Specified Skills
Educational Textbook for the Fishing Industry Skills Proficiency Test
(Fishing)(Net Fishing)

Japan Fisheries Association(First Edition: December 2019)Table of Contents

Roundhaul Fishing

1. Overview of Roundhaul Fishing ···································································· 2
2. Targeted Fish ····························································································· 2
3. Operation Systems and Trawlers ··································································· 2
4. Fishing Devices ··························································································· 5
5. Fishing Tools ······························································································ 7
6. Devices Installed on the Bridge ····································································· 8
7. Operation Methods ······················································································ 8
8. Operation Procedures ················································································ 10Gill Net Fishing

1. Types of Gill Nets and Their Uses ······························································· 14
2. Netting Fabrics ························································································· 15
3. Floats and Sinkers ···················································································· 18
4. Ropes······································································································· 18
5. Tying Techniques ······················································································ 19

Trawl Fishing

1. Names of Major Net Parts ·········································································· 23
2. Otter Roll Fishing Method ·········································································· 23
3. Bull Trawling Method ················································································ 25
4. Danish Seining Method ·············································································· 26
5. Danger Prevention ···················································································· 28

Fixed-Net Fishing

1. Characteristics of Fixed-Net Fishing ···························································· 30
2. Fundamental Elements of Fixed-Net Fishing ················································ 30
3. Names and Structures of Each Part of Trap-Type Fixed Nets ·························· 31
4. Names of Net Structures ············································································ 33
5. Net Hauling Work (Net Holding) ································································· 35
6. Processing Catch ······················································································· 39
7. Danger Prevention ···················································································· 39

Basket fishing

1. Basket Fishing ·························································································· 42
2. Classification of Basket Fishing Tools ·························································· 42
3. Basket Fishing Catch ················································································ 44
4. Types of Fish Caught by Different Basket Types············································ 44
5. Crab Basket Fishing ·················································································· 44
6. Operation Methods ···················································································· 45
7. Precautions for Red Snow Crab Basket Fishing ············································· 49
8. Shrimp Basket Fishing ················································································· 50
9. Shrimp Basket Fishing Tools ······································································ 50
10. Operation Methods ·················································································· 51
11. Precautions for Shrimp Basket Fishing ························································· 53

Roundhaul Fishing11. Overview of Roundhaul Fishing
Roundhaul fishing is a fishing method which entails using one or two trawlers toencircle a school of fish that has been found using a belt-shaped net then capturing
the fish inside after closing the net hem so they cannot escape. Roundhaul operations
are classified into two broad categories based on the operation time: daytime
operations in which either fish are caught directly in simple schools or schools of fish
are searched for and discovered attached to drifting objects such as driftwood, payaos,
and artificial rafts; and nighttime operations in which lights are used to attract andcatch schools of fish. Operation systems are also broadly categorized into two groups:
the single-ship roundhaul system, in which an equipped ship (usually a trawler) isused, and the ship-group roundhaul system, which is used for both single-ship
roundhaul fishing and dual-ship roundhaul fishing.

2. Targeted Fish
Roundhaul fishing targets large-catch pelagic fish in the waters around Japan. The
main species targeted are Japanese anchovy, Japanese sardine, jack mackerel,mackerel, blue mackerel, bonito, albacore tuna, yellowfin tuna, bluefin tuna, andyellowtail.

3. Operation Systems and Trawlers(1) Operation System
Roundhaul operation systems are divided into two main groups: the single-ship
roundhaul system, in which an equipped ship is used, and the ship-group roundhaul
system, in which a group of ships centered around a trawler is used. The former ismainly seen in overseas roundhaul fishing and the latter is mainly seen in small- to2

medium-scale and medium- to large-scale roundhaul fishing operations. The standard
structures used for these roundhaul systems are as shown in Figs. 1 and 2.

1 trawler

1 trawler
1 skiff

1 to 2 search vessels

1 to 2 lightvessels

2 work boats

2 to 3 carriers(2) Trawler
A trawler takes the central role in both single-ship and dual-ship roundhaul
operations, and all the essential fishing devices for operations are loaded on the
trawlers. The standard fishing devices for trawlers are shown in Fig. 3.

3

Fig. 3: Standard fishing devices for trawlers(1) Net hauler(6) Ball roller(2) Float handler(7) Ring-line davit(3) Power block(8) Purse winch(4) Large winding winch(5) Side roller(9) Purse reel(10) Capstan (also used for various winches)44. Fishing Devices(1) Net Hauler
A net hauler is a movable fishing apparatus
mounted on the stern of a trawler. It hoists net
gathered into a bar shape from the float side to thesinker side by inserting it into a v-shaped groove

Figure 4: Net hauler

which it rotates (Fig. 4).

(2) Side Roller
A side roller is a piece of equipment mounted on theright side of the trawler.
It rotates via hydraulic drive, pushing the net into
the top area and pulling it onto the ship using
friction (Fig. 5).
Figure 5: Side roller(3) Power Blocks
Power blocks are rotating drum devices which have rotating portions with wedgeshape structures and are attached to a crane or a derrick. They lift the bundled, barshaped roundhaul nets that have been hauled onto the ship by the net haulers to ahigh location, move them to a predetermined location for net storage, and perform
netting stacking operations (Fig. 6). There are also other similar fishing devices usedin netting stacking such as the net conveyor (handler) shown in Fig. 7 and float
handlers.
5Figure

s

7:

Net

conveyer(handler)
Figure 6: Power block(4) Purse Winch
A purse winch is a a direct-winding winch (Fig. 8) mounted on the left of the bowside deck that winds a purse wire which closes the net hem after the roundhaul net
has been cast. There are single-series and dual-series winches, and the single-series
type have their standing rollers and purse reels mounted separately.

(5) Ball Roller
A ball roller is a device that rotates two spherical pieces of rubber to enclose and lift
a net to haul or handle nets on the fish-catching side of operations. Typically, two to
three of these units are used, and they are attached to a movable arm (Fig. 9).

Figure 8: Purse winch

Figure 9: Ball roller

6(6) Fish Pump
A fish pump is a device used to transfer fish caught in nets during operations tocarriers, as well as to unload caught fish from carriers at the market (Fig. 10).

