Model Answer M Sc IV Zoology Fish Biology: Capture Fishery ... Answer 15/18.5.15-Dr. Santosh...

Model Answer M Sc IV Zoology Fish Biology: Capture Fishery 2015

AU-6229

SECTION-A (Multiple choice questions)

Q. 1-Answer

(i) a (ii) c (iii) c (iv) b (v) a (vi) d (vii) c

(viii) d (ix) b (x) b

SECTION –B (Descriptive type questions)

Q. 2- Answer:

Capture fisheries is exploitation of aquatic organisms without stocking the seed. Recruitment of

the species occurs naturally. This is carried out in the sea, rivers, reservoirs, etc. Fish yield

decreases gradually in capture fisheries due to indiscriminate catching of fish including brooders

and juveniles. Overfishing destroys the fish stocks. Pollution and environmental factors influence

the fish yield. The catches include both desirable and undesirable varieties.

Culture fisheries is the cultivation of selected fishes in confined areas with utmost care to get

maximum yield. The seed is stocked, nursed and reared in confined waters, and then the crop is

harvested. Culture takes place in ponds, which are fertilized and supplementary feeds are

provided to fish to get maximum yield. In order to overcome the problems found in capture

fisheries to increase the production, considerable attention is being given to the culture fisheries.

Culture fisheries is conducted in freshwater, brackish water and sea waters. With the

development and expansion of new culture systems, farming of a wide variety of aquatic

organisms like prawns, crabs, molluscs, frogs, sea weeds, etc. have come under culture fisheries.


Due to the culture of a variety of aquatic organisms, culture fisheries has been termed as

aquaculture.

Marine Fishery:

Fisheries is an important sector in India--it provides employment to millions of people and

contributes to food security of the country. With a coastline of over 8,000 km, an Exclusive

Economic Zone (EEZ) of over 2 million sq km, and with extensive freshwater resources,

fisheries play a vital role. Presently, fisheries and aquaculture contribute 1.07 per cent to the

national GDP, and 5.30 per cent to agriculture and allied activities, while the average annual

value of output during the Tenth Five Year Plan (2002-2007) was Rs31,682.50 crores.

Marine Fisheries contributes to food security and provides direct employment to over 1.5 mn

fisher people besides others indirectly dependent on the sector.

Groups of marine fishery:

The marine fisheries of India is broadly divided into two groups.

(1) Coastal fisheries or inshore fisheries

(2) Deep sea fisheries and off shore fisheries.

Further, coastal area has been divided into two:

1. East Coast

2. West Coast

Further, east and west coast is divided into 12 zones.

Coastal Fisheries (Inshore fisheries):

From taxonomy view-point, coastal fisheries may be divided into two types-

1. Elasmobranch fishery


2. Teleost fishery

Offshore and deep sea fisheries:

Q. 3- Answer:

A river is a natural watercourse usually freshwater, flowing towards an ocean, a lake, a sea, or

another river. In a few cases, a river simply flows into the ground or dries up completely before

reaching another body of water. There are five major river systems present in India. The Ganga,

the Brahmaputra, the Indus, the east coast, and the West coast river systems.

The Ganga river system:

Length: About 8047 km (largest river system in the World).

Origin: Gangotri in the Himalayas at a height of about 3129 km above the sea level.

States in India: Ganga passes UP, Bihar, some part of rajsthan, MP, and west Bengal. It joins

finally the Bay of Bengal.

Tributaries: The Ymuna river is one of the major tributaries of this system, which is about

1000km, long. The other tributaries are – Ram Ganga, Gomti, Ghaghara, Gandak, Kosi,

Chambal, Betwa and Ken.

Total catchment area: 9.71 lakh sq. km.

Annual rainfall: 25-77 inches.

Physico-chemical characteristics:

Temperature range : 16.50C in January- 31.5

0C in June to September

pH : 7.4 during June to August and maximum 8.3 during January to May

Turbidity : 100 ppm in January, 1100-2170 ppm during July to September

DO2 : 5.0-10.5 ppm during January to February while in monsoon 2.0 ppm

(July to September)


CO2 : 0.6 ppm – 10.0 ppm.

