their hybrids was achieved at the Lonavla fish seed farm of the TPCL, where hybrids between Tor khudree and Tor tor (F-1 generation) were bred even without hypophysation (Ogale and Kulkarni, 1987). The factors facilitating the breeding were the protein-rich diet given to the brood fish and the running water in the pond on a small scale. Artificial fertilisation was achieved without the administration of pituitary gland extract or any other hormone. This was another milestone in breeding mahseer in confined waters without injections of any sort, and gave a new direction for propagating and perpetuating this endangered species. Moreover it was predicted that what has been found true in the case of these hybrids is likely to be true in the case of other mahseer species also.

Tor khudree was bred several times without hypophysation at Lonavla. Recently, Tor putitora and Tor mussullah have also been bred without hypophysation at Lonavla. It is thus seen that the difficulties faced in obtaining ripe males and females from natural waters for stripping can be overcome by following piscicultural practices for breeding and raising fry, fingerlings and brood fish. Another advantage of pond culture practice is that fingerlings and brood fish can be raised at any fish farm suitable for the purpose. Over 100 000 eggs have been collected from the farm-raised stock of T. putitora within one year during 2000 - 2001, just by keeping a close watch on the brood stock and catching them during the mating.

TPCL's success in breeding pond-raised mahseers of all the species and Tor putitora in particular, with and without hypophysation in captivity, has led to development of many mahseer hatchery projects all over the country with the guidance of the TPCL.

3.3 Hybridization

In addition to the propagation of Tor khudree and Tor tor at Lonavla, they were hybridized with each other by using males and females of either species. The characteristics in both cases were intermediate as regards color and body form. The rate of growth is similar or slightly better than the pure strains but the hybrids are more active and agile.

After the introduction of Tor putitora in 1992 into the Walwhan lake and the proper identification of Tor mussullah, it was observed that any of the mahseer species could be hybridized. Even the F1 generation could be bred with hypophysation and sometimes even without it when provided with a proper protein diet, feed additives, exercise and running water. The eggs of the F1 generation could be fertilized successfully with the milt of any of the pure strains of mahseer to produce an F2 generation. Thus the Lonavla fish seed farm harbours most of the major species of mahseer and their hybrids and assumes the status of a National Center for Mahseer Studies.

3.4 Air transport of eggs

In order to facilitate the distribution of mahseer seed to distant places, efforts were successfully made to transport mahseer eggs by air in moist cotton from Bombay to Bangalore. In this method, fertilised eggs were allowed to harden for 24 hours, then placed on moist cotton in two layers in perforated plastic boxes and later packed in suitable tins. As the minimum hatching period is 60 hours, sufficient time is available for transport even over longer distances. The success of this method will enable transportation of fertilised eggs to any place in India and even abroad. The eggs can then be hatched in the normal manner and the resultant fry and fingerlings distributed in lakes and reservoirs (Kulkarni and Ogale, 1979).

3.5 Culture efforts

As regards commercial aquaculture, David (1953) has indicated the possibility of culture of Tor mosal mahanadicus recording a growth of 170-200 mm in four months, whereas the Deccan mahseer reared in Orissa could attain a growth increment of 107 mm in 254 days (Badapanda and Mishra, 1991).

Attempts have been made to culture mahseer in ponds. Investigations carried out by the NRC-CWF indicate that within a one-year period, a size of 210 mm length and 175 g weight can easily be obtained in properly managed ponds. However, stocking density and details of feeding were not mentioned in the report.

The author's experience in rearing Tor khudree shows that the species has a comparatively slow growth. Nevertheless, in village ponds near Lonavla, Tor khudree has grown between 600-900 g in one year. In the Bhatgar reservoir near Pune, the fish is reported to be growing even faster. In the Powai lake, Mumbai an angler landed a mahseer weighing 13 kg which was reported to be 9 years old. In the Shivsagar lake (INS Shivaji), a newly built reservoir, mahseer were released in 1991 and anglers are already landing fish weighing between 1 and 5 kg. The fish has established itself in this reservoir and started spawning in 1995. In 1997, Tor putitora fingerlings were introduced into the same reservoir and it would be interesting to note the growth rate of this species in Lonavla.

The TEC bought 1 200 fry of Tor putitora in January 1992 for raising in ponds and breeding by hypophysation. Approximately 500 fingerlings were released into the Walwhan Lake in July 1992. Recent reports by anglers indicate the weight ranges between 1.3-3 kg.

