Fisheries

1. Introduction to Fisheries

Fisheries is the science dealing with the study, production, management, conservation, harvesting, processing and marketing of fishes and other aquatic organisms. It is one of the fastest-growing sectors in India and plays a vital role in food security, nutrition, employment generation, foreign exchange earnings, and rural development.

India is the second-largest fish producer and among the leading aquaculture-producing countries in the world. Tamil Nadu has a long coastline, numerous reservoirs, tanks, rivers, estuaries, and ponds that support inland and marine fisheries.

Importance of Fisheries

• Provides high-quality animal protein.
• Generates employment for millions of fishermen and fish farmers.
• Supports export earnings through seafood exports.
• Contributes significantly to agricultural GDP.
• Improves nutritional security.
• Encourages integrated farming systems.
• Utilizes water resources efficiently.
• Supports rural and coastal livelihoods.

2. Classification of Fisheries

Marine Fisheries

Marine fisheries involve harvesting fish from seas and oceans.

Characteristics

• Saline water.
• Rich biodiversity.
• Mechanized fishing vessels.
• Large-scale commercial production.
• Includes continental shelf and deep-sea fishing.

Major Marine Fish

• Sardine
• Mackerel
• Tuna
• Seer fish
• Anchovy
• Pomfret
• Ribbon fish
• Sharks
• Rays

Marine Shellfish

• Shrimp
• Lobster
• Crab
• Oyster
• Mussel
• Squid
• Cuttlefish

Importance

Marine fisheries contribute nearly half of India's total fish production and most seafood exports.

Inland Fisheries

Fishing in freshwater and brackish water.

Resources

• Rivers
• Reservoirs
• Lakes
• Tanks
• Canals
• Village ponds

Freshwater Fishes

• Catla
• Rohu
• Mrigal
• Common carp
• Grass carp
• Silver carp
• Tilapia
• Pangasius

Brackish Water Fishes

• Milkfish
• Sea bass
• Pearl spot
• Mud crab
• Shrimp

3. Fish Biology

Understanding fish biology is essential for fisheries management.

External Parts of Fish

Head

• Mouth
• Eyes
• Gills
• Nostrils

Trunk

• Scales
• Fins
• Muscles

Tail

• Provides propulsion during swimming.

Types of Fins

Paired Fins

• Pectoral fins
• Pelvic fins

Functions: Steering, balancing, turning.

Unpaired Fins

• Dorsal fin
• Anal fin
• Caudal fin

Functions: Swimming, stability, speed generation.

Types of Fish Based on Skeleton

Cartilaginous Fishes

Skeleton made of cartilage.

Examples: Shark, Ray.

Characteristics:

• No swim bladder.
• Placoid scales.
• Five to seven gill slits.
• Internal fertilization.

Bony Fishes

Skeleton made of bones.

Examples: Rohu, Catla, Tilapia.

Characteristics:

• Swim bladder present.
• Cycloid or ctenoid scales.
• Single gill opening.
• External fertilization.

Fish Scales

Fish scales protect the body and reduce friction.

• Placoid – Example: Shark.
• Cycloid – Example: Carp.
• Ctenoid – Example: Perch.
• Ganoid – Example: Gar fish.

Respiration in Fish

Fish breathe through gills.

Mechanism

• Water enters through mouth.
• Water passes over gills.
• Oxygen diffuses into blood.
• Carbon dioxide diffuses out.
• Water exits through gill openings.

Factors Affecting Respiration

• Water temperature.
• Dissolved oxygen.
• Pollution.
• Fish activity.

Fish Reproduction

Most fishes reproduce sexually.

Modes

• External fertilization – Most freshwater fishes.
• Internal fertilization – Sharks and rays.

Types Based on Breeding

• Egg-laying (oviparous).
• Live-bearing (viviparous).
• Egg retaining (ovoviviparous).

Fish Development

Stages: Egg → Larva → Fry → Fingerling → Juvenile → Adult.

Fingerlings are commonly stocked in fish ponds for culture.

Feeding Habits

Herbivorous – Eat aquatic plants. Example: Grass carp.

Carnivorous – Eat smaller fishes. Example: Murrel.

Omnivorous – Eat both plants and animals. Example: Tilapia.

Plankton feeders – Example: Catla.

Bottom feeders – Example: Mrigal.

