Concerns about environmental threat posed to aquatic biodiversity in the Lake Victoria Basin have been increasing in intensity over the recent years.
However, it almost always never ceases to unsettle many a conservationist that, despite recorded decimation of various fish species in the expansive basin over the decades, it is still home to hundreds of species that are yet to be described.
Much research continues to be conducted, but the full extent of the diversity is still to be fathomed.
The basin, whose catchment extends to Rwanda and Burundi, includes lakes Kyoga, Albert and Edward in Uganda, and lakes Burigi, Ikimba and Malimbe in Tanzania, among various others in the region.
Lake Victoria itself, sustained by an intricate system of the lakes and the rivers feeding them, is shared by three of the East African countries, with Tanzania controlling 49 per cent of the expansive lake, Uganda 45 per cent and Kenya 6 per cent.
In view of its ecological place in the region and beyond, the recent assessment under the Red List series by International Union for Conservation of Nature (IUCN) reminds us yet again of the desperate situation besetting the basin.
Titled, ‘Freshwater biodiversity in the Lake Victoria Basin’, the survey singles out climate change, pollution from industrial and agricultural sources, over-harvesting and land clearance for agriculture as some of the culprits leading to the continued decline of many species, including the succulent African Lungfish (kamongo, whose delicacy is famously recounted in Kenya and Uganda).
It observes that the situation is particularly dire for many native species in Lake Victoria. In large part this has been due to the introduction of the predatory Nile Perch decades ago, in addition to environmental changes due to effluent in the water making it not conducive to the native species.
And, yet, ironically, despite its predatory habits, among the most threatened fish is the Nile Perch, one of the main commercial fish species in Lake Victoria.
Its overfishing has had a drastic impact such that scores of processing factories around the region have had to close for lack of the Nile Perch.
It stands out as a poster child of over-harvesting, but which, nevertheless, Tanzania, Uganda and Kenya have just launched a $1.8 million initiative dubbed Operation Save the Nile Perch to increase the fish stocks in the lake and save it from extinction.
Demand for the fish extends to Rwanda, South Sudan and the Democratic Republic of Congo that over the years, according to the Lake Victoria Fisheries Organisation (LVFO), the EAC body overseeing the lake, has seen an increase in the number of fishermen on the lake from 50,000 in the 1970s to over 200,000 people in 2015.
However, the IUCN lake-wide fish surveys were completed in 2017, of which the conservation organisation assessed the 651 freshwater species native to Lake Victoria. Of these, 20 per cent were found to be at risk of extinction.
Another 76 per cent of the 204 fresh water species only found in the lake were also marked to be at risk of extinction.
Hundreds of other species remain to be described, according to the authors of the report, let alone assess the state of their abundance or risk to extinction. This should change before we lose them.
Despite this gap, IUCN explains that the region’s freshwater fishes are highly vulnerable to climate change. The fishes are highly sensitive with seemingly poor adaptive capacity.
It mentions other invasive species, such as plants which also present an important threat to native biodiversity in the Basin, affecting 31 per cent of all species and 73 per cent of threatened species.
The purple-flowered water hyacinth, for instance, was accidentally introduced into the lake from South America in the 1980s and, at its peak, covered close to 10 per cent of the lake surface, observes the report.
Inevitably, the ongoing decline in freshwater biodiversity is impacting livelihoods of millions of people in the basin.
Though there have been sustained efforts to raise awareness on the ecological, environmental and socio-economic aspects relating to the lake basin, there also appears to be a lag heeding the warnings. The major polluters upstream and many of affected downstream appear unwilling or unable to act on curbing the imminent threat.
This has led to the concerted efforts by the regional governments, and specifically Tanzania, Uganda and Kenya, to enforce an agreement between them that the Nile perch, for example, should not be harvested until it is 50cm long, or weighing 2kg, regardless of the shores it is caught in the sections of the lake within the three countries’ jurisdictions.
Much, therefore, is happening to address the problem, but the efforts must remain sustained. We should also call for the necessary support for our scientists to map out the yet undesignated species.
In the meantime, we should expect more surveys such as the IUCN’s, which continue to raise the red flag and serve as independent reminders of our collective conservation responsibilities.
The views expressed in this article are of the author.