Using saline groundwater for culture of Marine Fish
Shortage of freshwater is a global issue and the changing climatic conditions or global warming has made it unpredictable in many parts of the world. Many developing nations are persistently facing drought and near drought conditions and the freshwater availability is a distant dream to them. Conditions in our desert areas such as Thar and Thal as well as dry hilly areas in the country are not different too. Thar faces drought every few years that claims loss of livestock and crops and in certain years precious human lives are also lost as was observed in the current year. This situation demands exploring additional resources of water for food production, and the saline groundwater is the most potential resource among them. It is readily available almost everywhere in plenty, even in extended drought hit African regions such as Ethiopia, Somalia and Angola and in our inland areas as well. Therefore there is a vital need for exploring the productivity of inland saline groundwater and the suitability of organisms to be farmed in such waters.
The utility of saline water for the agriculture has long been experimented but cost effective and practical solutions are rare, as almost all of the terrestrial crops are mainly dependent on freshwater or at least require large quantities of freshwater as a conjunctive effort. On the other hand marine environment provides for viable production systems and is being cropped with marine animals and plants all over the world, which is known as mariculture. Besides mariculture, the aquaculture of marine animals and plants in saline groundwater in inland areas is relatively a new type of aquaculture (known as inland saline aquaculture) and has progressed in many parts of the world including North and Latin America, Australia, Middle East, Southeast Asia and other parts of the world. Inland saline groundwater is being successfully used to grow many marine fishes such as sea bass, red drum, sea bream, striped bass, ornamental fishes, snapper, mulloway, shrimp, crab, silver perch, trout, eels, catfish and many other organisms like abalone, mussels, oyster, microalgae, artemia and seaweed. The production of high value marine fish and vannamei shrimp in inland saline well water is a growing industry in several countries including Thailand, USA, Australia, Brazil, Israel, Egypt, Vietnam, China, India etc. Alabama, Texas, Florida and Arizona states in the United States are among such areas where inland saline aquifer is being used to grow marine species like White leg Vannamei shrimp (Litopenaeus vannamei) and tiger shrimp (Penaeus monodon) on commercial scale.
The Inland saline aquaculture has tremendous potential for income generation and diversification; and offers an opportunity for a potentially productive use of salt-affected land that can no longer support traditional agriculture. It carries the promise to address hunger and food security in freshwater threatened nations and drought hit areas. In Pakistan inland groundwater reserves over a large area of the country are saline and the saline land in the irrigation command area exceeds 11.1 million acres across Pakistan. About 40,000 hectares are abandoned within the Indus Basin annually due to secondary salinization. There are large numbers of saline groundwater pockets in the canal command areas of Punjab and Sindh provinces. In Punjab province, 23% of the area has poor groundwater quality, while in Sindh province, 78% of the ground water is saline as the area of fresh groundwater is confined only to a narrow strip along the river Indus. Furthermore, about 56% of the total irrigated land in Sindh province is affected by salinity.
The number of people directly affected by saline, sodic and/or waterlogged soils in Pakistan was estimated to be about 16 million in 1998 which is expected to be doubled by the year 2020. There are many inland saline lakes also around the country. Additionally, the surface water supplies in provinces are not enough to meet the actual crop water requirements therefore the freshwater shortage has aggravated the productivity of the agricultural lands with more severity in the lower Punjab, Sindh and southwestern parts of Balochistan and the agriculturists are facing great economic losses, especially the small farmer is under crisis.
The land salinization associated with the use of poor quality groundwater in Punjab and Sindh provinces is a great threat to the agriculture sector with low yields and the resultant higher input requirements as such the sustainability of agriculture system and the capacity of the country to feed its growing population is foreseen a major issue. In this situation, the farmers need to be educated about living with salinity by making economic use of saline land and water, and that is very possible by adopting the inland saline aquaculture. The fishponds in saline lands may also serve as sacrificial basins (or salinity sink) for adjacent lands to recover from salinity, as already being practiced in saline and waterlogged areas in many places. Inland saline aquaculture provides an opportunity to convert a liability into a valuable resource and provides for diversification of the agricultural productivity through integrated systems. This can revitalize the salinity-hit regions in the country and may gear up economic uplift of rural economies by utilizing salinity hit agriculture lands for aquaculture. This will help in poverty alleviation and employment generation in areas currently under extreme poverty.
