Fisheries management refers to the rational exploitation of fisheries resources in such a way that economic benefits accrue to humans while resources are protected and conserved. It involves systematic procedures to ensure the continuous availability of fish resources. In Nigeria, fish production is mainly derived from three sub-sectors: Industrial/Commercial Fisheries, Artisanal Fisheries, and Aquaculture.

1. Industrial Fisheries

Industrial fisheries involve the use of highly mechanized techniques and fishing gear, referred to as fishing trawlers or vessels, most of which are imported. The skills and techniques required are advanced compared to artisanal fisheries.

The catch per unit effort and the profit margin from industrial fishing are higher. Currently, over 400 vessels are operating in Nigeria. Despite the significant investment and yield, industrial fisheries have contributed less than 10% of Nigeria’s domestic fish production over the years.

2. Artisanal/Small-Scale Fisheries

Artisanal fisheries are fishing operations practiced by small-scale fishermen in rural communities along coastlines and inland water bodies such as dams, lakes, and rivers. Fishermen use small to medium-sized canoes, typically ranging from 3 to 10 meters.

These fishermen often rely on simple, outdated, or crude fishing gear, including nets, traps, and various sizes of beach seine nets. The labour involved is immense, but the financial return is low. The catch per unit effort is significantly low, and fishermen face numerous social challenges. Despite these challenges, artisanal fisheries account for over 80% of Nigeria’s domestic fish production.

3. Aquaculture

Aquaculture has been defined in various ways, including “the art of cultivating the natural produce of water” and “the raising or fattening of fish in enclosed ponds.” It involves the rearing of aquatic organisms under controlled or semi-controlled conditions. Both freshwater and marine water fish are reared in well-designed and managed enclosures. Aquaculture is still developing and contributes about 5% of Nigeria’s domestic fish production.

Strategies Used in the Management of Fisheries

General Knowledge and Fisheries Management

Successful management of aquatic ecosystems requires fundamental knowledge about the state, properties, and dynamic interactions among the components of the system. In Nigeria, the need for food production, particularly fish, is urgent due to the growing population.

Procedures must be established to ensure the continuous availability of fish resources. Management techniques often used in both commercial and small-scale fisheries include:

Quota system
Regulation of fishing gear
Limitation on catch by individual fishermen
Limitation of fishing time
Limitation on fish size
Limitation on fishing area
Limitation on species caught
Open and closed fishing seasons

Culture Fisheries

Unlike capture fisheries, culture fisheries provide more control over the culture medium, depending on the type of enclosure used. The overall objective of management measures is to increase fish production. Some essential measures include:

Proper site selection
Well-designed and constructed ponds.
Selection of fish species
Choice of culture system (polyculture or monoculture)
Provision of good feed
Water quality management
Proper management of health and diseases
Harvesting of fish

Culture Systems in Aquaculture

A culture system refers to the medium in which fish are raised. These systems are categorized into three major groups: Open Systems, Semiclosed Systems, and Closed Systems. The choice of system depends on the organisms being farmed, the available resources, and the farmer’s objectives.

1. Open Systems: Open systems are the oldest form of aquaculture and involve the use of natural environments, such as seas or lakes, as fish farms. This system does not require water to be pumped into or out of the environment.

Fish are cultured directly in the sea or lake. Examples include dam beds, rafts, and fish cages. Open systems have lower capital expenses but present challenges like predation, poaching, and limited control over environmental conditions.

2. Semiclosed Systems: Semiclosed systems are popular for cultivating many types of organisms. Water is sourced from lakes, wells, or other natural sources and directed into specially designed facilities, such as ponds or tanks.

These systems offer greater control over growing conditions, allowing for higher production per unit area and uniform crops. However, semiclosed systems are more expensive to develop and operate than open systems, and they require more complex management.

Closed Systems: Closed systems involve little or no water exchange, with water undergoing extensive treatment. Though they have had limited commercial application, they show promise in laboratory experiments. High densities of fish can be raised under proper management, with full control over growing conditions.

Problems associated with closed systems include the need for efficient filtration systems and the risk of disease outbreaks. Examples include Water Recirculatory Systems (WRS) and flow-through systems.

Basic Principles in Fish Farming

Fish farming in Nigeria began in 1964 when an officer from the British Agricultural Department was seconded to initiate fisheries investigations. Fish farming is a lucrative business, but it requires expertise in various operations. Fish farming procedures include:

Site selection
Pond construction
Liming
Impoundment/flooding
Fertilization
Stocking
Feeding
Water quality management
Health and disease management
Harvesting the fish

1. Site Selection: Choosing the right site is crucial to the success of a fish farm. Factors such as soil type, water quality and quantity, and drainage requirements must be considered, especially for pond construction.

2. Pond Construction: Most freshwater fish are raised in ponds located on gently sloping land. Ponds are rectangular, circular, or square-shaped, with well-finished dikes and bottom slopes. They must be drainable for easy fish harvesting. Common types of fish ponds include embankment ponds, excavated ponds, and barrage ponds.

3. Liming: Liming involves adding lime to the pond bottom after construction. The dosage depends on the type of lime and the pond conditions. Liming raises the pond’s pH, kills harmful animals and plants, and eliminates pathogenic bacteria. It also enhances nutrient utilization from the pond bottom.

4. Impoundment/Flooding: Impoundment or flooding refers to introducing water into the pond before stocking fish. The water level should reach about 1.5 meters. Water quality parameters, such as dissolved oxygen and nitrogen levels, must be checked before impoundment.

5. Fertilization: Fertilizing ponds stimulates the growth of natural food organisms for fish. Organic and inorganic fertilizers are used to promote phytoplankton growth, which supports the aquatic food chain. Fertilizers can include animal manure, compost, and superphosphate.

6. Stocking: Fish species are selected based on biological and economic factors such as market demand, growth rate, and reproduction capacity. Stocking densities typically range from 3 to 8 fish per square meter. Farmers may practice monoculture or polyculture.

7. Feeding: Fish are fed both naturally occurring pond organisms, like phytoplankton and zooplankton, and supplementary feeds, which are formulated from ingredients such as fishmeal and soybean. Feeding should be done regularly, with fish receiving about 3–5% of their body weight in food daily.

8. Water Quality Management: Maintaining optimal water quality is essential for fish growth. Water parameters, such as dissolved oxygen, carbon dioxide, and total dissolved solids, should be monitored regularly to ensure fish remain healthy.

9. Management of Fish Health and Diseases: Fish health is managed through good water quality and nutrition. Preventive measures are prioritized, as disease outbreaks can threaten fish production. Fish are vulnerable to viral, bacterial, fungal, and parasitic infections, which can impact yields.

10. Harvesting the Fish: Harvesting occurs when fish reach marketable size. It can be done either partially or fully, depending on the farm’s production strategy. Feeding should stop at least a day before harvesting to minimize waste.

Fisheries management involves a series of systematic procedures aimed at ensuring the sustainable use of fish resources. While industrial and aquaculture fisheries contribute to domestic fish production, artisanal fisheries remain the largest source of fish in Nigeria. Proper management practices from site selection to fish harvesting are essential to maintaining a successful fish farming operation.

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