The underlying meaning of fish kills in cages on Lake Victoria

Fragile systems

Just like the COVID-19 pandemic slapped us in the face for overreliance on imported fish, the fish kills phenomenon in Lake Victoria in the past weeks has yet again exposed the fragility and, to a great extent, the lack of sustainability in our aquaculture sector.

The rapid growth in cage fish farming has been impressive and a sign of hope in our quest to significantly increase the Kenyan aquaculture output and fill the fish deficit. The Kenyan per capita fish consumption (~4kg) is less than half of the African average (~9kg), which is also less than half of the world average (~20kg). Yes, that is just how much we needed a “miracle.” Cage farming seemed to have been our silver bullet on this! The recent fish death and our reaction to it are just evidence that once we found the magic bullet, we failed to load the gun right, and it is just about the time that the chicken is back home to roost.

Some cage fish farmers in Kenya are devastated and counting losses after losing most, if not their entire stocks, to the recent fish kills on Lake Victoria. The horrifying images of floating fish have been all over the internet and have sparked quite a reaction. With multiple media channels covering the story, we have come up with more questions than answers. Our fish are dying, but why? What can we do about it?

Is it upwelling?

The physical properties of Lake Victoria, mostly influenced by temperature fluctuations and currents, affect its ability to support its rich (unfortunately diminishing) biotic component. These properties are responsible for the lake’s stratification, mixing between the top and bottom waters, exchanges between inshore and offshore waters, and effects of all the nutrient influxes from the lake’s catchment area. It is important to note that these properties vary on a diel, seasonal, or annual basis and will always affect the life in the lake. Since the lake is not homogenous in terms of its Physico-chemical properties, these variations are not uniform throughout the lake. This is one of the reasons why the fish kills only happened in some parts of the lake, notably in the Winam gulf.

Upwelling is, therefore, a seasonal phenomenon that has been happening on the lake since time immemorial. However, climate change, coupled with increased influxes of nutrients from the catchment (hello urbanization), makes it less predictable. This means that parameters such as temperature and oxygen will fall (or rise) to extreme ends (either too low or too high) at different times. Since upwelling is not a new thing, three questions stand out;

A)?????Why are the fish dying now?

B)?????Why in only certain areas?

C)?????Why in very specific farms?

It is not the first time that fish kills have been witnessed in LV. Anyone who has been by the lakeside long enough knows specific times of the year when vast numbers of Nile perch are washed ashore, all dead or just dying. The recent deaths could only mean the following.

1.??????The situation is getting worse. Upwelling entails the rising of the low-oxygen waters from the nutrient-rich bottom to the surface. “Low” is relative, and so is the concept of population. All the pressures on the lake combined have resulted in a situation whereby the bottom waters are close to an “anoxic” condition. This means that if this water gets to the fish, regardless of how short the exposure time is, they are very likely to die from asphyxia. I hate being the bearer of bad news, but the truth is that if we keep doing what we are doing (we all know what we are doing), the situation will only get worse.

2.??????Some parts of the lake are clearly not suitable for fish farming. These phenomena do not occur in the entire lake simultaneously, and their effects differ based on water depth and the prevailing water quality parameters. Whereas Lake Victoria is the largest freshwater lake in the world (largest in the tropics), it’s the 17th largest by volume in the world due to its shallowness. The shallow parts get affected more by these mixing activities. Many fish enclosed in a small space (A CAGE) in a shallow place are therefore doomed during upwelling. A special focus is on Winam gulf. The region, hallmarked by Kenya’s largest lakeside city – Kisumu, is clearly heavily polluted with very little proper water exchange. Over time, the sedimentation in the gulf due to runoff from rivers such as Sondu, Awach, Kibos, and Nyando, as well as other channels, has made this region even shallower.

So, is it upwelling? No!

Can we do anything to avoid this in the future?

Yes.

First, we start by going back to the basics and listening to the experts about where to locate fish cages. I mean experts. In as much as we are yet (by far) to streamline all matters of cage fish farming, we must admit that tremendous steps have been made by research institutions, the government, and the private sector to make the life of a cage fish farmer or a potential cage fish farmer easier. For example, the Kenya Marine and Fisheries Research Institute (KMFRI) did a preliminary suitability study of the lake regarding fish farming. Albeit inconclusive due to failure to consider all factors that affect fish farming, the mapping was indicative enough and ought to have informed local governing authorities and potential investors on where to put their cages. This has been notably ignored, and people have gone ahead to set up cage farms in the “red zones” when seeking convenience. From the just-ending Aquatic Resources and Blue Economy Conference (ARBEC) in Kisumu, KMFRI has even promised to include other parameters that were left out in the initial assessment of the lake.

