We’re working on producing all-male tilapia — Prof. Okayi

What is the study of fishery all about?Fishery is the act of studying fish and the different kinds of fishes found in our aquatic environment. The ecology of the water bodies hosting the fish is taking into consideration in terms of physical, chemical and biologic parameters. These factors enhance the wellbeing of the fish in […]

What is the study of fishery all about?
Fishery is the act of studying fish and the different kinds of fishes found in our aquatic environment. The ecology of the water bodies hosting the fish is taking into consideration in terms of physical, chemical and biologic parameters. These factors enhance the wellbeing of the fish in the water bodies.
What study are you undertaking in fishery at the moment?
A lot of studies have been undertaken in the area of fisheries. For instance, the UAM over the past 20 years, in conjunction with the department of fisheries, has gone a long way to study the kind of fish species available in River Benue fresh water bodies. Studies have been done to know the kind of species available; both the ones endangered in terms of environmental factors, and we have taken stocks of the available ones, as well as those of commercial values. We also took note of the ones preferred by people in the area mostly as a result of cultural and religious factors. For example, the Seventh Day Adventist Church faithful do not eat catfish while the Tiv elders prefer the tilapia fish. So, if any one wants to embark on artificial culture of these fishes, it is important to know their biology, when they breed, hibernate and when they go into hiding and of course, knowing that the fishes are abundant at a particular season of the year. 
The catfish, tilapia (bony fish) and cap (foreign) are commonest in the Benue water bodies, others are wild. We also have shrimp (shell fishes) in our fresh water here which is abundant. The economic advantage of shrimps cannot be overemphasized.  It is one of Nigeria’s staple food but we import a lot of it while in our oceanic areas like Calabar, Port-Harcourt and Lagos these shrimps are fished, we have about five species in the Benue river as well as its tributaries that are not exploited at all.
A lot of work has been done on shrimps. I personally got a grant from the Agricultural Research Council of Nigeria in 2009 and we started work on surveying the shrimps available in rivers Niger and Benue. The work was conducted between Makurdi, Jebba down to Lokoja and Idah. Our only challenge was that the project was awarded for three years but they sponsored it for one and a half years, then the story changed. I got a grant that was supposed to go for N18 million but a total of about N8 million was released, then we didn’t hear anything again about the project. We were told that a new minister came in and the project was stopped. There is a similar programme going on now which has to do with the West African Agricultural Project (WAAP).
One of my colleagues also got the award and a lot of work is going on too. We are trying to look at the culture of tilapia because it is a fish that can produce within seconds in large number. So we are trying to check this rapid population rate because as they produce within a short time in large number, it will retard their growth and then, you get a smaller size fish. So now, we are trying to see how we can produce all male.
Will this idea not affect production?
Customers are looking for flesh. They prefer bigger fish. So, the research is geared towards producing all male tilapia. We can still have a small fraction of where we allow the male and female to reproduce.
Why is it difficult to find big fishes these days?
It is like that because these fishes reproduce, one single fish can produce millions naturally and even through artificial propagation which affects size. They also quickly encounter environmental factors especially at the natural environment where another fish of higher specie preys on them. So, most of the fishes have physical adaptation in protecting their offspring, it is either they go into one corner to create a nest or some will hold their newly born in their mouth for some days before they can release them to escape. There are also chemical factors of pollution affecting the level of dissolved oxygen caused by human activities.
In our Benue river, for example, a lot of human and industrial activities are going on: the Benue breweries is releasing its influence into the water, the burnt bricks, people molding blocks by the riverside and the farmers doing irrigation farming, applying fertilizers and herbicides; all of these have a way of polluting the water bodies and affecting the young aquatic lives. If you see a place where they produce cassava, the cynic content is being drained to the river as well as hospital garbage, domestic sewage flowing from homes as it rains find their way into the river. The river is the receiving body of almost all the junks produced by humans. Even clearing of weeds now is done with chemicals, these are long degradable inorganic compounds that often find their ways during rainfall into the water bodies.
Some people think that the fishes bred in natural environment taste better than the ones in homestead ponds?
There has been that assertion and it is true. It is because those found in natural environment eat more of natural food, they are exposed to a lot of aquatic plants in the water with all its greenish and chloroquine inputs embedded in them and that is why even in the artificial level, you are encouraged not to feed your fishes completely with artificial feeds made up of compartments of maize, guinea corn, soybean. You allow the pond grow with artificial green algae to naturally fertilize the pond. The natural fish eat more of green plant in their natural environment while we stock the artificial one with more of artificial feeds enhancing their growth but losing their taste. The ones in natural environment have more nutrients embedded in their flesh than the ones cultured in the pond.
What do you think is threatening the lives of fishes in Nigerian waters?
Apart from human and industrial activities causing heavy pollution, there is also adverse effect of climate change. Globally, the ozone layers is being depleted, it causes the ocean to increase, thereby resulting to flooding which dislodges the ecological balance of animals in the water, especially fish. Often, it will take years to restore such ecological balance.
The illegal fishing net with small mesh size, use of toxic substances for obnoxious fishing, overfishing and over exploitation of fingerlings and juveniles of fish species, habitat loss and degradation, oil pollution in the Delta are also leading to extinction of aquatic life in Nigerian waters.