Marine Fisheries and Aquaculture

What to remember

• India's marine zone has territorial waters up to 12 nautical miles and an Exclusive Economic Zone (EEZ) up to 200 nautical miles from the coast.
• Marine capture fisheries use boats and gear (trawl, gill net, purse seine); aquaculture raises shrimp and fish in brackishwater ponds, cages and farms.
• Brackishwater shrimp farming in Andhra Pradesh is mainly Pacific white shrimp (Litopenaeus vannamei) and is regulated by the Coastal Aquaculture Authority.

1. Marine zones and units

• 1 nautical mile = 1.852 km. So 12 nm = 22.2 km and 200 nm = 370.4 km.
• In the EEZ the coastal state has sovereign rights over living and non-living resources.
• Territorial waters and nearshore areas are used by small boats; deep-sea fishing is done beyond.
• Marine fisheries of India are also divided into inshore (up to about 50 m depth), offshore (up to about 200 m) and deep-sea (beyond).

Water terms: salinity is measured in parts per thousand (ppt). Seawater is about 35 ppt. Brackish water lies between fresh water (below 0.5 ppt) and seawater. Estuaries, lagoons and mangrove creeks are brackish.

2. Important marine fishes and shellfishes

• Upwelling brings nutrients to the surface and raises plankton, which supports pelagic fisheries.
• The ocean region is also a source of seaweed.

3. Fishing crafts and gear

Crafts

• Non-motorised traditional craft: catamaran (kattumaram, logs tied together), dugout canoes and plank-built boats.
• Motorised craft: traditional craft fitted with an outboard or inboard engine.
• Mechanised boats: trawlers, gill-netters, purse seiners and liners.

Gears

Fishing-ban season: To protect breeding and fish stocks a uniform seasonal ban of 61 days is observed on the east coast from 15 April to 14 June (the west coast ban is 1 June to 31 July, in the monsoon), with mechanised fishing stopped. Traditional craft are generally allowed. Check the latest official dates every year.

Catch per unit effort (CPUE) = total catch ÷ fishing effort. Example: 600 kg in 40 hours = 15 kg per hour.

4. Fisheries management

• Maximum sustainable yield (MSY): the largest catch that can be taken yearly without reducing the stock.
• Mesh-size regulations: larger mesh lets small fish escape.
• Turtle excluder device (TED): fitted to trawl nets to let sea turtles escape.
• Overfishing, bycatch, juvenile fishing and illegal fishing harm stocks.
• Marine protected areas and mangrove conservation protect nursery areas. Coringa in the Godavari delta has an important mangrove wetland.
• Coastal Regulation Zone (CRZ) rules limit construction near the coast.
• Marine Products Export Development Authority (MPEDA), Kochi promotes marine product exports.
• Coastal Aquaculture Authority (CAA) regulates brackishwater farming under the Coastal Aquaculture Authority Act, 2005.
• Fishing harbours: Visakhapatnam, Kakinada and Machilipatnam are major fishing harbours on the Andhra coast. New harbours and landing centres are in development; check the latest official release.

5. Brackishwater shrimp farming

Species

• Penaeus monodon (black tiger shrimp): native, big, slower to grow, more disease sensitive.
• Litopenaeus vannamei (Pacific white shrimp): an introduced species, grows fast, tolerates wide salinity and is the main species cultured in AP. Stocking material must be SPF (specific pathogen free) seed, certified free of listed diseases.

Farm cycle

• 1. Site selection near brackish water source with clay-loam soil and tidal or pumped supply.
• 2. Pond preparation: drying, tilling, liming, filling through filter nets, fertilizing.
• 3. Seed selection: test post-larvae (PL) for disease by PCR in an approved lab.
• 4. Stocking at suitable density; acclimatize PL to pond salinity first.
• 5. Feeding: pelleted shrimp feed, with feed trays to check consumption.
• 6. Aeration with paddle wheels to keep dissolved oxygen high.
• 7. Monitoring: pH, salinity, DO, ammonia and shrimp health.
• 8. Harvest after about 3 to 4 months.

Water quality for shrimp

Diseases

Control is mainly by good pond preparation, biosecurity, SPF seed, probiotics and avoiding stress. Banned antibiotics must not be used.

