New Weed Threatens Fisheries Sector

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In short
The weed, locally known as Nankabirwa has spread along Lakes Albert, Kyoga and parts of the upper Nile. The weed forms dense mats that affect movement of fish, blocks boat access and other fishing activities, a development that poses a big threat to the sector.

There is growing concern among fishing communities in Uganda on the recurrence of Salvinia Molesta, a water weed which experts say is worse than the water hyacinth.

The weed, locally known as Nankabirwa has spread along Lakes Albert, Kyoga and parts of the upper Nile. The weed forms dense mats that affect movement of fish, blocks boat access and other fishing activities, a development that poses a big threat to the sector.

The Fisheries sector is the second highest foreign exchange earner for Uganda with earnings estimated at 136.2 million US Dollars (468 billion Shillings) as of December 14, 2015 from fish exports. The sector also employs over 700,000 people, according to the Uganda Investment Authority.

Dr. Fred Wanda Masifwa, a Senior Aquatic Research Officer with the National Fisheries Resources Research Institute - NaFIRRI says the weed suffocates aquatic life by draining oxygen needed for living organisms in water and blocks sun light from penetrating into the water.

He adds that local and international experts have embarked on research to guide in the control and elimination of the weed before it spreads to other water bodies.  
 
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Nankabirwa weed was first seen on Uganda's water bodies in 2013, according to data at the National Fisheries Resources Research Institute - NaFIRRI.

The International Conservation Union ranks the weed among the worst 100 invasive weeds in the world. Researchers say that the weed reproduces through vegetative propagation and can double its population in two days upon getting a favorable habitat.

They add that due to its rapid multiplication rate, the weed can double in volume thereby clogging water ways and covering up the entire surface of the lake. It spreads with the aid of fish nets, human being and birds that feed on some of its parts.

Dr. Fred Wanda Masifwa also calls for a ban on the movement of fishermen with fishing gear across various water bodies as a temporary control measure for the spread of the weed.

He says manual or mechanical control of the weed could only apply to small populations in Uganda, because both ways are prone to further spread the weed through breaking and relocation of some parts of the weed.
 
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Magidu Magumba, a former Beach Management Unit officer in Jinja says although such weeds have not been identified in Masese - Jinja district, upon spreading they may affect the fishing communities by blocking the transporters and fisher dealers from accessing communities for trade which affects trade and the entire economy of the communities.

At the end of last year, the Egyptian government offered to conduct an extensive research on the weed in order to provide a mechanism for its control and elimination.

Uganda last battled such a weed in the early 1990's when the water hyacinth invaded Lake Victoria.

During its peak, the water hyacinth reduced the supply of clean water, caused difficulties in water extraction, increased transportation costs and reduced fish catches. It also disrupted power generation at Jinja due to a build-up of the weed on the dam.