Caballero B. (ed.) Encyclopaedia of Food Science, Food Technology and Nutrition. Ten-Volume Set

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test to distinguish fish with ciguatera toxin (apart

from feeding portions to animals such as kittens).

Future Trends

0017 Despite overexploitation of many fish stocks and

consequent (if belated) control measures, it is clear

that fish will continue to play an important role as

food, chiefly as a consequence of improved methods

of farming both of freshwater and marine species. A

better understanding of fish stock management will

be important in keeping capture fisheries at around

present levels, which are probably not far from the

maximum sustainable. In contrast, aquaculture

(which provided 28.8 million tonnes in 1997) will

increase steadily. In 1996, over a quarter of the

world supply of food fish for human consumption

came from aquaculture (mainly Chinese carp and

other cyprinids). It also seems likely that there will

be an increasing amount of fish and fish products

entering international trade, particularly from de-

veloping countries, where exports almost doubled in

value between 1990 and 1995. Future trends here

seem likely to show different methods of keeping

fish free from spoilage such as by the use of controlled

atmosphere packaging using mixtures of N

,and

, and a large increase in the use of such products

as surimi. An entirely different reason for the future

importance of fish as food arises as the result of

dietary studies, which have either demonstrated or

suggested the value of fish diets in preventing some

common diseases in developed countries. For

example, fish are generally low in cholesterol and,

compared to meat, have a much more complex spec-

trum of lipids high in polyunsaturated fatty acids. Of

particular importance is the high proportion of the o-

3 series of fatty acids in oily fish, contrasting with the

o-6 fatty acids of vegetable origin. Epidemiological

studies indicate that significant reductions in coron-

ary heart disease may be obtained by the weekly

consumption of only 300 g of such fish. There are

also possibilities of modifying the diets of farmed

fish to augment the levels of other components valu-

able for the human diet. (See Fish Farming.)

See also: Fatty Acids: Dietary Importance; Fish:

Processing; Miscellaneous Fish Products; Fish Farming;

Preservation of Food

Further Reading

Cato JC (1998) Economic Values associated with Seafood

Safety and Implementation of Seafood Hazard Analysis

Critical Control Point (HACCP) programmes.FAO

Fisheries Technical Paper, Rome: FAO.

Cutting CL (1962) Historical aspects of fish. In: Borgstrom

G (ed.) Fish as Food, vol. 2, pp. 128. London: Academic

Press.

Dean B (1895) Fishes living and fossil. An outline of their

forms and probable relationships. In: Columbia Univer-

sity Biology Series, vol. 3. London and New York: Mac-

millan and Co.

Geiger E and Borgstrom G (1962) Fish protein – nutritive

aspects. In: Borgstrom G (ed.) Fish as Food, vol. 2,

pp. 29–114. London: Academic Press.

Hall GM (ed.) (1997) Fish Processing Technology, 2nd edn.

London: Blackie Academic & Professional.

Halstead BW (1978) Poisonous and Venomous Marine

Animals of the World, p. 1043. Princeton, NJ: Darwin

Press.

Lagler KF, Bardach JE, Miller RR and Passino DRM (1977)

Ichthyology, 2nd edn, pp. 506. Chichester, UK: Wiley.

Catching and Handling

P Chattopadhyay, Jadavpur University, Calcutta,

India

Introduction

0001The devices used to catch fish are known as gear, i.e.,

hooks, baits, nets, and rope. Fishing gear of numerous

designs is available for use in commercial or sport

fishing. Many factors have to be taken into consider-

ation when selecting the method and gear to be used

to catch a particular species of fish in a specific area.

The choice depends on the species being fished, value

of the individual species to the fisherman, the depth of

water, and the characteristics of the sea bed. The

different species of fish have different habits, move-

ments, and reaction to stimuli. Demersal species are

usually found near the sea bed, whereas pelagic

species are found anywhere between the sea bed and

surface. The movements and habits of each species

are controlled by water temperature, salinity, spawn-

ing habits, migration, available food resources, and

the temperature barriers that exist in any particular

location. A few methods of catching fish are discussed

below.

