Aquaculture being a fast growing food production system will continue to strengthen its role in contributing to food security and poverty alleviation in India and many developing countries. There are several emerging diseases for farmed fish in India, particularly for freshwater fish and prawns. The practice of seed import without adequate precautions could bring many new diseases to the aquaculture sector in Kerala. The indiscriminate capture of ornamental fish from the wild without adequate replenishment is a serious threat to the biodiversity of the state
Fish and fisheries products are the primary protein sources for some 950 million people worldwide, and are an important part of the diet of many more. Fish is the most heavily traded food commodity in the world. Aquaculture being a fast-growing food production system, will continue to strengthen its role in contributing to food security and poverty alleviation in India and many developing countries, in view of the stagnating yields from capture fisheries and increasing demand for fish and fishery products. Despite its high productivity, there is very little recognition of freshwater- dependent fishery production due mainly to a general lack of data and scientific literature compared with industrial marine fisheries. The majority of freshwater fisheries and aquaculture is small-scale and has received only scant attention during the past few decades.
The world production of fish reached an all-time high of about 172 million MT in 2018, largely contributed by the increasing aquaculture. The world inland and coastal aquaculture has been steadily increasing over the past few years. India with an area of 3.3 million sq. km and a population of over a billion people, occupies second position in the world in aquaculture production, contributing to over 10 million MT of fish. Inland aquaculture has been the major fish producing system in India. Most of the aquaculture activities in India could be regarded as rural aquaculture. Freshwater aquaculture in village tanks and ponds follow the improved traditional or semi-intensive composite culture/ polyculture system and they serve the household needs for fish and generate some additional income for the family.
Freshwater resources of Kerala
The state of Kerala is gifted with rich resources of freshwater bodies suitable for aquaculture. The state has a total freshwater area of 1, 58,358 ha, consisting of reservoirs (42,890 ha), private ponds (21,986 ha), irrigation tanks (2,835 ha), freshwater lakes (1,620 ha), panchayat ponds (1,487 ha), village ponds and other water holds (1,317 ha), and check dams, bunds, barriers or anicuts (1,138 ha). The state has 41 west-flowing and 3 east-flowing rivers, constituting an area of 85,000 ha.
There are 54 reservoirs in the state (2 major above 5,000 ha, 13 medium of 1,000 to 5,000 ha and 39 small of less than 1,000 ha). The total reservoir area is the highest in Idukki district(18,651 ha) followed by Palakkad (7,132 ha), Thrissur (3,706 ha), Kozhikod (3,172 ha) Kollam (2,590 ha), Pathanamthitta (2,505 ha) and Thiruvananthapuram (2,340 ha). The maximum number of small reservoirs is in the Idukki district (14) followed by Palakkad (10) Thrissur (6) and Pathanamthitta (3). The freshwater lake area is maximum in Idukki district (624 ha) followed by Kollam (440 ha), Thrissur (295 ha) and Thiruvananthapuram (250 ha).
Freshwater aquaculture development in Kerala
Modern fish culture in India became prominent with the success and perfection of induced spawning techniques for the Indian major and exotic carps. Catla catla and Labeo fimbriatus were successfully bred at Malampuzha, and this centre became the focus of inland fisheries development in Kerala. Trials conducted at different parts of the country laid the scientific foundation of composite fish culture techniques. Commercial hatchery production of giant freshwater prawn, Macrobrachium rosenbergii was also achieved with the experiments conducted at the Fisheries College, Kochi in 1987 resulting in a cost-effective technology.
Lack of diversification in aquaculture
At present, freshwater aquaculture system in Kerala remains restricted to carp culture in a few private ponds, prawn cum paddy culture in limited areas in Kuttanad and Kole lands, stocking of carps in a few irrigation reservoirs, and river ranching in a few rivers on a limited scale. No serious effort has been taken to develop coldwater fish culture, game fisheries, culture of indigenous fish species of Kerala, freshwater pearls, etc. The farming of Karimeen(Etroplus suratenis ) has recently emerged as a popular practice in ponds, and often in cages set in open water bodies. Advanced farming practices such as cage culture; pen culture and running water culture are emerging in many places, and have great potential for utilizing vast areas of freshwater bodies in the State.
The Kuttanad area (55,000 ha) and the Kole lands (13,632 ha) suitable for paddy cum fish culture in Kerala lie below the mean sea level, which make them prone to frequent floods. In many places, the flood water level is raised up to 4 feet above the existing embankments during heavy monsoon showers leading to crop loss. The recent floods have caused enormous damage to the freshwater ecosystems in the State, and this damage has not yet been assessed.
