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Conservation in Freshwater Fisheries:

Management is the Key

by Eugene Kruger

It is a truism that ‘conservation’ has become a politically correct buzzword throughout the modern world, but as with all noble intentions there is a fine line between what is practical, balanced and sound, as opposed to well intentioned but mostly misinformed emotional sentiment.

The latter (unfortunately) is the one that most easily attracts public awareness.

The leisure fishing sector is particularly vulnerable – all it needs is a photo of an angler’s catch with a caption decrying the "cruel, wasteful catch" to whip up emotions. The same brush as having no regard for nature then tars everyone who “goes fishing”.

The fact of the matter is that many inland impoundments in South Africa suffer from an over population of fish, particularly carp (Cyprinus carpio) and mudfish (Labeo spp.).

The scarcity of trophy-sized fish compared to the abundance of small fish is a clear indication of this, and is a symptom of dams that have lost their ability to accommodate a healthy population of fish. Such dams are in dire need of management to recover their carrying capacity.

There are various factors that cause such a state of affairs: drought, chemical, physical and other forms of pollution can all be contributing factors, but a major cause is mismanagement. Tragically, this mismanagement is more often than not applied quite innocently and with the best of intentions.


The modern definition of ‘conservation’ is: "the continued utilisation of a natural resource". Note that the concept of "utilisation" is used as opposed to "exploitation".

This means that the natural resource, in this instance fish, must be utilised in such a way that it does not become extinct. Simply put, we must not catch and kill more fish than what Nature can replenish.

Conservation, however, means far more than just conserving the number of fish; it also means looking after the habitat the fish live in.

A healthy population of fish means that the habitat is able to support a balanced number of fish of all age groups. Sufficient sexually mature fish must be present to ensure reproduction; sufficient immature fish must be present to replace mortality.

It follows, therefore, that besides acceptable water quality an impoundment must have sufficient space, food and oxygen to sustain such a population.

Leisure anglers can unfortunately exert little influence over water quality (excepting to place all possible pressure on government authorities when pollution takes place) other than contribute on a micro level by minimising their own pollution. What anglers can do, however, is to play an active part in the management of the waters in which they fish.


There are very few, if any, river systems in the country that do not suffer from one or other form of pollution. Even a breakwater in a river is a form of pollution in that it disturbs the natural flow of the river and therefore in turn disturbs the natural habitat of fishes and other aquatic life.

The building of dams has converted open eco-systems into closed eco-systems, and management is therefore vitally important to ensure the future of the habitat and the fish it supports.

An impoundment, namely a dam, is as much a closed eco-system as a fenced off game camp.

If the game is not managed according to a scientific plan, over population quickly takes place, leading to over grazing and all the other evils such a situation causes.

An important task of management is therefore to ensure that over population does not take place. This can only be accomplished by culling the excess population. Removing excess numbers ensures that there is sufficient space, food and so on to sustain the population.

A dam requires precisely the same management, but with the exception of certain cases, notably Bloemhof Dam where commercial utilisation takes place, it is very difficult to implement.

It is just about impossible to prevent over population using ethical rod and reel tactics. But in this very situation lies the opportunity for leisure anglers to contribute to sound management and to enjoy their fishing in the process.

"Prevention is better than cure" goes the old saying, and it is therefore vital that leisure anglers play their part in the management of our inland fisheries.

As follows: return large, mature fish, unharmed, back to the water, and remove (cull) ALL the small, immature fish. And do this every time you go fishing!

A general rule of thumb for carp is to cull all fish smaller than 3kg and to return the bigger ones. For moggel: cull the entire catch.


All this does not mean that the catch be allowed to rot on the bank. The exact opposite is true. There is only one acceptable reason for killing a fish, namely for food. There is however a case to be argued for having a trophy mounted by a taxidermist.

A fish that is caught must be regarded as a harvest out of nature, and must be respected as such. It is morally unacceptable that a fish is wasted – it must be used in one or another manner. Take it home for your own table, give it to someone else or use it for cat food – but USE it!

Fish that are returned to the water must be handled carefully. Handle it with wet hands, don’t let it thrash around on the ground, and never let a fish fall.

Take a photo or two and return it as soon as possible to the water. The operative word here is "place" – don’t throw it into the water!

If it is to be kept in a keep net, ensure that the net is in deep enough water and that it is big enough. Remember: the mature fish you return is the breeding stock for the future.

But cull the small ones by all means – over population is also pollution!

* Eugene Kruger is an experienced and knowledgeable angling writer and has written hundreds of angling articles over the past 25 years. He is a four times winner of the SFW Angling Writer of the Year Award, and is South African Representative of the International Game Fish Association.