Net Methods

Trawling

0002A fishing method in which a boat is dragging a large

net through the water is called trawling. When the net

is somewhere in the water column, it is called mid-

water trawling, but when the net is dragged along the

2408 FISH/Catching and Handling

ocean floor it is known as bottom trawling. Many

important species are caught with the bottom trawl.

Large ‘doors’ are used ahead of the net to keep the net

down yet opened wide (Figure 1). There are many

designs of these doors. The most common are otter

doors. Fuel consumption can be reduced by cutting

holes into the doors in appropriate places. Trawling

therefore requires a strong boat to pull the fishing

gear through the water as well as the fish. It disturbs

the bottom of the ocean but is still an efficient method

of catching large quantities of bottom fish. The

doors used for midwater trawls are much lighter

than those used for bottom trawling.

0003 If two boats are used, each dragging one side of the

net, the same opening of the net could be achieved

without using any doors (Figure 2). For this, cooper-

ation between two boats is necessary. Pair trawling is

a fuel-efficient method. The ability of smaller fish to

escape is controlled by the size of the net mesh. How-

ever, as the bag fills up with fish, and the larger fish

block the net holes, small fish become trapped deep

inside the net and are unable to escape. Regulating the

mesh size of the net may be partially effective in

minimizing the catch of undersized fish. Recent re-

search suggests that the shape of the net mesh may

affect its efficiency: a square mesh may allow for

better escape of undersized fish than the traditional

diamond mesh.

0004Table 1 shows some data on the relationship be-

tween fish length and weight. Table 2 relates the mesh

size of a net to the length of fish retained. The lengths

given represent the size at which about 50% of the

fish are retained and 50% can still escape through the

net. The data can also be expressed for a particular

fish (Table 3).

0005The popularity of trawling has been expanded with

the development of factory ships with facilities for

on-board freezing.

Seining

0006Seine nets are often used to catch schooling fish

(Figure 3). Pelagic fish, for example, mackerel, are

most easily caught in this way. These are upper-

water-column fish and swim large distances. Small

boats, sometimes two boats, set off from the mother

ship and carry a relatively small mesh net which is set

around the school of fish. If the net is a ‘purse’ seine, a

string on the bottom is then pulled tight so that the

bottom of the net can be closed off. The net is then

hauled in until most of the fish are in a small area of

water. This is called hardening of the net. The fish are

then removed from the water, with hand nets or with

Swivel

Edge line

Tow line

Otter board

Sinker line

Sinker

Float line

Float

fig0001 Figure 1 An otter trawl net. Reproduced from Yamaha Motors

(1986) Yamaha Fishery Journal Composite, p. 134, with permission.

Floats

Lead weights

Weights

fig0002 Figure 2 Two-boat midwater trawl.

tbl0001Table 1 Optimizing the catch by regulating mesh size

: length–

weight data for some common fish

Fish Weight (kg)

0.4 5 0.9 1.3 6

Length (cm)

Pollock 51

Cod 36 48 64

Haddock 38 46 66

Whiting 38 51

Red fish 31 38 51

Mackerel 31 41

Yellow tail 38 46

Rainbow trout 36

Mesh size refers to the main part of the net.

Data courtesy of the National Marine Fisheries Service.

tbl0002Table 2 Mesh size (cm) versus retention length (cm) for some

common fish

Mesh size (cm)

10 13 14 16 17

Retention length (50% retained)

Cod 34 45 47 49 56

Haddock 33 43 45 47 53

Yellow tail flounder 22 29 31 32 36

Pollock 34 44 46 48 54

Winter flounder 21 28 29 31 35

Dals (plaice) 24 31 33 34 39

Data courtesy of the National Marine Fisheries Service.

FISH/Catching and Handling 2409

mechanical unloaders (pumps). Purse seining is used

for the capture of species utilized in bulk reduction

processes such as fish meal or species of high value.