Chloride : 4.0-35.4 ppm

Phosphate : 0.05-0.21 ppm

Nitrates : 0.08-0.22 ppm

Silicates : 4.0-20.3 ppm

Carbonates : 1.0-12.0 ppm

Common phytoplanktons:

1. Members of Bacillariophyceae- ex.

2. Members of chlorophyceae- ex.

Common zooplanktons: Rattulas, Rotaria, Keratella etc.

Fisheries of Ganga river system:

Major carps: Labeo rohita, Labeo calbasu, Catla catla and Cirrhinus mrigala

Minor carps: Labeo fimbriatus, L. bata, Cirrhinus reba

Catfishes: Wallago attu, Mystus aor, M. tengara, Clarias batrachus, Heteropneustes fossils

Feather backs: Notopterus notopterus, N. chitala

Murrels: Channa marulius, C. striatus and C. puncatatus.

Mullets: Mugil corsula

Eels: Anguilla

Herrings: Setipina phasa

Hill stream fishes: Mahasears

Clupeids: Hilsa ilisha

Others: Pangasius pangasius, Silonia silondis, Gudusis chapra, G. godanahiai, Bagasius

bagasius, Eutropichthys vacha etc.


Prawns: Macrobrachium malcolmsonii, Palaemon lamarii, etc.

Gears used: Dragnets, cast nets and bagnets.

Q. 4- Answer:

Boats and /or rafts used to catch fish are called crafts, however, nets used for fish catching are

called gears.

Inland fishing crafts:

The crafts employed in inland fisheries may be described under two categories:

1. Rafts

2. Boats

1. Rafts: These are the most primitive type of boats, constructed from various indigenous

materials. In WB and Tamil Nadu, the stems of banana trees are tied together to form a floating

platform. In Bihar, on river Gangaes, earthen pots called Chatties are tied together to support a

light platform of bamboos.

Primitive men invented simple rafts from hides (skin) of the animals

Donga of WB is a simple type of dug-out canoe, made by hollowing out the stem of palmyara

palm. It is applied in paddy fields and low lying areas with shallow water. Such dug-out canoe in

Bihar is called Ekhta.

2. Boats: Boats are built from planks and are various types. They are sturdy and can with satnd

strong currents and tied in rivers and large lakes. One of the well known types is dinghy. Dhingi

is used in WB in conjection with purse nets and dipnets. Dhingi are without keels but narrow and

have a tapering bow and stern. Another common type boat is Chandi nauka, which is large and is

about 18 m long and 3 m wide. It is used to operate drift nets.


Inland fishing gears:

The nets or gears used in Inland fishing of India are numerous and diverse types. Few important

types are fall into the following categories.

1. Trap net 2. Hand Net 3. Drag net 4. Fixed net 5. Miscellaneous types

1. Trap net: There are three important varieties of trap nets (Figs), used generally in all India,

UP in particular.

a. Basket trap net

b. Pot trap net

c. Konch trap net

2. Hand Net: Mainly two types are commonly used (Figs).

a. Cast net

b. Triangular net

3. Drag net: Drag nets are generally used in summer season as the water becomes shallow in the

rivers. The common drag nets are:

a. Chanti net

b. Mahajal (Long drag net)

4. Fixed net: It consists of the long rectangular piece of mesh which is stretched from one bank

to other bank of the river and held up by several bamboo sticks in the middle. The net projects

about one to two feet above the surface of the water and is kept in this position throughout the

night with the help of bamboo sticks. Fishes swimming along the stream are entangled in the

bhog. This type nets are generally used in rivers of UP.

5. Miscellaneous types:

a. Been jal

Model Answer M Sc IV

b. Shanglo jal

c. Ber jal

Model Answer M Sc IV Zoology Fish Biology: Capture FisheryFish Biology: Capture Fishery 2015


Angling (Line fishing): Angling is the ancient method

fishing is to offer a real or artificial bait to entice the fish.

The use of crafts, gears, hooks and line operations are the

Unconventional fishing methods

fishing, light fishing, fishing by stunning etc.

Conventional fishing methods:

Hook and Line fishing: Previously, a thorn was

used as a hook, but now metallic hooks o

various shapes (Fig) and sizes are used.

