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The Value of Lake Fisheries
Mara River Basin, 2007
Interviewed: DINO MARTINS, Ph.D.
Entomologist, Turkana Basin Institute
Interviewer: ALISON M. JONES
Founding Director of NWNL
Introductory Note from NWNL
Kenya’s Lake Turkana is the terminus of Ethiopia’s Omo River. It’s under the protection of Lake Turkana National Parks, which cover 161,485 hectares (623 sq. miles), and is designated as a UNESCO World Heritage Site in 1997 (enlarged in 2001). This unique ecosystem is a migratory bird stopping point, and breeding grounds for Nile crocodile, hippopotamus and snakes.
As well, it has critical fisheries, healthier than those in the better-known and much larger Lake Victoria, source of the White Nile River. Dino’s blog is a wide-reaching resource on many topics addressing the biology, sustainability and values of this region, with a focus on the evolution of life and our role in a sustainable world.
All images © Alison M. Jones. All rights reserved.
NWNL: Jambo, Dino! As a scientist in East Africa, you have a focused interest in Kenya’s Lake Turkana Basin, a desert lake with international significance since about 90% of it is filled by Ethiopia’s Omo River. How did you become interested in this remote, desert region?
DINO MARTINS: I’m a Kenyan entomologist with very broad interests in evolution. I focus on how insects run the world, and how they are connected to human life and life itself. Thanks to Dr. Richard Leakey, I’ve worked with the Turkana Basin Institute for two years as a postdoctoral fellow. I do research and conservation there, as well as enjoying teaching and exploring the Lake Turkana Basin (formerly Lake Rudolph Basin).
The Fisheries of Lakes Turkana & Victoria
NWNL: Let’s discuss the ecology of lakes before we talk about their socio-economic values. The Mara and Nile Rivers are the other two NWNL African case-study watersheds. They are each connected to another great fishery, Lake Victoria. How would you compare these two great African lakes ecologically?
DINO MARTINS: Over the past few decades, Lake Victoria – the second-largest freshwater lake in the world – has had one of the most productive fisheries. But ironically, that which created its productivity was actually an act of “biological genocide.” That was the introduction of the very large Nile perch.
It’s a bit fuzzy as to who was really responsible; but nonetheless, once the perch was introduced, it completely inverted the food chain within the lake. Instead of having hundreds of different species within many ecological niches, there are now mass extinctions and a concentration of Lake Victoria’s biomass into a few species, primarily the Nile perch.
K-S-S-112Tourists’ catch of Nile Perch, L. Victoria
For quite some time, 200,000 to 300,000 tons of fish have been leaving Lake Victoria. It used to be a very, very stable fishery; but any ecologist would tell you, it became completely unsustainable as the population of this invasive Nile perch kept growing and growing and growing. It had to reach a tipping point, and that caused the lake’s fish stocks to collapse, a situation compounded by pollution. So Lake Victoria is now on the verge of ecological collapse.
In many ways what happened to Lake Victoria is similar to what happened to some of the U. S. Great Lakes. There were invasive species introduced there (including zebra mussels) – as well as massive amounts of pollution, huge amounts of industrial use, and disposal of waste in those lakes. The Great Lakes also reached a tipping point. These ecological lake stories are very well documented scientifically. Like Lake Victoria, all these lakes now have large amounts of anoxic water – water that is in effect “dead,” having become completely depleted of oxygen. It’s that anoxic water that causes fish die-offs.
However, Lake Turkana in many ways is still a “living” African lake, with a naturally healthy ecology and evolution. It has endemic species that have come about as a result of millions of years of evolution. The lucky thing about Turkana is that the Nile perch are endemic to that lake. They are an indigenous species there, so all the other species that occur with these predatory fish co-evolved with the perch. The reproductive strategies and life histories [of those smaller, less aggressive fish] accounted for high levels of predation from the perch, allowing the smaller fish to survive in the face of the other harsh conditions this lake presents.
In contrast, Lake Victoria was a much younger lake, much more innocent, when Nile perch were introduced, causing the lake to undergo what we called an “adaptive radiation.” It seems that lake’s species didn’t have the time to really evolve, or develop the ability to deal with, this massive disturbance that humans have produced recently.
NWNL: Is it likely that nature brought the Nile perch into Lake Turkana when there was some great geological shift? My understanding is that, epochs ago, the Omo River and Lake Turkana were originally part of the Nile River Basin. Then there was a shift that closed off the Omo Basin.
DINO MARTINS: Yes. Exactly. But it was geological time, rather than “ecological time” – which humans are really good at messing up.