Though many state Fisheries Departments have taken fry and fingerlings of Tor khudree for TEC's fish farm at Lonavla for culture and artificial propagation there are no data available for proper comparison. In most cases, mahseer fry were raised to fingerlings and stocked in reservoirs and rivers. In very few cases have the khudree fry been raised in ponds for more than 3 years. In Sikkim, khudree has grown to 750 g in 3 years (Bhutiya, 1995). In Karnataka the brood stock of Tor khudree has been developed from fry obtained from Lonavla. Their weight has reached up to 3kg but the time taken for this growth increment has not been recorded.

In Lonavla, experiments conducted on the culture of khudree have indicated that mahseer fingerlings could be grown to 110-120 g in monocultures at a stocking density of 11 000/ha in 8 months. This was tried a number of times with reduced and increased stocking densities with more or less the same results. In all these experiments the fish were grown only on artificial conventional feed of rice bran and groundnut cake (1:1). Professor Keshavnath at the College of Fisheries, Mangalore, conducted experiments on Tor khudree brought from Lonavla during 1983-1988. He reported an average growth of 113.02 g, 147.16 g and 159.72 g at stocking densities of 3 000, 4 500 and 6 000/ha, respectively, at the end of eight months.

Recent trials with the monoculture of Tor putitora in ponds at Lonavla were encouraging. The mahseer fingerlings were given only pelletized feed made of rice bran, groundnut cake and fishmeal (30:30:40), with a mineral mix. The average growth reported was 110 g and 90 g at stocking densities of 10 000 and 20 000/ha, respectively, at the end of eight months. Water temperature during the growth period was between 24°C and 28°C. Fresh water was released into the pond from February to May and then in September to October. The release of fresh water was not required during the interim due to heavy showers.

The trials have shown that the stocking density does not adversely affect the growth rate. The fry of golden mahseer brought by the TEC (Tata Electric Companies) from Himachal Pradesh in January 1992 has been grown and used as brood stock from 1995 onwards. In 1995 most of the female breeders were 600 g except for a few which ranged from 1 to 1.7 kg. In 1996 they had grown to 900 g and to 2 kg and in 1997 almost all specimens were over 1 kg and had matured fully. In Walwhan Lake golden mahseer introduced in 1992 grew to 3-6 kg and became established.

Based on the growth performance, conversion and feed utilisation a 40% protein content in the feed is optimal (Keshavnath, 1985). The compatibility of mahseer with other major carps under composite fish culture was tested at different densities and feeding the fish on a fish meal based diet. Mahseer growth was higher under composite culture yjam umder monoculture.

The results of these studies indicate the suitability of mahseer not only for inclusion in composite fish culture but also for monoculture. Since mahseer accepts pelleted feed and is capable of utilizing it efficiently, the species can also be used for river ranching and cage culture. Studies carried out at the TEC's fish farm also confirm that mahseer grown on pelletised feed develops into excellent broodstock for induced breeding.

3.6 Ranching of mahseer

With aquaculture acquiring the status of an industry a new phase is emerging. Wild fish stocks are supplemented substantially by hatchery-reared juveniles/fingerlings and later harvested when they grow up to table size. This release and recapture system is termed 'ranching' where hatchery reared seed of migratory fish are released into the wild with reliance on their homecoming instinct for recapture.

Ranching is defined as an aquaculture system in which juveniles are released to grow unprotected on natural foods in waters from which they are harvested at marketable size. Bardach (1980) said that in ranching the anadromous fish are reared for the early part of their life cycle, sent out to pasture in open waters and harvested when they have reached a certain size either by intercepting them on a known path or by directing their movements to facilitate recapture. Ranching is thus an effective method of retrieving the released dispersed fish. Ranching must not be confused with what is called enhancement or planting or augmenting fish stocks. Ranching means releasing eggs, fry and fingerlings in sections of reservoirs and rivers which the adult fish cannot reach on their spawning migration or which are unsuitable as spawning ground but can provide useful rearing areas for the young fish.

Ranching could be a timely and promising measure for rehabilitation of the endangered mahseer.The lack of a well established hatchery technology for mahseer and for rearing of its seed was one of the major obstacles in introducing the mahseer ranching. The others are mahseer's short-range migration for breeding and feeding and its ability to support riverine fishery above dams. The first problem has been solved and the latter two problems could be viewed as a blessing. Mahseer have a short return migration and will burn less fat while travelling back to their parent rivers. This makes it a very promising candidate species for ranching. The sole purpose of mahseer ranching would be the rehabilitation of this fish in all rivers, lakes and reservoirs where they were in abundance or could be established. A method of artificial imprinting coupled with ranching is also suggested for conservation of the species.

