objective 2: description of fisherieswebco.faocopemed.org/old_copemed/reports/tunidos/... ·...

Project FAO-COPEMED / Túnidos’99

Aim 2

OBJECTIVE 2: DESCRIPTION OF FISHERIES

Methodology: From the official information regarding the composition of the fleets and thecharacteristics of these fleets by method of fishing and/or base port. Surveys done onskippers of fishing vessels and captains of tuna traps for the description of the methods,fishing strategy and fishing technology. Object species and associated species. Fishingareas and season.

Results:

MOROCCO (INRH)

Objective 2.1

DESCRIPTION OF FISHERIES

In the Moroccan Mediterranean, the exploitation of tuna was mostly carried out by trap-netsimplanted according to the migration route of those species and to a lesser extent bylongline fishing.

In the beginning of the 90s, we witness the appearance of the drift gillnet, which producedan amazing development of the swordfish fishing in the Mediterranean. Furthermore, from1994, a small-scale fishery has allowed the capture of a noticeable amount of bluefin tunain the region of Ksar Sghir, by using the fishing rod.

Hereafter, we intend to describe the main fishing techniques used in the studied area for theexploitation of tuna and tuna-like species:

2.1 DRIFT GILLNET

This gear is specifically used for the swordfish fishing when it migrates through the Straits.Two fishing flotillas use this gear; one of them is in the port of Tanger and comprisesapproximately 160 longliners, the characteristics of which appear in (Fig. 2.1); The secondflotilla is based in the port of Nador and is composed of about 60 vessels. (Fig. 2.2)

2.1.1 Description of the fishing technique :

The drift gillnet is the main fishing gear used by longliners. It is made of polyamide andcomposed by multiple rectangular nettings which have a bolt-rope of floats on top and abolt-rope of plumb on the bottom. The netting without plumb mesures 100 m (Fig. 2.3).


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The most frequently found dimensions range from 2000 to 3000 m, and the predominantmesh size is about 400 m. The drop is limited between 11 and 15 arms.

The swordfish fishing is a seasonal activity, since it coincides with the passage of theswordfish through the Straits of Gibraltar. It starts around the end of March and continuesuntil October.

The choice of the fishing area is determined by the availability of the resource all over theseason, according to the different migration periods. Thus, between April and July, thefishing boats operating in the Straits are found in the west at an average distance of 10marine miles. From August to October, the drift nets are mainly drawn in the east of theStraits. Fishery usually takes place at great depths (up to 400 metres) in order to avoid thecontact of the net with a rocky bottom. The approximate situation of the swordfish fishingareas in the Moroccan Mediterranean is shown in Fig. 2.4.

TJB

38%

23%

28%

11%

2-5 tx 5-10 tx >10 tx sans données

CV

25%

31%

32%

12%

0-50 50-100 >100 sans données

Figure 2.1 : Characteristics of the longliner flotilla using drift gillnet in the port of Tanger(1999)


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TJB

23%

12%

58%

7%

2-5 tx 5-10tx >10 tx sans données

CV

20%

35%

35%

10%

<50 50-100 >100 Sans données

Figure 2.2 : Characteristics of longliner flotilla using drift gillnet in the port of Nador.(1999)


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Figure 2.3 : Diagramme of the drift gillnet used in the port of Tanger

37

36

35

34

37

36

35

34

234567

234567

37º06'N07º07'W

33º50'N01º53'W

36023604

3605

3504

3505

3506

3606

3406

Pesquerías de Pez Espada 1998

2.- Red de Enmalle a la deriva (GN-M)Marruecos (M)

Áreas de Pesca

2

HoceimaNador

35023503

2

3603

PROYECTO FAO-COPEMED / Gibraltar’98

2

2

Figure 2.4: Approximate situation of swordfish fishing areas in the MoroccanMediterranean


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Once in the net anchoring area, the fishing operation starts with the spinning of the gear onthe port side. The first luminous buoy, spliced to the first extremity of the net, begins to belet out. Then the net is thrown to the water. After having anchored 10 pieces, a second buoyis attached to the upper bolt-rope of the floats. A big float is attached between twosuccessive buoys. The operation continues until the total spinning of the gear. During thespinning operation, the speed of the vessel is very low, allowing the sailors to fix theintermingled parts of the net. When the net anchoring is completed, the tacking operationstarts. It consists of lifting the net from the starboard side with a net-hauler. This phaseneeds the cooperation of the whole crew; it starts with the lifting of the net up to the boardat the same time the captures are untangled with a hook.

The average duration of a haul is 12 hours, with a maximum of 20 hours and a minumum of8.

2.2 TRAP-NETS : Vessels, areas and fishing periods.

Moroccan trap-nets are drawn in the two maritime coasts. In the Atlantic, the followingtrap-nets are legally installed : « Punta Negra », «Los Cenizosos », and «Kénitra 1 », and«cap spartel ». In the Mediterranean there is only one operational trap-net known as« Principé ». These trap-nets deal with different phases in the migration of bluefin tuna.Thus, the Atlantic trap-nets target the bluefin tuna of genetic migration and they are drawnfrom April to June. On the other hand, the Mediterranean one targets the fish shoal ofgenetic migration as well as the trophic one and it is installed during a more extendedperiod (April-October).

The catch is essentially composed of bluefin tuna : Thunnus thynnus. The by-catch isrepresented by bullet tuna: Auxis sp, skipjack tuna : Katsowonus pelamis and swordfish :Xiphias gladius.

The geographical situation of the Moroccan trap-nets is illustrated in (Fig. 2.5)

Description of the gear and the fishing technique: The trap-net is a trap gear, anchored in afixed place when the migration of bluefin tuna takes place. It is generally drawn from thesurface to depths ranging from 20 to 100 m. It is composed by a net barrier going from thecoast to out to sea along several kilometres and also by a succession of nets allowing topoison the fish and lead it to the last siege called « chamber of death » or « Copo ». In thecase of Moroccan trap-nets, there are three chambers called «Camara », «Buchet » and«Copo ». The diametre of the mesh varies according to the different parts of the trap-net.The mesh size for the land net is about 90 cm and the size decreases progressively until it is20 cm in the «Copo ».


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2.3 FISHING ROD : vessels, areas and fishing period.

This is a novel bluefin tuna fishery in the region of the Straits of Gibraltar. It has becomemore and more important since 1994. Fishing is distributed in four sites : Ksar sghir, OuedR’mel, Diky and Ferdiwa, holding 114 vessels . Most of these vessels are wood boats, witha gross storage tonnage of 2 Tx (Fig. 2.6). They are equipped with a diesel motor on board.The fishing period normally goes from April to October.

Description of the gear and the fishing technique : The fishing gear used for the small-scalefishery of bluefin tuna is the line fishing, a fishing rod (HAND) containing more than onebait without exceeding 5 baits on the whole. The thread used is number 240 (2.4 mmdiameter), and it is 1000 m long. Baits are great-sized (reference 0 or 1). The ballast of thegear is assured by big stones weakly attached to the thread so that they get loose easlilywhen a tuna is captured.

The most commonly used bait is the mackerel. Depending the size of the mackerel, one ortwo pieces are used per bait.

The fishing operation consists of a series of manual liftings and descents of the fishing gearrelatively fast so that it appears that the bait is alive. When a tuna is captured, the boat istrawled far from the fishing areas. The fished tuna gives up after a fight that can last from 3to 5 hours. Big tuna pieces are towed by the boat. The haul is generally short and does notexceed 7 hours.

The fishery of bluefin tuna is carried out in deep areas (between 300 and 500 m). Theseareas are located at a distance of 3 to 5 km from the coast.