Figure

10:

Fish

pump

(Left:

Duringfishing

operations, Right: During unloading)

5. Fishing Tools
Float
Float line

NettingfabricStone (sinker)
Sinker line
Ring line
Ring

Wire

(1) Float LineA line with floats attached located on the upper side of a net which is used to float it.
(2) Sinker LineA line with sinkers attached on the lower side of a net which is used to sink it.
(3) Wire
A wire used to close the bottom of a net which is passed through the ring.
7

(4) Ring LineA short rope with a ring which is tied to a sinker line.

6. Devices Installed on the Bridge(1) Fishfinder
A device that searches for schools of fish under a ship.
(2) Net Sonde
A device that measures data such as the depth and sinking speed of a roundhaul net
and the temperature of the seawater.
(3) Sonar
A device that searches for schools of fish swimming in the sea.
(4) GPSA device that accurately records the ship’s position.

7. Operation Methods
For roundhaul fishing operations conducted at night using fish-luring lights,
operations are conducted in the following order after arriving at the fishing grounds:(1) finding the fish, (2) luring the fish, (3) casting the nets, (4) closing and hauling thenets, and (5) drawing in the fish. Ship groups conducting one-day operations departfrom the harbor in the evening and head for the fishing grounds, then return to theharbor the next morning and unload the fish at the market.

(1) Finding the fish
The ship group heads out for the fishing grounds together and searches for schoolsof fish using tools such as sonar and fishfinders after arriving.
8

(2) Luring the fish
After the ship group finds a school of fish, a lightvessel lights its fish-luring lights
in order to vertically position the location of these fish. In areas where underwater
lights are used, these underwater lights are also lit and put into the sea.
(3) Casting the nets
The trawler commences net casting while confirming the speed and direction of thecurrent, as well as the position of the school of fish. At the instruction of the chief
fisherman, one retrieval boat or lightvessel (or carrier) approaches from the stern of
the trawler and takes in the fish-catching end of the roundhaul net, commencing net
casting. The trawler then casts the roundhaul net from the stern portion and sails
around the lightvessel which continues luring the fish, traveling in a circular motion.
In this way, the netting is cast out in such a way as to surround the school of fish. At
the time of net casting, it is important to take care to make sure no crew members get
their feet entangled in netting or ropes.
(4) Closing and hauling the nets
After the roundhaul net has been cast, one end of the fish-catching side of the net
is taken in by the retrieval boat. The captain of the trawler verifies the sinking stateof the roundhaul net while watching the measurement values of the depth measurer,
closes and hoists the ring line, and commences net hauling work by closing the net
hem. When performing net hauling, multiple fishing crew members on the side of thedeck facing the stern side of the trawler load the net, which is hoisted via the powerblock, onto the deck while folding it. At this time, as the members are handling a wet,heavy net, they are careful to avoid getting their feet entangled, which could cause
them to be into the fishing equipment in operation.

9(5) Drawing in the fish
When the net-hauling work of the roundhaul net
has progressed and only the portion with thecaught fish remains in the water, the carrier
receives one end of the portion with the caught
Fig. 11: Drawing in thefish. When taking the caught fish onto the carrier,fish

the fish are drawn in either by scooping with atriangular net or a landing net or by using a fish pump (Fig. 11).

8. Operation Procedures(1) The lightvessel (or the carrier) approaches from the stern direction of the trawler,
and takes one end of the side with the caught fish.
(2) The trawler accelerates and travels around the lightvessel, casting the net.

(1)

(2)
Trawler

TrawlerLightvessel

Lightvessel

Lightvessel10(3) to (4): The trawler travels around the lightvessel while casting the net, and thelightvessel (or the carrier), which performs the role of the receiving boat, takes one
end of the portion with the caught fish.

(3)

(4)

Lightvessel

Lightvessel

Lightvessel

Trawler

Trawler(5) In net hauling work, the purse wire attached to the sinker side is wound first. Next,
the sinking situation of the net is confirmed using the depth measurer attached to
the net, and when the net hem reaches the lower layer portion of the targeted schoolof fish, winding of the purse wire commences using the purse winch installed on the
bow side of the deck of the trawler. In order to prevent the trawler from moving andcausing of the net to warp during net hauling, the lightvessel, which is connectedto the trawler with a rope, performs "back rowing" and pulls the trawler. When the
net hauling moves forward and the net becomes smaller, the carrier approaches the
opposite side of the trawler and takes in a part of the net, thereby arranging theshape of the net to make it easier to draw in the caught fish.

11

(5)
Lightvessel

Trawler

Carrier12Gill Net Fishing13

1. Types ofGill Nets and Their Uses
The fish-catching functions of gill nets include "gill catching," in which the net threads
tighten around the bodies of the fish caught in the mesh, and "tangle catching," in which
the spines and fins of the bodies of the fish get caught in the net threads.
Gill nets can be categorized from two perspectives. The first is dividing them by thethree layers of the ocean in which they are set: the surface layer, middle layer, andbottom layer; and the second by the two setting methods used: fixed and unfixed(flowing). By combining these two groups of categories, there are a total of six types of gillnets possible, but most gill nets fall into one of the following three types: surface layer
flowing type, surface layer fixed type, and bottom layer fixed type (Fig. 12).

Figure 12: Surface layer flowing type (top figure)and bottom layer fixed type (bottom figure) gill nets

14

Generally, a gill net simply referred to as a "gill net" is most often a bottom layer fixedtype gill net (single-layer net). This type of gill net is used in coastal fishing and offshore
fishing, and is the most common type in all gill net fishing. There are large variations interms of design and operation methods for this type of net.
The major targeted species for various gill nets are as shown below (Table 1).

