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Wednesday, May 22, 2019
Interview with aquaculture consultant Tom Shipton
GRAHAMSTOWN, May 31 2008 (IPS) - From time immemorial, fishermen on Lake Malawi have depended on the chambo to help feed their families – all without upsetting the stocks of this fish species. Following the start of commercial fishing on the lake, however, the annual catch of chambo plunged, from 3,250 tonnes in 1985 to 207 tonnes in 2002.
Government was eventually forced to put a stop to the commercial operations.
The Maldeco Aquaculture company was established in 2003 to build up chambo stocks through aquaculture – and Tom Shipton of Enviro-Fish Africa (a consulting firm based in Grahamstown, South Africa) hired as a technical advisor to the project. He recently chatted to IPS reporter Steven Lang.
IPS: Why did the Malawians turn to you for advice? TOM SHIPTON: Initially they hired a European consultancy to come down and do the assessments and so forth. It was a big project and they were planning on building 12 or 16 of these 12 metre cages, 10 metres deep. It’s similar to the salmon farms, using salmon cage technology; but they soon realised that their plans were not working.
IPS: And that’s where you came in? TS: Yes. They went to the Development Bank of Southern Africa (DBSA) for a large loan to do some more research and I went up there to look at the technical side.
Essentially what they had done is, they had taken the technology for Oreochromis niloticus (the Nile tilapia) and had assumed that it was the same for this new species (the chambo, for which the scientific name is Oreochromis karongae).
So, we were worried that if we used the model for the Oreochromis niloticus it might not work here.
IPS: What were the potentially critical differences? TS: At that time, we didn’t know what the fecundity was, what was the survival rate…They didn’t even know the growth rates, and if you don’t know the growth rates you can’t do a production schedule – so how do you plan your financials? There were a lot of biotechnical issues that needed to be resolved.
IPS: How did you go about addressing these issues? TS: The DBSA then put in half a million rand (about 65,000 dollars) of research money and we sent somebody up there, Dr Jerome Davis, for a nine month period just doing experiments: getting the various growth rates and looking at another species as well – the shiranus (Oreochromis shiranus) – and really just getting to the fundamental biology, looking at what kind of sex ratios you needed in your ponds, those kind of things.
IPS: What were the outcomes of this research? TS: What essentially did come out of it is that the karongae grows a lot slower than the niloticus, probably about a third slower – I’m not sure exactly. But, it really was quite significant.
They found that the shiranus, the other species that just got into the cages, actually grows a lot faster. But with the shiranus you get the males growing very fast and the females going into this precocious breeding…When you crowd them up, then the females feel stressed and they naturally go into this reproductive cycle where they start breeding at a very small size…So, you end up with thousands of small fish instead of the big fish which is the high value species.
This is a common problem with most Oreochromus, but the karongae is a late developer – which allows both sexes to grow larger. This means that you don’t have to have single sex populations.
IPS: Why is it better to have fewer large fish rather than many smaller fish? TS: Well, here in South Africa or in Europe it is a big problem because people like eating the larger fish, but up in Malawi it is not really such a big issue because the people eat small fish.
You’re wasting a lot of energy, because you’re putting a lot of energy in for reproduction, but what you really want to do is be getting into the growth of body mass.
IPS: The project has been underway for just on five years now. Is it achieving its goals? TS: They’re not up to full production; they’re not up to 3,000 tonnes yet, not anywhere near it. But, Malawi is a difficult country to get things going in.
One of the problems was that if you produce 3,000 tonnes per annum and you have a food conversion ratio of let’s say 1.5, that means you need four-and-a-half thousand tonnes of fish feed every year.
Now, you’re on the south-east arm of Lake Malawi, the roads very often get washed away during storms, then the aid agencies come along and they put down roads, but they’re not good quality roads – so they last a couple of seasons, then they break up.
IPS: And the feed has to come from outside? TS: Well, they’re looking at producing their own soya and their own basics, but at the moment most of it is.
That’s a major constraint. The other constraint is human resources. You’ve got a very high turnover of people as well: there are very few people in Malawi who have got the educational level to actually operate hatchery systems and be great admin managers.
And sadly the other reality is that HIV is a major problem up there. You train them up and then they die.
IPS: What are your feelings about the long term prospects of this project? TS: It is difficult, but the fact of the matter is that they have managed to put this farm together and it is functional. I am quietly hopeful. They might not get up to their 3,000 tonnes, but they’ve been there for five years, and they’ve learnt a lot of lessons. It’s coming on.
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