Figure 2.5 Geographical situation of the bluefin tuna fishing areas in MediterraneanMorocco


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TJB

6%

58%

36%

<1Tx 1-1,5Tx 1,5-2Tx

CV

93%

4%3%

<15 15-20 >20

Figure 2.6 : Characteristics of the small-scale flotilla fishing the bluefin tuna with fishingrod in the Mediterranean (Ksar Sghir) (1999)


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ESPANA (IEO)

Objetivo 2.2

BLUEFIN TUNA,Thunnus thynnus

Hand line

Bluefin tuna is captured by hand line (HAND- ICCAT code) from April to the end of theyear in relatively coastal areas (20 miles) in the South Mediterranean, Valencia andCatalonia. All these zones, characterised by bottom elevations (100 meters depth), are areasof bluefin congregations with a FL of 120-235 cm. There are two fishing seasons, Springand Autumn, called "from straight" and "back", respectively. The gear has a nylonmonofilament main line with a section of 180-200 mm and with n° 17 curved hook(Japanese type), baited with mackerel ( Scomber sp.) or sardine. Fishing can be done byhand or with the help of a manual brake. The fleet which pursue this type of fishing is veryheterogeneous, and is currently composed of 189 boats with the following meancharacteristics: 12.38 TRB, 87.35 HP and 8.71 m of length. Figure 2.7.

Gear description and fishing technology:

It is an artisanal gear composed of a hand-held line with weighted end and nº 0/1 or 1 hookof Japanese type (curved hook). Fishing by hand line is carried out by several artisanalboats from August to October. Main fishing grounds are those at Roquetas and the Strait ofGibraltar. This fishing modality was recently implemented in Estepona.

A hook baited with Scomber scombrus or Sardinela aurita is attached to a line of about 10-20 fathoms in length which, in turn, is attached to a main line of about 500 m in length. Thegear, once rolled, is stored in wooden boxes.

Currently fishing strategies involve double rigging, though sometimes three or four linesare employed by using buoys or auxiliary skiff. Two baited lines are shot close to tunafeeding grounds or secos (sea bottom plates). Each line is attached to a buoy or to thefishing boat and dead bait is thrown from the boat –brumeo-, in order to attract tuna. Oncehooked, tuna is brought onboard by means of a hand-held harpoon and a pulley. Figure 2.8.


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TRB

8%

67%

14%8% 3%

SIN DATO < 10 10-20 20-50 > 50

ESLORA

8%

58%

32%2%

SIN DATO < 10 10-20 >20

CV

8%

31%

40%

11%10%

SIN DATO < 50 50-100 100-150 >150

Figure 2.7 . Fleet of Hand Line (Mediterranean)


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Figure 2.8.- Bluefin tuna fishing by hand line. “Al Brumeo”.

Falseta


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Purse seine

Bluefin tuna fishing by purse seine is effected from April to October between 42° N- 38° Nlatitude and from the coast through 05° E longitude. The fleet is composed of 6 boatswhose mean characteristics are: 101.89 TRB, 792 HP and 26.79 m length. Figure 2.9

The net is 1400 m long and 180-200 m high. It is a large single-panel multi-sectioned net,mounted to a float rope and a foot rope. The foot rope has a steel wire running through thepursing rings by means of which the bottom of the net is closed. Figure 2.9 bis

TRB

14%

43%

43%

< 50 50-100 >100

ESLORA

14%

29%57%

< 250 250-500 > 500

CV

43%

57%

< 25 > 25

Figure 2.9 Fleet of Purse seine


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Figure 2.9 bis Purse seine


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Surface long-line

Bluefin tuna is a by-catch species on the surface long-lines for swordfish. Nevertheless,during May, June and July, there are some boats which, in the Balearic areas, target part oftheir effort on bluefin tuna catches. They introduce several modifications on their gear:bigger lines, bigger distance between ganging and number 17 curved hooks (Japanese type)baited with squid.

Traps

After reproduction in the Mediterranean, the bluefin tuna migrates (trophic migration)through the Atlantic. It is captured by traps which are located on both sides of the Strait ofGibraltar (Ceuta and La Linea). A traps is made up of a staked net comprising a leader net"rabera de fuera" which drives the fish through the cod end. Bluefin captured in July andAugust with this gear weight about 150 kg. In the last few years they are driven to fatteningpools.

Operative units, fishing area and fishing season.

As regards fishing by traps, two main areas can be characterized. Four traps (Conil,Barbate, Zahara and Tarifa; Figure 2.10) are located in the southern Atlantic area. All thesetraps target bluefin tuna and tuna like species during their genetic migration towardsspawning grounds (fase de derecho). Only traps located in Barbate and Ceuta catch tunaduring feeding migration (fase de revés). As regards traps in the Mediterranean Sea, onlythe one in Ceuta fishes bluefin tuna (Figure 2.10).


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Figure 2.10.- Traps location.

Fishing season during genetic migration (fase de derecho) lasts from April to June. Asregards feeding migration (fase de revés), fishing season lasts from July to October.Catches are mainly composed of bluefin tuna and, to a lesser extent, swordfish and smalltuna.

Gear description and fishing technology.

It is a fixed gear that intercepts bluefin tuna and tuna like when swimming towardsspawning grounds (derecho) or feeding grounds (revés). These traps are set out along thesouthern and eastern Spanish coast and northern African coast. Figures 2.11 and 2.12show a schematic drawing of a trap.

A buche type trap is composed of a large net, named leader, open at the surface and severalenclosures (raberas) and provided with various types of fish retaining devices which formthe cuadro.


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The rabera de tierra or kettle net is about one mile in length and actual mesh size of about60 cm. It is lowered into the water perpendicularly to the coast, where it is anchored.

The cuadro, rectangular in shape, is set up parallel to the coast. It is about 205 m in lengthand 50 m in width, with the bag net (copo) of about 30 m wide. The entrance is providedwith two retaining nets, endiches, which facilitate fish coming into the trap and avoidingfish going out. The aforementioned endiches are kept tense by means of steel ropes orcabestros.

The cuadro can have three or four enclosures which, for the first case, are: cámara, bucheand copo.

The cámara and buche are divided by the mojarcio, steel rope extending through thesurface and with smaller ropes, colinas, hanging down from it. These colinas are attachedto the mojarcio door, a net at the bottom, used to concentrate tuna and to avoid tuna goingback to the cámara.

If the cuadro is composed of four enclosures, another net, the bordonal, is set up betweenthe buche and the copo. Its characteristics and function are similar to those of the mojarcio.

Mesh size for every enclosure belonging to the cuadro is about 30 cm, except for the copowhich shows progressively decreasing mesh size: 12 cm as regards the safina clara, 8- 10cm for the safina espesa and 6- 8 cm at the matador.

The rabera de fuera is set up towards the sea. It is smaller than the rabera de tierra,attached to the cuadro by means of the legítima and contralegítima. It is L in shape andmesh size is similar to the rabera de tierra.

Each surface net is provided with a float rope and anchored by means of ropes of aboutthree times in length the bottom depth. As regards the foot rope, it is made of lead, stone oriron-chain attached along the lower edge of the net, so maintaining ground contact.

Net height is higher than bottom depth for a percentage depending on tides and currents,sometimes reaching up to 30%.

Netting ballast, floating response and depth are closely related to each other.

Bluefin tuna and tuna like species do not pass through the raberas, they swim along the netand reach the entrance of the cuadro. Those tuna not entering the cuadro are collected bythe legítima and contralegítima and sent back to the palmatorres, piece of netting near theentrance of the cuadro. As regards tuna swimming in the opposite direction to the entranceof the cuadro, they are intercepted by the rabera de fuera.

When there are a sufficient number of fishes inside the cuadro, they are driven to the copoand the door is lifted. In order to avoid tuna going out, several pieces of netting triangular


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in shape, (blancas), are set. Once the assistant vessels are ready, the net at the bottom of thecopo is lifted and the matanza starts. Fishermen, by means of hooks, bring fish on board.

Two kinds of traps can be characterized regarding its location: ida or de derecho, targetingbluefin tuna during migration towards spawning grounds, and de retorno or revés, thattargets bluefin tuna during feeding migration.

Figure 2.11.- Trap schematic drawing.

TRAPS CHARACTERISTICS. SOUTHERN ATLANTIC AREA.