The greatest damage is done to the fish at the time of

unloading from the boat because of the postmortem

physicological changes that have occured in the fish.

Fish in rigor should not be pumped. A modification of

the seining method is practiced from the shore. The

mother ship becomes a land-side attachment and the

net, after setting, is hauled to shore by either people

or a vehicle. This method is often used for more

valuable species such as blue fish, striped bass (in

New York), or for salmon (in Scotland).

tbl0003 Table 3 Relative rates of retention for cod

Length (inches) Percent retained

14 cm me sh 15 cm me sh

27 99 97

25 97 98

22 78 56

21.6 74 50

20 53 29

19.8 50 27

18 27 11

16 9 3

Data courtesy of the National Marine Fisheries Service.

1. Sharing the load of a net and moving

forward with their bows linked.

2. Separating from each other and casting

a net where a school of fish is located.

3. Surrounding the school.

4. Pursing begins.

5. and 6. Net hauling.

7. The bunt is positioned between two

boats and fish is scooped with a big dip net.

Holding rope

Purse wire

Operation method

Two-boat purse seining net

Bridle

Purse ring

12 3

Lead

Buoy

Bunt

Body

Wing

fig0003 Figure 3 Seine nets. Reproduced from Yamaha Motors (1986) Yamaha Fishery Journal Composite, p. 178, with permission.

2410 FISH/Catching and Handling

Gillnetting

0007 Gillnetting involves stretching out a net to intercept

fish (Figure 4). The net can be set at any level in the

water column by manipulating the rope length and by

the use of anchors and floats. Placement is often

chosen to intercept natural fish migration. The fish

do not see the net and simply swim into it. Once their

gills go through the net, they can no longer escape,

and they drown. The thrashing of fish prior to death

leads to both external and internal bruising. If the

nets are not well attended, the dead fish will be un-

treated for too long and will be of poor quality. For

this reason, gillnetting is one of the least desirable

ways to catch fish from a quality standpoint, even

though it is extremely efficient. It is an easy method

to use with small boats, for example, for salmon in

Alaska. The nets are generally hauled from one side of

the boat and immediately sent back to fish on the

other side, or a drum is used to wrap the net around

as fish are simultaneously removed by hand.

0008 Gillnetting has become controversial because of

‘ghost fishing’. With modern net materials like nylon,

these nets are difficult for fish to see and may continue

to catch fish after the fisherman has lost them.

Cast Nets

0009Weighted cast nets or variations thereof are usually

used by the artisan fisherman. These are simply

thrown out to sea from land or a small boat; the

weight around the net causes them to sink and trap

(catch) the fish.

Herding devices

0010Another net-based catch method involves the use of

traps, and weirs (Figure 5). These devices herd fish

into an area where they can then be easily removed.

This fixed gear is expensive and time-consuming to

build, and also depends on the fish coming to the trap

rather than a boat going to the fish. Thus, traps work

best when the migration of the desired fish species can

be predicted accurately. They often work best in

rivers or streams or close to the shore where natural

terrain features channel fish movement. The fish can

be caught live simply by hand-netting them out of the

Encircling gill net

Hunting gill net (drive-in net)

Rowing gill net

Bag

net

Bottom drift net

Floating drift net

Fixed-type floating gill net

Anchor

Sinker

Float

Bottom

Water surface

Buoy

Fixed-type bottom gill net

fig0004 Figure 4 Examples of gill and drift nets. Reproduced from Yamaha Motors (1986) Yamaha Fishery Journal Composite, p. 50, with

permission.

FISH/Catching and Handling 2411

trap. Otherwise fish can be kept alive in the traps for

some time and harvested when needed. Large pound

nets are used along the shore to collect and harvest

these fish.

Hooking Methods

Longlining

0011Longlining is simply the use of a long fishing line with

lots of hooks, usually evenly placed (e.g. every 1 m)

along the line (Figure 6). This method can be used on

rougher grounds (bottoms) where a trawler cannot be

used. This system has many important benefits over

trawling, including the potential for size and species

selectivity by the proper choice of hook size and

shape, and bait; lower energy cost; and less damage

to the ocean bottom.