Worked examples

• 1 ha pond stocked at 10 PL per m². Area = 10,000 m². PL = 100,000.
• With 80 % survival, 80,000 shrimp are harvested. If the average weight is 25 g, yield = 80,000 × 25 g = 2,000 kg.
• Count per kg = 1,000 ÷ average weight in g = 1,000 ÷ 25 = 40 per kg.

6. Mariculture and other farming

• Seaweed farming: Gracilaria gives agar; Kappaphycus gives carrageenan; brown seaweed such as Sargassum gives alginate. Seaweed is grown on ropes, bamboo rafts or nets.
• Mussel and oyster culture: grown on ropes or racks; they filter plankton and need no feed.
• Pearl oyster culture: nucleus is placed in the oyster to form a cultured pearl.
• Cage culture of marine fish: Asian seabass, groupers and cobia in sea cages.
• Sea cucumber: a regulated species; do not trade without permission.
• Crab fattening: soft crabs are fattened in small pens.
• Integrated multi-trophic aquaculture (IMTA): fish, shellfish and seaweed together to use waste.

7. Post-harvest handling

• Chilling and icing: the fish and ice are layered, commonly in a 1:1 ratio for short storage, keeping fish near 0 °C.
• Freezing: quick freezing preserves quality for export; common methods are block, individual quick freezing and plate freezing.
• Canning, drying, salting and smoking are other preservation methods.
• Fish meal and fish oil are made from low-value fish.
• HACCP (Hazard Analysis and Critical Control Points) is the safety system for export plants.
• Hygiene and cold chain control keep histamine formation and spoilage low.

8. Andhra Pradesh context

• Andhra Pradesh has a long coastline on the Bay of Bengal and many creeks and lagoons.
• The state is a leading place for brackishwater aquaculture, mostly Pacific white shrimp.
• Pulicat lagoon, Kolleru lake and the Godavari and Krishna estuaries are important wetland fisheries.
• Fishing harbours at Visakhapatnam, Kakinada and Machilipatnam support mechanised fleets.
• Always refer to the latest official release for scheme details and notifications.

Exam traps

• 1. Territorial sea is 12 nm; EEZ is 200 nm.
• 2. Purse seine encircles surface schools; trawl net is dragged near the bottom.
• 3. P. monodon is native; L. vannamei is exotic (introduced).
• 4. Kappaphycus gives carrageenan; Gracilaria gives agar.
• 5. White spot disease is viral (WSSV); vibriosis is bacterial.
• 6. SPF seed means free of listed pathogens; it does not mean disease-proof.
• 7. CAA regulates coastal aquaculture; MPEDA promotes exports.
• 8. Hilsa is anadromous; eel is catadromous.

One-liners

• 1. 1 nautical mile = 1.852 km.
• 2. Seawater salinity is about 35 ppt.
• 3. The EEZ extends to 200 nautical miles.
• 4. A purse seine is used for oil sardine and mackerel.
• 5. TED saves sea turtles from trawl nets.
• 6. L. vannamei is the Pacific white shrimp.
• 7. WSSV causes white spot disease.
• 8. Count per kg = 1,000 ÷ average weight (g).
• 9. Gracilaria yields agar.
• 10. Mussels and oysters are filter feeders.
• 11. Icing ratio is commonly 1:1 fish to ice.
• 12. MPEDA headquarters is at Kochi.

Practice questions

1. Kappaphycus is the source of

   1. alginate
   2. agar
   3. chlorophyll only
   4. carrageenan
   Answer

   D. carrageenan

   Kappaphycus gives carrageenan.

2. Statements: 1. Fresh water is below 0.5 ppt. 2. Brackish water lies between fresh and sea water. Which is correct?

   1. 1 only
   2. 2 only
   3. Both 1 and 2
   4. Neither 1 nor 2
   Answer

   C. Both 1 and 2

   Both statements are correct.

3. Which marine fish is anadromous?

   1. Hilsa
   2. Mullet
   3. Seabass
   4. Tuna
   Answer

   A. Hilsa

   Hilsa moves from sea to rivers to breed.

4. An average shrimp weighs 25 g. The count per kg is

   1. 250
   2. 40
   3. 25
   4. 4
   Answer

   B. 40

   1,000 ÷ 25 = 40.

5. Which species is the Pacific white shrimp?

   1. Fenneropenaeus indicus
   2. Penaeus monodon
   3. Macrobrachium rosenbergii
   4. Litopenaeus vannamei
   Answer

   D. Litopenaeus vannamei

   Vannamei is the Pacific white shrimp.