4. Aquatic Ecosystem

Food Chain in Aquatic Ecosystem

Sunlight → Phytoplankton → Zooplankton → Small fish → Large fish → Human beings.

Balanced food chains maintain healthy aquatic ecosystems.

Components

Abiotic

• Water
• Temperature
• pH
• Dissolved oxygen
• Carbon dioxide
• Salinity
• Nutrients

Biotic

• Producers: Phytoplankton.
• Consumers: Zooplankton, Fish, Predatory fish.
• Decomposers: Bacteria, Fungi.

Water Quality Parameters

Good water quality is essential for fish farming.

Temperature – Ideal: 25–32°C. High temperature reduces dissolved oxygen.

Dissolved Oxygen (DO) – Ideal: Above 5 mg/L. Low DO causes stress and fish mortality.

pH – Ideal: 6.5–8.5. Highly acidic or alkaline water reduces fish growth.

Ammonia – Produced from fish waste. High ammonia is toxic.

Management: Water exchange, aeration, proper feeding.

Transparency – Measured using Secchi disc. Ideal: 30–40 cm for ponds.

Alkalinity – Ideal: 50–150 mg/L. Provides buffering capacity.

Hardness – Important for fish health and plankton growth.

Plankton

Plankton are microscopic organisms floating in water.

Phytoplankton (plant plankton) – Examples: Chlorella, Diatoms. Importance: Oxygen production, primary food source.

Zooplankton (animal plankton) – Examples: Rotifers, Copepods, Cladocerans. Importance: Food for fish larvae.

Aquatic Weeds

Aquatic weeds reduce fish production.

Floating: Water hyacinth, Duckweed.

Submerged: Hydrilla.

Emergent: Typha.

Control: Mechanical removal, biological control, chemical control, water management.

5. Fishery Resources of India

Marine – Arabian Sea, Bay of Bengal, Indian Ocean.

Inland – Rivers, Reservoirs, Tanks, Lakes.

Brackish water – Estuaries, Lagoons, Mangroves.

6. Fisheries Resources of Tamil Nadu

Tamil Nadu is among the leading fish-producing states.

Important Resources

• Bay of Bengal coastline.
• Palk Bay.
• Gulf of Mannar.
• Mettur Reservoir.
• Bhavanisagar Reservoir.
• Vaigai Reservoir.
• Numerous irrigation tanks.
• Village ponds.

Major Fish Landing Centres

• Chennai
• Nagapattinam
• Cuddalore
• Thoothukudi
• Rameswaram
• Mandapam
• Kanniyakumari

7. Major Cultivable Freshwater Fish

Indian Major Carps (IMC)

Catla (Catla catla)

• Surface feeder.
• Fast-growing.
• Plankton feeder.

Rohu (Labeo rohita)

• Column feeder.
• Popular table fish.
• Good taste.

Mrigal (Cirrhinus mrigala)

• Bottom feeder.
• Consumes detritus.
• Excellent pond fish.

Exotic Carps

• Common Carp – Bottom feeder.
• Grass Carp – Consumes aquatic weeds.
• Silver Carp – Surface plankton feeder.
• Bighead Carp – Feeds on zooplankton.

These species improve pond productivity through composite fish culture.

Shellfish Culture

Includes Shrimp, Crab, Oyster, Mussel, Lobster. Shrimp farming contributes significantly to India's seafood exports.

8. Important Institutions

ICAR–Central Institute of Freshwater Aquaculture (CIFA), Bhubaneswar – Research on freshwater aquaculture, breeding, nutrition, and pond management.

ICAR–Central Marine Fisheries Research Institute (CMFRI), Kochi – Research on marine fisheries, mariculture, resource assessment, and conservation.

ICAR–Central Institute of Fisheries Technology (CIFT), Kochi – Research on fish processing, preservation, value addition, fishing gear, and quality assurance.

ICAR–Central Institute of Brackishwater Aquaculture (CIBA), Chennai – Research on shrimp farming, brackishwater aquaculture, aquatic animal health, and sustainable coastal aquaculture.

Fishery Survey of India (FSI) – Conducts marine fishery resource surveys, exploratory fishing, and assessment of fish stocks.

9. Aquaculture

Aquaculture is the scientific farming of fish, shrimp, crabs, molluscs, seaweeds, and other aquatic organisms under controlled conditions. It is one of the fastest-growing food production sectors and contributes significantly to India's fish production.