Unconventional fishing methods:

1. Electro fishing:

Model Answer M Sc IV Zoology Fish Biology: Capture Fishery

gling is the ancient method for catching fishes. The principle of line

fishing is to offer a real or artificial bait to entice the fish.

The use of crafts, gears, hooks and line operations are the Conventional fishing

Unconventional fishing methods include electro-

fishing, light fishing, fishing by stunning etc.

Conventional fishing methods:

Hook and Line fishing: Previously, a thorn was

used as a hook, but now metallic hooks of

are used.

Unconventional fishing methods:

Fish Biology: Capture Fishery 2015

fishes. The principle of line

Conventional fishing methods.


Electric current appears to be harmless for fish. It does not affect the growth, variability and

reproductive capacity of the fish.

Electrical fishing saves time, labor, money and man power.

In commercial fishing, A.C. and D.C. are used in fresh water, while I.C. is used in sea water.

2. Light fishing: The basis of light fishing lies in the fact that fishes represent phototaxis.

A 1000 W electric bulb is good for pelagic fishing; 100-500 W is generally employed in fresh

water fishing.

Red light has been reported useless, rather absolutely ineffective, yellow light in

combination with white light is found to be highly effective. Blue light has been reported to be

good for attracting fingerlings.

Q. 5- Answer:

Fish spoilage occurs chiefly due to three acting agents:

1. Microbial action,

2. Enzymatic action, and

3. Chemical action

1. Microbial action:

Microbial action involves mainly bacterial spoilage of the fish flesh. A large no of bacteria

present on the body, gills and gut of the fish find a good medium for development due to high

moisture (75-80%) contents in the fish flesh. Proteins, carbohydrates and fats present in fish flesh

are degraded by proteiolytic microbes (Psedomonas, Proteus etc), carbohydrate fermenting

microbes (Streptococcus, Leuconostoc etc) and fat decomposing some gram negative bacteria,

respectively.


2. Enzymatic action:

A large amount of fish flesh is spoiled by the action of digestive enzymes, which remain active

even after the death of the fishes and soften the flesh by autolysis and make the fish susceptible

to bacterial infection. For example: Proteinase can digest mus

spoilage and ATPase bring about complete removal of ATP from muscle tissue in 6

3. Chemical action:

It is more pronounced in fatty fishes like sardines, mackerels, trout, catla, grass carp etc, which

result become decolorized. Rancidity of fish oil starts by oxidation as fish flesh oil comes in

contact with the atmospheric air.

Q. 6- Answer:

Canning is the process of fish preservation

preserve them for long time. The

Salting:

Salting is a form of pickling and is a very old and common method of preserving fish in India

and also through the World. In salting, the fishes are treated with salt (NaCl) solution. Salt

dehydrates the killed fish by osmosis and enters their body tissues to incr

Model Answer M Sc IV Zoology Fish Biology: Capture Fishery

large amount of fish flesh is spoiled by the action of digestive enzymes, which remain active


to bacterial infection. For example: Proteinase can digest muscle proteins, catalase, the gill

spoilage and ATPase bring about complete removal of ATP from muscle tissue in 6


decolorized. Rancidity of fish oil starts by oxidation as fish flesh oil comes in

contact with the atmospheric air.

is the process of fish preservation, involves packing of fishes in the tin boxes to

preserve them for long time. The tin boxes are air tight and sterilized by heat.

is a form of pickling and is a very old and common method of preserving fish in India


dehydrates the killed fish by osmosis and enters their body tissues to increase the concentration

Fish Biology: Capture Fishery 2015

large amount of fish flesh is spoiled by the action of digestive enzymes, which remain active


cle proteins, catalase, the gill

spoilage and ATPase bring about complete removal of ATP from muscle tissue in 6-8 hours.


decolorized. Rancidity of fish oil starts by oxidation as fish flesh oil comes in

, involves packing of fishes in the tin boxes to

is a form of pickling and is a very old and common method of preserving fish in India


ease the concentration


saturation point. A concentration of salt above 25% stops further multiplication of microbes and

even kills them, specially the halophobic microbes.