TRAP LATITUDE LONGITUDE DISTANCE FROM COAST DEPTH

Nº 1 36º 02’ 00’’ N 05º 37’ 00’’ W 0.50’ 48 mNº 2 36º 07’ 00’’ N 05º 51’ 00’’ W 1.00’ 45- 50 mNº 3 36º 09’ 00’’ N 05º 55’ 00’’ W 2.45’ 50 mNº 4 36º 17’ 00’’ N 06º 16’ 00’’ W 5.90’ 50 m


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Figure 2.12.- Trap de derecho (spawning grounds)


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Baitboat

This type of fishing is carried out during the Autumn season. The number of boats, fromthe North of Spain, is varies depending on the years (Fig 2.13). The areas for this gear arelocated in the Northern side of the Balearic Islands and the Alboran Sea (there, the targetedspecies is albacore). Lines are baited with Trachurus sp. and Engraulis encrasicholus. Baitis captured with purse seine and kept alive on board. The pole-lines and hooks used are ofseveral sizes, depending on the length of the bluefin tuna.


Trolling Boat

This fishing modality, targeting bluefin tuna and albacore, is carried out by four vesselsfrom Algeciras, one from Tarifa and several from the Cantabrian Sea. Hooks are baitedwith live bait: Trachurus spp, Sardina spp and Sardinella spp.

Bait is maintained alive by on board fishponds, each fitted with artificial light and pumpsfor water oxygenation.

Poles, currently made of wood, are of varying length. The line attached on the end of thepole is about one meter longer than the pole. Usually, pole- lines are attached to the deck bymeans of a which facilitate the pole movement when bringing the hooked fish on board.

Smaller poles, Bambas, are not attached to the deck. They are about 1.5 m in length andbaited with live bait. They are used to keep tuna near the vessel.

Live bait fishing is carried out by means of a small purse seine. Later, once the fishpond,

vessels go to fishing grounds where bluefin tuna or albacore shoals are detected by sonar.

Fishing consists essentially in throwing bait in order to attract tuna . Each fishermanoperating a pole has access to a small fishpond, constantly supplied by other fishermen. Atthe same time, water is thrown from the deck in order to mimic the presence of a hugeshoal of potential preys and to distort sea surface layer, hence avoiding tuna trying to scape.

If no tuna shoal is detected, four lines fitted with nº 5/0 hook and baited with dead bait arethrown to the sea, waiting for tuna. This fishing modality is named Machucha.


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TRB

10%

56%

34%

< 100 100-125 > 125

CV

45%

48%

7%

< 100 100-125 > 125

ESLORA

25%

47%

28%

< 100 100-125 > 125

Fig 2.13 . Fleet of Baitboad (Algeciras)


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SWORDFISH, Xiphias gladius

Surface long-line

Swordfish is targeted by surface long-line all year round. Nevertheless, maximum activityoccurs during the summer and autumn months. The fishing area comprises the Spanishcoast to 42° N latitude and 07° E longitude. The fleet comprises 145 boats which meancharacteristics are: 24.95 TRB, 144.9 HP and 11.27 m length, based in Andalucia, Murciaand the Balearic Islands. Most of them practice this kind of fishing with temporary licences.Figure 2.14

The standard gear is made up of a nylon and plastic multifilament main line of 2.5-3 mmsection. Branches lines are connected to the main line with a distance between branches ofabout one fathom. Branches lines have a 1.60 and 1.80 mm section and a 7-10 fathomlength with 1 hook. Near the surface the main line is supported by buoys which have brightsignals and reflectors for location. Mean gear length is about 30 km ( actually up to 60 kmis allowed ). Mean number of hooks is between 1000 and 2000 per fishing operation.Hooks are baited with Sardinela aurita and Scomber spp.


As regards the long line fleet fishing in the Mediterranean Sea, no standard gear can becharacterized. Gear characteristics mainly depend on the vessel homing port as well asvessel carrying capacity. Fitting accessories may differ between vessels.

Gear is composed of a main line, made of nylon or plastic, set parallel to the sea surfaceand with branch lines hanging down from it. These branch lines are attached to the shank ofthe hook by means of a thin line.

Each gear is composed of a variable number of longlines, which have three lines connectedby floats. Lines are 100 m in length, each bearing 4 or 5 branch lines about 12- 17 fathomsfrom each other. The branch lines are attached to nº 1 hooks by means of thin lines ofvarying length.

As previously reported, mean characteristics are just for guiding purposes since no longlinecan be defined as a standard for the fleet fishing in the Mediterranean Sea.

Main line is made of nylon and plastic, with cross section ranging from 2.25 to 3 mm. Forbranch lines, material and size are similar to the main line. Thin lines for attaching hookshave varying cross section, ranging from 170 to 180 mm. Sometimes reaching 150- 160mm in cross section (140 mm as regards the artisanal fleet).

Currently employed buoys are bottles and/or plastic balls. In order gears may be located byvessels, buoys are fitted with transmitters. From two years onward, using thermometer has


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become a common practice among fishermen. Currently employed bait is Scomber spp andSardinella aurita.

Gear total length depends on the number of hooks to be set, which in turn depends on thevessel characteristics such as carrying capacity, number of fishermen, fishing season,fishing strategy and environmental factors. On the average, 90- 115 longlines (1000- 1300hooks) are set during winter and 130- 160 longlines (1500-2000 hooks) in summer andautumn.

The following table shows longline characteristics, material and length, for the gear used inthe Alborán Sea and Strait of Gibraltar:

Swordfish Surface longline in the Mediterranean Sea. Material and Length.

ITEM ALGECIRAS MOTRIL

3- 3.25 mm 2.5- 3 mmLength 60 km 50 km

Main lineMaterial Plastic

65 % nylon and 35% plastic

Length 1- 3 fathoms 1- 2 fathomsBranchesDistance 15- 17 fathoms 12- 15 fathoms

160-180 mm 150- 170 mmLines

Length 5- 10 fathoms 5- 7 fathoms

HookNº 1/0 and nº 1

1800- 2000Nº 1 and nº 21200- 2000

Gear is let down by nightfall and turned at daybreak by using a winch.

Figure 2.15 shows the scheme for drift long line targeting swordfish.


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TRB

10%

34%

26%

22%8%

SIN DATO < 10 10-20 20-50 > 50

ESLORA

11%

30%55%

4%

SIN DATO < 10 10-20 > 20

CV

9%16%

20%24%

31%

SIN DATO < 50 50-100 100-150 >150

Figure 2.14 Fleet of Surface long line (Mediterranean)


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Figure 2.15.- Surface long line scheme.


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HAND

PS

ESPAÑA

44

43

42

41

40

39

38

37

36

35

44

43

42

41

40

39

38

37

36

35

543210123456789

543210123456789

LL

SURF

BB

TRAP

IV -XIV -X

V -VIII

VI - IX

VII - XI

IV-VI

VII

V - VIX-XI

VII-VIII

X-XI

Figure 2.16. _______ (mapa españa)


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TUNISIA (INSTM)

Objective 2.3

DESCRIPTION OF FISHERIES OF GREAT PELAGICS IN TUNISIAN WATERS

1- INTRODUCTION

The family of Scombridae is without any doubt the most important one in the Tunisiancoast. We mention particularly bluefin tuna (Thunnus thynnus), little tuna (Euthynnusalletteratus), pelamid (Sarda sarda) and bullet tuna (Auxis rochei). The two former providea local industry, as a great amount of this fish is sold for canning. Bluefin tuna andswordfish constitute preferential species for the export market. These products are mainlyaddressed to Japan and several European countries.

The fishing gear used for their capture varies substantially and has gone throughenhancements according technological progress.

In this document, we intend to provide an exhaustive view of the fishing of great pelagicsand to review the gear used in Tunisian waters for the caputre of this fish, which are netsand the floating longline.