Objectives of Aquaculture

• Increase fish production.
• Meet the growing demand for animal protein.
• Improve farmers' income.
• Generate rural employment.
• Reduce pressure on natural fisheries.
• Increase seafood exports.

Types of Aquaculture

1. Freshwater Aquaculture – Culture of fish in ponds, tanks, lakes, and reservoirs. Major species: Catla, Rohu, Mrigal, Tilapia, Pangasius.

2. Brackishwater Aquaculture – Conducted in estuaries and coastal areas. Major species: Tiger shrimp (Penaeus monodon), White-leg shrimp (Litopenaeus vannamei), Mud crab, Asian seabass.

3. Marine Aquaculture (Mariculture) – Culture in seawater. Species: Mussels, Oysters, Seaweeds, Pearl oysters, Cobia.

Fish Feeding

Feed accounts for nearly 60–70% of aquaculture production cost.

Natural Feed: Phytoplankton, Zooplankton, Aquatic insects.

Artificial Feed: Rice bran, Groundnut oil cake, Soybean meal, Fish meal, Commercial floating pellets.

Nutrient Requirements

• Protein – Essential for growth.
• Carbohydrates – Energy source.
• Lipids – Provide energy and essential fatty acids.
• Vitamins – Support metabolism and immunity.
• Minerals – Required for bone development and enzyme functions.

Feed Conversion Ratio (FCR)

FCR = Feed given ÷ Weight gain.

Lower FCR indicates better feed efficiency. Example: 2 kg feed produces 1 kg fish → FCR = 2.

10. Composite Fish Culture

Composite fish culture is the practice of rearing different compatible fish species in the same pond.

Principle

Different fish occupy different feeding zones, reducing competition.

Feeding Zone	Fish Species
Surface	Catla, Silver carp
Middle	Rohu
Bottom	Mrigal, Common carp
Weed feeder	Grass carp

Advantages

• Efficient utilization of pond resources.
• Higher production.
• Better feed utilization.
• Reduced competition.
• Increased farmer income.

11. Pond Preparation

Proper pond preparation improves fish survival and productivity.

Steps

• Drain pond.
• Remove weeds.
• Eliminate predatory fish.
• Repair bunds.
• Apply lime.
• Fertilize pond.
• Fill with clean water.
• Stock healthy fingerlings.

Liming

Purpose: Neutralizes acidity, improves water quality, controls pathogens, enhances plankton growth.

Common materials: Agricultural lime, Quick lime, Slaked lime.

Pond Fertilization

Purpose: To increase plankton production.

Organic fertilizers: Cow dung, Poultry manure.

Inorganic fertilizers: Urea, Super phosphate.

Stocking Density

Stocking density depends on pond size, water quality, fish species, and feeding practices.

Overstocking leads to poor growth, oxygen depletion, and disease outbreaks.

12. Hatchery Management

A hatchery is a facility for breeding and rearing fish seed.

Objectives

• Produce quality seed.
• Ensure year-round fingerling availability.
• Improve survival rate.
• Supply disease-free fish seed.

Stages

Broodstock → Spawning → Egg incubation → Larvae → Fry → Fingerlings.

Induced Breeding

Induced breeding uses hormones to stimulate spawning.

Advantages: Timely seed production, higher fertilization, better survival, large-scale seed production.

Common hormones: Ovaprim, Ovatide, Pituitary extract.

Nursery Management

Nursery ponds rear fry into fingerlings.

Management includes: Water quality maintenance, feeding, predator control, disease monitoring.

13. Fish Diseases

Diseases cause heavy economic losses.

Causes

• Poor water quality.
• Overcrowding.
• Nutritional deficiency.
• Parasites.
• Bacteria.
• Viruses.
• Fungi.

Bacterial Diseases

Examples: Aeromoniasis, Columnaris disease.

Symptoms: Ulcers, Fin rot, Hemorrhage.

Control: Good sanitation, quality seed, antibiotics only under veterinary guidance.

Fungal Diseases

Example: Saprolegniasis.

Symptoms: Cotton-like growth, skin lesions.

Control: Salt treatment, potassium permanganate, maintain water quality.

Parasitic Diseases

Examples: Fish lice (Argulus), Gill flukes, Ich ("white spot disease").

Symptoms: Rubbing against pond walls, excess mucus, respiratory distress.

Viral Diseases

Important in shrimp farming.