Seed import and threat of diseases
A major share of the seed required for freshwater aquaculture is imported from AP, Tamil Nadu and West Bengal by long distance transport. The regulation of seed import is also weak and there is no effective control on the species brought and none of the quarantine conditions are followed in such live transport and stocking in the water bodies of Kerala.This practice poses serious biodversity and zootechnical issues. The appearance of several prohibited species of fish that naturally occur in the rivers of Southeast Asia or South American countries is a drastic example of the damage caused to Kerala’s aquatic ecosystem because of the largely unregulated import of fish to the State for farming and for the ornamental fish industry. There are several emerging diseases for farmed fish in India, particularly for freshwater fish and prawns. The practice of seed import without adequate precautions could bring many new diseases to the aquaculture sector in Kerala.
Lack of suitable feed for freshwater aquaculture
Groundnut Oil Cake and rice bran remain the most popular feed for the freshwater fish cultured in India. Further, ornamental fish industry still prefers imported feeds due to lack of indigenously- made feeds of good quality. Of late, farmers have begun using formulated feeds in limited quantities.
Capture based ornamental fishery Ornamental fishery is largely restricted to the sale of riverine collection of indigenous varieties alone for international destinations, directly or via the ports in Chennai, Mumbai or Kolkata. It is evident that only a fraction (less than 10%) of the wild caught fish reaches the final destination in the international market, while the rest is lost while transfer from the source of collection, and conditioning before export. The indiscriminate capture of ornamental fish from the wild without adequate replenishment is a serious threat to the biodiversity of the state. The fact that many of these species are listed as ’vulnerable’ or ‘endangered’ in the IUCN Red List of Threatened Species further compounds the problem.
Lack of value-added aquaculture products
Most of the freshwater fishes are marketed whole without any processing. No effort has been taken to make value-added products like fish fillets, surimi etc. The floating bones in the flesh of the carps might be the main hindrance to value addition.
At the national and the state level, aquaculture policies are being established to stimulate development. Many governments have intervened at the macro level by designating aquaculture as a priority area in their economic agendas, defining goals and targets and establishing guiding strategies to achieve them by facilitating reasonable access to credit, providing fiscal incentives and removing institutional constraints. However, in many cases, aquaculture administration still falls under more than one agency, which often hinders progress. This is true for our state also where aquaculture activities are taken up by agencies, the activities of which are often overlapping, and policies are contradictory in many instances.
Prospects for inland aquaculture development in Kerala Despite the many constraints that face the development, freshwater aquaculture in Kerala present a positive outlook. The proven success of extensive paddy cum fish culture in Vietnam and China could be emulated to suit these areas. Measures to improve fish production in the State by expanding farming areas and enhancing productivity of the aquaculture systems are essential.
Although non-endemic in the rivers, the Indian major carps, Chinese carps and common carp have become well established in the waters of Kerala and their propagation need to be encouraged. Endemic species like the pearl spot, (Etroplus suratensis, though exotic, it is at home in Kerala), Manjakoori (Horobagrus brachysoma), the native catfish (Clarias dussumeirii), and Gonoproktopterus curmuca enjoy great preference among Keralites. These species have been shown to grow well, and success achieved in their seed production by the Kerala Agricultural University.
Cage culture in the freshwater reservoirs of Kerala would contribute significantly in augmenting the fish and prawn production from the state, which has a direct bearing on export earnings. The cultivable space could be more effectively enhanced by utilizing the available water area, and facilitating easier harvesting compared to the conventional farming in earthen ponds. Cage culture does not affect the indigenous flora and fauna of the reservoirs or their water flow characteristics, and is therefore ecologically safe. Apart from offering direct employment to rural population, it would also create a new line of rural entrepreneurs, who could be trained to achieve maximum output from the limited resources available, without harming the environment. Cage culture is most suitable for freshwater lakes and reservoirs but may be practiced in any environment suitable for fish culture. It is promising to note that there has been a recent expansion in the cage culture of Karimeen in the fresh and brackish water bodies in some districts of Kerala. Cage culture of Karimeen, common carp, and other suitable fishes should be promoted in the reservoirs and freshwater lakes in the State.
