Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Fish stocks and fisheries in irrigation systems in arid Asia.

Abstract

The arid zone of Asia extends from the Mediterranean to the Pacific, including the following countries: Turkey, the Syrian Arab Republic, Iraq, Iran, the Russian Federation, Afghanistan, Mongolia, Pakistan, India, China, and countries of Central Asia, i.e. Turkmenistan, Uzbekistan, Kazakhstan, Kyrgyzstan and Tajikistan. In all of them most food crops are produced using irrigated agriculture. In Central Asia, including southern Kazakhstan, over 80 percent of the total water use is for irrigated agriculture. In Pakistan 78 percent of the arable land depends on irrigation as compared with 100 percent in Egypt, 33 percent in all Asia, 21 percent in Near East and Africa, 8.5 percent in Latin America and 2.7 percent in sub-Saharan Africa. In Central Asia, at the end of the 1980s there were over 40 large reservoirs already constructed, with their primary purpose being storage of water for irrigation, closely followed, in some cases, by hydropower production. Fisheries managers have had a number of options for fishery development in the irrigation systems, including reservoirs, major irrigation and drainage canals, and waterbodies established from residual irrigation water. Most options have been a response to the impacts caused by the manipulation of water resource for purposes other than fisheries. Stocks have been enhanced by introductions of species with known preference for such waterbodies and by regular stocking of seed produced in hatcheries. In slow flowing large canals and side storage reservoirs, such as those alongside the Karakum canal in Turkmenistan, fish with pelagic eggs, such as Aral barbel, razor fish, the introduced Chinese carps and white Amur bream (Parabramis pekinensis) have been doing well. Some of the drainage collecting depressions have been utilized; the Aral Sea catchment has 2 341 of these depressions, covering 7 066 km2 surface area. However, they are characterized by elevated salinities and high concentrations of agrochemicals, the latter being a major obstacle for using fish for human consumption. The fisheries management in waterbodies of irrigation systems of the arid countries in Central Asia has been facing not only major environmental problems, but also those arising from the transition to market economy. Co-management and community-based management of irrigation waterbodies is being considered among the options which could be applied under the new privatization policy. However, in the newly independent countries of Central Asia, the major problem is now lack of funds for urgently needed rehabilitation of some of the existing structures, as well as for the development of small-scale fish enterprises as an alternative to the still prevailing large fish production and fishery systems inherited from the Soviet era, which can no longer be maintained.