Methods of salting:

Three methods of salting have beenevolved.

1. Dry salting

2. Wet or brine salting

3. Cold salting

1. Dry salting:

In this method, fishes are first cleaned, and rubbed with salt powder and then packed in tubes or

cemented tanks. Dry salt powder is sprinkled in between layers, as the fishes are arranged in the

container. The ratio of salt to fish varies from 1 : 3 to 1 : 8 depending on local practice, weather

conditions and type of fish. After 2-3 days, the fishes are removed from the tubes or container

and dried in Sun for 2-3 days. Such preserved fish are of inferior quality but find good market

among the poor classes.

2. Wet or brine salting:

Cleaned fishes are packed in large containers having a concentrated salt solution (20-30%) and

stirred daily till properly pickled. Large sized fishes like the Indian salmon, seerfishes and black

pomfrets are gutted first and inside is cleaned. Also longitudinal slits are made in flesh to allow

penetration of salt. Salt is applied in in the following successive stages. On first day, half of the

salt is rubbed into the incisions and the fishes are the stored in the cemented floor of the curring

yard. On the second day, the fishes are shuffled so as to bring the bottom layer on top and half of

the remaining salt is rubbed and fishes are restocked. The stock is left undisturbed for 7-10 days.

The salty water that oozes out from the fishes is allowed to drain off. Wet salted fishes may be


sold without drying. It does not keep good for long and, therefore, has to be used within 3-4

months.

3. Cold salting:

This is done by spreading powdered salt and crushed ice on the fish. About 22-26 lb of powder

salt per 10 kg of fish is usually recommended. After salting, the conservation is done in cold

rooms, having a temperature range of 2-30C.

Before use, salt fishes are soaked in freshwater for long duration dependent removal of

salt from fish. After the fish has been soaked, it can be used in any way like fresh fish.

Q. 7- Answer:

Most of the captured fishes are utilized as food, while others are distasteful and considered

unsuitable for human consumption. Similarly, the materials discarded during fish processing also

become waste. Such fishes and discarded materials become an important source of raw materials

to fish bye-product industries and are used to produce several useful bye-products.

List of fishery byproducts:

Liver oils, Fish meal, Fish silage, Fish protein, Fish guano, Bone meal, Shark fins and fin rays,

Fish roes, Fish glue, Fish skin, Chitin, Chitosan, Fish surimi, Isinglass, Fish skin, Pearl,

Ambergries.

(I) Fish oil:

The most important fish bye-product industry is fish oil, which acts as a vehicle for fat soluble

vitamins i.e. A, D, E, and K, as well as a source of essential fatty acids for structure of cell and

function of membrane. The oil of fish is categorized into two main types, the fish liver oil and

fish body oil.


1. Fish liver oil:

Approximate chemical composition

� Fat 55-75%

� Protein 5-10%

� Water 20-36%

� Cholesterol 0.46-1.32%

� Vitamins A and D

� Iodine 158.7-166.6%

Depending upon extraction from fresh or stale livers, oil is grouped into 3 types:

1. Pale cod liver oil: It is obtained from liver of fishes that are brought alive to the shore.

This oil possesses highest medicinal value.

2. Light brown oil: It is procured from disintegrated livers of fish. Like pale cod liver

oil, it is also used in medicinal purposes in pharmacy.

3. Brown oil: Brown oil is not usually preferred in pharmacy because of its extraction

which is done from liver of stale fishes.

2. Fish body oil: Obtained from entire body.

(II) Fish meal (food for cattle):

Approximate Composition

� Protein 65-70%

� Fat 8-12%

� Ash 9-17%

� Water 6-10%


(III) Fish manure: It is used as fertilizer for coffee, tea, tobacco and rubber plantation because it

is rich in nitrogen and phosphates.

(IV) Fish silage:

Fish silage as described here is defined as a liquid product made from whole fish or parts of fish

that are liquefied by the action of enzymes in the fish in the presence of an added acid. The

enzymes break down fish proteins into smaller soluble units, and the acid helps to speed up their

activity while preventing bacterial spoilage. Silage made from white fish offal does not contain

much oil, but when it is made from fatty fish like herring it may be necessary to remove the oil at

some stage.