The applicable texts in terms of fishing policy in Tunisia contemplate four categories ofnets:

- Gillnets; which take the aquatic animals captured in their nets. They can bedivided into:

*fixed nets, which remain on the bottom and are not moved once drawn, forinstance trap-netting for tunas.*floating nets, which are immersed or kept near the surface and move underthe effect of the wind and the currents, for example drift gillnets or“mernine”.

- Surrounding or encircling nets are those which, without touching the bottom,capture the aquatic species by circling them, for example the purse seine.- Benthic trawling nets are those trawled to the bottom regardless of the route andthe way of towing, for example trawl and "tartarone" .- Pelagic trawling nets, are those immersed and trawled without ever touching thebottom, for example in pelagic trawling.

2- DRIFT GILLNETS

In this group, we can distinguish the gillnets formed by a single netting and the trammels,formed by three nettings. The gillnet can be adrift on surface or near the bottom, or drawnin the middle of the water or on the bottom.


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The drift gillnet (Mernine) is used along some Tunisian coasts, especially during thegenetic concentration of small tuna, such as the little tuna, the bullet tuna and the pelamid.It is a seasonal fishery.

The nets, which do not usually exceed 1000 metres are generally set up at night, so thatcatch can be gathered early in the morning; twilight and sun rising are the ideal momentsfor good catch. These nets are set up in the direction of the wind and are adrift by thevessel. This barrier is invisible at night for aquatic animals in general, and for tuna shoals inparticular (Euthynnus, Auxis, Sarda, Orcynopsis). Some of the pieces in the first line arecaptured and the rest turn back out to sea. (personal communication).

The performance of this gear is very unstable; it depends upon the effect of luck and alsoupon the passage of fish and their density. In fact, a 1000 metres long net set up on the wayof a fish shoal only captures a minimal fraction of it (1/20, according to the estimations ofprofessional fishers).

Gillnet fishing and drift gillnet are banned:- in the areas comprised between the Parallel of Borj Kélibia and the border betweenTunisia and Libanon.- in the area comprised between the Parallel of Borj Kélibia and the border betweenTunisia and Algeria at a distance not exceeding ten miles from the base lines ofTunisian territorial waters. However, according to an order by the Prime Ministerregulating fishery in Tunisia published in October 1995, the use of gillnet has beenallowed in Tunisian waters. In compliance with EEC and FAO regulations, thelength of these nets cannot exceed 2500 metres.

However, the mentionned order does not fix their drop. The minimum mesh size is 30 mm.Regulations are on course in order to ban completely this fishing gear from the year 2000on.

3-SURROUNDING OR ENCIRCLING NETS

Currently, around 70 seiner tuna fishing boats are dedicated to the tuna fishing along theTunisian coasts (DGPA, 1998).

These tuna fishing boats were introduced in 1976. Their hulls are mainly on wood with alength ranging from 15 to 38 metres and have a storage capacity ranging from 17.98 to 298tones; their crew is composed by ten people; the power of their diesel engines varies from110 to 999 hp; they can reach more than 12 knots at full speed. The distribution of thisflotilla by ports is shown in table 2.1.


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Table. 2.1 : Distribution by ports of Tunisian purse seiner tuna fishing boats

Port Vessels Length Storage PowerBizerte 1 24,75 99,9 500La Goulette 4 21,5-22,56 63-71,75 420-720Nabeul 1 19,5 64,16 400Sousse 1 16,6 28,9 177Monastir 7 15,05-26 17,98-119 220-260Mahdia 6 20-25,4 50-130,9 350-630Sfax 38 16-38 20-298,1 110-999Gabès 9 16-23 22-69 250-450Houmt Souk 2 22-24 87-98 430-650Tunise 69 15,05-38 17,98-298,1 177-999


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Figure 2.17- Purse seiner tuna fishing boat


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Tuna fishing boats are known, firstly by the importance of the back deck for the loading ofnets with an hydraulic crane. This crane is furnished with a multi-articulated and telescopicarm that can be oriented. At the extremity of the arm, a power block motor pulley isinstalled. Secondly, the gangway, set on an advanced position, is suspended by a fishingdeck with a vigilance post, allowing the localization at sight of tuna on surface or jumpinglittle tuna.

a- The resources of purse seine fishing

Although it is true that the statistic data of halieutic national catch are calculated accordingfishers, the fact is that it is extremely difficult to evaluate the current state of theexploitation of the resources taken by purse seiners. This is due to several reasons and ouraim is to find solutions for them.:

- Lack of data concerning the fishing effort (number of sea days)- Identification of specific captures- Difficulty for delimiting the areas frequented by these vessels.

We aim at solving these gaps by organizing meetings dealing generally with the fishery ofgreat pelagic species with the support of the administration and the backing of fishers inorder to raise public awareness. A statistical leaflet is given out in the beginning of eachcampaign to ship owners or fishing skippers.

4- FIXED NETS: TRAP-NETS

The word “trap-net” ("madrague" in French) has multiple etymologies: according toGOURRET (in DIEUZEIDE and NOVELLA, 1953), it comes from the Greek mandra,which means enclosure or fold and from the Latin aqua, which means water. The real namewould then be "mandrague", which has evolved to "madrague" with the time.

In Spanish “trap-net” is literally translated by “almadraba”, which denotes its Arabic origin.It is obvious that from all linguistic approaches, we can observe the use of this fixed fishinggear by the coastal peoples that have succeeded in the Mediterranean.

In Tunisia, tuna fishing has been practiced nearly since the beginning of times. It wasintroduced by the Phoenicians; the Arabs of the 7th century neglected it for a long time

(PLUSQUELLEC, 1956). From the 19th century this gear has experimented a rebirth. Infact we can situate around 1820 the first exploitations of


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Figure 2.18- Diagram of trap-netting in Sidi Daoud


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Tunisian tuna fishing boats in Sidi Daoud, Cap Zebib and Monastir. Then, for a century anda half it became a purely Italian industry and eventually the trap-nets were granted todifferent concessionaires. In the beginning of the century, the number of operational tunafishing boats was ten, without counting three other trap-nets granted in 1906 to Ras Salakta,at the outside of Menzel Temime and in the north of Mahdia, which did not seem to beexploited. These trap-nets were: Cap Zebib, in the east of Bizerte, Sidi Daoud, Ras ElAhmar, El Haouaria, Ras El Mihr, Ras Marsa, Monastir, Conigliera, Kuriat, Borj Khédija(not far from La Chebba). Today, only two trap-nets are exploited by l'Office National desPêches (ONP; National Fishery Office); that of Sidi Daoud and that of Monastir (Kuriatisland).

4-1- Conception

DIEUZEIDE and NOVELLA, 1953, defined the trap-net as follows : We borrow adefinition by DIEUZEIDE et NOVELLA, 1953 "If one does not take into account all itsaccessories –multiple and varied- the trap-net, generally speaking, looks like a massive boxwithout bottom or cover. The upper part appears on the surface of the sea level and thelower part adapts to the surface of the seabed. The sides are formed by vertical nets… Thiscover, which can be up to some one hundred metres long, is divided by transversal netsplaced vertically in a certain number of compartments and chambers with different namesin which the tuna is retained”.

GOURRET in DIEUZEIDE and NOVELLA, 1953 provided the following definition:“massive cover of net in which travelling fish are skillfully lead to where they cannotescape once they are hooked”.

Trap-nets, like all fixed nets, are composed by a main netting, a dam net and an enclosurenet. The enclosure net is composed by chambers; the last one of them is known as “corpo”or “death chamber” and it is disposed as a huge landing net. The operation consists ofputting into practice the principles obtained from millenary verifications about the directionof displacements, which are always made in parallel to the side, generally below 35 mdepth. In other words; to install net dams on the way of tuna shoals when they aremigrating (to or back); the extreme closest to land goes from the shore in direction out tosea up to the trap-net body and the opposite extreme goes from the trap-net to out to sea.The tuna finds the obstacle, tries to avoid it and gets hooked in the chambers. The fisherserect the dams, circle the fish and lead it towards the chamber of death. When all the fishare supposed to be reunited in the last chamber, the upper bolt-rope of the net is lifted, andthen fixed to the gunwales of the barge. Then the net is erected. Four vessels with twentymen on board of each lift slowly the bottom of the net and move it slowly towards thebarge. “Once the bottom is almost on surface, the tuna, feeling the breath shortage, arevictim of a mad panic and collide, splashing water and blood all over.” The rest of thisoperation, called “Matanza” consists of loading, manually or with the aid of hooks, thecaptured fish on board of one of the vessels.