Table 1: Main targeted species for various gill nets
Type of gill net

Main targeted species

Bottom layer gill

Herring, forktail bullhead, silver white croaker / nibea

nets

mitsukurii, types of sea bream, types of jack mackerel,
halibut, types of shark, types of crab

Fixed-type surface Herring, sardine, flying fish, mackerel, types oflayer gill nets

salmon/trout, types of shark

Flowing nets

Types of marlin, bonito, Spanish mackerel, types of
salmon/trout, mackerel, types of shark, herring, saury,yellowtail

Three-layer nets

Yellowtail, gizzard shad, seabass, types of sea bream,types of halibut/flounder, rockfish, flathead, cuttlefish,squid, prawn

2. Netting Fabrics
The general qualities required for netting fabric and materials for gill nets are as
follows.

15

(1) Difficult to see underwater(2) Soft net threads(3) Net threads with breaking strength sufficient to resist the swimming forceof fish(4) Net threads with suitable stretchiness for holding fish within the mesh(5) Mesh knots strong enough to tightly hold in fish

(1) Mesh Size
Mesh size is the most important factor in
deciding the quality of a gill net and isdetermined depending upon the type(s) of fishtargeted and the size accounted for by a large
proportion of these fish within a school. For ageneral gill net (single-layer net), when a fish

Fig. 13: Circumference of fish,
and inner circumference of meshpasses through a mesh, the net threads cut
into the body of the fish, resulting in gill catching (Fig. 13).
For gill nets which aim to catch fish using the tangling method, somewhat smaller
mesh sizes are often used.
(2) Hanging Ratio
The hanging ratio is the most fundamental design element of a gill net. "Hanging
ratio" is a ratio that is determined by the length of the netting fabric and the lengthof the rope that binds it, and the shapes of the diamonds that are formed in themesh are determined by this ratio. It is a ratio of the length of the netting fabricwhen it is stretched to the length of a portion that is constricted and shrinks when it
is bound by the rope afterward. A relatively small hanging ratio is generally used for16

a gill net when aiming for gill catching. Conversely, a large hanging ratio is often
used when aiming for tangle catching.
For a gill net, fundamentally, the float line and the sinker line have different lengths
from each other, and the sinker line is 3 to 10% longer than the float line. Thus, thehanging ratio differs slightly from the float line side to the sinker line side. This isbecause at the time of net casting, the netting fabric on the sinker line side contracts
more easily than that on the float line side; thus, the sinker line side is stretched inadvance. However, in the case of threads on a bottom-layer gill net, the net shape on thesea floor after setting is taken into account; thus, depending on the targeted fish, thesinker line may conversely be made shorter when laying the net flat.
(3) Vertical Mesh and Net Length
The size of netting fabric is expressed by the number of vertical mesh units andthe net length. The number of vertical mesh units is the number of mesh units
included in the breadth (height / length / depth) direction of the netting fabric. The
length of the netting fabric (in the horizontal direction when the gill net has been
formed) is expressed in meters. For ready-made products, the number of verticalmesh units depends on the breadth of the net-making machine, and the common
sizes are 100 and 200 mesh units. The netting fabric length is the length of one
finished net, commonly around 50 m.
(4) Color and Visibility
Many types of fish have eyesight sufficient for recognizing the presence of netting
fabric in the water, as well as the ability to distinguish colors. Currently, theelement determining whether a fish can recognize the presence of a net in the water
is thought to be the degree to which the material contrasts with the background. The
materials which are currently commonly used for gill nets, light gray multi-filament
thread and light blue synthetic fiber netting, achieve both transparency and low
background contrast.
173. Floats and Sinkers
A variety of materials lighter than water,such as wood, bamboo, and cork, have beenused for gill net floats. Currently, synthetic
resin products are typical. The mostimportant qualities for a float are residual
buoyancy and pressure resistance. There areboth filled and hollow floats, and two maintypes of shapes, threading floats, which havea hole through which a rope is passed, andflat floats, which are held between two ropes

Figure 14: Flat float (top figure) andthreading float (bottom figure)and used. The benefit of threading floats isthat there is no possibility of them coming loose, whereas flat floats have theadvantage of being easy to remove and attach for replacement when broken or toadjust buoyancy (Fig. 14).
For sinkers, any material that is sufficiently heavier than water, such as stone,
ceramic, iron, and lead can be used, but lead sinkers are the most common for use
with gill nets. Typically, the sinkers are barrel-shaped and have a hole throughwhich a rope is passed. In recent years, lead ropes, which have lead woven into therope fibers, are also used.

4. Ropes
Ropes are used mainly in the float lines and the sinker lines of gill nets, but there
are also nets that lack sinker lines and nets that use accompanying rope float lines.
Ropes are mainly selected based on specific gravity, operability (the roughness of the18

surface), breaking strength, and cost. Due to factors such as their specific gravity,ropes made from polyethylene and polypropylene materials which are less dense
than seawater are often used for float lines, and ropes made from polyvinyl alcohol(CREMONA, KURALON, etc.) and polypropylene are often used for sinker lines.

5. Tying Techniques(1) Netting Fabric and Edge Net (Sewing)
Basically, the latest method is to sew a few more meshes while gradually increasing
the thickness of the net thread, and it is standard to make the net thread of theoutermost portion about twice the thickness of the netting material.
Both ends of one gill net either have edge threads passing through the mesh in thevertical direction of the net, or are left with cut mesh. To reinforce this portion of thenet, fastening thread is used to lash the knots (Fig. 15).
Furthermore, when a part of the netting fabric tears, it is typical for the fishing crew
to conduct repair work themselves.

Edge netting
Fastening
threadBody netEdge
threadEdge netting
Figure 15: Edge sewing (net)and edge fastening
19

(2) Sewing
These is a great deal of variation in sewing used for the netting fabric, floats,sinkers, and ropes (Fig. 16). For the sewing of the float, a reverse lay rope with Slaying or Z-laying is used, and either one rope is passed through the hole in the floator two ropes are used to hold the float in place for sewing operations. When the
diameter of one rope is slightly reduced, this is called an accompanying line. The
yarn used to sew the netting fabric to the rope is called threading yarn. To avoid
concentrating force into a single portion of the netting fabric, it is better if not all of
the mesh is secured to a rope, and instead a design in which free movement ispossible for the threading yarn is used.
There are two methods of sewing a rope to netting fabric. One method is hanging arope in the air, making marks on the rope at intervals calculated during design, andsewing a similarly determined number of meshes at each mark. In the other method,
the rope is not hung, and no marks are made. Instead, the distance from one lashingpart to another is measured using the number of meshes while holding the rope, andpoints of return are sewn in conjunction with the hanging ratio (for instance, adistance of 10 meshes is stretched from one lashing portion, and if the hanging ratio
is 40%, the point four meshes back is decided to be the next lashing portion). Eachmethod has a disadvantage: while the former method is labor-intensive, the lattermethod does not allow the hanging ratio to be selected in a completely free manner(it can only be selected in units of half-meshes). In every part, a spun yarn made of apolyamide is often used when sewing components. This is because this surface of
this material has sufficient roughness needed for lashing, and a low cost.