Second, we use best aquaculture practices (BAPs) on farms. There is a low uptake and adoption of BAPs due to the low skill levels of some of the farmers and, in some cases, just utter disregard of advice in the hope of making quick money. Wrong stocking densities, bad feeding regimes, incorrect net type, and poor net/farm maintenance are just a few sins of a typical cage fish farmer who does not take BAPs seriously. Remember, the chicken is home to roost! Evidence? Fish are dying in farm A and not in farm B.

Third, learn from this experience. It is so unfortunate that so far, all we have done regarding the fish kills are mostly knee-jerk reactions. To fully solve a problem, especially one that is both complicated and complex, as one that we are facing now, a holistic approach that focuses on the cause of the problem rather than the problem itself works best. Lake Victoria is an immense (68,800m2) resource that cuts through three countries with plenty of economic activities on it and its catchment area (169,858km2) and is evidently facing the "Tragedy of the commons.". It is, therefore, wrong (borderline illegal) to try to single out one parameter as a “cause” to an “effect,” such as the fish kills.

Fourth, accept our contribution to the lake’s well-being. For example, if a farmer overfeeds their fish, the uneaten feed will eventually get to the lake bottom in the form of nutrients. The same is the designation of fish wastes and dead fish that are not collected from the lake (and do not end up in the belly of a bird). ?Back to BAPs. Compared to other anthropogenic activities on and around the lake, the impacts of cage fish farming may be relatively insignificant, but we need to be wary of it. Every responsible farmer should therefore take deliberate actions to reduce negative impacts on the lake.

Are we crying wolf?

I ask this question due to the following.

A)?????Most of those who have lost fish and those who claim to advocate for them are asking for “quick fixes.” Should the government decide to compensate for the loss, will the problem go away? Your guess is as good as mine. The “good Samaritan” approach is just not the way to go! Let us find a way to ensure that the fish do not die again under similar circumstances.

B)?????The loss is misreported. If the claimed values were true or even close to true, we would not have a fish deficit problem in this country. The values (KSH) and numbers (fish tonnage) reported as having been lost do not make sense. It shows that most farmers do not fully understand the aquaculture business basics. Money has been lost; that is a fact. However, reporting wrong figures does not solve the problem.

C)?????We do not seem to understand the problem. While some say that the fish died due to heavy rainfall, others claim that they were poisoned, and one article headlined it as having been caused by “unsuitable fish feed use.” Before we send out the police to go arrest, the said “culprits,” let us as a sector first understand the situation we are in and then make well-informed, science-based, sustainable, and adaptive decisions that would help solve the problem. Yes, we built a house on sand. Should we keep on building it high?

FYI: Do you know the boy who cried wolf? The young man didn’t like being out there on his own. He, therefore, decided to throw a tantrum by claiming that he was being attacked by a wolf. After a few calls for “help,” those inside got “used” to his game and stopped heeding his calls. When an actual wolf came by, his genuine cries were mistaken for his initial ploys. The rest is history. Are we crying wolf?

Way forward

The fish kills should not be the reason to quit fish farming. It should be a wake-up call for all stakeholders. Rather than take a step back, we need to leap forward, knowing better. We all must take responsibility and recognize our individual and collective roles in the aquaculture value chain. A resilient sector will only be created through robust synergistic interventions based on factual baseline information. We all want the same thing: food security and livelihood for farmers at all levels. And, of course, to not only see our lake survive but thrive. We are, therefore, technically on the same team. Basic teamwork principle: you work together, you succeed! Or as our ancestors put it: to go fast, you go alone; to go far, we go together. “Going far” implies sustainability. It means that our children and their children will also enjoy the resources we have today.

I have deliberately not used any picture of dead fish on this article because, before harvesting, fish are better alive. I have hope in this sector. This article is not intended as an attack to anybody but a reflective piece to encourage us to start the actual conversation.