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Figure 2.19- Joint plan of the land and sea installations of the tuna fishing boat in SidiDaoud (scale 1/25,000).


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Figure 2.20 Situation of Tunisian trap-nets (only the trap-nets in Sidi Daoud andMonastir are still active)


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5-3- Legislation

There are several special dispositions regarding tuna fishing boats detailed in the applicabletexts of the Tunisian fishery policy. We summarize them hereafter:

- The drawing period of each trap-net is fixed by means of an authorization.- Resulting from the demand presented every year before the 1st March by theconcessionaire, the Agriculture Minister fixes a trap-netting area, the limits of whichextend at least 4000 metres upstream and 1000 metres downstream from the pointwhere the land extreme and the trap-net body meet.- The advanced extremity of the trap-net body will be signaled night and day in themiddle of a vessel with deck and a 5 m height mast. Each boat will show twoballoons in the daytime; the upper one will be white and the other one will be red.The vessel with deck can be replaced by a buoy showing the following signals:

Trap-net in kuriat (Monastir)Coordinates: L = 35° 47' 50'' N.G. = 11° 01' 30'' EOrientation of the arm 352°Length of the arm 7550 metresExtremity signaled with a cylindrical buoy in horizontal black-and-white stripes.Cardinal buoy North

White light in the dark, period of 6 seconds, range of 8 miles.Position L : 35° 41' 15'' NG 11° 00' 56'' E.

Trap-net de Sidi DaoudCoordinates: L = 35° 01' 33'' N.G. = 10° 53' 32'' EOrientation of the arm 300°Length of the arm 4500 metresExtremity signaled by a vessel carrying two balloons, one over the other, 0.5 mdiameter and at a distance of 2 metres from each other. The upper balloon will bewhite, the lower balloon will be red.


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5- FLOATING LONGLINE

Nowadays, 40 vessels operate in Tunisian waters. The greatest part of the effort isconcentrated along the north coast of Tunisia. The two ports known by the landing ofswordfish are Tabarka and Bizerte. However, in 1998 two other cities have gainedimportance in terms of landing. These cities are Teboulba and Mahdia. The landings inthese two ports have reached 40% of the national catch, which varies between 200 and 400tones.

Tabl. 2.2- Distribution of Tunisian longliners targeting swordfish fishingPort Unités (m) Gauge (t) Power (hp)

Tabarka 9 10-13 8-16 45-115Bizerte 13 10,7-16,7 7-20,3 50-220La Goulette 4 10-15 10-18 60-110Nabeul 12 10,7-16 9,1-21 45-115Sousse 2 10,5-12 8,8-11 77-94Monastir 2 12 11,4-13 87-94Total 42 10-16,7 7-20,3 45-115

Longline is a Japanese tecnnique which has been successful in Japan.It needs very few sailors for its manouvers and the expenses for its maintenance are low.

This technique is spreading more and more along our coasts and it is used the whole year.

5-1- Conception

The longline is the fishing gear for the capture of swordfish and is composed by severalunits; each unit has a principal rod, to which some branches are attached. At the extremityof each unit there is a float. The extremities of the whole longline are marked by a float atthe beginning and a signal (ensign) at the end.

The main rod is a braided textile thread, with a diametre of 6 millimetres. Its lengthdepends upon the number of coupled units.

Each branch is composed of three parts:

- the two first parts are 10 metres long threads which have a diametre ranging from 4 to 5milimetres. They are attached one after the other and the second thread has a ballast.


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Figure 2.21- Floating longline


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- the last part is a steel cable between 2 and 3 metres long which ends in a bait number zero.

The floats are made of plastic. They are yellow and spherical, with a diametre of 500milimetres.

The signal is composed by a wooden stem, betwen 4 and 5 metres long. It has a red ensignin the upper extremity; two floats are attached to the stem at 3.5 metres of the upperextremity, in order to assure that the signal floats; a ballast with a weight of 6 to 7 Kg isattached to the lower part, in order to assure the vertical position of the signal in the water.

5-2- Legislation

There are no particular national orders regulating this fishing gear except for therecommendation of the CICTA adopted by Tunisia in the capacity of contracting country.This recommendation deals with the fishing in the Mediterranean during the months ofspawn. In this recommendation, the CICTA bans the fishing of bluefin tuna in thementioned area during the period from the 1st of June to the 31st of July with great pelagiclongliners longer than 24 metres.


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Figure 2.22 Approximate fishing areas of great pelagics according to the surveys carriedout to fishers.

Pêche authonidés

Pêche àl’espadon


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6-BIBLIOGRAPHY (Studies and publications of Tunisian tuna)

BELLOC, G., (1954)- Les thons de la Méditerranée. Cons. Gén. Pêche Méditer., Deb.Doc. Techn., N°2.BELLOC, G., (1961)- Inventaire des madragues méditerranéennes Coun., 6: 345-3712 (2) : 103-120BEN OTHMAN, S., (1971a)- Etude préliminaire sur l'ichtyologie du sud tunisien . Rapp.Comm. Int. Mer Méd. 20 (3) : 443-444BOURGE , (1908)- Les pêches maritimes de la Tunisie (TunisBOURGE , (1909)- La pêche au thon en Tunisie ; Bulletin trimestriel de la sociétéd’endseignement professionnel et Techniques des Pêches maritimes ;BOURGE , (1914)- Les pêches maritimes de la Tunisie. (6éme congrès nation. Des pêchesmarit., tenu à Tunis, Paris)BRANDHORST, W., (1977)- Les conditions du milieu au large de la côte tunisienne. Bull.Inst. Nat. Scient. Tech. Océanogr. Pêche Salammbô, 4 - (2-4) : 129-220, ill.GRUVEL, A., (1926)- L'industrie des pêches sur les côtes tunisiennes. Bull. Stn.Océanogr. Salammbô, n° 4 : 1 - 135; fig. 19 pl.DE FAGES, E et C.PONZEVERA.-(1908)- Les pêches maritimes de la Tunisie, 2émeédition. Mise au point par M. Bourge, Inspecteur de la navigation et des pêches, J.Picardet Cie, TunisDIRECTION DES TRAVAUX PUBLICS, 1932- Tableaux statisitiques (1931), Stat.Océanog. Salammbô, Pêches maritimes , Bull. N°28.DIRECTION DES TRAVAUX PUBLICS, 1933- Tableaux statisitiques (1932), Stat.Océanog. Salammbô, Pêches maritimes, Bull. N°31.DIRECTION DES TRAVAUX PUBLICS, 1934- Tableaux statisitiques (1933), Stat.Océanog. Salammbô, Pêches maritimes, Bull. N°33.DIRECTION DES TRAVAUX PUBLICS, 1935- Tableaux statisitiques (1934), Stat.Océanog. Salammbô, Pêches maritimes, Bull. N°35.DIRECTION DES TRAVAUX PUBLICS, 1937- Tableaux statisitiques (1935), Stat.Océanog. Salammbô, Pêches maritimes , Bull. N°36.DIRECTION DES TRAVAUX PUBLICS, - Tableaux statisitiques (1936), Stat.Océanog. Salammbô, Pêches maritimes , Bull. N°37.DIRECTION DES TRAVAUX PUBLICS, - Tableaux statisitiques (1937), Stat.Océanog. Salammbô, Pêches maritimes , Bull. N°38.HATTOUR A.,1979- Contribution à l’étude des scombridés des eaux tunisiennes). DEABiologie Marine et Océanographie, Universtité de Tunis .Faculté des Sciences. 1-168.HATTOUR, A., (1984)- Analyse de l'âge, de la croissance et des captures des thons rouges(Thunnus thynnus) et des thonines (Euthynnus alletteratus) pêchés dans les eauxtunisiennes Bull. Inst. Nat. Scient. Tech. Oceanogr. Salammbô, 11: 5-39.HATTOUR, A., (1994a)- La pêche au thon rouge (Thunnus thynnus) à la madrague de SidiDaoud ICCAT, Rec. Doc.Sci. :(SCRS/ 94/105).