20

Float line

Accompanying
Float

float line

Basket yarn

Float

Basket (threading) yarn

Float line

Basket (threading) yarn
Float line

Float

Connecting
threadSinker (stone) line
Sinker (stone)

Stone line

Stone line

Basket (threading) yarn
SinkerLead (sinker) rope

Basket (threading) yarn

Basket(threading) yarn

Crossing
threadSinkerFigure 16: Various sewing methods of float
part and sinker part
21

Stone lineTrawl Fishing22

1. Names of Major Net Parts
Generally, the net is made up of asleevenet

forcollecting

sea

Head rope

CodendSleeve net

creatures at a mouth near the frontof the net, a body net, and a codend
for collecting fish. The foremost
Body net

portion of the sleeve net has thelargest

mesh,

and

the

mesh

Ground rope

gradually gets smaller from there,
Figure 17: Names of major parts ofwith the mesh size of the codend

trawl nets

being the smallest. A head rope is
attached from the upper end of the sleeve net to the upper part of the front end of the
body net, and a ground rope is attached from the bottom end of the sleeve net to thelower part of the front end of the body net (Fig. 17).

2. Otter Roll Fishing Method
This is a fishing method in which the net is opened to the left or right using an otter
board (Fig. 18).
This enables operations with a single vessel, and because fishing operations can be
conducted even in a moderate storm, this method is used all over the world.

23

Figure 18: Otter roll fishing method(1) Otter Boards and Rigging
An otter board is a board made from iron, wood, or FRP. Since these boards maintaina certain angle (angle of incidence) with respect to the direction of the towrope, similar
to the wing of an airplane, a pressure differential between the front and back of theboard translates into net-opening force, enabling them to open the nets.
Otter boards also have the function of creating "sand smoke," which swirls up due tocontact with the seafloor, which the surrounding fish see as a threat, causing them tobe lured toward the net opening.

24

(2)

Net

CastingandTowing chain

Hauling Method
At

the

start

of

Otter board
Otter pennant (tip connection
wire)

Warp

operations, the net is caststarting with the codend.

Eight-ring
Otter stopper

At this point in time, there
are connections between
the net, the net pennant,the hand rope, the play

Play wire
Hand rope

wire, and the warp, in thatorder (Fig. 19), but the
otter

board

is

Net pennant

Fig. 19: Otter roller rigging

notconnected. The otter board is hanging down from a top roller in the stern gallows anda towing chain is connected to the warp, creating a state in which the warp, the otter
board, and the net are connected.
At the time of net hauling, when the warp shortens, the winding speed slows down,
and the otter board is wound until it is lifted to the gallows. Afterward, the sameprocedures as net casting are conducted in the opposite order.

3. Bull Trawling Method
This is a fishing method in which a net is opened and drawn by having two vessels
draw the net while maintaining a certain interval of distance between them (Fig. 20).
Since it is a simple net drawing method, it is used around the world, but it requires
more ships and considerably more effort than otter trawling and Danish seining.
25

(1) Towrope and Rigging
Two vessels draw the net
while expanding its mouth, and
fish

are

frightenedandgathered together with a long,thick compound rope.

(2) Net Casting and Hauling
Figure 20: Bull trawling method

MethodIn the bull trawling method,

two fishing vessels, a lead ship and a secondary ship, form a team. After the lead shipcasts the net, the secondary ship approaches the lead ship, transfers the end of its
own towrope to the lead ship, and connects to a towline on one side of the lead ship's
net, commencing net drawing. For net hauling, the secondary ship approaches thelead ship and passes the end of the towrope to the lead ship. The lead ship hoists thetowrope using the winches on both sides to perform the net hauling. Meanwhile, thesecondary ship commences casting work for its own net.

4. Danish Seining Method
A buoy is attached to the end of a towrope and cast into the water, and starting fromthis point, the ship travels in a path so as to draw a diamond shape in the water, thus
casting the first towrope, the net, and the second towrope, in that order. Next, thebuoy is taken onto the ship and the net is hoisted using the two ropes (Fig. 21).

26

Compared to other trawling methods,
Danish seining has comparatively slow
towing speed, and the fishing tools arelight.
With conventional net drawing (acompound rope), the diameters at theship side and the net side are different,so after net hauling, work is involved inwhich the towrope has to be reversed toprepare for the next net casting. In
recent years, however, towropes which
either are even or have symmetry arebeing used more often, enabling eitherside to be connected to the net side.

Figure 21: Danish seining method

Further, tools such as reels and net
winches which reel in towropes have become common.

27

5. Danger Prevention
Since the inside of trawling ships are narrow and sway, and there are wires andwinches in operation, crew members must be sufficiently mindful of such locations as
the following during operations.
・Sides of the ship with winches in operation
・Areas of ropes or wires that are under strong tension
・Slipways near sterns and areas near gangways
・Lower parts of derricks when nets are suspended
・Areas near the sides of ships during rolling (both sides)
・Decks that are slippery due to fish blood or oil

28

Fixed-Net Fishing29

1. Characteristics of Fixed-Net Fishing
Fixed nets are some of the most commonly used fishing tools in coastal fishing inJapan. Fixed-net fishing is used to catch a wide variety of fish, and the fish caught
using this method still alive when caught. In addition to direct consumption byhumans, these caught fish can also be applied to diverse uses such as live bait forother fishing operations. Since even when large numbers of fish have been caught innets, a portion of this catch can be kept as live fish, adjusting shipment volume issimple, and these adjustments can be used to prevent deflation due to market
oversaturation.