3.7 Imprinting

Imprinting is an irreversible learning process in which at a critical impressional age of its life span an animal gets a life-long imprint of any chemical or sound to which it is introduced and this has a bearing on its future behavior. Two promising techniques are known. Imprinting could be sound or chemicals. The large aquatic environment in which ranched fish stock may migrate to feed or for other reasons will make it potentially important to train and recall them by some means. It has been demonstrated that it is the sense of smell by which some fish recognize the waters in which they hatched and from where they migrate to the sea. This phenomenon has been termed 'imprinting' and such fish are called anadromous fish, such as salmon and hilsa.

3.7.1 Imprinting with sound

In this method the mode of recall is by sound. It has been observed at TPCL's Walwhan fish farm that it is possible to train the mahseer to congregate near a sound source in the ponds, lakes and reservoirs. Initially the cement nurseries at the farm were chosen for training the fish. For generating sound a plastic bucket was tapped a few times before the feed was given at a fixed time twice a day. Though the method was crude it proved to be successful. The mahseer fry (20 mm) can be trained in 15 - 30 days in cement cisterns and they continue to respond in the bigger ponds/lakes as well even after they grow up to 300 mm and even more. If this fish is released after the completion of training it will continue to respond even in natural habitat.

The Tata Power Company Ltd. has done some preliminary work on mahseer ranching at Walwhan. In the first experiment trained fish from the farm ponds were released in the protected site in Walwhan Lake, undisturbed by currents and high noise level. In another experiment floating cages with synthetic fiber netting of different mesh sizes were employed for cage culture experiments and also simultaneously for training the fish to sound impulses. The cages for the experiments had a size of 3 x 3 x 3 m. Trained fingerlings of mahseer of average 13 cm and 35 g were stocked from farm ponds into the cages, 500 in each cage (half a million/ha). For generating the sound plastic bucket was tapped with hand for a period of 30 seconds and then the feed was given. The already trained fish started responding within a week of their stay in cages. After the cage culture experiments were over the trained fish were released in the protected area very near to the cages. Releasing time was the same as the daily feeding time and the bucket tapping was continued. In both cases the trained fish released in the protected area of the lake started responding to the bucket tapping and came for feeding regularly, near the source of sound. The place and time of feeding, the source of sound, and the feed is same every day. Moreover it was observed that the fish from the wild (bigger size) also started responding during the duration of the cage culture experiments and were also attracted to the bucket tapping (sound impulse) and congregated near the source of the sound. It was observed that the fish from the lake followed the boat from the shore to cages and back expecting the food.

TPCL has been doing this work on training mahseer in small ponds since 1972, though this was the first time the observations were recorded in Walwhan Lake of The Tata Power Co. Ltd. Fujiya (1980) has done pioneering work on training of sea bream for ranching. At the TPCL mahseer farm, fish of all stages were trained to congregate near a sound source by feeding the fish at fixed intervals immediately after the sound was made. In a few days (15-30 days) several fish gathered near the origin of the sound. Almost all the sizes of mahseer (fry, fingerlings and adults) could be trained to respond to the sound within 15-30 days. It would be interesting to record how long this conditioning lasts.

3.7.2 Imprinting with chemicals

The other mode of recall is by scent rather than sound. Artificial imprinting with chemicals may be tried on mahseer but we must try and find out whether they can recognize the spawning site by odour. The other aspects, which need to be investigated are, various aspects of imprinting processes, age span at which successful imprinting can be accomplished, peak period at which imprinting is most effective and how long the conditioning will last, and the concentrations of various chemicals used for imprinting and special preferences of the mahseer species for various chemicals at different concentrations.

Once the fish are trained it is suggested that the same conditioning procedures are used but the amount of food should be reduced to encourage the fish to use natural food (Fujiya et al., 1980). For successful ranching, the recapture or harvesting methods must be refined. The recapture operations should be carried out several times but at intervals, to be effective.

Ranching is basically a means of taking advantage of the natural growth of the fish in open waters. Ranching is a highly attractive proposition, which could go a long way in conservation and rehabilitation of the mahseer fishery in India.