Turkana’s Socio-Economic Values
NWNL: Dino, how does the ecology of this lake affect local and regional economies?
DINO MARTINS: In what is an otherwise fairly food-stressed environment, the lake has a thriving fishery which provides a really important source of high-quality animal protein. The local people depend on fish in the deltas that stretch all the way around the entire lake. The fish stocks that get shipped out are focused on Nile perch. The Nile perch is so valuable that if somebody has a Nile perch, they’ll take it to Lodwar.
The other day a guy was carrying this big perch. I said, “Please, please stop. Let me just get a picture of this for my students.” As I was getting him in the right position, he was holding this huge fish on his head. A dealer came running up, saying, “You’re trying to steal my fish. You’re trying to buy it!” I said, “No, no. I just want a photograph of it.” Another dealer came up. There was a huge fight, over this valuable fish. You see, if they could get it filleted and somehow onto a plane or into some vehicle to a town, there is a multiplication of its value.
NWNL: How big was this fish?
DINO MARTINS: This Nile perch was about 1.5 meters (5 feet) long. It is amazing that you still have such alpha-predator fish, reaching these sizes. In that sense, it shows that Lake Turkana is healthy in that it has some functioning food chains, which Lake Victoria doesn’t have.
091003_TZ_1877Sardines, Lake Victoria
In Lake Victoria today there are outbursts of algae, and there are lake sardines. Everybody loves these sardines, because they can catch them in large quantities. But this little fish is basically a grasshopper. All it does is respond to the absence of predation and high levels of algae. They go through boom-and-bust cycles, thus the Lake Victoria is not a stable system at all.
Whereas in Lake Turkana, you see quite a bit of fish diversity when you go into the fish markets or spots where the fishermen hold their fish. There is some local over-exploitation; but because the lake is so large, it is hard to access. That inaccessibility protects Lake Turkana.
NWNL: What part of Lake Turkana is accessible enough to allow the “local over-exploitation” you mention?
DINO MARTINS: Ferguson’s Gulf is the real confluence of all the extremely dramatic environmental and socioeconomic issues facing Lake Turkana today. A fish market there, called Karakol, is one of the main fisheries for the lake. Ironically, at present, most of the fish brought in there is being dried or smoked and then driven to Kisumu, on the shores of Lake Victoria.
130118_K_1932Fish markets at Karakol and Ferguson’s Gulf
NWNL: Kisumu is on the edge of Lake Victoria. Why is fish being driven from one lake to another?
DINO MARTINS: Because Lake Victoria is overfished. It is polluted. It’s a “regional toilet,” basically. The demand for fish there is very high, especially in communities living around the lakes used to having fish. There is an extremely high population-density around Lake Victoria – one of the highest in the world. So there is a huge demand.
The irony is that the value of Lake Turkana fish is extremely low in terms of money when it is traditionally dried and smoked for the Lake Victoria market. If they could get that to Nairobi as fresh fish, they would have a much, much higher premium. Then, fishermen on the lake, living in poverty basically, would be much better off.
Of course, a lot of infrastructure would be needed to allow that to happen. There has been some help with fishermen’s associations. I think USAID, or one of the big aid agencies, has funded setting up fishermen’s associations, called “beach management units.”
Is Lake Turkana Over-Fished?
Illegal Fishing on Lake Turkana
NWNL: You’ve mentioned Lake Turkana is over-fished. I’ve talked with others who’ve known the lake and its fisheries for years. They say there are “way too many fishermen’s long lines” on the lake and that it’s overfished. Some say, “The fish are gone.” Others are not quite as extreme, but say “Yeah. It’s pretty well done.” And yet you’re saying something very different.
DINO MARTINS: I say it’s “locally overexploited” – but there are still parts of the lake that do have fish. There are even lakes within this lake, on Central Island. They are phenomenal. On Central Island is a freshwater lake, an alkaline one and one freshwater lake that has so many fish that even the crocodiles can’t eat all of them. They just lie about on the shore. Central Island is protected now, and so there are still fish there. So, compared to Lake Victoria, there are still fish in Lake Turkana.
030827_K_1342Lakes on Central Island
NWNL: I’ve heard several causes attributed to the declines in Lake Turkana’s fisheries, from overfishing to environmental issues such as less rain, more alkalinity in the water and lower water levels.
A 1995 essay by Jeppe Kolding from Norway says Lake Turkana’s fish declines are because of people, as well as not enough rain. Others say in rebuttal: “Ah well. Look twice at that one. This guy was publishing for NORAD, a Norwegian group devoted to profiting from those fisheries. NORAD had an axe to grind as to why their productivity was not as expected. They were trying to prove that they were not responsible.”
