adminWalter Nyamukondiwa Chinhoyi Bureau
LAKE Kariba exudes invincibility with its gigantic outlook, myriad crawling, creeping and swimming creatures which the human scope has not fully grasped despite countless hours spent investigating the bluish green waters.
The waters betray depth of both base and content.
Is it not God’s nature to amaze? We continue to discover in amazement His ingenuity while some of those touted as having made profound discoveries have long gone and yet still the world continues to discover in amazement.
Although Lake Kariba is a man-made lake, God’s nature has superimposed itself with things that even those that designed the lake never envisioned. In his infinite wisdom, God gave nature the ability to regenerate even when familiar habitats are disturbed as what happened when animals were displaced during the construction of the dam wall in the 1950s.
We look in awe at how a lake that was supposed to harness water for electricity generation has swelled in width a staggering 32km across and a mammoth 282km in length – to accommodate an array of fish and other animal species while still offering sustenance to people on its boundaries and beyond.
In its calmness and a ripple of periodic waves see-sawing towards the banks lies a world yet to be fully discovered. In its belly lies a myriad living things discovered and yet to be discovered by man’s inquisitive and prying mind. One of nature’s penchants to bewilder was the recent discovery of what was viewed as an intruder, the Australian Red Claw Crayfish, by a fisherman sometime in 2010. His instinct told him that this specie was not on the original cast of actors in the lake’s drama of existence.
Was it a threat and how had it managed to find its way into the lake when man’s mechanisms for passing on information from generation to generation such as oral tradition had not made mention of the fish? But what is this creature whose very look does not inspire pity or endearment from the lake’s supposed guardians man?
The Australian Red Claw Crayfish is known by the scientific name Cherax Quadricarinatus and was originally found in the fresh waters of Australia, hence the name. Characterised by claws that look like scissors protruding on either side, four pairs of legs and antennas, the fish is in the same family as the lobsters and other crustacean species which despite their appearance have emerged to be premium delicacies which are for the well to do in societies across the globe.
While a kilogramme of beef goes for about $5,00, the crayfish sells for anything upwards of $12 per kg.
Although Kariba has largely frowned on the thought of eating the fish, it is reportedly being flown out of the country where exotic tastes are tolerant. Kariba district administrator Mr Amigo Mhlanga confirmed the development but said the process is often mired in secrecy.
“Not much is known about what is happening with the fish but we know for a fact that there are some people who are breeding and exporting the crayfish,” he said.
Some hotels are said to be eyeing the fish as an item on their menus. Johnson Kamhuka, a fisherman, said the fish is now very common in the lake and is mostly caught using cages.
“Not many people are used to the idea of eating the crayfish because we have always known the bream and other fish types. This is an alien fish that we started seeing in recent years,” he said.
Like all intruders, people want to know where it came from and if it does not have an effect on the indigenous fish types like the bream. The fish is reported to have escaped from a fish farm in Siavonga across the border in Zambia where it was being bred and because of their breeding habits they have since spread along the lake’s shore. If locals had misgivings about the fish and its look, then their hatred has been fed by reports that fish stocks of other types are diminishing. There are reports of diminishing fish stocks confirmed by both researchers and fishermen alike with muted suggestions that it could be because of the crayfish.
“We used to easily catch fish in the lake but lately it is a struggle to get the white bream. We do not know why things are like this,” said another fisherman.
University of Zimbabwe Lake Kariba Research Station chief technician Mr Elmon Dhlomo confirmed the development saying, “Our indigenous fish species like the white bream are diminishing and yet at the same time we find that exotic species like the Nile tilapia and the catfish are doing well. We are yet to establish the cause of the decline.”
The bream’s breeding cycle is slow compared to the exotic species and this is offsetting the indigenous species. Another factor is that the tilapia can evolve from male to female thereby aiding the multiplication of the specie. Mr Dhlomo said the institution is now encouraging the farming of fish on a larger scale to balance out demand while also promoting the eating of white meat to stem some cancers known to develop through having red meat.
“We have embarked on programmes to train people in fish farming on a large scale considering that we have many dams in the country so that people have white meat more often as compared to red meat which causes some cancers,” he said.
He said fish farming was a way of ensuring food security in the country.
The decline in fish stocks has been attributed to overfishing which does not allow the fish time to breed. Lighlone Marufu, a lecturer and PHD student with the University of Zimbabwe, said the feeding pattern of the fish can provide answers on whether they are causing the decline in fish stocks in the lake.
“The crayfish is an omnivore which feeds mainly on detritus (rotting things) mainly found on the shoreline and preliminary findings have shown that tiger fish are feeding on it. The fish has been found in the stomach of the tiger fish.”
He said preliminary data has so far not shown that the crayfish feeds on other fish types. There was, however, a possibility, he said, that the Crayfish can disturb eggs as it scours the lake floor in search of food.
Researchers have noted that the fish is rapidly increasing in the lake. The fish has spread through attachment to floating weeds and humans have also aided on its spread. A research conducted in 2012 showed that the fish was found on 10 of the 12 sites where traps were set on the lake shores.
The fish was found on the Sanyati, Bumi and Kariba basins of the lake.
There are currently 19 sites in the lake where the fish has been found.
Residents in Kariba have called on the Parks and Wildlife Authority to issue licences so that they can be harvested as they see it as an opportunity to make money while also controlling their numbers. Zimparks commercial director recently told our sister paper, The Chronicle, that the authority had started issuing fishing permits to individuals, cooperatives and companies.
Feedback: [email protected]
Online Reporter