Example: White Spot Syndrome Virus (WSSV).

Control: Biosecurity, disease-free seed, pond disinfection, avoid infected broodstock.

Biosecurity

Biosecurity prevents disease entry and spread.

• Use certified seed.
• Disinfect equipment.
• Restrict visitor entry.
• Quarantine new stock.
• Remove dead fish immediately.

14. Fish Harvesting

Harvesting is the collection of marketable fish.

Partial Harvest – Only larger fish are harvested.

Complete Harvest – Entire pond is harvested.

Methods

• Seine net
• Gill net
• Cast net
• Drag net

15. Fish Preservation and Processing

Fish spoils rapidly because of its high moisture content.

Preservation Methods

• Icing – Most common preservation method.
• Chilling – Maintains freshness.
• Freezing – Long-term storage.
• Drying – Traditional preservation.
• Smoking – Improves flavour and shelf life.
• Salting – Removes moisture.
• Canning – Long-term storage in sealed containers.

Fish Processing

Processing improves shelf life and market value.

Products: Fish fillets, Fish pickle, Fish cutlets, Fish curry paste, Fish powder, Fish oil, Fish meal.

Fish By-products

• Fish Oil – Used in pharmaceuticals and nutraceuticals.
• Fish Meal – Protein-rich animal feed.
• Fish Silage – Livestock and poultry feed.
• Fish Leather – Prepared from fish skin.
• Collagen and Gelatin – Used in cosmetics and medicine.

16. Fisheries Economics

Importance

• Employment generation.
• Export earnings.
• Rural development.
• Nutritional security.

Factors Affecting Profitability

• Feed cost.
• Seed quality.
• Disease incidence.
• Market price.
• Water availability.

Fish Marketing

Channels: Producer → Wholesaler → Retailer → Consumer.

Modern marketing includes: Cold chain, refrigerated transport, online marketing, value-added products.

Fisheries Cooperatives

Functions: Credit support, input supply, marketing, insurance, welfare activities.

17. Government Schemes

Pradhan Mantri Matsya Sampada Yojana (PMMSY)

• Increase fish production.
• Improve exports.
• Create employment.
• Develop infrastructure.
• Promote sustainable fisheries.

Blue Revolution – Focus on fish production, aquaculture development, modern technology, and fisher welfare.

Kisan Credit Card (KCC) – Extended to fish farmers for working capital and investment needs.

e-Gopala and Digital Fisheries Initiatives – Support digital registration, advisory services, and access to government benefits.

18. Fisheries in Tamil Nadu

Important Marine Districts

• Chennai
• Chengalpattu
• Villupuram
• Cuddalore
• Mayiladuthurai
• Nagapattinam
• Thiruvarur
• Thoothukudi
• Tirunelveli
• Kanniyakumari

Major Inland Resources

• Mettur Reservoir
• Bhavanisagar Reservoir
• Vaigai Reservoir
• Amaravathi Reservoir
• Numerous irrigation tanks

Major Cultured Species

• Catla
• Rohu
• Mrigal
• Tilapia
• Pangasius
• Vannamei shrimp

19. Fisheries Conservation

• Ban on destructive fishing methods.
• Mesh size regulation.
• Closed fishing seasons.
• Marine protected areas.
• Mangrove conservation.
• Stock enhancement.
• Artificial reefs.
• Pollution control.

20. Climate Change and Fisheries

Effects

• Rising sea temperature.
• Ocean acidification.
• Cyclones.
• Sea-level rise.
• Reduced fish breeding.
• Migration of fish stocks.

Adaptation

• Climate-resilient aquaculture.
• Early warning systems.
• Improved hatcheries.
• Water conservation.
• Diversification of cultured species.

21. Important TNPSC Facts – One-Liners

• India is the second-largest fish producer globally.
• Shrimp is India's leading seafood export commodity.
• Catla is a surface feeder.
• Rohu is a column feeder.
• Mrigal is a bottom feeder.
• Grass carp controls aquatic weeds.
• Silver carp feeds mainly on phytoplankton.
• White Spot Syndrome Virus is a major shrimp disease.
• Dissolved oxygen should generally be above 5 mg/L.
• Ideal pond pH: 6.5–8.5.
• Feed is the largest operational cost in aquaculture.
• Composite fish culture maximizes pond productivity.

22. TNPSC CTS Practice Questions with Answers