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DAM-L fish in lake vic down/LS (fwd)
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Date: Fri, 2 Nov 2001 14:02:42 -0800
To: irn-safrica@netvista.net
From: Lori Pottinger <lori@irn.org>
Subject: fish in lake vic down/LS
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Business
Monday, October 22, 2001
------------------------------------------------------------------------
Fish in Lake Victoria Down by 0.6m
By W. WAKABI
THE EASTAFRICAN
EAST AFRICAN fisheries researchers have reported a sharp fall in fish
stocks in Lake Victoria in the past two years. The researchers also
cite a decrease in the average weight and size of the Nile perch, one
of the most economically valuable species in the region.
A study by an inter-governmental agency, the Lake Victoria Fisheries
Research Project (LVFRP), conducted between 1999 and February this
year, points to a reduction of fish stocks in the lake by about one
third.
It says that there was a worrying decline in commercial species,
including the Nile perch or mbuta, which are in high demand in the
Europe.
The scientists attributed the change in the physical characteristics
of the region's premier commercial fish to the deteriorating marine
ecosystem in the lake and indiscriminate fishing.
Mr Ogutu-Ohwayo of the Fisheries Research Institute in Jinja, Uganda
said the decrease in the weight of the Nile perch suggested that its
capacity to reproduce had significantly diminished.
According to the LVFRP report: "The findings show a declining biomass
index, with the total for all species falling from 2.1 to 1.5 million
tonnes between August 1999 and February 2000."
The surveys were conducted at six-month intervals, taking into
consideration the variations in weather patterns.
Large quantities of immature fish are being landed in the lake,
according to the findings. Moreover, it noted, the size of the mature
ones had also decreased.
Said the report: "Several species are now maturing at smaller sizes.
This is an indicator of over-fishing."
The scientists say part of the problem is that very small fish are
being caught through illegal fishing techniques, in particular, by
beach-seining and gill-netting with mesh sizes below the allowed
minimum.
Declining yields are attributed to the poor environmental state of
Lake Victoria, the second largest fresh water lake in the world.
"It is therefore unlikely that we can sustain the high yields
realised soon after Nile perch was introduced in Lake Victoria and
other lakes in the 1970s," Mr Ogutu-Olwayo said. This posed a high
risk on the fish export industry in East Africa.
Some 60 per cent of the species in the lake are said to have become
extinct due to predation by the Nile perch. Research findings also
show that about 62.7 per cent of the fishing canoes that land the
Nile perch in the lake use methods that also net the immature Nile
perch.
The introduction of exotic species into the lake has been partly
blamed for the extinction and near-extinction of some of the original
species.
"The [exotic] Nile perch preys on the primary grazers, contributing
to an increase in algae, oxygen depletion in the deeper levels of the
lake, and loss of biodiversity," says a report from the Lake Victoria
Environment Management Programme.
Researchers also attributed the drastic change in the Lake Victoria
marine ecosystem to the discharge of industrial effluents into the
lake and contamination of the rivers upstream.
Lake Victoria's annual fish catch ranges between 400,000 and 500,000
tonnes, generating, $3.4 billion annually. The industry employs than
100,000 people directly and more than two million indirectly.
The fisheries department says the catching of immature fish is a
threat to the breeding patterns in the lake and it is likely to
impact negatively on the population.
The department further says that in the absence of a comprehensive
law on fishing in the lake, illegal nets and poison are used to
indiscriminately land fish.
Other problems facing the lake include the displacement of fishermen
and traders following a sharp rise in the number of large commercial
trawlers and processing plants around the lake.
--
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Lori Pottinger, Director, Southern Africa Program,
and Editor, World Rivers Review
International Rivers Network <'})))>><
1847 Berkeley Way, Berkeley, California 94703, USA
Tel. (510) 848 1155 Fax (510) 848 1008
http://www.irn.org
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