Farming of freshwater prawns
Unlike the non-endemic carps, the freshwater prawn (M. rosenbergii) is a native of the rivers of Central Kerala and is one of the most suitable species for culture in fresh and low saline waters, either as a monoculture candidate or in polyculture along with carps, milkfish, gray mullet etc. Considerable potential for freshwater prawn farming exists in many parts of Kerala where waterlogged areas are available that are otherwise unsuitable for agriculture. The State has rich resources of wetlands, which remain fallow during major parts of the year. A majority of such areas could be brought under freshwater prawn farming to enhance production and productivity from these fallow water bodies.
Paddy cum fish/prawn culture
Rice and prawn integrated culture in alternate crops is an age-old practice in many Southeast Asian countries. Several successful trials have been conducted in China, Vietnam, Indonesia, and the Philippines, which have proven their success. The rice cultivation and prawn culture are mutually beneficial, and enable to enhance the production from unit area without any ecological hazards. Steps should be taken to promote paddy cum fish/prawn culture in the state by suitably modifying the paddy fields wherever possible. The alternate or concurrent culture of rice and fish/prawn would serve to increase the income of farmers while economising the production. The use of fertilizers and pesticides could be eliminated by this system of crop management. The coastal belt of Kerala has a unique system of paddy cultivation in saline soils known locally as Pokkali cultivation. The term Pokkali refers to a salinity resistant rice variety largely cultivated in Central Kerala especially in the Ernakulam district. Pokkali cultivation is fast losing ground due to the non-profitability of operations arising out of low yielding varieties of paddy and the high cost of labour involved. The saline resistant, tall variety of paddy cultivated in pokkali lands offers a unique opportunity to culture freshwater prawns simultaneous with the paddy crop during June to October. The cultivation of high value freshwater prawns along with paddy would make the culture system more sustainable, eco-friendly and economical. The farming of prawns along with Pokkali is mutually beneficial. Left over feed and the excreta of the prawn will act as manure for the paddy, and paddy plants will act as a biofilm for the development of periphyton, which constitute an ideal feed component for the prawn.
Ornamental fish culture
The state has a rich resource of indigenous ornamental fish in various river systems that have the potential to earn income to the state. Among these fishes, a few like Puntius denisoni are very valuable in the international market. Indiscriminate collection of these fish from the wild is a threat to the biodiversity. A certification system should be introduced for the export of indigenous fishes, to the effect that only captive bred and reared specimens are allowed to be shipped overseas. While regulating the export, the import norms of new varieties of aquarium fish need to be liberal. The nature and requirements of the world ornamental fish trade are quite dynamic. To be competent, new varieties need to be introduced in the international market. The exporter needs to be updated on the current trends and the varieties traded in the prevailing market. Hence, the licenses for importing ornamental fish need to be made liberal to facilitate breeding them in captivity in our local conditions and re-export. Importing limited number of brood stock should be permitted liberally after strict quarantine. Presently, Kerala exports only wild caught fish to the international market. Most of the other exotic ornamental fish are being exported from Chennai, Kolkata and Mumbai. This need a change and the priority should be shifted to exotic varieties and captive bred native fishes. The ornamental plants in aquarium involve a sizeable trade in the international market. These plants should be artificially propagated on a mass scale and explore the market possibilities.
Serious effort to protect the biodiversity is needed in the case of indigenous ornamental fishes and coldwater fishes. In addition there were several recent issues with regard to introduction of exotic species like the African catfish Clarius gariepineus, pacu, gar fish, etc. in Kerala, which has made its way into the country through Bangladesh, or through ornamental fish imports, and are now established in many parts of India. Their recent entry into the open water bodies of Kerala is a major threat to the State’s aquatic systems. Despite the abundance of rich freshwater resources including rivers, reservoirs, lakes etc. and the presence of two active monsoon periods, the impact of freshwater aquaculture in contributing to the food sector is far less compared to other states like Andhra Pradesh, where water is a scarce commodity. Suitable technologies and methods need to be devised to enhance production and productivity from inland aquaculture, while safeguarding the environment. This would bring about substantial increase in the number of jobs in inland aquaculture. Freshwater fish culture could also serve to enhance depleted wild fish stocks thereby increasing the value of commercial landings for fishermen and enriching the State’s aquatic inland resources. Paddy cum fish/prawn culture and cage or pen culture of prawns in reservoirs and other suitable water bodies appear to have great potential in augmenting the production from freshwater aquaculture. Since paddy is intimately associated with the life in Kerala, being the staple food, its integration with fish and prawn thereby catering to both domestic as well as export markets could have great influence on the nutrition of the population, apart from increased exports.