0012Placing the bait on to numerous hooks is very

labor-intensive. New forms of mechanical baiters

have been developed that replace the tremendous

effort involved in hand baiting. It is also labor-

intensive to remove the bait and fish from the line as

it is hauled back on board. Equipment to do this

automatically has been developed. If longlining is

done properly, the fish can be processed on board

one at a time as they are brought on board.

fig0005 Figure 5 A small fixed net. Reproduced from Yamaha Motors

(1986) Yamaha Fishery Journal Composite, p. 67, with permission.

(a)

(b)

(c)

12 10

1. Trunk line

8. Float 9. Antipressure float

10. Marker fla

11. Marker li

ht 12. Radio buoy 13. Anchor

2. Branch line 3. Sekiyama 4. Snood 5. Hook

6. Swivel 7. Buoy line

fig0006 Figure 6 Examples of longlines. (a) Drift longline; (b) bottom longline; (c) vertical line bottom longline. Reproduced from Yamaha

Motors (1986) Yamaha Fishery Journal Composite, p. 219, with permission.

2412 FISH/Catching and Handling

0013 The hooks used for longlining must be of the

appropriate size for the fish that is to be caught. The

choices of hook size and bait make this form of fish-

ing very selective (Figures 7 and 8). Since each hook is

designed to catch fish above a certain size, this tech-

nique is particularly effective in avoiding undersized

fish. Hook shape may also affect species selectivity as

well as the amount of bait needed (a major expense

with longlining). The Mustad Company of Norway

has developed the most advanced longline systems

appearing on the market.

Trolling

0014 Trolling is usually done close to the water surface.

The boat moves through the water with a number of

lines each attached to a pole (Figure 9). A number

of hooks are attached to each line. The fish are almost

always landed live. Trolling allows for selective hand-

ling of fish and thus leads to a very high quality. Troll-

caught salmon are particularly prized, especially if

they are to be smoked subsequently. The absence of

either internal or external bruising maximizes the

appearance and the recovery (weight) of this

extremely expensive product. It must be noted that

subsequent careful handling is important to preserve

the higher initial quality.

Tilefish

Crimson

sea bream

Red sea bream

Bdryx splendens Centrophid fish

Cutlass fishPike congerRayGlobefishFlatfish

Mackerel Yellowtail Halfbeak

Tuna Marlin Shark

fig0007 Figure 7 Various fishing hook shapes. Reproduced from Yamaha Motors (1986) Yamaha Fishery Journal Composite, p. 220.

(a) (b) (c) (d)

fig0008Figure 8 Use of vertical lines. Reproduced from Yamaha

Motors (1986) Yamaha Fishery Journal Composite, p. 211.

FISH/Catching and Handling 2413

Jigging

0015 Jigging was first developed commercially in Japan.

When fish are caught by this method, bait and/or

special lights (at night) are used to attract the fish to

an area (Figure 10). The fish tend to bite on any

flashing item including the many hooks present in

the water. Some part of the catch may also be snagged

on the hooks. The system of powerful lights on the

boat coupled with brightly colored jigs and small in-

the-water lights is particularly attractive to certain

species of squid. Bait is an important cost in all the

hooking methods, particularly longlining. Each long-

line hook uses about 45 g of bait. Therefore, there is

an interest to develop appropriate baits, i.e., those

that can withstand the physical constrains of the

mechanical system and also attract the appropriate

fish. Research is being done currently on taste prefer-

ences of fish, i.e., flavor attractants. This will help to

develop appropriate artificial baits.