2. Fundamental Elements of Fixed-Net Fishing
Traps are the most developed widely-used type of fixed nets in Japan, and they
fundamentally consist of the following four elements.
Dredge: A single, simple net that stretches to the coast from an enclosing net. It has
an action which providing stimulation that changes the migration route of a schoolof fish, luring them toward the entrance of the enclosing net. The mesh size of aleader net is extremely large, ranging from 30 to 90 cm, and most fish arephysically able to pass through.
Enclosing net: The largest net enclosure, which first takes a school of fish into a net
and is made up of numerous panels. It is also called a "movement space." It stops
the migration of schools of fish and retains and holds the fish in the span until
they head toward the funnel. Thus, all of the panels of the enclosing net are placedwith schools of fish ascending and being led to the funnel and eventually the box
net in mind.
Funnel: The side near the enclosing net is called the outer funnel, and the part that30

passes into the box net side is called the inner funnel. The outer funnel is unified
with the enclosing net panels and forms a movement space, and the inner funnel
reinforces the snaring function of the box net and has prevents fish from escaping
the box net. In addition to having the function of guiding fish toward the box net,
the inner funnel has a function of joining the enclosing net with the box net.
Box net: This net has the fundamental functions of drawing in schools of fish fromthe funnel and storing and holding them until net hauling is performed.

3. Names and Structures of Each Part of Trap-Type Fixed Nets
(1) Names of Each Net Part
The fixed nets covered here are the standard trap-type fixed nets used in Japan.
The names of each major part of the fixed net (trap) shown in Fig. 22 are as follows.
A: Leader net: Generally, this net is set up on the costal side with respect to the bodynet. A net set up facing an offshore side with respect to the body net is called an
offshore leader net, and a leader net on the coastal side is called a shore leader net.
B: Front net opening: the opening of a net that fish enter and exit through. Generally
it is on one side of the leader net, and is opened on the side opposite to the box net.
The net opening on the other side of the leader net that is opened on the side of thebox net is called the rear net opening.
D: Movement space: A location that is enclosed by side nets from the outer funnel tothe movement space crossing. Generally, this location does not have a bottom net.
It is a space in which schools of fish that have entered are retained.
E: (Movement space) crossing: Originally, this was a straight line with a right angle
on the offshore and land sides, but as it is upstream from the tide, it is sometimes
formed in the shape of a "<" to reduce tidal resistance.
31F: End of the movement space: The location in which the offshore side of the net
opening is reached.
H: Outer funnel (net): A net with the purpose of guiding schools of fish in the
movement space to the box net. The slope from the seabed and the manner offunneling into the box net are both important.
J: Inner funnel (net): Continuing from the outer funnel, this is a net attached to theinner side of the box net. It serves the purpose of preventing schools of fish thathave entered the box net from escaping.
L: Tether (net): A net that determines the width of the joining portion between theouter funnel and the box net. This term may also indicate the width.
M: Box net: A net that retains a school of fish. Generally, it is the net used for net
hauling and fish catching, but as stated below, there are also structures in which
multiple box nets are connected.
N: Fish catching (keeping area, box net crossing): Originally, this referred to a net
portion woven with fine mesh and having thick thread, used to catch fish on the box
net crossing side. However, the term is also used to indicate the box net crossing.
O: Safe net: A net fish are temporarily chased into for the purpose of keeping them
alive when too many fish have entered the trap.
P, P': Arrowhead (wave front) large floats: These refer to large floats on the movement
space side which support side tethers for offshore and land. Generally, these floats
are on the upstream side of the tide.
Q, Q': Large floats: These refer to large floats on the box net side which support side
tethers for offshore and land.
R: Body tethers: These are ropes that connect the end of the leader net, the ends ofthe side tethers for land, and the ends of the side tethers for offshore and land.
32

Refers to the maximum width of the rope.
W: Net opening sea depth: A basic value that determines the scale of each part of a
fixed net.
P to Q (P' to Q'): Side tethers for offshore and land: Ropes that form the basis for
hanging each part of a net.

O

Figure 22: Structure of fixed net andname for each part

4. Names of Net Structures
Fixed nets have a structure in which each part of the net necessary for a side tether(rope) (including the movement space, funnel, and box net) is suspended. The basics
for tethering include two side tethers (main sides) that run parallel to each other and33

are on the offshore side and the land side and crossing tethers that are hungperpendicular to these (Fig. 23).
For a single fixed net, when continuously connecting a funnel with a box net asshown in Fig. 24 and there are two box nets, this is referred to as a fixed net with adual box structure. Coming from the movement space, these areas are called the firstlevel funnel, the first level box, the second level funnel, and the second level box.

Anchor line

Side tether(main side)

Leader net side
tetherFigure 23: Side tethers of a fixed net

34

First levelbox
Movement spaceFirst level funnel

Secondlevel box

Second level funnelFirst level
box

Secondlevel box
Sea surface

SeabedFigure 24: Fixed net with dual box structure (horizontal
projection and cross-sectional view)

5. Net Hauling Work (Net Holding)
For net hauling, 1 to 3 vessels ranging in size from 5 to 20 tons are used. The
commanding ship, which plays the central role, is called the o-naka vessel inJapanese and is particularly large. At the time of net hauling, there are two
accompanying ships, one on the offshore side and one on the land side, surrounding
this commanding ship. The ships close to the offshore and land sides of thecommanding ship are referred to as side vessels. In addition to these, carriers for thefish to be caught or sculling boats (small boats with outboard motors) may also be
used. The standard net hauling states are as indicated in Figs. 25 and 26.