(V) Isinglass: It is a high grade collagen produced from the air bladder or swim bladder of cat

fishes, carps, sturgeons, cods etc. It is in the form of shining powder. Isinglass is used principally

for the clarification of wines, beer and vinegar.

(VI) Fish glue: It is a sticky substance and is prepared from different wastes (eg bones, scales

and fins etc) discarded during processing.

(VII)Fish Surimi: (literally "ground meat") refer to a paste made from fish or other meat, as

well as multiple Asian foods that use Surimi as its primary ingredient. It is available in many

shapes, forms, and textures, and often used to mimic the texture and color of the meat of lobster,

crab, and other shellfish.

Ambergris (Latin: Ambra grisea, Ambre gris, ambergrease or grey amber) is a solid, waxy,

flammable substance of a dull grey or blackish color produced in the digestive system of sperm

whales. Freshly produced ambergris has a marine, fecal odor. However, as it ages, it acquires a


sweet, earthy scent commonly likened to the fragrance of rubbing alcohol without the vaporous

chemical astringency. Although ambergris had been highly valued by perfumers as a fixative

(allowing the scent to last much longer), it has largely been replaced by synthetics.

Q. 8- Answer:

The chemical composition is described in view of the nature and function of the main chemical

constituents, their variation with season and their contribution to the human diet.

Importance of fish chemical composition:

The processor, the nutritionist, the cook and the consumer all have a direct interest in the

composition of fish. The processor needs to know the nature of the raw material before he can

apply correctly the techniques of chilling, freezing, smoking or canning. The nutritionist wants to

know what contribution fish can make to the diet and to health, and the cook must know for

example whether a fish is normally lean or fatty in order to; prepare it for the table. The

consumer is interested not only in whether a particular fish tastes good, which is a matter of

opinion, but also in whether it is nutritious.

While the consumer is interested mainly in the edible part of the fish, that is the flesh or muscle,

the fish meal manufacturer is concerned with the composition of the whole fish, and the

processor of fish oils wants to know what is in the liver. Measurement of constituents of fish

products is sometimes necessary to meet specifications or to comply with regulations. For

example, the fish content of fish cakes or the oil content of fish meal may need to be known in

order to meet certain commercial or legal requirements. Fish is one of the most valuable sources


of high grade protein available to man in this hungry world, and a knowledge of its composition

is essential if the fullest use is to be made of it.

The principal components of fish muscle/flesh:

Water

The main constituent of fish flesh is water, which usually accounts for about 80 per cent of the

weight of a fresh white fish fillet. Whereas the average water content of the flesh of fatty fish is

about 70 per cent, individual specimens of certain species may at times be found with a water

content anywhere between the extremes of 30 and 90 per cent.

The water in fresh fish muscle is tightly bound to the proteins in the structure in such a way that

it cannot readily be expelled even under high pressure. After prolonged chilled or frozen storage,

however, the proteins are less able to retain all the water, and some of it, containing dissolved

substances, is lost as drip. Frozen fish that are stored at too high a temperature, for example, will

produce a large amount of drip and consequently quality will suffer. In the living fish, the water

content usually increases and the protein content decreases as spawning time approaches; thus it

is possible, with cod for example, to estimate the condition of the fish by measuring the water

content of the muscle.

In cod, the water content of the muscle is slightly higher at the tail than at the head; this slight

but consistent increase from head to tail is balanced by a slight reduction in protein content.

Protein


The amount of protein in fish muscle is usually somewhere between 15 and 20 per cent, but

values lower than 15 per cent or as high as 28 per cent are occasionally met with in some species.

All proteins, including those from fish, are chains of chemical units linked together to make one

long molecule. These units, of which there are about twenty types, are called amino acids, and

certain of them are essential in the human diet for the maintenance of good health. Furthermore,

if a diet is to be fully and economically utilized, amino acids must not only be present but must

also occur in the correct proportions. Two essential amino acids called lysine and methionine are

generally found in high concentrations in fish proteins, in contrast to cereal proteins for example.

Thus fish and cereal protein can supplement each other in the diet. Fish protein provides a good

combination of amino acids which is highly suited to man’s nutritional requirements and

compares favourably with that provided by meat, milk and eggs.