Other Techniques

0016A number of more unusual techniques may also be

used. Spears and harpoons may be used for some of

the larger fish. Fishermen sometimes simply detonate

a bomb in the water and then collect all the dead fish

– usually of low quality. A wide variety of other catch

methods are used for shellfish. These animals often

live below the ocean floor and thus require techniques

like surface dredging (Figures 11 and 12) or raking

and tonging to recover the product (Figures 13 and

14). A dredge has steel teeth that scrape and stir up

the ocean floor. The scallops are then caught in a large

steel bag behind the dredge. Tongs are really a pair of

forks with a center pivot that are used to pick up

clams or oysters from the ocean floor. Classical rod

Surface trolling

One-line trolling

Three-line trolling

Seven-line trolling

Middle-depth trolling

fig0009 Figure 9 Examples of trolling. Reproduced from Yamaha

Motors (1986) Yamaha Fishery Journal Composite, p. 211.

Sea anchor

Reel guide

Drift roller

Windlass

Machine body

fig0010 Figure 10 Automatic squid-fishing jigs. Reproduced from

Yamaha Motors (1986) Yamaha Fishery Journal Composite, p. 24.

Coiling roller

Speed reducer

Pulley

Dredge net

About 200 m

2.2 m

9−12 cm in mesh size

33 cm

2.25 m

Chain

75 cm

2.3 cm

fig0011Figure 11 Operation of a dredge. Reproduced from Yamaha

Motors (1986) Yamaha Fishery Journal Composite, p. 75.

fig0012Figure 12 An oyster dredge. Reproduced from Wheaton FW

and Lawson TB (1985) Processing Aquatic Food Products. New

York: John Wiley, p. 95, with permission.

2414 FISH/Catching and Handling

and reel fishing can be used commercially for larger,

more valuable fish like tuna and swordfish.

0017 There are many other methods used to catch fish as

well as a variety of other types of equipment, such as

pots and traps for shellfish (Figure 15). Most of these

methods are adopted to the specific fish and local

fishing conditions.

0018Traps are often used in areas through which fish

regularly move or congregate. Traps are set in rela-

tively shallow water adjacent to the land. They may

be of many sizes and configurations, but all aim to

prevent fish from leaving once they enter; any vessel

can set and attend a trap.

0019Pots are used to capture crustaceans whose princi-

pal movement is by legs on the sea bed; pot fishing

may be inshore or deep-sea. Pots of different sizes and

configurations are set out and attract the species

by means of baits, either cut-up fish or other sea

creatures, or in a prepared, packaged form. Once

the animal enters the pot through a specially designed

entrance, it is unable to exit again and is trapped.

0020Harpooning can be used commercially on large

species having high individual value. Work and time

involved in searching, capturing, and bringing aboard

each fish restricts the operation to valuable species. A

retrieving line runs from the pole of the harpoon to

the operating vessel; both the hunting and retrieving

lines are run out from coils or tubs positioned on the

vessel’s foredeck.

Handling and Preservation on Ships

0021Handling of fish on ships needs special care. Fish

begin to spoil immediately after death. Since the rate

of spoilage is increased by any rise in temperature, the

refrigeration of the catch by chilling or freezing is

necessary. Spoilage is caused by enzymic, bacterial,

and oxidative changes. Enzymes are present in the

flesh and stomach of the fish, and the gut wall and

the neighboring flesh, which are penetrated and

softened by these enzymes after death, are thus easily

invaded by spoilage bacteria. For this reason, in

trawl, seine, and line fisheries for demersal fish, the

fish is gutted and washed immediately after catching.

In pelagic fisheries, where small fish are caught in

greater numbers and not gutted, the spoilage is

(a)

(b)

fig0013 Figure 13 Oyster tongs. (a) Patent tongs; (b) hand tongs.

Reproduced from Wheaton FW and Lawson TB (1985) Processing

Aquatic Food Products. New York: John Wiley, p. 100, with permis-

sion.

(a)

(c)

(b)

fig0014 Figure 14 Clam rakes. (a/b) Hard clam rakes. (c) Soft shell

clam hoe or fork. Reproduced from Wheaton FW and Lawson TB

(1985) Processing Aquatic Food Products. New York: John Wiley, p.

101, with permission.

fig0015Figure 15 A New England loster pot. Reproduced from

Wheaton FW and Lawson TB (1985) Processing Aquatic Food Prod-

ucts. New York: John Wiley, p. 85, with permission.

