Effects of Water Hyacinth on Fishery Resource and Its Expansion Trends in Ethiopian Water Bodies: A Review

Abstract

Ethiopia is gifted with a variety of aquatic ecosystems. Aquatic ecosystems are often viewed as highly productive biological systems. At present Water hyacinth ( Eichhornia crassipses ) have been ranked as one of the world’s worst invasive weeds causing problems to millions of users of water resources. The water hyacinth appeared in Ethiopia in 1965 at the Koka Reservoir and in the Awash River. Other infestations in the country include Gambela Region, the Blue Nile from just below Lake Tana into Sudan, Lake Ellen near Alem Tena and currently expanding to almost rift valley lakes. Assessment 2014 study shows that close to one-third or more than 30% of the shoreline of the north-eastern part of the Lake’s shore is now invaded by water hyacinth. Under favorable conditions water hyacinth can double its mass every 5 days and it also grows from seed which can remain viable for 20 years or longer. Water hyacinth can also greatly affect fish catch rates, because mats of water hyacinth can block access to fishing grounds and clog eye of the net. Water hyacinth reduces fish stock for Tilapia and young Nile Perch by limiting access to breeding, nursing, and feeding grounds. Water hyacinth affects fish catchability especially when dissolved oxygen is reduced as a result of dense water hyacinth mats, this risk killing the fish. Access to sites becomes difficult when weed infestation is present, loss of fishing equipment. Further expansion of this plant will lead to drying up and shrinking of the lake. Depending on the degree of evapo-transpiration and the lake size, there would be completely dry-up and disappearance of the Lakes. As control measure several methods biological, physical chemical and integrated control approaches are under taken. Keywords: Water hyacinth, Fishery, Expansion trends, Water bodies DOI: 10.7176/JNSR/10-11-04 Publication date: June 30th 2020