Fat

Taking all species into account, the fat content of fish can vary very much more widely than the

water, protein or mineral content. Whilst the ratio of the highest to the lowest value of protein or

water content encountered is not more than three to one, the ratio between highest and lowest fat

values is more than 300 to one.

The term fat is used for simplicity throughout this leaflet, although the less familiar term lipid is

more correct, since it includes fats, oils and waxes as well as more complex, naturally-occurring

compounds of fatty acids.

There is usually considerable seasonal variation in the fat content of fatty fish; for example a

starved herring may have as little as ½ per cent fat, whereas one that has been feeding heavily to


replenish tissue may have a fat content of over 20 per cent. Sardines, sprats and mackerel also

exhibit this seasonal variation in fat content. As the fat content rises, so the water content falls,

and vice versa; the sum of water and fat in a fatty fish is fairly constant at about 80 per cent.

Although protein content falls very slightly when the fat content falls, it nevertheless remains

fairly constant, somewhere between 15 and 18 per cent.

The fat is not always uniformly distributed throughout the flesh of a fatty fish. For example in

Pacific salmon there may be nearly twice as much fat in muscle from around the head as there is

in the tail muscle.

In white fish of the cod family, the fat content of the muscle is always low, usually below 1 per

cent, and seasonal fluctuations in fat content are noticeable mainly in the liver, where the bulk of

the fat is stored.

The minor components of fish muscle

Carbohydrates

The amount of carbohydrate in white fish muscle is generally too small to be of any significance

in the diet; hence no values are given in the tables. In white fish the amount is usually less than 1

per cent, but in the dark muscle of some fatty species it may occasionally be up to 2 per cent.

Some molluscs, however, contain up to 5 per cent of the carbohydrate glycogen.

Minerals and Vitamins

These include a range of substances widely different in character that must be present in the diet,

even if only in minute quantities, not only to promote good health but also to maintain life itself.


Although fish is very unlikely to be the only source of an essential mineral in the diet, fish does

provide a well balanced supply of minerals in a readily usable form. The table of mineral

constituents of fish muscle gives values averaged from a large number of species and is intended

to serve only as a rough guide. It would be impracticable in this short note, and of limited value,

to give a detailed analysis for individual species.

Composition tables for fish often include a value for total ash. Since ash consists largely of a

number of different minerals, and the total rarely exceeds 1-2 per cent of the edible portion, this

figure has also been omitted, except from the table of fish products.

Vitamins can be divided into two groups, those that are soluble in fat, such as vitamins A, D, E

and K, and those that are soluble in water, such as vitamins B and C. All the vitamins necessary

for good health in humans and domestic animals are present to some extent in fish, but the

amounts vary widely from species to species, and throughout the year.

The vitamin content of individual fish of the same species, and even of different parts of the

same fish, can also vary considerably. Often the parts of a fish not normally eaten, such as the

liver and the gut, contain much greater quantities of oil-soluble vitamins than the flesh; the livers

of cod and halibut for example contain almost all of the vitamins A and D present in those

species. In contrast, the same two vitamins in eels, for example, are present mainly in the flesh.

Water-soluble vitamins in fish, although present in the skin, the liver and gut, are more uniformly

distributed, and the flesh usually contains more than half the total amount present in the fish. The

roe, when present, is also a good source of these vitamins.


In general the vitamin content of white fish muscle is similar to that of lean meat and, with the

exception of vitamin C, can usually make a significant contribution to the total vitamin intake of

man and domestic animals.

The mineral and vitamin content of fish is not markedly affected by careful processing or by

preservation, provided storage is not very prolonged.

Nutritional value of fish:

NUTRIENTS NUTRITIONAL VALUE

Good source of protein Needed for growth and repair

Essential fatty acids Needed for cell membranes, cannot be

made by body

Low in calories Good for lower fat diets

Minerals – iron, zinc, iodine, selenium Wide range of minerals

Vitamins A and D Found in oily fish – important for

growth and bones

Model Answer M Sc IV Zoology Fish Biology: Capture Fishery ... Answer 15/18.5.15-Dr. Santosh...

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