6. The Exclusive Economic Zone of a coastal state extends up to

   1. 24 nautical miles
   2. 12 nautical miles
   3. 350 nautical miles
   4. 200 nautical miles
   Answer

   D. 200 nautical miles

   The EEZ is 200 nm.

7. A 1 ha pond is stocked at 10 PL per m². How many PL are needed?

   1. 100,000
   2. 1,000,000
   3. 10,000
   4. 1,000
   Answer

   A. 100,000

   1 ha = 10,000 m²; 10 × 10,000 = 100,000.

8. The authority that regulates coastal brackishwater farming is

   1. MPEDA
   2. Coastal Aquaculture Authority
   3. NABARD
   4. FSSAI
   Answer

   B. Coastal Aquaculture Authority

   CAA works under the 2005 Act.

9. Statements: 1. P. monodon is a native shrimp. 2. L. vannamei is an introduced shrimp. Which is correct?

   1. 1 only
   2. 2 only
   3. Both 1 and 2
   4. Neither 1 nor 2
   Answer

   C. Both 1 and 2

   Both statements are correct.

10. The safety system required in export fish processing plants is

    1. CRZ
    2. HACCP
    3. MSY
    4. TED
    Answer

    B. HACCP

    HACCP identifies and controls hazards.

11. 80,000 shrimp of 25 g each are harvested. Total yield is

    1. 2,000 kg
    2. 200 kg
    3. 800 kg
    4. 20,000 kg
    Answer

    A. 2,000 kg

    80,000 × 25 g = 2,000,000 g = 2,000 kg.

12. Marine Products Export Development Authority has its headquarters at

    1. Mumbai
    2. Visakhapatnam
    3. Kochi
    4. Chennai
    Answer

    C. Kochi

    MPEDA is in Kochi.

13. The uniform fishing ban on the east coast is mainly meant to

    1. ban traditional craft
    2. stop all fishing forever
    3. raise price
    4. protect breeding and stock
    Answer

    D. protect breeding and stock

    The ban protects spawning during the monsoon period.

14. Which is an example of a small pelagic fish?

    1. Croaker
    2. Sole
    3. Pomfret
    4. Oil sardine
    Answer

    D. Oil sardine

    Oil sardine is a schooling pelagic fish.

15. Which fish is farmed in cages in brackish or sea water in India?

    1. Rohu
    2. Asian seabass
    3. Catla
    4. Mrigal
    Answer

    B. Asian seabass

    Seabass is cultured in cages and ponds.

16. Statements: 1. A gill net entangles fish. 2. A trawl net is dragged by a boat. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both statements are correct.

17. Which gear is hauled along the sea bottom to catch shrimp and demersal fish?

    1. Trawl net
    2. Cast net
    3. Ring seine
    4. Purse seine
    Answer

    A. Trawl net

    Bottom trawls target shrimp and demersal fish.

18. MSY stands for

    1. Marine Stock Yield
    2. Maximum Sustainable Yield
    3. Mean Seasonal Yield
    4. Minimum Safe Yield
    Answer

    B. Maximum Sustainable Yield

    MSY is the greatest catch that can be sustained.

19. 200 nautical miles is about

    1. 200 km
    2. 1,852 km
    3. 185.2 km
    4. 370.4 km
    Answer

    D. 370.4 km

    200 × 1.852 = 370.4.

20. Statements: 1. Salinity is measured in ppt. 2. Seawater has a salinity of about 35 ppt. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    C. Both 1 and 2

    Both statements are correct.

21. Which gear works mainly by entangling fish in its mesh?

    1. Gill net
    2. Trawl net
    3. Purse seine
    4. Dredge
    Answer

    A. Gill net

    Fish get caught by gills in the mesh.

22. Which seaweed yields agar?

    1. Sargassum
    2. Ulva
    3. Kappaphycus
    4. Gracilaria
    Answer

    D. Gracilaria

    Gracilaria is the main agar source.

23. Statements: 1. EEZ extends to 200 nm. 2. Territorial sea extends to 200 nm. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Territorial sea is 12 nm.

24. The method of testing shrimp post-larvae for virus uses

    1. Thermometer
    2. PCR
    3. ELISA only
    4. Microscope only
    Answer

    B. PCR

    PCR is the standard method.