DINO MARTINS: Okay, that’s complicated. The issue with the NORAD fisheries, and all aid in Turkana, is very, very complex. It is another kettle of fish! I think ecological conditions do drive a number of the lake’s fishery-related phenomena. Let’s put it that way. However, remember this is, and has been, a desert lake for a long time. Its fish are adapted to these conditions in many different ways. There are species that can simply shut down, or aestivate. These species pause their life history and remain in a kind of dormancy within certain parts of the lake.
[1. Aestivation (from Latin aestas, summer): a state of animal dormancy, similar to hibernation, characterized by inactivity and a lowered metabolic rate. It is a response to high temperatures and arid conditions in order to avoid the risks of desiccation.]
Invasives in Lake Turkana
NWNL: You have spoken of issues regarding Lake Turkana’s fauna. What about its flora?
DINO MARTINS: The flora is another major contributor to the decline of fish stocks. There are river deltas that are large, large areas of this lake that very few people get to. They are being trashed. There is no question about that. For instance, the Kerio River’s delta is choked with invasive prosopis.
[2. Prosopis is a genus of flowering plants in the pea family. It contains around 45 species of spiny trees and shrubs in subtropical and tropical regions worldwide, incuding the pesky Mesquite found in southern US and Mexico. They often thrive in arid soil and are drought resistant. Often with extremely deep root systems, their wood is usually hard, dense and durable. Their fruit pods may contain large amounts of sugar. Its local common name in Kenya is “algarroba.”]
130117_K_0897Invasive prosopis on Turkwell River, Lodwar
I took students there to show them the delta’s grasses and bulrushes, as well as its birds, dragonflies and nursery beds where the fish live. We literally had to physically claw our way through prosopis for about an hour before we got to any sort of spot where there was just a little bit of native reeds and grass still growing.
Prosopis looks like acacia, comes from Hawaii and takes over. That is really bad for young fish nurseries that naturally occurred in these deltas when they were rich in sediment, plants and insect species. Now the Kerio Delta is almost completely dominated by prosopis.
Satellite pictures show that on the ground the Turkwel Delta is no longer easily accessible to people. But traditionally it was cultivated by the Turkana. Yet, for some reason, the Turkwel Delta has less prosopis in it than does the Omo Delta, further north, which is being heavily impacted by burning, grazing and increased salinity.
All of these deltas, via their rivers, connect to forests in the highlands of western Kenya and of southern Ethiopia. There is massive deforestation in all of those areas. Kenya only has 1.7% of its forest cover remaining. It is just insane so you also see that on the Kerio and the Turkwel Deltas.
NWNL: Lake Victoria, like Louisiana wetlands in the US, has been terribly degraded by the lovely but invasive, fast-growing water hyacinth (Eichhornia crassipes). Is that non-native species a problem in Lake Turkana? I saw a bit of it growing in the Omo Delta in 2009. However, Halewijn Scheuerman, Honorary Warden of Lake Turkana National Parks, said then it was not a problem because the hyacinth needs a root system to hold it in place. He explained that couldn’t happen in the Omo Delta due to extreme annual flooding that raises water levels by 60 feet in parts of the river. How do you assess the water hyacinth issue today in both lakes?
091002_TZ_1359Invasive water hyacinth in Lakes Turkana & Victoria
DINO MARTINS: The water hyacinth, a beautiful plant from South America, was introduced to East Africa and Lake Victoria [in the 1980s]. It is a serious problem in Lake Victoria because of the water’s putrification, due to all the sewage and stuff going into the lake. This enrichment of nutrients encouraged its massive growths.
It is present in Lake Turkana, but nowhere near as prevalent as it is in Lake Victoria. However, if we continue doing to Lake Turkana what has happened to every single lake in the world, I would imagine the water hyacinth will keep spreading. I suggest we use it as an indicator – a bio-indicator – because the more silt, more nutrients, more sewage, and more use of the lake as a toilet that occurs, the more these invasive species will grow.
NWNL: What will be the impact of the increased nutrients coming down the Omo River from the cotton and sugarcane plantations?
DINO MARTINS: Sadly, the kind of agriculture that’s being nationally promoted, both in Ethiopia and Kenya, is being driving by the need to produce, produce, produce more food, more biofuels, or whatever it may be. Growers aren’t thinking about sustainability or engaging with processes at the watershed level.