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HATTOUR, A., (1994b)- La pêche aux thons en Tunisie: Analyse démographique du thonrouge (Thunnus thynnus) et de la thonine (Euthynnus alletteratus) capturés par lesmadragues tunisiennes. ICCAT, Rec. Doc.Sci. : (SCRS/ 94/108).HATTOUR, A. (1995)- La pêche de l'espadon (Xiphias gladius) en Tunisie : Analysepréliminaire de la relation taille poids, GFCM-ICCAT-SCRS 95/9HATTOUR, A. (1998)- Capture des grands pélagiques dans les eaux tunisiennes :correction à apporter aux anciennes données déclarées . GFCM-ICCAT-SCRS 98/94HELDT, H., (1926)- Résumé de nos connaissances actuelles sur le thon rouge Thunnusthynnus (L). Bull. Stn. Océanogr. Salammbô, 5 : 1 - 44.HELDT, H., (1927a)- Le thon rouge Thunnus thynnus (L) mise à jour de nosconnaissances sur ce sujet. Bull. Stn. Océanogr. Salammbô, 7 : 1 - 24.HELDT, H., (1927b)- Contribution à l'étude des races de thons (Thunnus thynnus l).Caractères biométriques du thon tunisien et considération sur sa croissance. Ann. Stn.Océanogr. Salammbô, IV : 1 - 54HELDT, H., (1928a)- Le thon rouge (Thunnus thynnus L). Progrès des recherches sur laquestion. Bull. Stn. Océanogr. Salammbô, 9 : 1 - 37HELDT, H., (1928b)- Pelamys Bonaparte (Verany 1846). Fiche éditée par laComm.Intern. Expl. Scient. Mer Médit.HELDT, H., (1929). Le thon rouge (Thunnus thynnus L). Examen des travaux publiés(1928). Observations nouvelles. Bull. Stn. Océanogr. Salammbô, 13 : 1 - 26HELDT, H., (1930)- Le thon rouge et sa pêche (Thunnus thynnus L). Nouveaux aspects dela question. Bull. Stn. Océanogr. Salammbô, 18 : 1- 69.HELDT, H., (1931)- Le thon rouge et sa oêche. Eléments d'un nouveau rapport.Bibliographie du sujet. Bull. Stn. Océanogr. Salammbô, 21 : 1 - 165HELDT, H., (1932)- Le thon rouge et sa pêche. Rapport pour 1931. Bull. Stn. Océanogr.Salammbô, 29 : 1 - 168.HELDT, H., (1932)- Repérage des bancs de thons par avion. Application à la pêche. Etudedes migrations.. Bull. Stn. Océanogr. Salammbô, 26.HELDT, H., (1943)- Etude sur le thon, la daurade et les muges. Histoires d’écailles etd’hameçon. Broch. Stn. Ocèanogr. Salammbô, n° 1 : 48p.HELDT, H., (1953)- Les migrations des poissons. Bull. Soc. Sc. Nat. Tunisie, 6 (1-4) : 113- 122.PLUSQUELLEC, PH., (1956)- Les madragues de Tunisie. Pêche maritime, 942 : 385 -389.POSTEL, E., (1956 c)- Les affinités tropicales de la faune ichthyologiques du golfe deGabès. Bull. Stn. Océanogr. Pêche Salammbô, 53 : 64 - 68.POSTEL, E., (1956a)- Note succinite sur quelques espadons tunisiens. Bull. Mus. Nat.Hist. 2ème série, 28 (6) : 509 - 511.POSTEL, E., (1956b)- Données biométriques sur quelques scombridés tunisiens. Bull. Stn.Océanogr. Pêche Salammbô, 53 : 50 - 63.POSTEL, E., (1962)- Les thonidésd'Afrique du Nord. Bull. Inst. Pêche marit. Maroc., 20(3): 17-22.ROULE, L., (1914)- Etude préliminaire sur la biologie et la pêche du thon commun(Orcynus thunnus L.) dans la Méditerranée occidentale ; Vième congrès de Pêche à Paris


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ROULE, L., (1916)- Sur la migration et la pêche du thon (Orcynus thynnus L.) sur noscôtes méditerranéennes; Comptes rendus de l'Académie des Sciences, t. 163, Paris.ROULE, L., (1916a)- Observations sur la sténothermie du thon commun. C. R. de la Soc.de Biologie, t. 79.ROULE, L., (1917)- Etude sur les aires de ponte et les déplacements périodiques du thoncommun (Orcynus thynnuqs L.) dans la Méditerranée occidentale ; Annales de l’InstitutOcéanographique, VII, 7, ParisROULE, L., (1924)- Etude sur les déplacements et la pêche du thon (Orcynus thynnus L)en Tunisie et dans la Méditerranée occidentale. Bull. Stn. Océanogr. Salammbô, 2 : 1 - 39.ROULE, L., (1926)- Etude complémentaire sur le thon de la Tunisie. Annale. Stn.Océanogr. Salammbô, 2 : 1 - 16.VINCIGUERRA, D., (1884)- Materiali per la studio della fauna tunisina raccolti da G etL. Doria. 1 . Pesci. Ann. Mus. Civ. Star. Natur. Genova, t. 20 : 393-445


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MALTA (NAC)

Objetive 2.4

Fisheries Desciption

2. Bluefin Tuna Fishery Background in the Maltese Islands

Bluefin tuna (Thunnus thynnus) fishing season in Malta starts during the month of May andextends until the month of July.

Fishing for bluefin tuna has been undertaken by Maltese fishermen for a very long time.Statistics kept at the Department of Fisheries show that as early as 1920 a substantialamount of tuna was already being landed regularly during the season. However althoughthis trend continued for a long period, the limitations of the local market and the lack offacilities to store tuna for eventual preservation made it uneconomical for fishermen to keeptargeting this fish. In fact there was a period when tuna used to be imported from Italy andNorth Africa in just enough quantities to boost the local catches which were then derivedsolely from our small set nets (‘Tunnara’) which were situated in the north of the island.However even this activity proved to be uneconomical and these were wound up in the1960’s due to financial difficulties. Since then and up to the 1980’s, although landings oftuna were substantial, these were caught as by-catches of swordfish longlines. It must benoted that during the 70’s and 80’s the dolphin fish (‘lampuka’) and swordfish were themainstay of local fishing.

The upsurge in bluefin tuna landings came about as a result of the tapping of the Japanesemarket in1989 and in fact one will find that from a mere 48,669 kilos in1990 landings shotup to 353,014 in 1995 as a result of diversification of the fishing effort by the largervessels. The decrease in landings during the last 3 seasons may be attributed to the largepresence of tuna purse seiners off the Maltese Islands.

In 1998 tuna were targeted by 52 multi-purpose vessels ranging from 10 to 20 metres, 150full-time fishermen and part-time fishermen. The total landings were 244,749 kg of which108,768 kg (45 %) was exported.

The decrease in landings from 1995 onwards may be mainly attributed to the large presenceof foreign tuna purse seiners just off the Maltese Islands, which carry out a very efficientoperation.

The gear used is drifting surface longline and is baited with Atlantic mackerel and/orJapanese squid. The maximum number of hooks set in a longline is 2,500 and this dependsmostly on the size of the boat. The lines are set during the afternoon and the operation goeson till around 8.00 p.m. since fishermen reckon that this is the prime time for the fish tobite. The lines start being retrieved from around 10.30 p.m. onwards.