With the possibility of transporting mahseer eggs or fry by air or train a centrally located national fish seed farm would be able to meet the demand from other areas for ranching this fish. Trained personnel who look after the eggs and fry would be necessary for achieving success. Proper selection of ranching and farm sites and organised effort to continue the work year after year would be essential to rehabilitate and preserve mahseer resources, especially when numerous dams and river valley projects are changing the ecosystem in which mahseer migrates and breeds.

3.8 Cage culture

In the year 2001, for the first time culturing of golden mahseer and Deccan mahseer in floating net cages has been tried at Walwhan Lake of the Tata Power Company Ltd. The size of the net cage is 9 m² (3m x 3m), with a depth of 3 m. The net is made of synthetic fibre supported on a pipe frame floated with the help of nine 200 litre drums. The top of the cage is covered to prevent the fish from jumping. It is advisable to have a double walled synthetic netting on the side and bottom as a precaution to prevent escape of fish. The corners are anchored to the bottom of the lake and also secured to the shore. Four net cages are floated and all are accessible by a floating walkway. The net cages are fixed in the lake over more than 4 meter depth. Fingerlings, each of 35 to 40 g, were stocked in January 2001 at a rate of 450 per cage. The stocking density is approximately half a million/hectare. The fish are being fed twice a day for 10 to 15 minutes with pelletized feed. The mahseer have grown to an average of 170 g in 5 months.

Recent observations predict excellent results and would promote cage culture in India. These cage culture experiments are being coupled with ranching and imprinting with sound. In earlier experiments the imprinted fish released in the ranching area of Walwhan Lake responds to the sound impulse to which they were trained while in cages and come to the shore.

4. CONSERVATION AND PROTECTIONOFMAHSEER

Action plan for conservation of mahseer should include:

• Stricter enforcement of fishing rules to prevent fishing with explosives, poisoning, etc.

• Prevention of killing brood fish and juveniles.

• Replenishment of stock by artificial propagation.

In case of reservoirs, following steps are recommended to conserve mahseer:

• fish farm should be constructed in close proximity of every dam,

• a few tanks and ponds should be reserved in each farm for mahseer,

• mahseer should be bred by collecting ripe spawners from the streams joining the reservoir and stripping them for artificial fertilisation of eggs or using pituitary hormones.

Hatchlings should be grown to the fingerling size and then released into reservoirs and downstream rivers.

Further trials of methods of transporting mahseer eggs in moist cotton (Kulkarni and Ogale, 1979) are needed to easily transport the eggs to any part of the country.

Tata Electric Companies are involved in the rational management of the entire environment of the catchment areas of their hydroelectric reservoirs from forest to fish. TPCL has taken the initiative and undertaken excellent work in regarding environment protection, adopting a holistic view by taking care of the catchment area, including erosion, afforestation, and breeding of mahseer for its conservation and rehabilitation.

The annual average collection of eggs for the last 30 years is four to five hundred thousand per year, the maximum being a little over one million in 1988. The total tally of fertilised eggs collected from 1970 to 2001 breeding seasons is over 10.4 million, with 8.1 million of fry/fingerlings produced (Annex 1). Approximately 0.2 million mahseer fingerlings are released annually in the hydroelectric reservoirs of TPCL and the mahseer population therein has increased substantially. Over 1.06 million fry and semi-fingerlings have been given to 20 State governments and 4 angling associations during the last 30 years (Annex 2). For a summary of results of induced and natural spawning of golden mahseer at the Lonavla fish farm see Annex 3.

Extension

Four workshops were organised in 1986, 1987, 1991 and 1995 to focus attention on the need for urgent steps to be undertaken to conserve this important game fish of India. The experience gained and the results obtained by TPCL at the Walwhan fish seed farms were shared with eminent scientists and environmentalists, directors of fisheries from different states, and senior officials of agriculture I.C.A.R. and directors of the I.C.A.R and other fisheries institutes from all over India. TPCL has also extended training facilities to many state government officers and also organised a short course for officers from the Northeastern Hill Council. Scientists from the Laos P.D.R. also participated in the training programme.