(1) Upon arrival at the fixed-net fishing ground, the ships are driven within the net
toward the border between the outer funnel and the inner funnel of the fixed net,
commonly referred to as the "tightener" (peak, three openings) along the central
35tethers from the offshore side and the land side, for the purpose of net hauling.
(2) With the commanding ship in the center, the side ships line up alongside it on theoffshore and land sides and connect to one another using ropes between the bowsand sterns to prepare for operations.
(3) At the same time, the commanding ship releases two spearing ropes, one from its
bow on the movement space side and one from its stern, and connects to the central
tethers. (When using a single spearing rope, it is released from the central portionof the commanding ship.)(4) Hoist the hand ropes for net hauling attached to the bottom sides of the tightenerpart and both elbow parts (corner parts of the box net on the offshore and landsides of the inner funnel), and lower the central tethers to hold the net bottom near
the seafloor. During this step, the inner funnel is closed, and the box net becomesan enclosed net with no entrance or exit.
(5) Loosen the tether ahead of the inner funnel. (There is also a method whichtightens and hoists a net in front of the inner funnel.)(6) Continuing from the net hoisting of the tightener and both elbow parts, lift thefish catching (standing area) side to the sea surface. In this case, there are two
approaches used depending upon the net hauling method. These are a net haulingmethod in which netting fabric is sequentially lifted up to the sea surface by ahauler referred to as a ball roller (catch hauler), then attached to one side of thehauling vessel while the ships move; and a rope lifting method in which a line rope
(net-hauling rope) attached to the bottom of a box net is hoisted using a standingroller (capstan) attached to the net hauling vessel, thereby sequentially lifting net
fabric to the sea surface while the ships move.
(7) The spearing ropes are stretched and the ships move toward the area of the inner36

funnel. Using the ball roller or the standing roller, the netting fabric and the rope
are sequentially hoisted to the sea surface and the net is tightened toward the
direction of the standing area (fish catching area).
(8) When tightening toward the fish catching area from half of the box net, the net
is tightened so as to aggregate it while ensuring a swimming space for the fish.
(9) When the fish catching area is close, the two side vessels and the commanding
vessel move closer together to encircle the net part (standing area) of the fish
catching area in a backward "c" shape.
(10) Next, the two side vessels separate to the outside of the net, and of these, oneside vessel nears the fish catching side from outside of the net, encircles the net
together with the commanding vessel inside the net, and stops tightening the net.
(11) The fish inside the net, which was squeezed in a bag shape, are caught using
the landing net. This work is called fish drawing. The fish can be housed by either
the commanding vessel or the two side vessels.
(12) When hauling a fixed net using only the commanding vessel, during the fishdrawing step, the commanding vessel's derrick is used, one end of the float side of
the fish catching net is lifted to prevent the catch from escaping while securing a
bag-shaped space, and fish drawing operations are carried out (Fig. 27).
(13) After the fish drawing is completed, the spear ropes are removed, and the net
hoisted to the tightener is released. The inner funnel and other components are
returned to their original state as well. The tethers and other elements of the net
are also readjusted.

37

A

B

C

Figure 25: Net hauling work as seen fromabove in the order of A, B, and C

Spearing rope

FunnelFigure 26: A cross-sectional view of net hauling work
The top figure is B from Fig. 25, and the bottom figure indicates thestate of C.

38

Figure 27.: A single net hauling vessel (commanding ship)
drawing fish
6. Processing Catch・Fish caught by fixed net fishing are either kept in a tank as live fish or aretransferred to a fish hold mixed with ice water and seawater and kept in a fresh
state while they are transported to the harbor.
・As live fish and fish with high levels of freshness can be sold for high prices,
especially during the summer, it is important to use large amounts of ice tomaintain freshness.

7. Danger Prevention
When performing operations on a fixed-net fishing vessel, crew members must be
sufficiently cautious of the following during operations.

1. During net casting, be careful not to be caught in a rotating capstan or catch
hauler.
39

2. When hoisting fishing equipment, etc. using cranes, be careful not to approach theside of the machine.
3. When pulling a net or rope, be careful that your fingers do not get entangled.
4. At times of strong waves or wind, there may be significant horizontal swaying(rolling) or vertical swaying (pitching) of the ship, so be careful.
5. The sides of the ship (bulwarks) are low, so be careful not to fall overboard.
6. When casting an anchor or sandbag into the sea, be careful not to get caught in
the rope.

40

Basket Fishing41

1. Basket Fishing
Branch lines are attached to a long main line, and basket nets with barbs thatprevent sea creatures such as crabs and shrimp from escaping once they have entered
are tied to the tips of the branch lines and sunk to the seabed. This is a type of fishingin which bait is put inside the baskets and sea creatures are lured in and caught.
2. Classification of Basket Fishing Tools
Various types of baskets are used around the world. When categorized according totheir shapes, the baskets are grouped as shown in Fig. 28.
(1) Frustum basket: When put on the seabed, this type of basket is highly stable. It isalso convenient when stacking baskets on a ship. Frustum baskets are used not onlyin Japan, but also other countries such as America and Canada. Some of the mainbaskets used in Japan are crab baskets (Fig. 28-a), shrimp baskets (Fig. 28-b), andJapanese Babylon / spiral shellfish baskets (Fig. 28-c). Generally speaking, crabbaskets have one entrance (a chute) on the top of the basket, while shrimp baskets
have two entrances on the sides of the basket.
(2) Cuboid basket: The netting fabric of the corners of this basket tend to fray during
operations. Examples of this type are the conger baskets used in Saga Prefecture andthe spiny lobster baskets used in Miyazaki Prefecture (Fig. 28-d), but overall this typeis uncommon in Japan. However, in America, cuboid baskets are used in basket fishingfor red king crab and snow crab (Fig. 28-e).
(3) Semi-cylindrical basket: It is convenient to create the frames for these baskets usingwood and bamboo. These semi-cylindrical baskets are also known as uke, and are usedaround the world to catch spiny lobsters (Fig. 28-f). In Japan, they are used for basket
fishing for blowfish in locations such as Nagasaki Prefecture and Kumamoto
Prefecture, as well as for catching cuttlefish in Wakayama Prefecture (Fig. 28-g).
42(4) Folding baskets: This structure enables the basket to be folded, allowing even small
ships to use large numbers of baskets. Folding baskets are used in various locations
such as Shizuoka Prefecture and Kagoshima Prefecture to catch blue crab (Fig. 28-h).
King crab basket

Crab basket

Lobster basket

Glass float

Shrimp basket
Blowfish basket

Folding blue crab basket
Japanese Babylon/spiralshellfish basket

Bait

Stone

Spiny lobster basket
Inkwell basket

Figure 28: Various basket shapes

Sea urchin basket

43(Shoichi Takeuchi: 2-1 Fishing Methods for Basket Fishing,
Fisheries Science Series 36. Basket Fishing, Kouseisha-kouseikaku Corporation 19811)

3. Basket Fishing CatchThe catch from basket fishing is mainly types of crab and shrimp. In addition, otherseafood such as Japanese babylons / spiral shellfish, blowfish, conger eels, and squidare
also caught with basket fishing, and all of these are premium seafood. Within the catch,main targets include red snow crab and northern shrimp.

