Crayfish research underway in Kariba

A multi-sectoral taskforce is carrying out investigations into the feeding and breeding habits of the invasive crayfish in Lake Kariba to establish its relationship with other species.

This comes amid fears that the crayfish could be consuming smaller fish like the kapenta and disturbing breeding of other fish such as the tilapia.

Progressive decline of fish and kapenta catch by fishermen in the lake have added fuel to speculation that the crayfish could be causing the reduction.

The taskforce comprises the Zambezi River Authority (ZRA), the University of Zimbabwe Lake Kariba Research Station and the Zimbabwe Parks and Wildlife Management Authority.

In an interview last week, ZRA chief executive Engineer Munyaradzi Munodawafa said preliminary findings of the research have shown that the crayfish type might not have significant impact on other fish.

“We are still investigating the crayfish and now we have a team from the University of Zimbabwe who accompany us each time we go into the lake to carry out environmental checks and balances and monitoring,” he said.

“The initial mitigation measure put in place has been that Zimparks has provided a lot of licences for the harvesting of the crayfish so that they can control the population.”

Eng Munodawafa said there were no conclusive evidence that the crayfish in the lake was preying on smaller fish like kapenta.

From a peak of between 30 000 and 54 000 tonnes of kapenta in 1998, harvests have declined to around 7 000 tonnes per annum.

Zimbabwe reduced fishing by 30 percent in 2015 through the seven-day full moon window which saw catches increasing to around 188kg per rig each night from around 88kg in Kariba Basin 5.

Eng Munodawafa said there was need for caution as crayfish had a tendency to eat anything they came across.

“After the study, then we will know whether to go further to eradicating it,” he said.

“But currently from what we see, the population is not very high. Where there is the kapenta fish we have found that there is also the crayfish population, but there has not been any marked changes.”