FISH/Catching and Handling 2415

quicker. Rancid odors and flavors are produced when

atmospheric oxygen combines with fat in the fish, and

temperature is the most important single factor

affecting the rate of spoilage.

Chilling

0022 The chilling system should maintain the lowest pos-

sible temperature. Considering the problem of qual-

ity, length of voyage, labor, and investment, chilling in

melting ice is the most common method. An alterna-

tive to this is the use of chilled or refrigerated sea

water (CSW or RSW), which has the additional ad-

vantage of handling the catch. The landing deck or

container must be kept clean to prevent contamin-

ation of each haul by previous landings, and constant

attention to hosing the landing deck area is necessary.

Baskets, boots, and other items in contact with the

catch should be thoroughly washed before the fish are

landed. Fish should be carefully handled on the deck

to avoid bruises and cuts; after landing, they are

shifted to holding bins and mixed with ice to cool

them. Gutting is done manually or by automatic gut-

ting equipment on board. Gutting should remove all

the guts and liver, and the belly cavity should be

opened sufficiently to make the washing effective.

After washing, the gutted fish are stored in melting

ice to bleed; this insures that the flesh is free from

discoloration. Chilling of fish in ice is done through

stowage in bulk, in boxes, in pens, or in shelves.

0023 In bulking, the fish and ice are mixed in intimate

contact in order to achieve maximum storage life. It is

carried out in a hold divided into pens fitted with

removable shelves of wood or metal. Bulking to a

depth greater than 40 cm is not recommended and,

with some species, the limits are lower; otherwise,

there would be excessive weight loss owing to the

pressure. With bulking, there are difficulties in

unloading the catch owing to the problem of separat-

ing the ice and the fish, a process which may involve a

large amount of labor. Sometimes, for this reason,

substantial water is added and fish are pumped out

with a centrifugal pump.

0024 The boxing of fish is usually preferred to bulking

because of better cooling, and the elimination of

handling of the fish (bruising and injury) at the

dock, leading to an improved quality of product at

the point of consumption. Boxing involves placing ice

and fish in a container (box) of standard dimensions

(normally 30 and 65 kg capacity) and stowing the box

in the hold. The only real disadvantage is that boxing

requires more hold space per unit weight of fish;

return of reusable boxes may also be a problem.

0025 In the shelf stowage system, the fish is stowed in

single layers, gut cavity down, on a bed of ice. Some-

times a little ice is spread on top. This insures

complete bleeding and retards spoilage by chilling,

but it is a process which is not widely used on vessels

because it is not space-efficient and the fish may

become dehydrated as a result of the movement of

air over the unprotected fish.

0026In pen stowage, fish and ice are placed in alternate

layers to a depth of 70 cm, a second pen board is

placed over the bottom pen, and the same process is

repeated. This storage system is widely used for

stowing fish in ice. In general, crushed or flaked ice

is used in the chilling of fish on board. The storage life

of fish in ice can be slightly extended through the use

of antibiotics or salt-water ice. Antibiotics such as

chlorotetracycline and oxytetracycline in concentra-

tions up to 5 p.p.m. in ice are permitted in some

countries to inhibit bacterial action. Separation of

salt and water during freezing or melting is a problem

with salt-water ice. Immersion of fish in CSW or RSW

is used as an alternative to ice for the chilled storage

of fish. The sea water may be chilled by the direct

addition of ice (CSW), or by mechanical refrigeration

with a heat exchanger (RSW). Storage of fish in CSW

or RSW helps in unloading the fish from the vessel, as

they can be pumped out and into a holding tank.