5. CONCLUSIONS

All the species of mahseer are amenable to hypophysation, egg taking and artificial fertilization. At least one large size hatchery is required in each state. Efforts must be made to breed mahseer species on a large scale. Breeding of mahseer without hypophysation is perhaps the easiest method of egg collection. The TPCL design of hatchery and culture techniques are very simple and most successful and are recommended for adoption. Once the mahseer seed is available state governments of India and fish farmers can use mahseer fry and fingerlings for river ranching, raceway ponds and running water culture. Introduction of mahseer in aquaculture will be excellent for increasing the spectrum of fish species under culture. Thus if the suggested remedial measures are implemented in stages the mighty mahseer of India can be restored to its glory much to the delight of anglers and scientists in the country.

Acknowledgment

I am grateful to the management of the Tata Power Company Ltd. which has made it possible to carry out the above observations at the lakes and farm facilities.

References

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Bhutiya, 1995. Summary of Proceedings of the Workshop on Conservation and rehabilitation of Mahseer. Organised by Tata Electric Companies.

Das, P., 1992. Ex-situ conservation of coldwater fish germplasm. National Workshop on R&D Needs in Cold Water Fisheries: pp. 30-31 and 35-43. Haldwani.

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Desai, V.R., 2002. Synopsis of Biological Data on the Tor mahseer, Tor tor (Hamilton, 1822). FAO Fisheries Synopsis No. 156. FAO, Rome. 36p.

Fujiya, 1980. Training of fishes applied to ranching Red Sea bream in Japan. In: Fish Behaviour and its use in the Capture of Fishes (J.A. Bardach et al., eds): pp. 200-209. ICLARM Conference Proceedings 5, ICLARM, Manila.

Hora, S. L., 1940. The game fishes of India: parts VIII to XVII: Mahseers of India. - J. Bombay nat. Hist. Soc. vols 41 to 44.

Jhingran, V.G. and K.L. Sehgal, 1978. Cold Water Fisheries of India. Inland Fisheries Society of India. Barrackpore. 239p.

Keshavnath 1985. Final Report of the Research Schem. Study on the breeding and Culture of Tor species available in Karnataka.

Kulkarni, C.V., 1971. Spawning habits, eggs and early development of Deccan Mahseer, Tor khudree (Sykes). J.Bombay nat. Hist. Soc. 67: 510-521.

Kulkarni, C.V., 1980. Eggs and early development of Tor tor Mahseer. J. Bombay nat. Hist. Soc. 77: 70-75.

Kulkarni, C.V., 1991. Role of aquaculture in the conservation of Mahseer.

Kulkarni, C.V. and S.N. Ogale, 1978. The present status of Mahseer (fish) and artificial propagation of Tor khudree (Sykes). J. Bombay nat. Hist. Soc. 75: 651-660.

Kulkarni, C.V. and S.N. Ogale, 1979. Air transport of Mahseer (Pisces) eggs in moist cotton wool. Aquaculture 16: 367-368.

Kulkarni, C.V. and S.N. Ogale, 1986. Hypophysation (induced breeding) of Mahseer, Tor khudree (Sykes). - Pb. Fish Bull. 10(2): 23-26.

Menon, A.G.K., 1992. Taxonomy of the mahseer fishes of the genus Tor Gray with description of a new species from the Deccan. J. Bombay nat. Hist. Soc. 89(2): 210-228.

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ANNEX 1

Mahseer eggs/fry/fingerlings produced at the Tata Electric Companies Mahseer

Farms Lonavla, District Pune (Maharashtra)

(For both species, total of eggs: 14 272 752; fingerlings: 8 126 130)

A) Tor khudree and Tor mussullah

B) (Tor putitora)

ANNEX 2

Semi-fingerlings and fingerlings of Tor khudree and Tor mussullah have been given gratis to the following State Governments, agencies and angling associations

ANNEX 3

Summary of results of induced and natural spawning of Golden Mahseer (Tor putitora) at the Tata Electric Companies' Mahseer Farm, Lonavla, District Pune (Maharashtra, India)

+Females collected from brood stock pond in oozing condition while being chased and directly stripped to collect eggs. (Fry - 83 194)

*Females collected from Walwhan Lake along with the brooders of Deccan mahseer during the rainy season and found in oozing condition and stripped for artificial fertilization. (Fry - 49 756)

Females bred by hypophysation (induced breeding) with either Ovaprim or Ovatide. (Fry - 84 180)

Total: 217 130.

Males of Golden mahseer were observed to be in oozing condition through out the year. If properly reared it will be possible to breed Golden mahseer throughout the year. The above data confirm that Golden mahseer can adapt to any conditions and breed in captivity with or without injections.