4. Types of Fish Caught by Different Basket Types(1) Crab basket fishing: Various kinds of crab are caught, such as red snow crab, snow
crab, horsehair crab, blue crab, blue king crab, and northern king crab.
(2) Shrimp basket fishing: In areas such as the Sea of Japan northern shrimp (deepwater shrimp, Alaskan pink shrimp), Pandalus hypsinotus (Botan shrimp), andMorotoge shrimp (Hokkai shrimp) are caught.
(3) Spiral shellfish basket fishing: Spiral shellfish (Japanese babylons) are caught.
(4): Other: Seafood such as octopuse, squid, eel, and blowfish are caught.

5. Crab Basket Fishing
Crab basket fishing is mainly conducted in the Sea of Japan, and the main catch
species are red snow crab and queen crab.

44

6. Operation Methods
There are 8 to 10 crew members for 70 to 100 ton fishing vessels. For vessels smaller
than this, there are 6 to 7 crew members. After loading the baskets, the arrangementof fishing equipment installations is as shown in Fig. 29.

1 set, 150 baskets or less, 6 to 10 km

Flag buoy

Floating rope, 2 to 3 times
water depth

Water depth

Main line

Branch line

Throwing rope
Stone
Throwingrope

Crab basket

Crab basket

Figure 29: Arrangement of fishingequipment installations(1) Basket casting (putting the baskets into the water)
i. First, a location where many crabs are expected be caught is searched for based on
factors such as fishing conditions to that point, the water temperature, the water
depth, and the substratum, and a basket casting spot is determined.
ii. A floating rope (the length varies depending on the depth of the water, and is about
2 to 3 times that of the water depth) with flag buoys (marks) on it is cast from the left
side of the stern.
iii. A main line, throwing rope, and sinker stone are tied to the tip of the floatingrope and cast out.
45

iv. Next, the basket nets on the end of the ropes (branch lines) tying together the mainline and the basket nets are cast into the water.
v. For bait, fish such as mackerel, mahi, and frigate tuna.
vi. At the time of basket hoisting, the baskets are loaded onto the stern withoutbinding the bottoms of the basket nets with ropes. The ropes are bound when casting
the baskets. This is to make it easier to load the baskets onto the stern.
vii. There are up to three sets of fishing equipment (3 x 150 = 450 baskets). First, one
set is cast, then the ship moves a certain distance away and the second set is cast,then the ship moves a certain distance away again and the third set is cast.
viii. During basket casting, sufficient caution must be taken to ensure crew members’
feet do not become entangled (caught) in ropes.
(2) Basket hoisting (hoisting the baskets)
i. The main elements of basket hoisting operations are shown in Fig. 30. The mainline is wound by a drum on the left-side center via a roller on the left-side bow. At
this time, operations are conducted with the wind either behind the side on which thebasket is hoisted (left side), or behind the bow.

46

Roller

Disconnect the branch lines. Take out the
crabs and send to the conveyor belt.

Crab basket
Hatch

DerrickBasket with bait

Derrick
Drum

Carry the baskets
to the stern on theconveyor belt

Drum

Coil the rope, load it
onto the stern, andplace the baskets
on topCrab basket

Figure 30: Main elements of basket hoisting operations for red snow crabbasket fishingii. When the baskets reach the sea surface, they are hooked using a bar with a hookattached to the end, and lifted using a derrick.
iii. If there is caught seafood in the baskets, the ropes on the bottoms of the baskets
are undone to remove the catch. If crabs have been caught, they are separated intolarge, medium, and small sizes, inserted into a draining basket filled with ice, andput into the fish hatch.
iv. If red snow carbs have been caught, catching female crabs and male crabs under
9 cm is prohibited, so any catch smaller than this is released.
v. Bait is put into emptied baskets without tying the ropes at the bottoms of the nets,
the baskets are carried to the stern by a conveyer on the left side, and the baskets
are prepared for the next casting.
47

vi. The hoisted main line is sent from the bow to the stern on the left side of the ship,
and the main line is coiled in an orderly fashion to prepare for the next basket casting.
Next, the branch lines with the baskets attached to them are tied to the main line,
and the baskets are loaded onto the stern.
vii. Bycatch in red snow crab basket fishing includes porous-head eelpouts, Japanese
babylons / spiral shellfish, and other species.
viii. After one set of baskets has been hoisted, the next set of baskets is immediately
cast from the stern if fishing conditions are good.
ix. If the fishing conditions were bad for the first set of baskets, a search is carriedout to determine a new basket casting location (fishing ground). The baskets are castwhen good grounds are found, and the second set of baskets that had been cast aheadof time is hoisted afterward.
x. These operations are repeated, the third set of baskets is hoisted, and then when
the third set has been cast, the ship returns to the harbor to unload the caught
seafood for the market.
xi. If one set of baskets is hoisted and the fishing conditions are good, the next set ofbaskets is cast right away. In this case, basket hoisting and basket casting takes 4 to
5 hours. Assuming it takes about 8 hours round-trip to go to and from the fishingground, the number of hours taken for one voyage is this travel time plus the time
for operations multiplied by three sets (4 to 5 hours for each), or 12 to 15 hours. Thismeans the total time is 20 to 23 hours when fishing conditions are good. If the fishingconditions are poor, a case of selecting a different fishing ground and conducting
operations there involves incurring more time to travel to that fishing ground.