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Fishing is undertaken to the West, South and South East of the Maltese Islands between the35th and 36th parallels with the following parameters: on the Western limit Latitude35:52:00 Longitude 13:30:00 (50 miles from Marsaxlokk harbour) to the southernextremity Latitude 35:21:58 Longitude 12:25:24 (30 miles from Marsaxlokk harbour) to thesouth east Latitude 35:22:74 Longitude 15:03:14 (37 miles from Marsaxlokk harbour)which covers approximately 2,000 square miles (Busuttil, C 1999, pers. comm.).

At the beginning of the season, i.e. in May, the effort is undertaken mainly in the SouthWest area of the region and consequently further to the east according to the normalmovement of the bluefin tuna. The season ends in July.

The main landing zones are Marsaxlokk, St. Paul’s Bay and Marsascala harbours in Malta,whilst those in Gozo are Mgarr and Marsalforn harbours. Marsaxlokk is the harbour wheremost of the tuna is landed.

The tuna is usually gutted (removal of internal organs and gills) on board and is unloaded atthe fish market in Malta. The tuna for export is the prepared (removal of head and bones)and exported directly either by plane or by boat in freezer containers.

The potential catch size per boat per season for the Maltese fishermen amounts toapproximately 80 bluefin tuna and ranges between 50 and 100 according to the year.

According to records kept by the Fisheries Department landings in kilograms for bluefintuna since 1980 were as shown below. Table 2.3

Year Amount of bluefin tuna caught /kg1980 23,6091981 32,1681982 39,8041983 31,1991984 20,7721985 41,2021986 32,2621987 25,3901988 34,4051989 36,8951990 48,6691991 63,3111992 48,2211993 150,8341994 343,6711995 353,0141996 239,8671997 236,2721998 244,709

Table 2.3 Bluefin Tuna landings 1980 -1998


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2.1 Bluefin Tuna Fishing Methods in the Maltese Islands

2.1.1 The ‘Tonnara’

Bluefin tuna has always been one of the most important and studied fish because of itseconomic value and migratory habits, and throughout the years man has invented variousways of catching it. It is to the credit of Grand Master Pinto that tuna fishing wasintroduced to our islands, utilising a ‘tonnara’ net constructed from large hemp of fibres ofthe coconut palm. The first tuna net was laid on 3 April 1748 at Pinto’s expense. The sitechosen was ‘Il-Fgura’ in Mellieha where the fish was known to pass a few kilometres awayfrom the coast. The net was raised for the first time about two months later and besidestuna, a large number of other fish were caught. The ‘tonnara’ proved successful and aslocal fishermen became more expert, catches increased considerably.

The ‘tonnara’ (Fig. 2.23) consists of two parts, namely a long fine-meshed net extending atright angles from the coast and a series of chambers, made of vertical nets anchored bystone slabs and kept vertical by means of floats. During its reproductive season, the bluefintuna seeks out warm water and thus it swims around the coasts. In so doing, it feels thefine-meshed net by its sensitive nose and in attempting to evade it, it swims away from theshore into the labyrinth of nets. Generally the fish then continues to follow its originaldirection and hence enters the ‘tqila’. If the fish takes the opposite direction, it also findsthe net closing the ‘tonnara’ at the opposite side of the ‘tqila’. The fishermen also scare thetuna towards the ‘tqila’ while closing the openings between one chamber and another sothat the fish cannot swim back. When all the fish have entered the ‘tqila’, this chamber isclosed and the fishermen surround it with their boats. This chamber differs from the othersin that it has a horizontal floor of netting called the cradle. When the boats havesurrounded the closed ‘tqila’, the cradle is freed from its anchors and is lifted so as toconfine fish in a small volume. Here the tuna is stunned with iron bars and is lifted into theboats by long-poled hooks. When all the fish have been secured on the boats, the cradle isonce more allowed to sink to the seabed and anchored. This operation is called the‘metanza’.

Today this expensive device is not used any more in Malta and is decreasing in popularityin other places of the Mediterranean. In Malta, bluefin tuna is caught by longlines which isa less expensive method and requires a much smaller crew. However, the ‘tonnara’ is stillused in different parts of the Mediterranean including Libya, Tunisia and Morocco.

2.1.2 Surface Long-lines

The long-line (‘konz’) (Fig. 2.24) is the most popular method for tuna fishing in ourislands. In August 1953, the British Government decided to invite Mr. T.W. Burdon, thenthe deputy Director of Fisheries in Singapore, to prepare a report on the fishing industry in


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our islands. Mr. Burdon suggested that tuna fishing should be carried out by the long-line,as this was a less expensive implement than the ‘tonnara’ and did not require such a largenumber of fishermen working together concurrently. It was however only in the sixties thatthis fishing system became widely used.

The long-line, which is of a surface drift type, can vary from 20 kilometers to 120kilometers in length; hence its name. It is usually kept afloat (‘konz tal-wicc’). The mainline is usually monofilament with a diameter ranging between 1.8 – 2.0 mm. Along themain line, there are the side lines / snood (‘brazzol’) which are about 6 m long. The snoodsare also made of monofilament but with a smaller diameter of around 1.6 mm. Thedistance between two consecutive snoods is usually around 54 m. The snoods arealternatively fitted with a small white buoy. Floating flags tied to long bamboo rods areused along the line and these begin to vibrate vigorously when a fish is caught. At the endof each side line, there is a hook to which the bait is attached. The hooks used are of theJapanese round type. The number of hooks used by each fishermen is usually in the regionbetween 1500 and 2500. The length of long-line and number of hooks used depend on thevessel and the crew. The bait used for fishing for bluefin tuna includes Atlantic mackereland squid, which are alternatively attached to the hooks. The squid provides a better baitfor the bluefin tuna but is in turn much more expensive.

Early in the afternoon, casting of the long-line starts with a speed of about 7 knots. Itbegins at a distance of about 15 kilometers from the coast and may take till about 8:30 inthe evening, i.e. just before sunset.


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Figure 2.23 The ´Tonnara´


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Figure 2.24 Typical Maltese Surface Longlines

Hauling starts at around 10:30 and is done with special belt hydraulic winches. The masterof the boat uses a strong light fixed to the bow of the boat to spot the small marker buoys.Hauling is done at a speed of about 6 to 7 knots. The time spent on hauling depends on theamount and type of fish caught because if for example the fish caught are still alive, itwould take much longer to haul the fish on board.

Since the long-line is very long and consists of many hooks, it is very liable to getentangled. It is therefore wound up in a circular basket and the hooks are attached to strapsof cork which are fixed around the rim of the basket. The long-line is then ready to be usedagain without any problems.


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2.2 Collection of Data

The first part of the project involved the collection of information regarding the vesselswhich go fishing for tuna. In this respect, the data collected gave a brief overview of thevessels involved in the tuna season. Fishing effort data are very important in studyingcurrent fisheries activities as well as the status of stocks and in forecasting future trends.The fishery craft statistics enabled us to decide how to conduct the sampling for thisproject.

Since in Malta registration of all boats is required by law, with the help of FisheriesOfficers, the boats which are yearly engaged in tuna fishing were identified and for eachfishing craft, the following information was collected from the respective owners. Table2.4

Craft Registration NumberPortCrewNumber of HooksType of VesselLength of Vessel (m)Width of Vessel (m)Draught of Vessel (m)Propulsion (hp)

Table 2.4 Fishing Vessels Data Forms

2.2.1 Craft Registration Number

The craft registration number of each vessel was obtained from the Fisheries Departmentsince in Malta registration of fishing boats is required by law.

The owners of the two fishing vessels were contacted and asked to help with this project byallowing an observer on board to stay on the fishing vessel during fishing. The observerson board were taught how to collect the necessary information by the procedures describedbelow.

2.2.2 Port

There are various ports scattered around the Maltese Islands as shown in Figure 2.25,where tuna fishing vessels can be anchored but the main ones include: Mgarr in Gozo andMarsaxlokk in Malta.