I don’t know why policymakers, governments, whoever it is…, don’t understand that just chopping or burning down even one tree here impacts thousands, tens of thousands, hundred of thousands of lives – and not just human lives, lives of everything. That chain of responsibility is completely broken. Unfortunately the communities that are most heavily impacted are the poorest, most vulnerable, and voiceless. Their suffering and local political, socioeconomic and environmental problems are never connected to what happens thousands of miles away.
ET-Delta-227Remnant of riverine forest used for crops now
But in the Turkana Basin, it is very clear where those nutrients come from, because 90% of the lake’s water comes from the Omo, and only 10% from the Turkwel and Kerio, which don’t flow a lot of the time.
NWNL: Who and how many people depend on Lake Turkana’s water? NGOs like International Rivers have tried to construct the number, with their publications estimating that about 300,000 live around Lake Turkana. Yet here in Kenya people say, “We are nowhere near that number.”
DINO MARTINS: It would be hard to come up with an accurate number as to how many people depend on Lake Turkana’s water. Hundreds of thousands live directly around the lake. You could expand it to cover the entire basin: the Omo-Turkana Basin which includes large areas of the southern Ethiopian region, as well as the Kerio River Valley, the Cherangany Hills all the way to Mount Elgon, and parts of Kenya that are very underdeveloped and neglected. Then you would be looking at several millions of people.
Gatherings in Omo Valley 070915_ET_9207
NWNL: Well then your population number for the Omo-Turkana Basin is up on the high end with International Rivers.
DINO MARTINS: Yes, if you are talking about the entire Omo-Turkana Basin – but not if you are just talking about the lake. The Omo is the dense part. Yet the Kerio and Turkwel River Basins are becoming much more settled. Turkana used to be the place where you’d go for hundreds of miles and not see a person. It’s harder to do that now: you do see people.
Turkana woman with children 130123_K_3183
NWNL: What has caused that rise in population?
DINO MARTINS: It’s a demographic time bomb, as it is in much of that part of the world. There is a large part of Africa where there traditionally has not been much infrastructure, not much healthcare, and many social problems, all combined with extremely conservative traditions. That is just changing right now. For example, one of the field assistants at the Turkana Basin Institute is my age, 34. He has 17 children, I believe. That gives a sense that while socio-culturally and economically all these things are coming together, they have not quite caught up with traditions.
Population numbers are always such a red herring that I have problems with saying anything about it; but the Omo-Turkana Basin is definitely a part of the world that is increasing in population very fast. Like anywhere, there are more births than deaths.
Women still don’t have much of a say – if they have any – over reproductive rights. I do trust the population studies that show that giving women basic rights and education has an immediate impact on the number of children. Women won’t keep having children they can’t feed or educate.
070913_ET_9046Two-day old Karo baby
Future Lessons from L. Turkana Basin
NWNL: On upstream tributaries of the Omo River, Ethiopia is building a cascade of 5 large hydro-dams. What water-level impacts will these Gibe Dams have in the long term, ecologically? In your perspective, why is it important to save Lake Turkana?
DINO MARTINS: Lake Turkana is a desert lake. It has a phenomenal evolutionary history, a large component of which we know about via our search for human history – by Dr. Leakey, particularly. Relative to the planet’s current trends of global warming, rain fluctuations and new extremes, this is an environment that has already seen a lot of extremes.
We have a lot to learn from the Lake Turkana Basin regarding how organisms cope and adapt to life in extreme conditions. For example, there are these ants that I’m looking at. They come out during the hottest part of the day in Turkana, which is unusual because it gets really hot. These ants specialize in foraging in temperatures up to 70 degrees Celsius [158 degrees Farenheit], which we know is physiologically impossible. Above 60–62 degrees [140–143 degrees Farenheit] is really pushing it.
Certain molecular processes are just not going to work beyond a certain temperature. But these ants run around and seem fine. They have a lot of tricks to cope with the heat, but basically they have adapted. This is the amazing thing about this entire environment. You have species here that are adapted and are adapting to these extremes.
I note how thin these margins of adaptability are. As evolutionarily biologists, that is fascinating. But I think it also holds a plan for us and for life on the planet – because having to face extreme weather conditions, as in the Turkana Basin, is where we are going.
130122_K_2758Life in the Turkana Basin
NWNL: Thank you, Dino, for your unique point of view on these two great African lakes. You have clarified many issues for us.
[Posted by NWNL on July 28, 2017. — Transcription edited for clarity by Alison M. Jones, NWNL Director. Our Interview Guidelines describe the NWNL protocol for editing raw transcripts.]