25. A catamaran is a

    1. large trawler
    2. deep-sea liner
    3. traditional craft of tied logs
    4. hatchery tank
    Answer

    C. traditional craft of tied logs

    Kattumaram is a log-raft craft.

26. Which organism is farmed to produce cultured pearls?

    1. Clam
    2. Pearl oyster
    3. Squid
    4. Mussel for food
    Answer

    B. Pearl oyster

    A nucleus is inserted into pearl oysters.

27. Which of the following is a filter-feeding mollusc?

    1. Shark
    2. Seabass
    3. Mussel
    4. Tuna
    Answer

    C. Mussel

    Mussels filter plankton.

28. Statements: 1. Mussels need supplementary feed. 2. Mussels filter plankton. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    B. 2 only

    Mussels are fed by filtering.

29. Statements: 1. CAA regulates coastal aquaculture. 2. MPEDA regulates coastal aquaculture under the 2005 Act. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    MPEDA promotes exports; CAA has the 2005 Act.

30. Which net encircles a school of fish and is closed like a purse?

    1. Trawl net
    2. Cast net
    3. Gill net
    4. Purse seine
    Answer

    D. Purse seine

    Purse seine pursed at the bottom.

31. Statements: 1. White spot disease is caused by a virus. 2. Vibriosis is caused by a virus. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Vibriosis is bacterial.

32. With 100,000 PL stocked and 80 % survival, how many shrimp are harvested?

    1. 100,000
    2. 20,000
    3. 80,000
    4. 8,000
    Answer

    C. 80,000

    80 % of 100,000 = 80,000.

33. Alginate is obtained from

    1. blue-green algae
    2. brown seaweed
    3. green algae only
    4. red seaweed only
    Answer

    B. brown seaweed

    Brown seaweeds like Sargassum give alginate.

34. A boat catches 600 kg in 40 hours of fishing. CPUE is

    1. 24 kg/hour
    2. 150 kg/hour
    3. 10 kg/hour
    4. 15 kg/hour
    Answer

    D. 15 kg/hour

    600 ÷ 40 = 15.

35. Which of these is an introduced (exotic) shrimp species in Indian farms?

    1. Fenneropenaeus indicus
    2. Penaeus monodon
    3. Metapenaeus dobsoni
    4. Litopenaeus vannamei
    Answer

    D. Litopenaeus vannamei

    Vannamei was introduced.

36. White spot syndrome in shrimp is caused by a

    1. fungus
    2. protozoan
    3. virus
    4. bacterium
    Answer

    C. virus

    WSSV is a virus.

37. One nautical mile is equal to

    1. 1.852 km
    2. 1.609 km
    3. 1.0 km
    4. 2.0 km
    Answer

    A. 1.852 km

    Standard conversion.

38. Which disease is caused by Vibrio bacteria with a toxin in shrimp?

    1. Early mortality syndrome (AHPND)
    2. White spot
    3. EHP
    4. Black gill only
    Answer

    A. Early mortality syndrome (AHPND)

    AHPND is Vibrio-toxin related.

39. Territorial waters extend up to

    1. 200 nautical miles
    2. 3 nautical miles
    3. 12 nautical miles
    4. 24 nautical miles
    Answer

    C. 12 nautical miles

    Territorial sea limit is 12 nm.

40. Statements: 1. Gracilaria yields agar. 2. Kappaphycus yields agar. Which is correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Answer

    A. 1 only

    Kappaphycus yields carrageenan.

41. SPF shrimp seed refers to seed that is

    1. free of all possible diseases
    2. free of listed pathogens
    3. imported without tests
    4. pure wild caught
    Answer

    B. free of listed pathogens

    SPF means specific pathogen free.

42. Typical seawater salinity is about

    1. 350 ppt
    2. 0.35 ppt
    3. 3.5 ppt
    4. 35 ppt
    Answer

    D. 35 ppt

    Average ocean salinity.

43. Which are standard preservation methods for fish?

    1. Washing in lime
    2. Boiling in oil only
    3. Icing, freezing, canning
    4. Sun burning
    Answer

    C. Icing, freezing, canning

    Icing, freezing, canning and drying are standard.

44. TED in a trawl net stands for

    1. Trawl Extension Design
    2. Tuna Escape Door
    3. Tidal Exchange Device
    4. Turtle Excluder Device
    Answer

    D. Turtle Excluder Device

    TED lets turtles escape.