Freezing

0027Freezing at sea is necessary if the vessel remains at sea

for a period up to 90 days. Storage in ice, or by other

means of chilling, is adequate up to 15 days, after

which the fish rapidly become inedible. If fish are

frozen on board and stored at low temperature, the

fishing vessel can remain at the fishing grounds until

the hold is full. This improves the economics of fish-

ing, and the general quality of fish landed. Depending

on the facilities available on board and the markets,

fish may be frozen in the round, gutted, gutted and

headed, or in the form of fillets. A number of conven-

tional freezers may be used at sea with little modifica-

tion. The freezer and its refrigeration system have to

conform to national regulations and insurance re-

quirements for a fishing vessel. Many countries do

not allow the use of ammonia as a refrigerant in

fishing vessels. The design, operation, and type of

refrigeration system must take into account the move-

ment of the vessel, vibration, sea-water corrosion,

and the extra rough usage under conditions at sea.

Fish to be frozen and iced fish are handled in the same

way, except that the former are frozen rather than

merely cooled. Filleting is the step before freezing,

and the fish should be held at chill temperature,

below 5



C, from catching to freezing, in order to

retard spoilage and avoid the ill-effects of rigor mortis.

0028Rigor mortis, or death-stiffening, is the physical

change that occurs in all animals, including fish, as a

result of a series of complex reactions that go on in

2416 FISH/Catching and Handling

the flesh tissue after death. It is one of the factors

which, after a certain period of time, retards the

postmortem autolytic and bacterial decomposition

of the flesh and its protein, and thus extends the

shelf-life. Rigor mortis in fish starts 1–7 h after

death and its peak in slaughtered fish, kept in ice,

lies between 5 and 22 h after death; the total duration

of the rigor is 30–120 h. A prolongation of the rigor

mortis period is of great economic importance, and

harvesting and on-board handling practices should

aim to extend rigor and maintain fish quality. Rigor

mortis lasts longer when the fish has exerted less

muscular activity prior to death, as it is refrigerated

immediately. Immediate slaughtering of the fish after

capture also appreciably extends rigor. The onset of

rigor mortis is quicker at higher temperatures, and

may occur only 10–20 min after death at about 30



It is therefore essential that the fish is chilled quickly

to avoid problems arising from rigor mortis during

freezing. If possible, it is desirable to freeze fish before

rigor mortis begins. Freezing in rigor can damage the

fish, and only poor-quality frozen fillets or blocks can

be made from such fish. However, while some fish can

be frozen postrigor, others become quite unsaleable.

In addition, prerigor frozen fillets are sometimes

subject to contraction upon thawing; they should be

transferred to the cold store immediately on removal

from the freezer.

Handling in Port

0029 Containers, boxes, and the portable sections of a fish

room are handled by cranes. The discharge of a large

vessel stowing its catch in pens and shelves is achieved

by filling a basket with fish, attaching it to the end of

a rope, hoisting it up and swinging it ashore; this

operation may be mechanized using bucket elevators

and ship-to-shore conveyors. In the chilled or refriger-

ated sea-water systems of stowage, pump unloading

is convenient and widely used. The fish which are

frozen on board are unloaded by standard, endless

looped-canvas elevator belts. After landing, the fish

should not be exposed to warm ambient temperatures

of the auction market. Fish can be sold, after taking

random samples from the boxes, containers, or

shelves, as soon as the vessel arrives in the port, so

that the fish can be unloaded directly on to the

waiting transport. Cleanliness, care, and cooling are

most important for first-class fish.

0030 It is common to land fish at a market (fish pier)

where it is put up for auction. This is also convenient

for the ship and secures maximum prices for the fish.

However, since these auctions can cause delay in the

further distribution of the fish, affecting its quality,

there should be several sales during the day and a

corresponding distribution system (e.g., special fish

trains) to avoid such problems. This will help to

insure that the fish reach inland wholesale or retail

dealers in time for further sale. Fish should always

remain in ice throughout the period in the market,

and special market boxes or kits can be used. Fish

intended for distribution fresh and uprocessed are

usually brought from the market or other landing

points to a packing house. They are iced or reiced

and packed in nonreturnable or returnable containers

with the requisite insulating properties for transport

to the inland wholesaler or retailer.

See also: Fish: Processing; Shellfish: Commercially

Important Crustacea; Spoilage: Chemical and Enzymatic

Spoilage; Bacterial Spoilage