48

7. Precautions for Red Snow Crab Basket Fishing(1) The periods when red snow crab basket fishing is allowed are determined by eacharea.
(2) There are periods when red snow crab basket fishing is prohibited.
(3) The prices of red snow crabs are decided based on size, and caught crabs are
categorized into large, medium, and small based on the sizes of their shell widths (thebreadths of their shells) on the ship. The categories are as follows. Large: 12 cm andabove, medium: between 10 and 12 cm, and small: over 9 cm.
(4) For resource conservation, catching male crabs with shell widths of 9 cm or less andfemale crabs of all sizes is prohibited. If any such crabs are caught, they must be
immediately released. Catching snow crabs via red snow crab basket fishing is
prohibited as well, but since they inhabit different water depths, there is no bycatchor mixing.
(5) Engaging in red snow crab basket fishing with the intent of catching other types ofcrabs (such as snow crabs) is prohibited.
(6) Red snow crab basket fishing operations are prohibited in waters shallower than
800 m.
(7) The size of meshes must be 15 cm or larger.
(8) The maximum number of baskets allowed in one set is 150.
(9) After returning to harbor, the caught crabs must be immediately sent to a processing
location and boiled or otherwise processed. Out of the catch, those crabs which arestill alive are sold as live crabs or put into a fish tank at a fishermen's cooperativeand shipped at an appropriate time.
(10) The number of crabs caught is thought to be even more strongly influenced bywhether operations can be permitted due to weather, such as whether weather
49

conditions are good or inclement, than other factors such as the influence of seasonsand fishing ground conditions.

8. Shrimp Basket Fishing
In shrimp basket fishing, species such as northern shrimp (Alaskan pink shrimp),
Pandalus hypsinotus (Botan shrimp), and Morotoge shrimp (Hokkai shrimp), arecaught, and out of these, northern shrimp have the largest catch volume. This species
is also known by the name "deep-water shrimp," and these shrimp are familiar to people
all around Japan. Northern shrimp are the largest shrimp resource in the Sea of Japan,
and are mainly caught by offshore trawling, small-scale trawling, and basket net
fishing. Basket net fishing is conducted along the coast of the Sea of Japan from
Hokkaido down to the area off the coast of Tottori Prefecture. In addition, bycatch suchas porous-head eelpouts and Japanese babylons / spiral shellfish are also mixed in.

9. Shrimp Basket Fishing Tools
Generally, a side-opened basket with an opening on the side of the basket as shownin Fig. 31 is used. Most baskets have a frustum shape. The number of baskets used isdetermined by each prefecture based on various conditions such as the circumstancesof other fishing operations.

About 40 cm

50Fig. 31: Shape of a shrimp basket

The interval between baskets should be decided when attaching the baskets to themain line based on the breadth (length) of the range inhabited by the shrimp, in otherwords, the range of the distribution of shrimp that can be caught with one basket.
However, in actuality, work-related issues (whether to tie the branch lines with thebaskets attached to the main line before basket casting or to cast the baskets whiletying the branch lines to the main line), and the differing time for hoisting the baskets
depending on the length between baskets on the main line and the speed of basket
hoisting should also be considered when determining the length of these intervals. For
bait, seahorses, arabesque greenlings, snow crabs, and herring are used.

10. Operation Methods(1) Basket castingi. The basket casting spot is determined by investigating factors such as fishingconditions to that point, the water temperature, the water depth, the substratum,and the seabed topography.
ii. After the spot is determined, the flag buoys (markers), floats, and floating rope (2to 3 times the length of the water depth) are inserted into the water from the stern.
iii. A main line, a throwing rope of 25 to 45 m, and a sinker stone are tied to the very
end of the floating rope and cast.
iv. Next, the ship drives forward at full speed, and the basket nets on the ends of theropes (branch lines about 3 m long) which tie together the main line and the basket
nets are cast into the water. The interval between baskets ranges from 5 to 8 m.
v. The baskets are prepared for casting by inserting bait during basket hoisting andtying ropes to their bottoms.
vi. Fig. 32 shows conditions when shrimp baskets have been cast into the sea.
51

1 setFlag buoy

Floating rope, 2 to 3 times
to the water depth

Water depth
Branch lines, approx.3 m

Main line

Throwingrope,
approx. 25 to 45 m
Stone
Throwingrope

Crab baskets

Crab baskets

Figure 32: Conditions when shrimp
baskets have been cast into the sea(2) Basket hoistingi. As shown in Fig. 33, a clipping drum at the front of the right side is used to hoist
the flag buoys, followed by the floating rope.
ii. Next, the sinker stone and the main line are hoisted, and when the branch lines
and the baskets attached to them come up, the baskets are detached from the mainlines, including the branch lines.
iii. The ropes on the bottoms of the basket nets are undone, the catch is removed,
shrimp and other seafood are separated, and the shrimp are put into a live seafoodtank. Emptied baskets are placed on conveyor belts on the right side of the ship andsent to the stern.
iv. The hoisted main line is sent from the bow to the stern on the left side of the shipusing the drum, and the main line is coiled in an orderly fashion to prepare for the
next round of basket casting. Moreover, the branch lines with the baskets attached
are tied to the main line, and loaded onto the stern portion.
52

Clipping drum
Direction of progression

Disconnect
thebranchlines, and take the shrimp
out of the baskets.
Conveyor belt
Hatch

Rope
Insert the bait.

Coil the rope, and put thebaskets on top.

Figure 33: Shrimp basket fishing hoisting method

11. Precautions for Shrimp Basket Fishing・Shrimp basket fishing is only allowed during limited time periods.
・After fishing, the shrimp taken from the baskets are immediately placed in live fishtanks. Live fish tanks should be filled with sea water chilled to a temperature of about
0°C, with oxygen supplied from the bottom.
・When the ship returns to the harbor, shrimp are sorted based on whether they arealive, their size, and whether they are pregnant.
・In Japan, whether shrimp are pregnant can affect the prices in some areas. Pregnant
shrimp earn higher prices in the Kanazawa area, while large shrimp that are notpregnant are preferred in the Kansai area. This is due to differences in the taste of theeggs and the texture of the meat when shrimp do not have eggs.
53