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During the data collection exercise, the port from where each fishing vessel operates wasrecorded.

Figure 2.25 Main Fishing Ports

2.2.3 Number of Hooks

In Malta, tuna is caught by means of the surface drift long-line. This is usually made up ofa main line along which are the side lines. At the end of each side line, there is a hook(Figure 2.26) to which the bait is attached.

The number of hooks used for each fishing trip is very important for Fishery Statistics inorder to calculate the Catch per Unit Effort.


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Figure 2.26 : Hook used in catching BFT

2.3 Fishing Vessels used During the Bluefin Tuna Season

2.3.1 The ‘Luzzu’

The ‘luzzu’ is a typical Maltese fishing boat. It is fusiform in shape (tapering at both ends)and carvel-built with a vertical stem pot at the prow which s slightly higher than the stern.Both the bow and the stern rise above the rest of the vessel in order to protect the crew fromthe spray of the sea when the boat is moving against the waves.

The luzzu-type boat was introduced in Malta in the beginning of this century when somemen from Mosta brought a design of an English fishing boat to Marsaxlokk and boatsstarted being built according to this new design. Initially, as all other fishing boats, theluzzu was propelled by sails and oars, but, as motor engines were increasingly applied tothe vessels the number of ‘luzzijiet’ increased considerably. Today, many of them have acabin installed, and a store for fish.

The name ‘luzzu’ possibly originates from ‘lozzu’ which is the Maltese name given to theMediterranean barracuda. Like this fish, the ‘luzzu’ is fusiform in shape; the original nameof this fishing boat was indeed ‘lozzu’ and not ‘luzzu’. The length of this fishing boatusually reaches 15 m. Registered ‘luzzijiet’ belonging to full time and part time fishermen,as on 31 December 1998, amounted to 270 in Malta and 78 in Gozo.


Aim 2

2.3.2 Multi Purpose Vessel

The other fishing vessels used for bluefin tuna fishing are the launch or multi purposevessels. On 31 December 1998, there were 59 of them registered in Malta and 20 in Gozo.These launches are all equipped with a cabin and are also widely decked. They aremoderately fast vessels, with plenty of comforts for the crew and ample space for storingand handling all the various fishing implements and the captured fish.

2.4 Results

The data collected is summarized in Figure 2.27, 2.28, 2.29 and 2.30 below.

Port

58%

10%

32%

M'Xlokk Mgarr Others

Figure 2.27 Number of Fishing Vessels per Port

Length (m)

6-12 12-18 18-24 >24

24%

47%

24%6%

Figure 2.28 Length Range of Fishing Vessels in Marsaxlokk


Aim 2

Power (CV)

0-200 200-400 400-600 >600

18%

44%32%

Figure 2.29 Power Range of Fishing Vessels in Marsaxlokk

LENGTH (m)

6-12 12-18 18-24

17%

50%

33%

Figure 2.30 Length Range of Fishing Vessels in Mgarr


Aim 2

LIBYA (MBRC)

Objetive 2.5

Bluefin tuna (Thunnus Thynnus L.) is a large pelagic fish and highly migratory one it iswidely distributed specially in the Atlantic and Mediterranean reagons is believed that itmigrates every year from the Atlantic through the strait of Gibraltar to the Mediterranean asreported by Sella 1926 and reviewd by Heldt, 1927, 1943. The syno names of the fish asreported by Heldt 1927 is as fallows:

1758. Scomber thynnus L. ................. (Syst. Nat. X. p. 297).1817. Thynnus thynnus Cuv ............... (Règne animal 2, p. 313).1826. Thynnus mediterraneus ............. Risso. (Hist. Nat. Eur. Mer. III, p. 414).1831. Thynnus vulgaris C. V. ............. (Hist, Poiss. VIII, p. 58).1831. Thynnus brachypterus C. V. ..... (Ibid., p. 98).1845. Thunnus .................................... South (Encycl. method.).1860. Thynnus thynnus ....................... Gunth. (Catal. II, p, 362).1880. Orcynus thynnus ....................... Lutk. (Spol. Atlant., p, 460).1889. Albacora thynnus ...................... Jordan (Man. of the Vertebrates... Chicago).1896. Thunnus thynnus ....................... Jord & Ever. (Fish. Nort-Mid. Amer. ,II.p,470

The route of migration usually takes place along the African coast (Morocco, Algeria,Tunisia, Libya) up to Misurata keeping a distance from the Libyan coast,Fig.(11) most of the fish is large size, mature fish it is supposed that itspwan in theMediterrean during early summer Sara, (1963).

Taking this apportunity the fish is caught by several methods, such as trapnets, long lineand pursesiene similarly those methods have been applied to catch blue fine tuna in Libyaand the following is discription of each method operated in 1999.

Trap nets : four traps only have been put in operation in 1999 out of 10 traps during theperiod between 1949 - 1955 Fig. ( 12 ), they are in the following order starting from theeast to the west GAZIRA, ZREG, ZELETIN and GARABULLI each one is a large fixednet Fig ( 13 ) is placed in the form of a huge trap about 3.2 K.M. in GAZIRA and ZREGand 3.6 in K.M. in ZELETIN while in GARABULLI about 2.4 K.M. only from the shorethe exact locality, fishing ground and the size of trap nets showed in table 2.5 between thetrap net and the shore a leader net is streched which extards from the surface to the bottomand stay in postion by enormous anchors and floots.


Aim 2

Table 2.5 Discribtion of the trap nets operated during Year 1999.

Name ofthe fishing

groundN. E.

Waterdepth

Bottomguality

Length ofleader net

Lengthof bodyof net

Gazira 32° 20′ 15° 09′ 40 mixed sand& rocks

3 - 2 k.m. 480 m.

Zreg 32° 26′ 10′′ 14° 54′ 20′′ 36 mixed sandand rock

3 - 2 k.m. 475 m.

Zeletin 32° 32′ 14° 27′ 38 sand and rock 3 - 6 k. m. 454 m.Garabulli 32° 48′ 12° 40′ 38 2 - 4 k.m. 332 m.

During the migration of BFT and other related species from west to the east they encounterthe leader nets lined up in a North - South direction, they fallow the leader up to thechambers of the traps Fig ( 13 ) till they reach the last chamber which is reffered to as the(death room) which has all sides including the bottom made of nets. The catches takes placein the last chamber by lefting the nets as in Fig ( 14 ) and the houling is repeated once thereare sutable number of fish and a good wheather. Figure 2.31


Aim 2

Figure 2.31


Aim 2

SURFACE LONG LINE

The Libyan fleet using long line to catch blue fin tuna consists of six fishing vessels four ofwhich were made in Spain in 1991, the length of each is 60 meters, the width, 9.50 metersdepth 4.42 meters draft is 3.60 meters the total weight of each is 937 tons, the other twowere made in Japan in 1980 and 1987 the length of one of them is 56.08 meter while theother is 50.15 meter the total weight is 409 and the other 299.84 tons the length of the lineis about 100-120 k.m. and the number of hooks between 2500 to 3000 hook the fishing areais in the west part of the Gulf of Sirte between 16° 17′ E and 31° 32′ N. Figure 2.32

PURSE SEINE

The Libyan fleet using pursesiene consists of 5 fishing vessels all made in Holand in 1990-1991 each one has the following specifications:

Over all length 32.0 meterslength B.p. 28.5 metersBreadth 8.21 metersDepth 4.25 metersDraft 3.30 metersGross tonnage 260 tonsnet tonnage 103 tons

The length of the net ranges between 1000 to 1200 meters and the depth of the net between80 to 100 meters.

During 1999 some of those vessels have been in operation in the Libyan water in an areabetween 32° 30′ - 33° 30′ N and 14° to 15° E. Figure 2.32


Aim 2

Figure 2.32

objective 2: description of fisherieswebco.faocopemed.org/old_copemed/reports/tunidos/... ·...

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