Besides deteriorating traditional agriculture in salinity-hit areas, the situation of freshwater aquaculture is also not encouraging mainly due to shortage of freshwater. The state of wild stocks on the other hand is well known for being overexploited. With the salinization of coastal lands due to increasing sea intrusion, which according to some estimates has claimed more than 2.2 million acres of fertile land, the population relying upon the traditional agriculture has also shifted its profession to fishing. The ever-increasing fishing activity combined with unsustainable fishing practices has resulted in devastation of the natural fisheries resources that are at the brink of collapse. The heavy fishing pressure has caused decline in the bigger fish populations thus reducing the natural recruitment of fish on one hand and the reduced catches have forced the poverty ridden fishermen, on the other hand, to resort to the use of fine meshed nets onboard or fixed in the creeks which catch the juvenile fish of larger species and small edible fishes as well as endangered, associated or dependent species. There is no any distinction for target or non-target species. Under these circumstances the major portion of catch comprises small size fishes of less commercial value, which are sold as trash fish in most cases, and return just pennies to the fishermen. At the moment these diminishing fisheries resources are not enough to support a large dependent populations any more. This situation is similar for riverine areas and large inland lakes in the provinces. Additionally, the poverty-ridden communities are reduced to rely on mangroves for firewood, fodder and for their livelihood needs, thus are a major cause of heavy logging in mangrove areas. This results in habitat degradation and thus has detrimental effect on fish & shellfish growth and recruitment. This situation just not have adverse impacts on the marine ecosystem & biodiversity but also is putting more constraints on the coastal livelihoods and leading to a point of virtually no return. The potential of the country’s fisheries sector once estimated to be one billion dollars is stagnant at 200-300 million dollars.
Under these circumstance the prospects for artisanal fisheries growth and traditional agriculture in the salinity hit areas in the country are diminished and the opportunity for rearing of the freshwater fish species is also no more available due to shortage of freshwater, therefore the development of inland saline aquaculture is essential if we are to address declining capture fisheries and deteriorating traditional agriculture in salinity hit areas. Research based development: It is necessary to keep in mind that the development without research has done more harm than help in the country as such there is need to establish a sound research base on the subject before gearing up for further development. Only the meaningful research will lead to identify potential inland saline areas for aquaculture of certain marine fish and shellfish species, based on the ionic composition of groundwater, which has great influence on the physiology of cultured animals, and thus their growth and survival. The successful research will lead to opening up new vistas for small-scale aquaculture development in salinity-hit inland areas of the country.
The research areas that need attention for the proper development of inland saline aquaculture may include but are not limited to;
Identification of appropriate saline land tracts that are suitable for marine fish & shellfish culture, through water sampling and water quality analysis for identifying certain limiting nutrients such as potassium and magnesium in the saline groundwater
Ascertain suitable marine fish & shellfish species for culture in identified inland saline areas through experimentation
This is the era of multidisciplinary and integrated development; therefore the traditional approach of solitary and single subject research needs to be changed. Besides water quality analysis the inland saline groundwater areas need to be explored, mapped and monitored with the help of scientific approaches and technologies such as Geographic Information System (GIS) and Remote Sensing,
This will help in developing spatial models for small-scale sustainable Inlandsaline aquaculture development for real benefits to the affected people
In order to ensure that the results of this research reach the common man, there is need to go beyond conventional ways of presenting research outcomes in large volumes of reports and make them securely locked in shelves; rather the result outcomes ought to be presented through interactive GIS maps to be available online for selection of lands for farming and for further research, development and policy making.
Courtesy of Dawn Karachi. The original article published in "Economic & Business Review" on 14th July 2014; and can be viewed at http://www.dawn.com/1119126